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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]

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 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 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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

LED occupies a broad market due to its many advantages as a fourth-generation solid-state light source. However, single-component white LED generally has the disadvantages of high coloring temperature, low thermal stability, and low luminous efficiency. In order to solve these problems, Gd 5 Si 2 BO 13 :Dy3+,Eu3+ was prepared by a high temperature solid state method using a newer borate matrix based on Gd 5 Si 2 BO 13. A colour-tunable warm white phosphor was achieved by energy transfer between Dy3+ and Eu3+. The crystal structure, luminescence characteristics, thermal stability of luminescence, fluorescence lifetime and energy transfer mechanism were systematically studied, and the samples obtained had excellent luminescence performance. Its thermal stability of 150 °C luminescence was 83.77%. By adjusting the ratio of Eu3+, its color changes from cool white light to warm white light and finally moves to red light. Its corresponding color temperature can be adjusted to a range of 5475k∼2128 K. The packaging w-LED application test and the application test of colorless fluorescent anti-counterfeiting printing ink were carried out, and both showed excellent performance. This is the first time that Dy3+ and Eu3+ have been studied in Gd 5 Si 2 BO 13 , further understanding the newer substrate Gd 5 Si 2 BO 13 , and promoting the application of single-component warm white LED. Therefore, Gd 5 Si 2 BO 13 :Dy3+,Eu3+ have good market application prospects. [Display omitted] • Through the energy transfer between Dy3+ and Eu3+, Gd 5 Si 2 BO 13 :Dy3+/Eu3+ shows excellent Warm white light performance. • The phosphor showed good luminescence thermal stability, UV stability and wet resistance stability. • The color temperature of the sample was adjusted from 5475K to 2128K by adjusting the doping concentration of Eu3+. • The LED application test with Gd 5 Si 2 BO 13 :Dy3+,Eu3+ package shows good performance. [ABSTRACT FROM AUTHOR]

The preparation of metal sulfide electrodes using the synergistic effect between multi-metal elements and their application to the field of supercapacitors is a highly promising technology. For metal sulfides, which have been extensively studied, the introduction of new structures (cobalt pentlandite structure) can promote the improvement of metal sulfide systems and give them new vitality for better design, improvement and development of high-performance supercapacitor materials. In this study, we have designed a ternary metal sulfide (FeCoNi) 9 S 8 with a cobalt pentlandite structure in the form of nanoflowers, in which the three atoms of Fe, Co, and Ni occupy equal positions in the crystal structure, and the synergistic effect between the atoms can be well realized in the structure. The optimized FCNS-2 has shown a remarkably high-specific capacity (970 F g−1 at a current density of 1 A/g) as well as favorable cycling stability (87.1% capacitance retention over 5000 cycles at 6 A/g). Moreover, a button-type asymmetric supercapacitor (ASC)was fabricated utilising our designed electrode material together with an activated carbon (AC) electrode and showed a relatively high-energy density of 50 Wh kg−1 for a power density up to 1353 W kg−1 and excellent cycle stability. Also, two ASC can power a red LED for 22 min, which has shown its attractive and promising possibilities for practical energy storage devices. [Display omitted] • We synthesized cobalt pentlandite (Fe,Co,Ni) 9 S 8 samples and found their good using potential in supercapacitor electrodes. • The structure–activity correlation and the real active sites of the optimized FCNS-2 were investigated by DFT calculations. • The FCNS-2//AC HSC device shows energy/power density of 50 Wh g-1/1535 W kg-1 and great stability after 10000 cycles. • Providing an important addition to the family of polymetallic sulfide materials used as supercapacitor electrodes. From the perspective of improving energy density, research efforts to design electrode materials that can be used in supercapacitors based on mature transition metal sulfides are already so common and efficient but insufficient. So it is a nice approach to empower the traditional transition metal sulfides with new vitality by composite structures to enrich the family of metal sulfides. In this study, we synthesized a kind of cobalt pentlandite structured (Fe,Co,Ni) 9 S 8 originally existed only in natural ores by relatively mild means, and found that such structured materials have good potential for use in supercapacitors. The optimized (Fe,Co,Ni) 9 S 8 sample presents a remarkably high specific capacity of 135 mAh/g at 1 A/g as well as favorable cycling stability. Density functional theory simulations confirmed the metallic properties of such sample, and Co sites are more favorable for the adsorption of OH–. Moreover, a button-type hybrid supercapacitor was fabricated utilizing our designed electrode material, presenting a relatively high energy density of 50 Wh kg−1 at 1353 W kg−1 and good cyclic stability. Moreover, two such hybrid supercapacitors can power a red LED for 22 min, which has shown its attractive and promising possibilities for practical energy storage devices. [ABSTRACT FROM AUTHOR]

