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Whitlockite-type structure phosphors have been widely studied due to their adjustable chemical composition and abundant crystal location. Whitlockite-type phosphors can be doped with rare earth elements to achieve the emission of warm white light. White light-emitting diodes (w -LEDs) have become increasingly popular and play a significant role in many applications, such as Biosensing and fluorescent labeling. In this work, The Ca 2.6 K 0.2 La 0.2 (PO 4) 2 (CKLP) whitlockite-type phosphors co-doped with Dy3+ and Sm3+ were entered via a high-temperature solid-phase reaction. Their crystal structure, luminescence characteristics, and temperature sensitivity were explored in detail. Through doping Dy3+ and Sm3+, can obtain white light and warm white light. As the concentration of Sm3+ increased, their lifetime decreased from 0.483 ms to 0.059 ms, confirming interionic energy transfer in the host. The CKLP: 0.06Dy3+, 0.06Sm3+ phosphor prepared by Fluorescence Intensity Ratio (FIR) technology has suitable temperature sensing performance. Its relative sensitivity (Sr) and complete sensitivity (Sa) are high up to 4.48 × 10−3 k−1 and 1.021%K−1 at 298 K. The results show that CKLP: Dy3+ and Sm3+ phosphors used in w -LEDs and display devices will present excellent application potential in new optical thermometry. • The whitlockite-type structure phosphor realized white light emission. Obtained excellent color temperature coordinates, high sensitivity and realized the control of warm white light. • The whitlockite-type structure phosphors are a candidate material for non-contact optical temperature sensing and have potential anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]

Following the rapid growth of lightning technology, the development of red-emitting phosphors is effective for improving color temperature and color rendering index for w-LEDs devices. Herein, a single phased garnet phosphor with cation and polyhedron substitution modification was firstly prepared. For Mg 3 Gd 2 Ge 3 O 12 : Bi3+, Eu3+, the intensity has been remarkably improved by about 16% compared to the one without Bi3+ sensitization. The energy transfer mechanism is identified in this work. Based on cation and polyhedron substitution strategies, novel phosphors with different compositions were obtained and further modified the PL properties. With Lu3+ substitution, the bond lengths between Bi3+ ion and anion ligands are decreased and the site symmetry has been strengthened, which leads to a 21 nm blue shift when Lu3+ totally replaced Gd3+ ions. In addition, Lu3+ and [SiO 4 ] substitution strategies both effectively increased symmetric rigid structure, which leads to a significant improvement in thermal stability, indicating the samples own great potential in optical applications This work provides a new insight to synthesis red-emitting phosphors for warm white-LEDs. [ABSTRACT FROM AUTHOR]

A novel orange-red emitting orthosilicate phosphor LiGd 9 (SiO 4) 6 :Mn2+ (LGS:Mn2+) belongs to hexagonal lattice with P 6 3 / m space group was synthesized via solid-state method and the phase composition, crystal structure as well as luminescence properties were examined for potential application in near ultraviolet (n -UV) pumped white light emitting diodes (w -LEDs). The as-prepared LGS:Mn2+ phosphor exhibits three excitation bands peaked at 273, 312 and 410 nm, which corresponds to the transitions of Gd3+ from ground state 8S 7/2 to 6I 7/2 , 6P 7/2 and Mn2+ from ground state 6A 1 (6S) to the individual components of the multiplets [4A 1 (4G), 4E(4G)], respectively. Upon excitation at 312 nm, the phosphors display an intense broad orange-red emission peaked around 594 nm, which ascribed to the typical spin-forbidden transition (4T 1 (4G)-6A 1 (6S)) of the Mn2+ ions. The concentration quenching mechanism and average separation distance in conjunction with fluorescence decay times of Mn2+ ions in LGS:Mn2+ phosphor were discussed. The indispensable parameters for application in n -UV high-powered w -LEDs, such as the thermal quenching of photoluminescence and internal quantum efficiency of LGS:Mn2+ phosphor, have also been investigated in detail. The above results indicate that LGS:Mn2+ could play a key role as an orange-red emission for potential application in n -UV-based w -LEDs. • LiGd 9 (SiO 4) 6 O 2 :Mn2+ luminescent materials were synthesized successfully. • This phosphor have excellent thermal stability and emission efficiency. • High energy transfer efficiency could be obtained between Gd3+ and Mn2+ ions. [ABSTRACT FROM AUTHOR]

Highlights • The ET mechanism has been confirmed by the luminescence spectra and fluorescence decay curves. • The ET interaction mechanism was determined to be dipole–quadrupole interaction. • The emission color of as-prepared phosphor could be adjusted from green to yellow. Abstract The Ca 9 La(PO 4) 5 (SiO 4)F 2 :Tb3+,Sm3+ phosphor with apatite structure has been successfully synthesized by high temperature solid-state reaction, and its luminescence properties as well as energy transfer mechanism has been investigated in detail. The energy transfer (ET) efficiency increases with increasing Sm3+ doping content, that was confirmed by the luminescence spectra and fluorescence decay curves of corresponding ions. The ET interaction mechanism was determined to be dipole–quadrupole interaction. The emission color of Ca 9 La(PO 4) 5 (SiO 4)F 2 :Tb3+,Sm3+ phosphor could be adjusted from green (0.272, 0.489) to yellow (0.363, 0.395) area through controlling the dopant ratio of Tb3+/Sm3+. The above results indicate that the Ca 9 La(PO 4) 5 (SiO 4)F 2 :Tb3+,Sm3+ phosphor has a great potential in white light-emitting diodes application. [ABSTRACT FROM AUTHOR]

Abstract A series of novel luminescence phosphors Ca 9 La(PO 4) 5 (SiO 4)Cl 2 : x Eu2+ (CLPSCl:Eu2+) with apatite structure have been synthesized by a high temperature solid-state reaction. The phased purity of as-prepared phosphors was verified through XRD technique. For further discussion, a series of analysis were performed such as the photoluminescence emission and excitation spectrum and decay lifetime to identify the luminescent properties of CLPSCl:Eu2+ phosphors. The CLPSCl:Eu2+ displays broad excitation spectra ranging from 250 to 450 nm, and intends emission intensity at 461 nm under 345 nm. The optimum Eu2+ concentration of CLPSCl is 8 mol%. The luminescence decay lifetime of the optimum phosphors was measured to be 275 ns. All of the results obtained highly indicate that CLPSCl:Eu2+ is potentially blue-emitting phosphor for application in white LEDs. [ABSTRACT FROM AUTHOR]

Abstract The novel apatite-type phosphor Ca 9 Tb(PO 4) 5 (SiO 4)F 2 :Mn2+ (CTPSF:Mn2+) has been successfully synthesized and it demonstrated a potential for optical thermometry. The energy transfer process between Tb3+ and Mn2+ was of resonant type via a dipole-dipole mechanism based on the Inokuti–Hirayama theoretical model, and the energy transfer (ET) efficiency and ET rate were estimated. In view of the energy transfer behavior, a strategy, involving the use of Tb3+ and Mn2+ dual-emitting centers with different thermal quenching behavior, has been developed to achieve temperature sensitivity and good signal discrimination. The temperature dependence of the fluorescence intensity ratios (FIR) for the dual-emission bands peaking at 548 and 595 nm was studied in the range of 298–573 K under excitation of 377 nm ultraviolet light and the maximum relative sensitivity was approximately 1.92% K−1 at 423 K. It is expected that this preliminary study will provide an important advance in exploring novel ratiometric optical thermometry. Highlights • Novel apatite-type phosphor Ca 9 Tb(PO 4) 5 (SiO 4)F 2 was synthesized. • Energy transfer mechanism is estimated based on Inokuti–Hirayama model. • Non-contact thermometry was developed with a new inorganic material. • The maximum S r of the as-prepared phosphor was as high as 1.92% K−1. • This work provides an insight to design ratiometric optical thermometry. [ABSTRACT FROM AUTHOR]

