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The construction of active materials with controllable optical response facilitates the development of advanced photonic devices. However, the achievement of robust active materials with wide wavelength tunable and broadband emission remains a great challenge, mainly due to the fixed energy levels of conventional active dopants and limited inhomogeneous broadening in common hosts. Here, the study proposes that the cluster in the mesoscopic scale of ≈1 nm may break this bottleneck issue and demonstrate a strategy for the management of photon emission by engineering the cluster evolution. The amorphous glass as the host to tailor the characteristic configuration of Te clusters from 1 to 2 nm by control of the topological structures in glass is employed. Impressively, it presents a distinct optical response totally different from the conventional active centers and this enables to construct of active photonic glass with continuously tunable emission from 888 to 1064 nm. More importantly, Te cluster‐activated photonic glass fibers are fabricated and the broadband on‐off gain is successfully achieved. Furthermore, benefiting from the unique tunable emission, novel near‐infrared devices are constructed and their application in imaging is demonstrated. The approach of cluster engineering mediated tunable optical response is believed to bring new opportunities for developing advanced photonic devices. [ABSTRACT FROM AUTHOR]

Over the past decades, supramolecular luminescent materials (SLMs) have attracted considerable attention due to their dynamic noncovalent interactions, versatile functions, and intriguing applications in many research fields. From construction to application, great efforts and progress have been made in color‐tunable SLMs in recent years. In order to realize multicolor luminescence, various design strategies have been proposed. Macrocyclic chemistry, one of the brightest jewels in the field of supramolecular chemistry, has played a crucial role in the construction of stimuli‐responsive and emission‐tunable SLMs. Moreover, the flexible and tunable conformation and multiple noncovalent complexation sites of the macrocyclic arenes (MAs) afford a new opportunity to create such dynamic smart luminescent materials. Inspired by our reported work on the color‐tunable supramolecular crystalline assemblies modulated by the conformation of naphth[4]arene, this Concept provides a summary of the latest developments in the construction of color‐tunable MA‐based SLMs, accompanied by the various construction strategies. The aim is to provide researchers with a new perspective to construct color‐tunable SLMs with fascinating functions. [ABSTRACT FROM AUTHOR]

The doping of bismuth (Bi) ions in borosilicate glasses has gained attention for its potential applications in LED light sources and imaging displays. Here, gadolinium oxide (Gd2O3) was introduced into the glass matrix in varying concentrations using a high‐temperature melting method to investigate its impact on the luminescence properties of Bi ions. The resulting glass exhibited bimodal emission peaks at 465 and 750 nm when excited with 325 nm light. The luminescence intensity and fluorescence half width at half height initially increased, followed by a subsequent decrease as the Gd2O3 content in the glass increased from 10 to 43 mol%. Additionally, the color of the luminescence transformed from purple–red to green under white light irradiation. The composition and excitation wavelength of the glass can be adjusted to achieve selective tuning of the luminescence. [ABSTRACT FROM AUTHOR]

Pr3+-Er3+ co-activated glass-ceramics containing Ba 3.75 Gd 0.833 Nb 10 O 30 crystalline phase were prepared as a multifunctional material. The optimum heat treatment condition was determined to be 750 °C/90 min, as this condition is most favorable for luminescence. As the Pr3+ concentration increases, the emissions of 3P 0 and 1D 2 energy levels show different trends, leading to a shift in luminescence from orange to yellow. With the introduction of Er3+, the co-doped sample achieves orange-yellow-green tunable luminescence. The 0.3%Pr3+-0.3%Er3+ co-doped sample exhibits alternating yellow-orange-green luminescence during continuous excitation in the range of 250–500 nm, which has potential applications in optical anti-counterfeiting. In the temperature interval of 298–458 K, the maximum temperature sensitivities based on the NTCLs of Pr3+ and Er3+ were 0.82 × 10−2 K−1 (S a) and 1.40 % K−1 (S r). Meanwhile, the thermal repeatability ratio is higher than 92.3 %, which proved that it is a potential temperature sensing material. In addition, the concentration quenching, energy transfer and luminescence phenomena involved were analyzed in depth and their mechanisms were explained. [ABSTRACT FROM AUTHOR]