Pc -LEDs (phosphor-converted light-emitting diodes) are a relatively new generation of light sources frequently used for room lighting, backlighting, and plant development on account of numerous advantages, such as compactness, good stability, low energy consumption, and environmental friendliness. However, the absence of red-light emission limits the practical application of pc-LEDs. For example, pc-LEDs have a high correlated color temperature and a low rendering index. Here, a group of far-red emitting Mn4+-doped Ca 2 GdZr 2 Al 3 O 12 (CGZA: Mn4+) phosphors was effectively synthesized using a solid-state reaction technique at 1450 °C. The phase purity, morphology, and fluorescence properties of prepared phosphors were investigated using XRD, SEM, PL/PLE, and fluorescence decay analysis, respectively. Under a 344-nm excitation, CGZA: Mn4+ emitted high-purity far-red light with a peak at approximately 702 nm. Phosphor quenching was observed once the Mn4+ concentration reached 0.3 mol%. The concentration quenching mechanism of Mn4+in the CGZA matrix resulted from electric dipole-dipole interactions. An important result was that the PL band was well superposed on the absorption bands of phytochromes Pr and Pfr. The PL intensity was 50% of the initial value at 373 K. These experimental results demonstrated the board application potential of the prepared phosphors for plant breeding. • Mn4+ is found to show far red photoluminescence in Ca 2 GdZr 2 Al 3 O 12 host for the first time. • A discussion is given on the luminescent properties of Mn4+ ion in Ca 2 GdZr 2 Al 3 O 12 host. • The Ca 2 GdZr 2 Al 3 O 12 :xMn4+ far-red phosphors are promising for use in plant cultivation lighting. [ABSTRACT FROM AUTHOR]

• Durability of porous perlite geopolymer was investigated in hot and humid environment. • The simulation of extremity of environment temperature and humidity on samples was conducted. • The durability effects of porous perlite geopolymer was analyzed. • The improvement of durability of porous perlite geopolymer was proposed. Porous geopolymers can be potentially applied in building thermal insulation. In this work, we investigated the durability of porous perlite geopolymer by long-term aging experiments under high temperature (50 ℃) and relative humidity (98%). Samples were characterized by digital photo analyses, scanning electron microscope (SEM), X-Ray Fluorescence Spectroscopy (XRF), X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectrum (FT-IR), Solid-State Nuclear Magnetic Resonance (SS NMR), compressive strength measurements and thermal conductivity analyses. Results show that Na+ has great influence on the stability of porous perlite geopolymer. The hydrated Na+ in the pore reacts with CO 2 to form Na 2 CO 3 ·H 2 O, and part of Na+ enters and breaks geopolymer gel network, resulting in the deterioration of physical properties. When soaked in HCl or CaCl 2 solution, the geopolymerization is improved; at the same time, Na+ in the pore reacts with Cl– to form NaCl, and Ca2+ reacts with Cl– and OH– to form CaClOH, which jointly prevents Na+ from entering and breaking gel network and results in the improvement of durability of porous perlite geopolymer. Aging process promotes further polymerization in porous perlite geopolymer, which might also contribute to physical property variations of porous perlite geopolymer. This paper not only clarifies the mechanism of performance variation of porous perlite geopolymer in hot and humid environment, but also offers guidelines for the design and durability research of other porous geopolymers. [ABSTRACT FROM AUTHOR]

Cryolite was considered to be an ideal up-conversion host material due to its low phonon energy, which can effectively suppress the radiation-free transition process of excited state energy levels. In the present paper, a novel up-conversion material K 3 YF 6 :Ho3+, Yb3+ with cryolite structure was prepared successfully using a high-temperature solid state method. The up-conversion luminescence properties of K 3 YF 6 doped with different Ho3+/Yb3+ doping ratio were investigated and the optimal doping ratio were confirmed in this system. Under 980 nm excitation, Ho3+/Yb3+ co-doped K 3 YF 6 revealed a strong green emission at the 541 nm, 549 nm and a weak red emission peaking at 666 nm, corresponding to the 5F 4 , 5S 2 →5I 8 and 5F 5 →5I 8 transitions of Ho3+, respectively. All the red and green up-conversion emission of K 3 YF 6 :Ho3+, Yb3+ belong to two-photon process and energy transfer from Yb3+ to Ho3+ simultaneously. Additionally, to understand the energy transfer and electronic transition process of the red and green light emitted, the possible luminescence mechanism were also analyzed in this paper. All the results indicate that Ho3+/Yb3+ co-doped K 3 YF 6 have potential application value in green up-conversion luminescent materials. • Single-phase up-conversion luminescent materials K 3 YF 6 : Ho3+,Yb3+ with cryolite structure were obtained for the first time. • The up-conversion luminescence properties and mechanism of the as-prepared samples were analyzed under excitation of 980 nm. • Two-phonon up-conversion phenomenon was confirmed. [ABSTRACT FROM AUTHOR]