Whitlockite-type structure phosphors have received extensive attention and research due to their adjustable chemical compositions in isomorphic compounds and providing rich crystal positions for doping activators. Ca 2.6 K 0.2 La 0.2 (PO 4) 2 whitlockite-type phosphors with Dy3+ singly doping and Dy3+, Eu3+ co-doping were prepared via high temperature solid-phase reaction, and the crystallographic characteristics, luminescence properties and temperature sensing performance were investigated in detail. The prepared phosphors are pure phase and both Dy3+ and Eu3+ enter into the matrix and produce blue, yellow and red emissions. The CCT values of the emitted light from Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+ phosphors increase with the Eu3+ concentration rises, changing from cold white light to warm white light. The integrated emission intensity of Dy3+ in the phosphor decreases with the change in the doping ratio of Dy3+ and Eu3+, causing by the energy transfer from Dy3+ to Eu3+. The Ca 2·6 K 0·2 La 0·13 (PO 4) 2 :0.06Dy3+, 0.01Eu3+ phosphor shows temperature sensing performance based on FIR technique, with the maximum relative sensitivity calculated to be 0.181% K−1. All the results reveal that the Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+ phosphors can be applied to w-LEDs and display devices, and can be used as a new type of optical thermometer. Dy3+/Eu3+ co-doped Ca 2·6 K 0·2 La 0·2 (PO 4) 2 phosphor applied for w-LEDS and temperature sensing. [Display omitted] • Single-phase luminescent materials Dy3+, Eu3+ co-doped Ca 2·6 K 0·2 La 0·2 (PO 4) 2 phosphor with whitlockite structure was synthesized for the first time. • The concentration quenching and energy transfer mechanisms were investigated. • The emission color of Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+phosphors changes from natural white light to warm white light with the increase of Eu3+ concentration. • The samples showed temperature sensing performance with maximum S a to be 2.06 × 10−3 K−1 and S r to be 0.181% K−1 under 303 K. [ABSTRACT FROM AUTHOR]

A novel apatite structure phosphor Ca 9 La(PO 4 ) 5 (GeO 4 )F 2 :Dy 3+ (CLPGF:Dy 3+ ) with a hexagonal lattice in the P 6 3 / m space group was synthesized via a facile solid state technique. The crystal and fine local structure as well as their photoluminescence properties were investigated in detail. The CLPGF:Dy 3+ phosphor can absorb in the UV-vis spectral region of 290–475 nm and exhibit two intense emission bands centered at 485 and 580 nm, which ascribes to 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ , respectively. The concentration quenching of Dy 3+ emission occurs via the energy transfer among the nearest-neighbor ions and the corresponding quenching mechanism was verified to be the dipole-dipole interaction. The quantum efficiencies of the phosphors were examined to be 72.9% and its luminescence intensity at 150 °C decreases to 93.8% and 98.6% of the initial value at room temperature, which corresponds to 4 F 9/2 to 6 H 15/2 transition and 4 F 9/2 to 6 H 13/2 transition of Dy 3+ ions, respectively. Their interesting photoluminescence properties indicate that the CLPGF:Dy 3+ phosphor is a promising white-emitting candidate for w -LEDs applications. [ABSTRACT FROM AUTHOR]

The simple high-temperature solid-state route was adopted to synthesize a series of related Ba 3 LaK(PO 4 ) 3 F: x Eu 2+ (BLKPF: x Eu 2+ ) blue phosphors. The photoluminescence (PL) and diffuse reflection spectra have been investigated in detail. These phosphors which can be well excited by the 388 nm near ultraviolet light, produce the emitted blue light peaks located at about 460 nm. The critical Eu 2+ concentration quenching mechanism was ascribed to the dipole–dipole interaction, and the optimum concentration was eventually proved to be 0.1 mol. All above results indicate that Ba 3 LaK(PO 4 ) 3 F: x Eu 2+ phosphor can act as an appropriate candidate of the blue phosphor in the future. [ABSTRACT FROM AUTHOR]

A series of Dy3+-doped MGd 9 (SiO 4) 6 O 2 :Dy3+ (M = Li, Na, K) phosphors that generated white emission were prepared using the high temperature solid-state technique. Simultaneously, the phase composition, crystal structure, electronic structure, as well as the luminescence properties of the as-prepared phosphors were investigated in detail. The structural refinement showed that the MGd 9 (SiO 4) 6 O 2 crystallized with the hexagonal apatite-type structure. The unit cell parameters increased gradually and the main peaks of the samples in XRD patterns shifted towards high angles with the substitution of alkali-metal ions (from Li+ to K+). Under the excitation of 350 nm, the as-obtained MGd 9 (SiO 4) 6 O 2 :Dy3+ phosphors gave bright white emission with the major emission peaks centering at 454, 477 and 573 nm. And the R y/b , CIE chromaticity coordinate and the corrected color temperature (CCT) of the phosphors were adjusted from 0.96, (0.3256, 0.3625) and 4602 K to 1.13, (0.3369, 0.3582) and 4201 K attributing to the substitution in the crystal structure. The thermoluminescence study of MGd 8.90 (SiO 4) 6 O 2 :0.10Dy3+ (M = Li, Na, K) showed good stability and the decay lifetimes of the samples were estimated to be about 470 μs. All the results suggested that the luminescence properties could be modified by the substitution of alkali metal ions, and the MGd 9 (SiO 4) 6 O 2 :Dy3+ (M = Li, Na, K) phosphors have potential application as white emission candidate for w -LEDs. • Novel Dy3+ doped apatite structure phosphors were successfully synthesized. • The symmetrical environment could be modified to a certain extent owing to substitution of alkali metal ions. • The DFT calculation was used to check the electronic structure. [ABSTRACT FROM AUTHOR]

An activators lattice migration strategy was customized for developing tunable- luminescence phosphors in Ce doped β -Ca 3 (PO 4) 2 families. By dint of XAFS and DFT calculations, we predicted the local crystal environment of each lattices and migrated Ce3+ from M(3) to another strengthened site with a lower coordination number, shorter bonding bond length, and greater polyhedral distortion, M(5). Relevant parameters were identified for dealing with interference caused by the electronegativity change during structural modification and some applications emerged for display and information security. [Display omitted] • Activators lattice migration strategy was proposed for tunable-emission phosphors. • The specific occupation and 5 sites local crystal environment of Ce were predicted. • Ce3+ was migrated to another site with a strengthened crystal field by modification. • The relative intensity of ε CFS and ε NE determined an abnormal emitting mechanism. • Δ D (C e 3 +) were identified to deal with the interference of electronegativity difference. The luminescent properties of phosphors are determined by the electronic configuration of their activators and the crystal environment in which they are embedded. By manipulating the site-selective occupancy of activators, we can coordinately control the local crystal field and electron cloud distribution to master the movement of emission wavelength and obtain a color-tunable phosphor. The system of β -Ca 3 (PO 4) 2 is an excellent carrier for crystal-site engineering to modify luminescent performance. It has five distinct crystal sites and a strong photoluminescence response. However, due to low doping concentration and structural complexity, the specific occupation of Ce remains unknown. We discussed the specific position of Ce in this study and proposed a novel activators lattice migration strategy for controlling the relative strength of crystal field splitting (CFS) and the nephelauxetic effect (NE) to control luminescence properties. By combining X-ray Absorption Fine Structure (XAFS) with DFT calculation, we predicted the local environment of each crystal lattice and migrated Ce3+ from M(3) to a strengthened crystal field site with a lower coordination number, shorter bonding bond length, and greater polyhedral distortion, M(5) , resulting in phosphors with tunable luminescence emission. Relevant parameters Δ D (C e 3 +) were identified for dealing with interference caused by the electronegativity difference during a structural modification. Some potential applications emerged as a supplement and an intriguing QR-code and response program for epidemic prevention were demonstrated. This structure–activity relationship-based strategy provides new inspiration for designing luminescent materials with tunable emission and a broader range of applications. [ABSTRACT FROM AUTHOR]

An appropriate solid-state route was adopted to synthesize a series of related Ba 3 Sc(PO 4 ) 3 : x Sm 3+ red-orange phosphors. The Rietveld method was used to explore the structure of the phosphor. At present the PL, PLE, diffuse reflection and decay curves have been investigated in detail. These phosphors can be accurately excited by the 406 nm n-UV light and produce the emitted red-orange light whose peaks locate at about 566 nm, 603 nm and 650 nm. The quantum efficiency of Ba 3 Sc 0.95 (PO 4 ) 3 :0.05Sm 3+ was 53.5%. All above results indicate that Ba 3 Sc(PO 4 ) 3 :Sm 3+ phosphor can act as a suitable candidate of the warm components of n -UV w-LEDs. [ABSTRACT FROM AUTHOR]

Ba 3 Sc(PO 4 ) 3 :Eu 2+ ,Tb 3+ (BSP:Eu 2+ ,Tb 3+ ) phosphors were successfully prepared via conventional high-temperature solid-state reaction, their luminescence properties as well as energy transfer mechanism have been investigated in detail. The energy transfer mechanism was proposed to be the dipole–quadrupole mechanism, and the energy transfer efficiency was also estimated. BSP:Eu 2+ ,Tb 3+ phosphors showed a broad emitting band centered at 518 nm and several sharp emission peaks, which were assigned to the 5 d →4 f allowed transitions of Eu 2+ ions and characteristic optical 5 D 4 – 7 F J ( J =6, 5, 4, and 3) transitions of Tb 3+ ions, respectively. The emission color of BSP:Eu 2+ , y Tb 3+ exhibited a controlled luminescence evolution in the green area owing to the Eu 2+ –Tb 3+ energy transfer process. [ABSTRACT FROM AUTHOR]