Tb3+ and/or Sm3+ doped SiO 2 –B 2 O 3 –Na 2 O–ZnO–MoO 3 -Gd 2 O 3 transparent glass-ceramics containing NaGd(MoO 4) 2 nanocrystals were successfully prepared by the melt-quenching method and subsequent heat treatment process. The optimal schedule to achieve heat treatment was crystallized at 650 °C for 5 h. The strongest green luminescence (545 nm: 5D 4 →7F 5) was obtained under 376 nm excitation when the Tb 2 O 3 -doped amount was 0.3 mol%. A thorough investigation was conducted to explore the mechanism of energy transfer from Tb3+ ions to Sm3+ ions, which is caused by quadrupole-quadrupole interactions. Tb3+-Sm3+ co-doped SiO 2 –B 2 O 3 –Na 2 O–ZnO–MoO 3 -Gd 2 O 3 glass-ceramics can achieve green, yellow, and red multi-color tunable luminescence as the amount of Sm 2 O 3 doping changes, which indicates that it holds promising potential in applications such as ultraviolet-transformed white light-emitting diodes and various optical apparatus. [ABSTRACT FROM AUTHOR]

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others. [ABSTRACT FROM AUTHOR]

The solid-state reaction method was used to develop a series of Na 2 Ca 1-x-y Ce x Mn y P 2 O 7 phosphors in an H 2 –N 2 environment. The crystal structure of the pyrophosphate host, valence state of dopants (Ce, Mn), emission behavior of dopants, energy transfer mechanism, and thermal quenching behavior were thoroughly examined. Doping with Ce3+ and Mn2+ ions enhanced the photoluminescence characteristics of Na 2 Ca 1-x-y Ce x Mn y P 2 O 7 while having negligible effect on the host's phase purity. Under 365 nm UV light irradiation, the addition of Ce3+ ion in the Na 2 CaP 2 O 7 host revealed an asymmetric band with the typical blue emission around 415 nm and a shoulder around 455 nm. To obtain white light, Mn2+ ion was supplementarily substituted to the present system. When the Mn2+ ions concentration was elevated in the Na 2 CaP 2 O 7 host, the emission intensity of 560 nm peak corresponding to Mn2+ transition enhanced significantly at the cost of Ce3+ emission of 415 nm. The systematic decrease of Ce3+ emission intensity and corresponding increase in the Mn2+ intensity with the increase in Mn2+ concentration indicated the possibility of effective energy transfer from Ce3+ to Mn2+ ions. The obtained results indicated that energy transfer from the Ce3+ to Mn2+ ions governed by dipole-quadrupole interaction. Because of the efficient energy transfer, the blue emission from Ce3+ and the orange red emission of Mn2+ provide white light from a single host along with high value of activation energy and low thermal quenching behaviour make the present phosphors to be suitable for high-power LEDs. [ABSTRACT FROM AUTHOR]

Hydrogen‐bonded organic frameworks (HOFs) have shown great potential in separation, sensing and host‐guest chemistry, however, the pre‐design of HOFs remains challenging due to the uncertainty of solvents′ participation in framework formation. Herein, the polarity‐evolution‐controlled framework/luminescence regulation is demonstrated based on multiple‐site hydrogen‐bonded organic frameworks. Several distinct HOFs were prepared by changing bonding modes of building units via the evolution of electrostatic forces induced by various solvent polarities. High‐polar solvents with strong electrostatic attraction to surrounding units showed the tendency to form cage structures, while low‐polar solvents with weak electrostatic attraction only occupy hydrogen‐bond sites, conducive to the channel formation. Furthermore, the conformation of optical building unit can be adjusted by affecting the solvent polarity, generating different luminescence outputs. These results pave the way for the rational design of ideal HOFs with on‐demand framework regulation and luminescence properties. [ABSTRACT FROM AUTHOR]

This work investigates the optical properties of Yb3+ ions doped GeO2-PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices. [ABSTRACT FROM AUTHOR]

It is still a great challenge to obtain multicolor tunable luminescence and improve the stability of luminescence through reasonable design of materials in the field of white light‐emitting diodes (WLEDs). In particular, it is more important to improve the luminescence intensity and stability of blue‐emitting materials. Here, the properties of CsPbBr3, CsPbBr3:Na, and NaPbBr3 are investigated theoretically by using density functional theory (DFT). Based on the DFT theoretical calculation results, it is assumed that unexpected performance may be achieved by replacing Cs in CsPbBr3 with Na or passivating the surface of CsPbBr3 with Na. As expected, the tunable luminescence from blue to green is successfully achieved from CsPbBr3:Na, and the stability is improved. After experimental optimization, the obtained CsPbBr3:Na (CPBN‐4) with high luminescence stability is used as blue‐emitting materials to construct the WLED devices with excellent color quality (CRI 92) and correlated color temperature of 9582 K. [ABSTRACT FROM AUTHOR]