Up-conversion phosphors BaLa 2 ZnO 5 co-doped with Ho 3+ /Yb 3+ were synthesized by high temperature solid-state reaction method. The phase composition of the phosphors was characterized by X-ray diffraction (XRD). The structure of BaLa 2 ZnO 5 : 0.75% Ho/15% Yb phosphor was refined by the Rietveld method and results showed the decreased unit cell parameters and cell volume after doping Ho 3+ and Yb 3+ , indicating Ho 3+ and Yb 3+ have successfully replaced La 3+ . Under the excitation of 980 nm diode laser, the strong green and weak red up-conversion emissions centered at 548 nm, 664 nm and 758 nm were observed, which originating from 5 S 2 , 5 F 2 → 5 I 8 , 5 F 4 → 5 I 8 and 5 S 2 , 5 F 2 → 5 I 7 transitions of Ho 3+ ions, respectively. The optimum doping concentrations of Ho 3+ and Yb 3+ were determined to be 0.75% and 15%, and the corresponding Commission International de L'Eclairage (CIE) coordinates are calculated to be x =0.298 and y =0.692. The related UC mechanism of Ho 3+ /Yb 3+ co-doped BaLa 2 ZnO 5 depending on pump power was studied in detail. The results indicate that BaLa 2 ZnO 5 : Ho 3+ /Yb 3+ can be an effective candidate for up-conversion yellowish-green light emitter. [ABSTRACT FROM AUTHOR]

Er 3+ and/or Yb 3+ doped Sr 2 ScF 7 up-conversion (UC) phosphors were synthesized, and the optimum doping concentrations of Yb 3+ and Er 3+ in the Sr 2 ScF 7 host were found to be 20% mol and 7% mol, respectively. Under excitation of 980 nm laser, the UC spectra of the samples is composed of three green emission bands from 510 to 570 nm centered at 525, 543 and 551 nm and two red emission band from 640 to 690 nm with two peaks at 657 and 671 nm, which is attributed to the 2 H 11/2 , 4 S 3/2 → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions of Er 3+ , respectively. The UC emission color of Er 3+ can be tuned by adjusting the intensity ratio of red to green emission through manipulating the population of red and green emitting states. [ABSTRACT FROM AUTHOR]

Emission-tunable phosphors Ca 9 La(PO 4 ) 5 (SiO 4 )F 2 :Ce 3+ ,Tb 3+ with apatite structure were synthesized by a solid-state reaction. The phase structure, photoluminescence (PL) properties, lifetimes and the PL thermal stability were investigated, respectively. The phosphor exhibited an asymmetric broad-band blue emission (Ce 3+ ) with peak at 403 nm and the line-type green emission with peak at 543 nm (Tb 3+ ). The varied color of the phosphors from blue to green can be achieved by properly tuning the relative ratio of Ce 3+ /Tb 3+ through the energy transfer from Ce 3+ to Tb 3+ ions. The critical distance was calculated to be 8.78 Å by using the concentration quenching method. When the temperature turned up to 150 °C, the emission intensity of Ca 9 La(PO 4 ) 5 (SiO 4 )F 2 :Ce 3+ ,Tb 3+ phosphor was 77% of its initial value at room temperature, which indicated the good thermal stability of the sample. All the properties indicate that the Ca 9 La(PO 4 ) 5 (SiO 4 )F 2 :Ce 3+ ,Tb 3+ phosphor has potential application of color-tunable w -LEDs. [ABSTRACT FROM AUTHOR]

An anti-defect engineering strategy, inspired by photocatalytic and photovoltaic materials, was proposed to develop high-efficiency phosphors in whitlockite families. Significant enhancement of photoluminescence intensity (2.46 times), thermal stability (87.92% at 150 °C), cathodoluminescence intensity (3.34 times), quantum efficiency (IQE sharply up to nearly 100%) were simultaneously realized by constructing a rigid structure and removing vacancy defects. The developed phosphors exhibited promising applications in the fields of warm-white LEDs, plant growth lighting and information security. [Display omitted] • Anti-defect engineering strategy is proposed to develop high-efficiency phosphors. • The internal quantum yield is sharply improved from 38.90% to 99.07%. • The mechanism of improvement is revealed by defect-related characterizations. • DFT calculation shows the positive role of Debye temperature and alkali metal ions. • Promising applications in warm-white LEDs / plant-growth lighting are demonstrated. Lacking an effective strategy to simultaneously address the challenges of quantum efficiency, luminescence intensity and thermal stability has become the key bottleneck for further development and large-scale application of solid-state lighting technology. Herein, inspired by the defect-engineering used in photoelectrocatalytic and photovoltaic materials, we acted in a diametrically opposite way and unprecedentedly proposed an anti-defect engineering strategy to develop high-efficiency phosphors. By constructing a rigid structure and introducing alkali metals M to remove cation vacancy defects, similar to building blocks and jigsaw puzzle, we developed three groups of whitlockite phosphors, namely Ca 3- x Sr x (PO 4) 2 :Ce3+, Ca 3 (PO 4) 2 :Ce3+, M and (Ca 0.5 Sr 0.5) 3 (PO 4) 2 :Ce3+,Na+,Mn2+, and synchronously realized the significant enhancement of photoluminescence intensity (2.46 times), thermal stability (87.92% at 150 °C), cathodoluminescence intensity (3.34 times), quantum yield (from 38.90% to 99.07%). We characterized the defect concentration by positron annihilation technique (PAT), and calculated Debye temperature (ΘD) and simulated the occupation of M according to DFT theory to reveal the improvement mechanism. Some advanced applications were also explored in this work, including warm-white LEDs, plant growth lighting and information security. The anti-defect engineering proposed in this work may contribute to the further development of high-efficiency phosphors for the next-generation smart solid-state lighting technologies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Near-infrared emitting phosphors LaOCl:Nd3+/Yb3+ were prepared. [•] LaOCl:Nd3+/Yb3+ samples show strong near-infrared emission lines in the region of 1060–1150nm and 980–1050nm. [•] The possible energy transfer mechanism between Nd3+ and Yb3+ was discussed. [ABSTRACT FROM AUTHOR]

Novel reddish Mg 3 Gd 2 Ge 3 O 12 : RE3+ (RE = Sm, Eu) phosphors with high thermal stability have been designed and developed. In this work, Mg 3 Gd 2 Ge 3 O 12 was first synthesized for being used as the phosphor host. The X-ray diffraction and Rietveld refinement testified that the MGGO: Sm3+ and MGGO: Eu3+ crystallized in a cubic unit cell with space group I a-3d (230). The photoluminescence properties were studied in detail, MGGO: Sm3+ and MGGO: Eu3+ can be obviously excited at 403 and 395 nm, which could guarantee efficient absorption through commercial n -UV chip. Benefiting from the inverse garnet highly rigid framework, MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors had a favorable thermal resistance due to large activation energies (MGGO: 0.04Sm3+: 0.291 eV, MGGO: 0.9Eu3+: 0.238 eV). The emission intensity of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ can still preserve about 97.85% and 91.58% at working temperature (423 K) compared to the initial intensity (298 K). All results indicated Mg 3 Gd 2 Ge 3 O 12 : RE3+ (RE = Sm, Eu) phosphors have potential usage for full-spectrum w-LED applications as red component. • Crystal structure of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors are investigated in detail. • MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors have a favorable thermal resistance due to large activation energies. • MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ can be obviously excited at 403 and 395 nm. • CIE chromaticity coordinates of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ are (0.5153, 0.4709) and (0.4937, 0.3765). [ABSTRACT FROM AUTHOR]

Abstract: A visible-light-active TiO2−x N x photocatalyst was synthesized in electric field. The N-doping TiO2 film had a thickness of about 70–80nm. The results of the photocatalytic experiments showed that the vis-activity rose largely. XPS and XRD analysis implied that the doping N substituted the oxygen-deficient in TiO2 film. The Einstein shift in optical absorption spectrum of the N-doped film was also observed by the UV–VIS with a cut wave length of about 550nm. Based on the experiment, it could be concluded that the N doping is effective to narrow the gap and enhance the photocatalysis. [Copyright &y& Elsevier]