Currently, developing thermostable and color tunable phosphor via energy transfer strategy is a significant research topic in solid-state lighting field. Herein, the sensitizer Dy3+ and activator Sm3+ are solidly dissolved into the Ba 2 Y 2 Ge 4 O 13 (BYGO) matrix to prepare color-tunable germanate phosphors BYGO:Dy3+,Sm3+. Under 365 nm excitation, the energy transfer-induced tunable emission of Dy3+/Sm3+ co-doped phosphors are investigated. The energy transfer mechanism is ascribed to the quadrupole-quadrupole interaction. The thermal quenching investigation manifests that the BYGO:Dy3+,Sm3+ phosphor has excellent thermostability (the emission intensity at 423 K reduces only 6.9 %) and resistance to chromaticity shifting (the chromaticity shifting parameter at 473 K is as low as 3.94 × 10−3). Meanwhile, the ∼365 nm InGaN chip-excited w-LED device is fabricated with commercial phosphor BaSi 2 O 2 N 2 :Eu2+ and the title material, showing satisfactory electroluminescence performance. This work reveals that the title phosphor is a suitable candidate for solid-state lighting. • Due to the Dy3+→Sm3+ ET, the tunable emission of the BYGO:Dy3+,Sm3+ phosphor is realized. • The BYGO:Dy3+,Sm3+ phosphor shows excellent luminescent thermostability and chromaticity shifting resistance. • The fabricated w-LED device outputs satisfactory white light (0.3399, 0.3680). [ABSTRACT FROM AUTHOR]

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.

A series of europium-ion doped CaLa 4 Si 3 O 13 phosphors were synthesized by using a conventional high-temperature solid-state method. X-ray powder diffraction patterns and photoluminescence spectra were utilized to characterize the as-prepared phosphors. The phosphors show tunable luminescence owing to the existence of Eu2+ and Eu3+ emission. A typical emission maximum of Eu2+ is about 460 nm, and Eu3+ shows a predominant 5D 0 -7F 2 transition emission. The emission of Eu2+ shifts toward the long wavelength side with increasing doping concentration. The site occupancy of Eu2+ and Eu3+ is analyzed according to their luminescence behaviors. The Eu3+ ion at the Ca2+ site can be partially reduced to Eu2+, but at the La3+ site cannot be reduced. The controllable reducing of Eu3+ is explained according to the crystal structure of the host. Utilizing site selection to control the reducing of Eu3+ is considered as an alternative strategy to design novel Eu3+ and Eu2+ codoped inorganic phosphor. [ABSTRACT FROM AUTHOR]

Luminescent silver nanocluster zeolite composites have aroused intensive attention of the research community because of their outstanding optical performances. Herein we report one such luminescent nanocomposite by assembling silver nanoclusters within the analcime (ANA) zeolite by sonicating the silver-exchanged ANA zeolites in the presence of an appropriate amount of terephthalic acid (TPA). The addition of TPA can prevent the formation of larger nonluminescent silver nanoparticles (Ag NPs), increase the photoluminescence quantum yield, and adjust the emission color of the resulting luminescent composites, varying from orange to yellow to white via changes in the TPA concentration. It is believed that the TPA molecules added during the synthesis process favor the dissolution of large nonluminous Ag NPs formed on the surface of the zeolite, leading to a significant decrease in both the number and size of the Ag NPs. In addition, a warm-white light-emitting device was fabricated by integrating the composites on a near-ultraviolet 365 nm chip. Our method might demonstrate a perspective for the rational synthesis of luminescent silver nanoclusters. [ABSTRACT FROM AUTHOR]

Sm3+ and Ce3+ singly doped and Sm3+ and Ce3+ co-doped Sr3B2O6 phosphors are prepared via a high-temperature solid-state reaction method. The crystal structure and phase purity are characterized by X-ray diffraction (XRD) analyses. The Sm3+-doped sample displays an emission in the orange-red region, with the strongest emission line at about 648 nm and possessing a good luminescence thermal stability between 78 and 500 K. With the increase in the Sm3+ content, the concentration quenching is observed due to the cross-relaxation (CR) processes among the Sm3+ ions. Upon 340 nm excitation, the Ce3+-doped phosphor presents a broad emission band in the blue region with a maximum at about 420 nm, which overlaps well with the 6H5/2 → 6P3/2 excitation line of Sm3+ and implies the possible energy transfer from Ce3+ to Sm3+. The spectral and decay measurements of the Ce3+ and Sm3+ co-doped samples are conducted and the Inokuti–Hirayama (I-H) model is adopted to analyze the luminescence decay dynamics of the donor Ce3+. Owing to the evident sensitization of the Sm3+ by the Ce3+ ions, the co-doped samples exhibit color variation under different wavelength excitations, endowing them with potential applications in optical anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The rapid development of global telecommunication, cloud computing, big data, consumer electronics create increasing demands to expand the capacity and rate of data transmission for next generation broadband optical communication. It raises a great challenge for current rare‐earth ions doped fiber amplifiers due to the narrow emission bandwidth of rare‐earth ions. In this context, broadband near‐infrared (NIR) emitter based optical amplifiers are in urgent demand. Here, broadband optical amplification in S + C + L bands is achieved for the first time in PbS quantum dot (QD)‐doped low‐melting‐point glass fiber. With the pump of a 976 nm laser, the on‐off gain of PbS QD‐doped fiber (PQDF) ranges from 1.4 to 8.7 dB in 1500–1630 nm, while that of PbS QD‐doped glass ranges from 6.9 to 8.4 dB in 1530–1630 nm. Both QD‐doped glass and optical fiber show tunable luminescence covering the entire optical communication windows (O + E + S + C + L + U). The much higher quantum yield of PbS QDs in glass than that of colloidal QDs, the ultra‐broad and controllable emission bands and bandwidth make PbS QDs doped glass and fiber promising for applications in next generation broadband optical fiber amplifiers and tunable fiber lasers.