Rare earth doped luminescent sensing materials as non-contact thermometers have attracted extensive research interests due to their wide applications in areas like military, medical care, aerospace, etc. How to expand the working temperature range and improve the sensitivity has become the focus. In this work, we synthesized a series of apatite-structured luminescent temperature sensors M 2 La 7.9 Ce 0.1 (SiO 4) 6 O 2 (M = Ca, Sr, Ba) via isomorphic substitution. By monitoring the differential changes of emission intensities from Ce3+ at the 7-coordinate and 9-coordinate site respectively when temperature varies, the real-time temperature can be determined. These materials were proven to possess the maximum absolute sensitivity up to 0.825 × 10−3 K−1, 2.63 × 10−3 K−1 and 4.33 × 10−3 K−1, respectively. Meanwhile interesting regular patterns were observed for their temperature sensitivities with the substitution of Ca, Sr and Ba. Furthermore, through studying the temperature sensitivity of Ba 2 La 8 (SiO 4) 6 O 2 : x Ce3+ samples with different concentrations, it was found that when the Ce3+ content was at the optimal doping concentration of 0.7, the absolute sensitivity of the sample reached 14.64 × 10−3 K−1 at 573 K. This finding has opened up a new avenue for designing fluorescent temperature sensors. Synopsis: In this work, Ce3+ were doped into a series of phosphor-structured matrices containing two cationic sites (7-coordinated Ce1 and 9-coordinated Ce2 sites) via the solid-state high-temperature method. Due to the different temperature dependencies of luminescence intensities between the two Ce3+ sites, their intensity ratio could be used for temperature calibration. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAP) commonly undergoes doping with various dopants, leading to the emergence of new properties. In this study, HAP is co-doped by terbium (Tb) and europium (Eu) to impart HAP with photoluminescent properties. By controlling the Tb3+ amount to 7.5 × 10−5 mol unchanged, it is observed that when the doping amount of Eu3+ reaches 4.0 × 10−5 mol, the band gap measures 3.919 eV, with maximum fluorescence intensity. Notably, a dipole-dipole energy transfer type from Tb3+ to Eu3 was identified during this process. Concentration quenching occurs when the Eu3+ amount exceeds 4.0 × 10−5 mol. In addition, the Tb3+ and Eu3+ co-doped HAP demonstrates excellent thermal stability and a more comprehensive emission wavelength range than Tb3+-doped HAP or Eu3+-doped HAP. Considering these properties, Tb3+ and Eu3+ co-doped HAP phosphor and aramid/polyphenylene sulfide (ACFs/PPS) fiber paper are organically compounded, resulting in functional fabrics with excellent low-temperature stability. These available fabrics are made of luminescent crystals and fibers can be applied in fields such as high-performance textile testing. Notably, when a specific laser irradiates the damaged area of the textile, fluorescence is not detected by the detector. Moreover, Tb3+ and Eu3+ co-doped HAP has also been shown to be used in the light-emitting diode (LED) to produce the HAP-LED that emits warm white light without commercial phosphors. That expands the application of HAP in anti-counterfeiting, flexible wearables, high-performance textile testing, and semiconductor devices. The color-tunable Tb3+ and Eu3+ co-doped HAP is prepared by hydrothermal synthesis co-precipitation. The energy transfer process between Tb3+ and Eu3+ is proved and the application possibility of Tb3+ and Eu3+ co-doped HAP in fluorescence anti-counterfeiting and LED is discovered. [Display omitted] • The energy transfer mechanism of Tb3+ and Eu3+ in HAP was studied. • By controlling the doping amount of Eu3+, the fluorescence color of Tb3+ and Eu3+ co-doped HAP was tunable. • It expands the application of hydroxyapatite in fluorescent anti-counterfeiting and LED. • HAP exhibited excellent stability when combined with fibers for anti-counterfeiting applications. • The LED emitting bright white light was prepared by using Tb3+ and Eu3+ co-doped HAP without commercial phosphor. [ABSTRACT FROM AUTHOR]

Cryolite-type materials have advantages of low phonon energy, easy rare-earth ion doping, and stable physicochemical properties, and they are considered ideal matrices for up-converting luminescent materials. In this paper, a series of K 3 LuF 6 :Er3+,Yb3+ up-converting materials with cryolite structure were prepared for the first time by high-temperature solid-phase method. The compositions, structures and luminescent properties were systematically characterized by X-ray powder diffractometry (XRD), field emission scanning electron microscopy (SEM) and fluorescence spectroscopy (PL). Under 980 nm excitation, the sample emission spectra mainly consisted of green and red emission bands with peaks at 525, 546 and 662 nm, corresponding to the 2H 11/2 -4I 15/2 , 4S 3/2 -4I 15/2 and 4F 9/2 -4I 15/2 electron transitions of Er3+, respectively. In addition, the temperature sensing characteristics of two thermally coupled energy levels (2H 2/11 and 4S 3/2) were studied based on the fluorescence intensity ratio (FIR) technique in the range of 79–579 K. All the results show that K 3 LuF 6 :Er3+/Yb3+ up-converting luminescent materials have excellent temperature sensing performance in the ultra-wide temperature range and have broad application prospects in the field of temperature sensing. [ABSTRACT FROM AUTHOR]

Abstract A set of Eu3+, Dy3+ and Tb3+ doped novel scheelite-type LiCaGd(WO 4) 3 (LCGW)-based phosphors was prepared via a conventional solid-state reaction method. The X-ray diffraction (XRD), transmission electron microscopy (TEM) analysis, characteristics of luminescence, PL thermostability, decay lifetimes, as well as CIE coordination were investigated to characterize the as-prepared samples in detail. The XRD analysis indicated that the Eu3+, Dy3+ and Tb3+ ions were incorporated into the LCGW host lattice. Under the ultraviolet radiation, the characteristic emission lines of Eu3+ (5D 0 –7F 2), Dy3+ (4F 9/2 –6H 13/2) and Tb3+ (5D 4 –7F 5) ions were observed. The Eu3+ and Tb3+ single-doped LCGW fluorescent powders showed bright red and green emissions, respectively, without concentration quenching. As well as the Dy3+ doped LCGW phosphors radiate a strong yellow light at optimal Dy3+ concentration 0.08 mol. The efficient energy transfer phenomenon was observed for the Eu3+/Dy3+ and Tb3+/Dy3+ ions. The emission color of the LCGW: x Tb3+/0.08Dy3+ samples was tuned from yellow (0.4074, 0.4727) to green (0.3604, 0.5521) via adjusting the Tb3+ concentration. The emission color of LCGW: y Eu3+/0.08Dy3+ can be tuned from yellow (0.491, 0.3856) to red (0.5694, 0.3512) by variation of the Eu3+/Dy3+ ratio. Additionally, the thermal stability of the luminescence in the LCGW phosphors doped by Eu3+, Tb3+, Dy3+ ions was studied. The results verified that the LCGW:Ln3+ (Ln = Tb, Eu, Dy) phosphors are promising for applications in white LEDs. [ABSTRACT FROM AUTHOR]

Abstract A series of reddish-emitting apatite-type phosphor LiGd 9 (SiO 4) 6 O 2 :Sm3+ was prepared by using an appropriate solid-state method. The photoluminescence (PL), photoluminescence excitation (PLE) spectra, and decay times of the samples were characterized to investigate the photoluminescence properties for application in white light-emitting diodes (w -LEDs). The photoluminescence investigations showed that LiGd 9 (SiO 4) 6 O 2 :Sm3+ phosphor emitted reddish emission, which ascribed to the transitions of the Sm3+ from the 4G 5/2 excited state to the 6H 5/2 , 6H 7/2 , and 6H 9/2 states, respectively. The critical quenching concentration of Sm3+ in LiGd 9 (SiO 4) 6 O 2 phosphors were determined to be about 3 mol%. Moreover, the spectroscopic data and fluorescence decay dynamics indicate that the energy transfer from Gd3+ to Sm3+ ions takes place in LiGd 9 (SiO 4) 6 O 2 : Sm3+ phosphor. All the results indicated that the LiGd 9 (SiO 4) 6 O 2 : Sm3+ phosphor could efficiently assimilate the near ultraviolet (n -UV) light and act as a suitable warm light candidate for n -UV w -LEDs. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is one of the core reaction modules of important renewable energy technologies with applications in water splitting, metal-air (oxygen) cells and regenerative fuel cells. However, OER catalysts are forced to operate with a significant intrinsic overpotential and inefficient charge transfer due to the adsorption energy scaling balance between the reaction intermediates. It is critical to develop an understanding of structure-activity relationship of catalysts, determine the speed control steps and improve catalytic activity. In this work, cobalt pentlandite (Co , Ni , Fe) 9 S 8 (CNFS) electrocatalysts were successfully prepared by combining the earth-abundant transition metal elements Co, Ni and Fe into a single structure. Benefiting from the structure, nanoflower morphology, and the synergistic effect among the three elements, the optimized sample requires an overpotential of only 335 mV to drive a current density of 50 mA cm–2 under alkaline conditions. The experimental results establish a composition-structure-function relationship, and the density functional theory results further indicate that the Fe sites bind more moderately to the intermediates and the electron synergistic effect occurs dynamically during the OER cycle reaction. This work not only provides a very promising catalyst candidate for efficient OER processes but also highlights the superiority of the cobalt pentlandite structure in the rational design of efficient OER electrocatalysts. • We synthesized natural mineral structures of cobalt pentlandite (Co,Ni,Fe) 9 S 8 structured OER catalysts. • Synergistic effect among the Co, Ni and Fe accelerates charge transfer and results in superior catalytic activity. • DFT calculations illustrate that the cobalt pentlandite (Co,Ni,Fe) 9 S 8 have an active OER site at the interface Fe site. [ABSTRACT FROM AUTHOR]