A series of SiO 2 -B 2 O 3 -ZnO-La 2 O 3 -BaO (SBZLBa) glasses doped with Dy3+ and Eu3+ were synthesized using the melt-quenching technique. Their optical characteristics and potential applications in W-LED devices were investigated. The structural effects resulting from doping the glass with Dy3+ and Eu3+ ions were elucidated through infrared spectroscopy and an examination of the physical properties. The variations in emission intensity within the fluorescence spectrum validated the sensitizing effect of Dy3+ on Eu3+ within the glass matrix. By manipulating the transitions of both Dy3+ and Eu3+, the excitation wavelength was altered, enabling the realization of cool white, neutral white, and warm white luminescence, thus accommodating the diverse requirements for white light emission in lighting applications. After incorporating 1.0 mol% of Dy 2 O 3 and 0.8 mol% of Eu 2 O 3 , respectively, the glass exhibited CIE coordinates of (0.3332, 0.3535), positioning it within the white light spectrum and in close proximity to the ideal white light coordinates of (0.33, 0.33). The SBZLBa-Dy 2 O 3 –0.8Eu 2 O 3 glass exhibited a quantum yield of 5.98 %. It has been demonstrated through acid and alkali resistance tests that this glass possesses excellent chemical stability. Additionally, temperature-dependent emission spectra have revealed that the luminous intensity of the glass maintains over 85 % of its room temperature value at 185 °C, with Eα determined to be 0.2387 eV. [ABSTRACT FROM AUTHOR]

Currently, the development of single-phase white emitters is an interesting research topic. Researchers have paid much attention to tune white-emitting of Dy3+-activated phosphors via Tm3+ sensitization strategy. However, the role of Tm3+ sensitization on luminescence thermostability was usually underestimated. Herein, color-tunable germanate phosphors Ba 2 Y 2 Ge 4 O 13 (BYGO):Tm3+,Dy3+ were prepared. The white light emission is achieved due to the effective energy transfer from Tm3+ to Dy3+. A BYGO:Tm3+,Dy3+-based w-LED exhibits warm white-emitting. Moreover, the back-energy transfer of Dy3+→Tm3+ contributes to the improvement of luminescence thermal stability. Meanwhile, the difference of temperature-dependent Tm3+ and Dy3+ emissions realizes satisfactory temperature sensing properties. This work provides a deep understanding for the role of Tm3+ sensitization strategy on color tuning and thermostable improvement, promoting multifunctional utilizations of Dy3+-activated phosphors. [Display omitted] • BYGO:Tm3+,Dy3+ achieves white light emission due to the effective ET from Tm3+ to Dy3+. • Excellent luminescent thermal stability comes from the Dy3+→Tm3+ BET. • The title phosphor exhibits excellent temperature sensing properties. [ABSTRACT FROM AUTHOR]

Bi3+/Tb3+/Mn2+-activated SrZnSO phosphors were prepared to investigate their luminescence characteristics. The SrZnSO:Bi3+, SrZnSO:Mn2+ and SrZnSO:Tb3+ phosphors, excited by the NUV/blue light, show blue, orange and green emissions, respectively. The Bi3+ → Tb3+, Tb3+ → Mn2+ and Bi3+ → Mn2+ energy transfer processes take place in Bi3+/Tb3+-, Tb3+/Mn2+-, Bi3+/Mn2+- and Bi3+/Tb3+/Mn2+-activated SrZnSO phosphors, which result in tunable luminescence of these phosphors. The CIE coordinates were calculated on the basis of the emission spectra, and they reflect the emission color changes of phosphors. For the Bi3+/Tb3+-, Tb3+/Mn2+- and Bi3+/Mn2+- activated SrZnSO phosphors, the emission points are located in the cyan, yellow and white light regions, respectively. For the Bi3+/Tb3+/Mn2+-activated SrZnSO phosphors, the light is in warm white light region. [ABSTRACT FROM AUTHOR]