A series of solid solution phosphors Ca 9 La(PO 4 ) 5 [(Si 1- x Ge x )O 4 ]F 2 :Ce 3+ with apatite structure in the P 6 3 / m space group have been prepared. The novel solid solution phosphors show continuously controlled violet-blue emission. It is found that both substantial spectra broadening (45 → 100 nm) and red-shift (404 → 422 nm) can be realized with the continuous introduction of [GeO 4 ] 4- into the crystal lattice which has been simulated by a crystal-field model. The above results indicate that the tetrahedral substitution is interesting to induce spectral tuning properties based on the chemical composition control of the iso-structural solid solutions. [ABSTRACT FROM AUTHOR]

The constructed high-efficient cyan-emitting phosphors establish a bifunctional platform involving high-color-quality lighting and anti-counterfeiting application. [Display omitted] • Ca 8 ZnY(PO 4) 7 :Eu2+ phosphors exhibited a broad cyan-emitting spectra (FWHM = 78 nm). • The quantum yield of Ca 8 ZnY(PO 4) 7 :Eu2+ phosphor is as high as 72.11 %. • The CRI value of warm w -LED devices was greatly enhanced from 83.9 to 90.5. • The transparent anticounterfeiting film held great potentials in packaging field. Constructing the broad-band emitting luminescent materials with high quantum yield is of great significance towards their widespread applications. Herein, series of Eu2+ activated, whitlockite-type Ca 8 ZnY(PO 4) 7 phosphors are developed towards bifunctional platform involving the white LED and anti-counterfeiting field. Benefiting from the typical 5d-4f transitions among Eu2+ ions, the broad asymmetric cyan-emission spectra (FWHM = 78 nm) is generated under 365 nm excitation with a highest quantum yield of ∼72.11 %. The optimal doping concentration of Eu2+ ions in the Ca 8 ZnY(PO 4) 7 host is determined as 4 % and the concentration quenching mechanism is mainly attributed to a dipole–dipole interaction. Impressively, after exploiting the newly discovered cyan-emitting phosphors Ca 8 ZnY(PO 4) 7 :Eu2+, the CRI value of as-prepared warm w -LED devices is remarkably enhanced from 83.9 to 90.5. Moreover, the w -LED exhibits an applicable correlated color temperature (CCT = 4176 K) and good color stability. Additionally, the transparent anticounterfeiting film is fabricated based on the highly efficient phosphors and soluble PVA, which presents anticounterfeiting performances due to their bright cyan emission upon UV light. Notably, their sustainability, excellent flexibility and foldability provide more possibilities applied for anticounterfeiting field. These results suggest the highly efficient phosphors Ca 8 ZnY(PO 4) 7 :Eu2+ are promising bifunctional luminescent platforms, for both high-color-quality lighting and anticounterfeiting applications. [ABSTRACT FROM AUTHOR]

In this study, La 2 (MoO 4) 3 doped with Eu3+ was synthesized by the high-temperature solid-state method. The phase composition of the Eu3+-doped La 2 (MoO 4) 3 sample was confirmed by X-ray powder diffraction (XRD) analysis, and the microstructure was observed via the scanning electron microscopy (SEM). Under the excitation at 211 nm, the room temperature emission spectra of Eu3+ in the samples with different doping levels were recorded. In addition, the prepared La 2 (MoO 4) 3 : x Eu3+ (x = 0–0.25) phosphors were color tunable. A non-contact optical thermometer with high sensitivity and high-temperature resolution was fabricated based on the different thermal quenching behaviors of the Mo–O group and Eu3+ center. The fluorescence intensity ratio (FIR), temperature resolution (ΔT), maximum absolute and relative sensor sensitivity (Sa and Sr) of La 2 (MoO 4) 3 :Eu3+ were calculated according to different thermal quenching effects between room temperature (298K) and 573K of Eu3+ and Mo–O group. These results show that La 2 (MoO 4) 3 :Eu3+ has excellent sensitivity and temperature resolution, good reversibility and reliability, as Sa = 0.0525 K-1, Sr = 0.3724. % K−1, ΔT = 0.0806 K and the FIR error was only 0.62%. Therefore, the Eu3+-doped La 2 (MoO 4) 3 is a promising candidate material for high performance non-contact optical thermometers. [ABSTRACT FROM AUTHOR]

A series of blue-emitting La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ ( x = 0, 1, 2, and 3) phosphors with apatite structure were synthesized by a solid-state reaction. The crystal structure and the photoluminescence properties were investigated in detail. The crystallographic occupancy of Ce 3+ in La 2.90 Ce 0.10 Ba 7 (SiO 4 ) 3 (PO 4 ) 3 F 2 and La 5.90 Ce 0.10 Ba 4 (SiO 4 ) 6 F 2 were studied based on Rietveld refinements results and the crystal chemistry rules. La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ exhibited strong blue light emission in the range of 407–414 nm with high thermal stability upon excitation at 276 nm. Besides, the activation energy E of La 5.90 Ce 0.10 Ba 4 (SiO 4 ) 6 F 2 and La 2.90 Ce 0.10 Ba 7 (SiO 4 ) 3 (PO 4 ) 3 F 2 phosphors were calculated to be 0.152 and 0.177 eV. These results suggest that La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ is a potential blue phosphor candidate for near-UV-pumped w -LEDs. [ABSTRACT FROM AUTHOR]

Currently, the application potential of Cr3+ doped near-infrared (NIR) fluoride phosphors excited by blue light is promising. However, the development of near-infrared fluoride phosphors with wider emission bandwidth remains a challenge. Herein, we employed the hydrothermal method to prepare K 2 NaCrF 6 :Fe3+ phosphors. Upon excitation at 432 nm, the K 2 NaCrF 6 :xFe3+ phosphors exhibited broad near-infrared emission, with the main peak ranging from 752 nm to 780 nm. As the Fe3+ concentration increased, the luminescence intensity of the K 2 NaCrF 6 :xFe3+ phosphor decreased, accompanied by a redshift in the emission band and an increase in the full width of the emission spectrum half-peak. These changes can be attributed to the dipole-dipole interaction, specifically the energy transfer between Fe3+ and Cr3+, leading to the 4T 2 (4F) → 4A 2 (Cr3+) and 4T 1 (4G) → 6A 1 (6S) (Fe3+) transitions. • K 2 NaCrF 6 :Fe3+ phosphors display application potential for near-infrared (NIR) fluorescence when excited by blue light. • The developed phosphors exhibit a broad near-infrared emission bandwidth (752–780 nm) under 432 nm excitation. • Increasing Fe3+ concentration leads to redshift and broadening of the emission spectrum. • Luminescent changes are attributed to dipole-dipole interactions and efficient energy transfer. • Cr3+ and Fe3+ enables synchronous excitation processes, offering versatility for applications in spectroscopy. [ABSTRACT FROM AUTHOR]

Rare earth ion doped fluorescent powder, as a key material for the application of white light-emitting diodes (w-LEDs), green components often face the problem of poor thermal stability. Developing fluorescent powders with excellent thermal stability is of great significance. This article synthesized a series of Gd 5 Si 2 BO 13 :Tb3+ blue phosphors and non rare earth Bi3+ ion doped Gd 5 Si 2 BO 13 :Tb3+ green phosphors using a high-temperature solid-phase method. The phase structure and photoluminescence characteristics of the sample were analyzed in detail through XRD, excitation and emission spectra, as well as attenuation curves. The energy transfer from Bi3+ to Tb3+ was studied and confirmed through photoluminescence spectra and lifetime decay curves. Research has shown that the addition of Bi3+ significantly enhances the emission intensity of Tb3+ in the near ultraviolet range, and tunes the emission color of Gd 5 Si 2 BO 13 :Bi3+ and Tb3+ from blue to green, attributed to the energy transfer from Bi3+ to Tb3+. In addition, the addition of Bi3+ increased the thermal stability of single doped fluorescent powder Gd 5 Si 2 BO 13 :0.55Tb3+ from 88.21 % to 92.82 % at 150 °C, proving that the Gd 5 Si 2 BO 13 :Bi3+ and Tb3+ samples have good thermal stability. This study not only deepens our understanding of the new main material Gd 5 Si 2 BO 13 , but also provides a reference for the development of green phosphors with excellent thermal stability. [Display omitted] • A series of Gd 5 Si 2 BO 13 :Bi3+, Tb3+ phosphors were successfully synthesized. • The co-doped Gd 5 Si 2 BO 13 :Bi3+, Tb3+ phosphors have excellent emission intensity and thermal stability. • The Gd 5 Si 2 BO 13 :Bi3+, Tb3+ green phosphors is promising for use in high-power LED lighting devices and backlight displays. [ABSTRACT FROM AUTHOR]

Near-infrared excited up-conversion phosphors of RE 3+ /Yb 3+ (RE = Ho, Tm) co-doped SrIn 2 O 4 were synthesized by a solid-state reaction method. X-ray diffraction analysis revealed the phase composition of those samples, and the up-conversion spectroscopic properties were studied in terms of up-conversion emission spectra. Under 980 nm near-infrared laser excitation, strong green emission with the peak at 546 nm was observed in SrIn 2 O 4 : Ho 3+ /Yb 3+ , which can be assigned to the characteristic 5 S 2 ( 5 F 4 ) → 5 I 8 transition of Ho 3+ . Furthermore, SrIn 2 O 4 : Tm 3+ /Yb 3+ showed bright blue emission with the peak at 486 nm, which is associated with the 1 G 4 → 3 H 6 transition of Tm 3+ . The UC power studies indicated that the luminescence of SrIn 2 O 4 : Ho 3+ /Yb 3+ and SrIn 2 O 4 : Tm 3+ /Yb 3+ are attributed to two-photon and three-photon process, respectively. The possible UC luminescence mechanism and energy transfer in SrIn 2 O 4 : RE 3+ /Yb 3+ were discussed. [ABSTRACT FROM AUTHOR]

This study employs molecular dynamics modeling to examine the interlayer microstructures of montmorillonite intercalated with different chains of C n mimCl montmorillonites with varying chain lengths, intercalation amount, arrangement and energy. C 4 mim + and C 8 mim + arrange themselves in monolayers, while C 12 mim + and C 16 mim + in parallel bilayers or tilt aligning. The basal spacing of montmorillonite and the corresponding energy increased as the chain length of organic cations is increased. It is indicated that no bond has been formed for N + O due to the minimum distances of no less than 3.1 Å and angles of 35°–45° between N + in C n mim + and silicon–oxygen tetrahedron. These modeling results provide insights into the understanding of synthesized C n mim + -montmorillonite microstructure and guidelines for relevant engineering applications. [ABSTRACT FROM AUTHOR]

The lanthanide-doped fluorescence intensity ratio (FIR) temperature measurement technology for detecting inaccessible objects has attracted the attention of many scholars. In fact, FIR technology can achieve high-precision and non-contact temperature measurement, which is widely used in the biomedical and industrial fields, among others. In this study, novel pyroxene-type CaScAlSiO 6 :Tb3+/Sm3+ ceramics (CSAC) were synthesized using the traditional high-temperature solid-phase method, with the crystal structure, energy transfer mechanism, and optical behavior of the ceramics subsequently studied in detail. The use of 5D 4 →7F 5 and 4G 5/2 → 6H 7/2 (I 544nm /I 602nm) energy level transitions as an optical thermometer has great potential, with the maximum absolute and relative sensitivity of the sensor found to be 0.1403 K−1 and 1.65%K−1, respectively. In addition, the material was cycled three times in the temperature range of 77–287 K and demonstrated a particularly high degree of credibility, with the luminous intensity having a particularly small effect on the temperature changes. Overall, the results indicate that the green-light-emitting CSAC:0.08Tb3+/0.01Sm3+ ceramic has great potential for use in optical cryothermometers. [ABSTRACT FROM AUTHOR]

Color-tunable manganese/europium/tellurium-doped halide perovskites are synthesized and can be used to post processing fibers for LEDs and anti-counterfeiting and detection materials. [Display omitted] • Color-tunable manganese/europium/tellurium-doped halide perovskites are synthesized. • Perovskites are composited with flexible fibers to prepare luminescent fibers. • The perovskite crystals can be used to fabricate light-emitting diode lamps. • Expanding the application of compound flexible fiber and perovskite. All-inorganic metal halide perovskites exhibit excellent optoelectronic properties, and cesium lead halide perovskites have been the most extensively studied perovskites. Despite their excellent performance, the toxicity of CsPbX 3 (X = halide) perovskites is a significant hurdle in the path of their widespread commercialization, posing challenges for large-scale applications. The lead-free characteristic and inherent air stability of Cs 2 NaBiX 6 render them promising alternatives to CsPbX 3 perovskites. Herein, we report the lead-free double perovskite crystals (PCs) derived from Cs 2 NaBiCl 6 incorporating doping with three distinct elements. This doping strategy effectively regulates the emission wavelength of Cs 2 NaBiCl 6 , with particular emphasis on Eu-doped and Te-doped Cs 2 NaBiCl 6 , which have been scarcely reported in previous studies. Light-emitting diodes (LEDs) have been fabricated by these perovskite crystals. The white LED was prepared by Mn-doped Cs 2 NaBiCl 6 with a high color rendering index (CRI) of 95.5. In addition, fiber paper, composed of aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS), exhibits sustained fluorescence characteristics in different environments under an ultraviolet lamp when post-processed with perovskite. The photoluminescence quantum yield (PLQY) of flexible luminescent fibers prepared from Cs 2 (NaBi) 0.95 Mn 0.10 Cl 6 PCs and ACFs/PPS fibers can reach 18.27 %. This fluorescent fiber paper holds potential applications in fields such as fluorescent anti-counterfeiting and intelligent wearable devices. By irradiating with a specific wavelength of the laser, the damaged area of fiber textiles can be quickly detected based on changes in fluorescence intensity. The integration of luminescent crystals and fibers into functional fabrics opens avenues for utilization in high-performance textile testing and other domains. [ABSTRACT FROM AUTHOR]

Abstract: Carbon foams with phenolic resin as precursor and aluminosilicate as reinforcement were prepared at different final pyrolysis temperatures. The microstructures, mechanical and thermal properties of the foams were investigated by scanning electron microscopy, mechanical testing and the laser flash method, respectively. The results show that the cells are mainly open with incomplete cell membranes, and the alumninosilicate particles are located in cell walls. The surface of cell openings becomes rougher as the final pyrolysis temperature increases. The ultimate compressive strength increases from 0.45 to 1.74MPa when increasing the final pyrolysis temperature from 1100 to 1550°C. The thermal conductivity ranged from 0.37 to 0.52Wm−1 K−1 at room temperature and decreases with increasing the final pyrolysis temperature. The occurrence of the mullite phase plays a key role in the changes of the mechanical properties and thermal conductivity of the foams. [Copyright &y& Elsevier]

The series of novel phosphors Ca 9 La(PO 4) 5 [(Si 1- x Ge x O 4)]F 2 :0.15Dy3+ with x = 0, 0.25, 0.50, 0.75 and 1 (CLPS 1- x G x F:0.15Dy3+) with apatite-type structure (space group P 6 3 / m) has been synthesized. The crystal structure and electronic structure have been studied by powder X-ray diffraction (PXRD) in combination with the atomic-scale density functional theory (DFT) calculations. A combination of Raman, nuclear magnetic resonance (29Si NMR) spectroscopy and the evolution of Dy3+ ions photoluminescent properties was used to characterize the local crystal structure features. Based on the variation of the [SiO 4 ] by [GeO 4 ] tetrahedral substitutions in the apatite-type structure, the difference in the thermal stability and decay curves of CLPS 1- x G x F:0.15Dy3+ phosphors were referred to crystal chemical stability of as-prepared compounds, which is also confirmed by the values of polyhedral distortion, bond valence sum (BVS) and DFT calculations. The present study provides new insights the synthetic methodology and fundamental characterizations into the design of new phosphors combined with theoretical methods. [ABSTRACT FROM AUTHOR]

The effect of zirconia coatings deposited by the Sol–gel technique on the oxidation of mild steel was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and measuring the weight gain. It was found that the thickness of zirconia coatings is a crucial factor affecting the oxidation kinetics and that a multi-layer coating is much more effective than the single-layer one. Auger electron spectroscopy (AES) was used to evaluate the depth composition of the coatings. The results suggest that the zirconia coatings deposited on mild steel just retard the oxidation, but do not suppress the oxidation. [Copyright &y& Elsevier]

We synthesized Tb3+-doped Cs 4 MnBi 2 Cl 12 perovskite crystals by the crystallization. These PCs have extremely strong PL intensity and stability at high temperatures, sunshine and low temperature. The Tb3+-doped Cs 4 MnBi 2 Cl 12 PCs have excellent luminescent properties and stability and can be used in luminous composite fibers and white LED devices field. [Display omitted] • Experiment under normal pressure environment, cost reduction and facile operation. • The Cs 4 Mn(Bi 1- x Tb x) 2 Cl 12 PCs have excellent stability in air. • The PCs have a excellent fluorescence performance with a PLQY of 25.45%. • The PCs were applied to ACFs/PPS composite paper with orange emission. • The composite paper can maintain stability in different real environments. In recent years, all-inorganic perovskites have attracted considerable research attention. However, the advancement of lead-based perovskites has encountered substantial challenges, redirecting current research efforts toward lead-free alternatives. In this study, we synthesized novel Cs 4 MnBi 2 Cl 12 perovskite crystals at 80 °C. Furthermore, Tb3+ ions were introduced to enhance the fluorescence properties and stability of the as-prepared perovskite crystals (PCs). The photoluminescence quantum yield (PLQY) of Tb3+-doped PCs was 25.45 % (∼598 nm), making a two-fold increase compared with the original PCs. In the PCs, [BiCl 6 ]3− octahedrons serve as energy collectors, generating excitons, while [MnCl 6 ]4− octahedrons function as luminescence centers of the receptor. Owing to their entirely inorganic composition, the PCs exhibited exceptional stability under sunlight and across a wide range of temperatures. Finally, we applied the PCs to fiber composite paper and an light-emitting diode (LED) device, which retained their specific stability after the modification. The findings of this study offer nover insight for incorporating perovskites into fiber applications and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Self-reduction of Eu3+ was realized in three-dimensional BaMgP 2 O 7 host using the energy-saving method in air environment. Incorporating charge compensators Li+/K+ can precisely control the self-reduction process, and its mechanism was elucidated using a charge compensation model. Furthermore, this work explored some advanced applications, such as plant growth, fingerprint visualization, and screen printing. [Display omitted] • Eu3+ self-reduction was achieved in three-dimensional pyrophosphate under atmospheric without hazardous gas. • Hetero-valence Eu2+/Eu3+ are obtained and luminescent properties were investigated. • Controlling high-valent ions' self-reduction using Li+/K+ charge compensators. • Advanced applications such as plant growth, fingerprint visualization, and screen printing are explored. • Ecofriendly luminescent materials are pivotal for advancing phosphor applications. The exploitation of ecofriendly luminescent materials is crucial for advancing phosphor applications. Herein, Eu3+ self-reduction was performed using the energy-saving high-temperature solid-phase method in air environment. Achieving controllable self-reduction is challenging for high-valent rare-earth and transition metal ions. Therefore, we incorporate charge compensators, such as Li+/K+ to control the reaction and obtain hetero-valent Eu2+/Eu3+. Experimental results indicate that charge compensators can eliminate vacancies, suppress self-reduction, and affect luminescence properties. Moreover, a nonequivalent substitution mechanism about self-reduction using a charge compensation model is discussed here. Notably, Eu2+ shows a strong blue narrow-band emission peak at 410 nm with a full width at half maxima of 34 nm, overlapping well with that of chlorophyll. The phosphors are nontoxic and exhibit high contrast under ultraviolet light, which can be utilized for forensic science detection. The precisely controllable self-reduction of phosphors can contribute to the development of next-generation smart and green materials. Advanced applications of the phosphors for plant growth, fingerprint visualization, and screen printing are also explored. [ABSTRACT FROM AUTHOR]

Light and stress dual-responsive piezoelectric semiconductor NaNbO 3 /g-C 3 N 4 heterojunction exhibits excellent water flow weak force-driven piezo-photocatalytic degradation of various antibiotics and drugs. [Display omitted] • NaNbO 3 /g-C 3 N 4 heterojunction were prepared by high-energy wet ball-milling. • The formation of heterojunction allows an intimate interfacial interaction. • It exhibits excellent water flow-triggered piezo-photocatalytic activity. • Piezo-photocatalytic TC degradation efficiency reaches 87.3 % within only 10 min. • Polarization and heterojunction synergistically promotes photocharge separation. Photocatalysis is a green and sustainable technology for pollution control, but has the disadvantage of fast recombination of photogenerated charges. Piezocatalysis has recently been widely studied for environmental purification, while it always involves the high-frequency ultrasonic vibration that inevitably causes high energy consumption. In this work, a water flow weak force-driven piezo-photocatalytic system that integrates light and stress dual-responsive components is developed in NaNbO 3 /g-C 3 N 4 heterojunction. As piezoelectric semiconductors with both piezoelectric and semiconducting properties, the piezoelectric polarization field of NaNbO 3 and g-C 3 N 4 induced by high-speed stirring not only produces strong polarization, but also directly triggers efficient piezocatalysis, and the spatial separation of interfacial carriers is accompanied by the formation of type-II heterojunction. The above merits endow NaNbO 3 /g-C 3 N 4 with outstanding water flow-triggered piezo-photocatalytic degradation for various antibiotics and drugs, including tetracycline hydrochloride (TC), oxytetracycline (OXY), ciprofloxacin (CIP), chloramphenicol (CHL), and paracetamol (PAR). Specifically, the TC degradation efficiency reaches up to 87.3 % within only 10 min, which makes it one of the best piezo-photocatalysts, even exceeding those irradiated by ultrasound. This work may open up a reference perspective for the engineering design of dual-active piezo-photocatalyst systems, and for the in-situ purification of diversified wastewaters on the basis of hydrodynamic properties. [ABSTRACT FROM AUTHOR]

Porous geopolymers are energy saving, environment-friendly and simple in preparation. However, the thermal conductivity (TC) of present porous geopolymers as well as other inorganic thermal insulation materials can be hardly below 0.050 W m-1 K-1 in the markets. In order to further decrease the TC of porous geopolymers, it is vital to understand the heat transfer mechanism of this type of materials. In this work, we made a comparison among the main heat transfer models for porous two-component system reported so far including series model, parallel model, geometric mean model, Maxwell-Eucken equation, Hashin spherical structure model and novel effective medium theory (NEMT) based on the data reported in references and obtained by our group for porous geopolymers, and found that NEMT could describe the heat transfer mechanism of porous geopolymers better. Then we systematically studied the relationship among the effective TC (k e), porosity (ε), TC of solid skeleton (k s) and TC of the uniform medium reflecting the heat conduction of the solid skeleton to air (k m) based on the calculations with NEMT. It was found that it is essential to increase ε and decrease k s and k m for reducing the TC of porous geopolymers. Under the guidance of above calculations, we successfully designed and obtained some porous geopolymers with TC as low as 0.040 W m-1 K-1. This paper offers not only several porous geopolymers with low TC, but also an idea to design novel thermal insulation materials. [ABSTRACT FROM AUTHOR]

• Inorganic thermal insulation material with triple-hierarchical pores was designed. • A special heat treatment method was used to create different size of pores. • The density decreased by ∼15% and thermal conductivity decreased by ∼10%. • Softening coefficient (water resistance) was remarkably improved by ∼80%. Inorganic thermal insulation materials are incombustible, cheap, and perdurable, and can thus effectively avoid such shortcomings of organic materials. Nevertheless, the physical properties, such as thermal conductivity and apparent density, are usually not as good as the organic thermal insulation materials. In present work, we designed and synthesized a new kind of inorganic thermal insulation material with admirable and intriguing triple-hierarchical porous structures by combining the ambient temperature foam method and simple heat treatment. The final products contained triple-hierarchical pores in the range of hundreds of microns, several microns to tens of microns, and submicrons to several microns. Compared to products without heat treatment, the apparent density of this kind of inorganic thermal insulation material was 0.148 g·cm−3, which decreased by 15%, and the compressive strength was 0.30 MPa; the thermal conductivity reached 0.047 W· m −1· K −1 which reduced by 10%, and the softening coefficient (the ratio of the samples' strength under saturation with that in dry condition) was improved from 0 to ∼80%. Therefore, this work not only provided a new type of thermal insulation material with hierarchical pores, but also has great significance for the design of inorganic thermal insulation materials with high performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]

It is urgent and crucial to develop highly efficient broadband Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) which are applied in tiny solid-state NIR light sources. However, a lot of NIR phosphors suffer from low quantum yield and poor thermal stability in recent years. Hereon, the solid-state reaction synthesis process was used to create a new garnet Ca 2 GdZr 2 Ga 3 O 12 :Cr3+ (CGZG:Cr3+) phosphor, which can produce a broad range emission peak at (12,437 cm-1, 804 nm) with a full width at half maximum (FWHM) of (67567 cm−1, 148 nm). At 373 °C, thermal stability was determined to be 76%, an IQE of 75% and an EQE of 26% was observed. When driving current at 150 mA and 320 mA, the device achieved the output power of 473 mW and 968 mW. The results demonstrate CGZG:Cr3+ phosphor-convert NIR LEDs have great potential for applications in night-vision and biomedical imaging NIR spectroscopy technology. • The Ca 2 GdZr 2 Ga 3 O 12 :Cr3+ is found ultra-broadband near-infrared photoluminescence with peak at 804nm.and FWHM 148 nm. • The Ca 2 GdZr 2 Ga 3 O 12 :Cr3+ near-infrared phosphors with the very high outpower 968 mW@320 mA. • The Ca 2 GdZr 2 Ga 3 O 12 :xCr3+ is promising for use in night-vision and biomedical imaging NIR spectroscopy technology. [ABSTRACT FROM AUTHOR]

Phosphor is the decisive material in white light-emitting diodes (WLED), affecting light quality. Silica phosphate has good stability, low cost and environmentally friendly features, so it has great application potential. In this paper, a self-activated reddish-orange phosphor Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 : x Sm3+ was prepared by the high-temperature solid-phase method. The phase purity of the sample was verified by X-ray diffraction (XRD). The Rietveld refinement method was used to resolve further the sample structure and the location of the substitution of rare earth ions. The photoluminescence properties were studied in detail using fluorescence spectra, temperature-dependent emission spectra and other characterization methods. The electron transition and energy transfer processes of Gd3+ in Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 were analyzed. The fluorescence decay curve of the sample was obtained, which belongs to the double exponential curve, and the decay lifetime depending on the Sm3+ doping concentration was calculated. Furthermore, a WLED device was assembled, and warm white light was obtained, with a spectrum showing characteristic red emission, proving to complement the missing red component of commercial WLEDs. These results indicate that Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 : x Sm3+ phosphor has great potential for application. • The reddish-orange-Emitting phosphor Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 : x Sm3+ was obtained via the high-temperature solid-state method. • The structure of Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 : x Sm3+ phosphor, including the incorporation sites of Sm3+, were investigated. • The mechanism of energy transfer in the luminescence process of samples was studied. • The optical properties of Ca 3 Gd 7 (PO 4)(SiO 4) 5 O 2 : x Sm3+ reddish-orange-emitting phosphor were investigated carefully. [ABSTRACT FROM AUTHOR]

Highlights • A novel thermal insulation material was made utilizing perlite tailings. • A more energy-saving preparation method was conducted. • It showed low thermal conductivity (0.04 W·m−1·K−1) and density (0.102 g·cm−3). • The preparation technique reported in this paper is of application prospect. Abstract Installing thermal insulation materials on the external and/or interior wall is a primary means for the conservation of building energy. Expanded perlite is one of the most widely used inorganic building insulation materials nowadays. However, it not only consumes a large amount of energy in the fabricated process, but also produces a great deal of perlite tailings during the exploiting or smashing process. In this work, a new kind of light foamy thermal insulation materials were prepared utilizing perlite tailings by an energy-saving and environment-friendly method. The influences of each raw materials, including perlite/sodium silicate, H 2 O 2 , cetyltrimethyl ammonium bromide and rock wool, on the physical properties (such as pores characters, thermal conductivity and mechanical strength) were discussed in detail based on the formation processes of the foamy thermal insulation materials. The optimized foamy materials showed low thermal conductivities (0.040–0.060 W·m−1·K−1) with low apparent densities (0.1–0.2 g cm−3) and relatively high mechanical strength (0.09–0.6 MPa). As compared with other reported inorganic thermal insulation materials, this new type of thermal insulation material was very light and exhibited much better heat-insulated performance. Therefore, this work not only proposed a new energy-saving method for obtaining a kind of promising non-flammability insulating materials, but also solved the problem of solid tailings utilization. [ABSTRACT FROM AUTHOR]

Abstract The supercapacitance performance of birnessite, which is a common layered manganese oxide mineral with the general formula of (Na, K, Ca) x (Mn4+, Mn3+) 2 O 4 ·1.5H 2 O, is greatly hindered by poor electrical conductivity, especially when the areal mass loading of the active materials is high enough for practical application. Heterogeneous atom doping is an effective way for improving the supercapacitance performance of birnessite. Herein, we mainly investigate the influence of Fe doping on the crystal structure, electronic structure and capacitance performance of birnessite [(Na, K) x (Mn4+, Mn3+) 2 O 4 ·1.5H 2 O] in detail by combining the experiments and theoretical calculations/simulations. It is found that Fe atoms mainly substitute the central trivalent Mn in [MnO 6 ] octahedral after doping without changing the crystalline phase of birnessite. Meanwhile, the particle size and surface area of Fe-doped birnessite continuously increase with the increase of the content of Fe dopant. On the other hand, the electronic conductivity of the doped birnessite firstly increases and then decreases with the increase of the Fe content due to the reduced indirect band gap and the increased number of the boundary/grain interfaces. Based on these results, the influences of Fe doping on the supercapacitance performance of birnessite electrode with very high areal mass loading of ∼10–12 mg cm−2 are elaborately discussed related to morphology, structure, electrical conductivity, and ion diffusion properties. Graphical abstract Image 1 Highlights • Fe (III) mainly substituted Mn (III) in [MnO6] octahedral after Fe doping. • Particle size decreased and surface area greatly increased after Fe doping. • The indirect band gap of Fe-doped birnessite calculated from DFT reduced. • 5 mol% Fe-doped samples showed the best capacitance performance. [ABSTRACT FROM AUTHOR]

A series of novel Na 3 Ga (1- x ) F 6 : x Eu 3+ ( x  = 1%, 3%, 5%, 7% and 10%) phosphors were synthesized by hydrothermal synthesis method. The crystal structure and luminescence properties of Na 3 GaF 6 :Eu 3+ were characterized by X-ray powder diffraction (XRD), Scanning electron microscope (SEM), photoluminescence (PL) and photoluminescent excitation spectra (PLE) as well as decay curves. The results indicated that Eu 3+ can replace Ga 3+ in the lattice of Na 3 GaF 6 without any impurity. The micro-particle of the phosphor was uniform and regular with a smooth surface. Upon 395 nm excitation, the phosphors show intense reddish-orange color including a series of narrow peaks attributed to the typical f–f transition of Eu 3+ . Not like most of other rare-earth doped sample, the Na 3 GaF 6 :Eu 3+ phosphors show obvious anti-thermal quenching behavior. All the results demonstrated that Na 3 GaF 6 :Eu 3+ phosphors exhibit good luminescent properties and might have a potential to applications in lighting technology. [ABSTRACT FROM AUTHOR]

Abstract Because the commercialized graphitic carbon as an anode material is still limited by low capacities and poor long cyclic stability, new carbonaceous materials with good electrochemical performance are still needed to be sought. In the present work, a new fluorinated carbon material was obtained from natural black talc ore by HF acid-treating method. The influences of heat treatment on the composition, morphology and structure characteristics of the fluorinated carbon were investigated and possible fluorination/defluorination mechanisms were proposed. As an anode material for Li-ion battery, the electrochemical performance of the samples was greatly influenced by their surface characteristics. The fluorinated carbon showed high capacities of ∼756 mAh/g and ∼620 mAh/g at rate of 0.1 C and 0.2 C, which resulted from more active sites provided by plenty of fluoride groups on the surface of the fluorinated carbon. In contrast, the sample annealed at 800 °C exhibited relatively high capacity of ∼477 mAh/g at rate of 0.1 C with excellent rate performance due to its better electrical conductivity caused by the removal of the fluorine groups. The present work provides a new direction for the application of black talc and other similar natural minerals. Graphical abstract Image 1 Highlights • A new fluorinated carbon material was obtained from natural black talc ore. • The effect of heat treatment on the fluorinated carbon were investigated. • The electrochemical performances of these samples were studied as anode materials. • The fluorinated carbon annealed at 800 °C exhibited excellent rate performance. • The lithium storage mechanism of these samples were explored. [ABSTRACT FROM AUTHOR]