Rare earth ions doped luminescent materials have drawn considerable attention as they can generate both upconversion and downshifting emissions. Here, the rare earth ions Pr3+/Er3+ codoped perovskite oxide Bi 4 Ti 3 O 12 is proposed as a dual-mode temperature sensor and anti-counterfeiting material based on its up/down-conversion luminescence. Under 481 nm excitation, the intensity ratio of green emission (∼523 nm in Er3+) and red emission (∼611 nm in Pr3+) brings about a very high absolute sensitivity (S a) of 2% K−1 at 568 K and a maximum relative sensitivity (S r) of 1.03% K−1 at 478 K in the temperature range of 298–568 K. In addition, the upconversion green emissions of Er3+ yield a relatively-high S r of 1.1% K−1 at 298 K with 980 nm excitation, which can provide self-calibration coupled with down-conversion luminescence temperature sensing mode. Besides, this phosphor also shows tunable luminous colors for the potential application in the anti-counterfeiting field under various excitation wavelengths. [ABSTRACT FROM AUTHOR]

By balancing the luminescent modes of KLSO: yTb3+/xBi3+ phosphors in the fields of thermal response, time resolution and luminescent color, a novel differential display strategy is designed to achieve an anti-counterfeiting application with flexible transition properties. [Display omitted] Optical anti-counterfeiting and encryption have become a hotspot in information security. However, the advanced optical anti-counterfeiting technology still suffers from low security by single-luminescent mode. Herein, we present a novel multi-mode anti-counterfeiting strategy based on K 3 LuSi 2 O 7 : Tb3+/Bi3+ (KLSO: Tb3+/Bi3+) phosphors for the first time. KLSO not only provides various lattice sites for Bi3+ ions occupying to achieve tunable luminescence but can also be non-equivalently substituted by Tb3+ ions to produce persistent or thermo-luminescence. Furthermore, in the pattern "8888" constructed by the mixture of polyacrylic acid (PAA) with KLSO: Tb3+/Bi3+ phosphors, we selectively trigger the three luminescent modes of Bi3+ and Tb3+ ions to realize the design of differential display in the fields of thermal response, time resolution, and luminescence color for optical anti-counterfeiting. The differentiated display can only be presented under specific multi-stimuli response, which further improves the security of information. Our work provides a new insight for designing advanced materials and can be expected to inspire future studies to explore optical anti-counterfeiting technology. [ABSTRACT FROM AUTHOR]

Bi3+/Tb3+/Mn2+-doped Sr 3 Y 2 Ge 3 O 12 phosphors were synthesized, and their luminescence performance was investigated. Upon excitation with UV/NUV, the Sr 3 Y 2 Ge 3 O 12 :Bi3+, Sr 3 Y 2 Ge 3 O 12 :Tb3+ and Sr 3 Y 2 Ge 3 O 12 :Mn2+ phosphors showed prominent cyan, green and red emissions, respectively. Energy transfer processes occur in Bi3+/Tb3+, Bi3+/Mn2+ and Bi3+/Tb3+/Mn2+-codoped Sr 3 Y 2 Ge 3 O 12 phosphors, which leads to tunable luminescence. The calculated CIE coordinates on the basis of the emission spectra indicate that the tunability of the luminescence for the Bi3+/Tb3+-codoped Sr 3 Y 2 Ge 3 O 12 phosphors is not conspicuous. Their light is mainly located in the cyan light region. However, for the Bi3+/Mn2+-codoped Sr 3 Y 2 Ge 3 O 12 phosphors with a fixed Bi3+ concentration of 2 mol% and changing Mn2+ concentration, the emission shifts from the blue light region to the near white light region. After the doping of the Tb3+ ions in the Sr 3 Y 2 Ge 3 O 12 :2%Bi3+/5%Mn2+ phosphors, white light is generated. The CCTs of the light of the Bi3+/Tb3+/Mn2+-codoped Sr 3 Y 2 Ge 3 O 12 phosphors decreased continuously with increasing Tb3+ concentration. Warm white light is generated by the Sr 3 Y 2 Ge 3 O 12 :2%Bi3+/5%Tb3+/5%Mn2+ phosphor. [ABSTRACT FROM AUTHOR]

Single-phase white phosphors have broad application prospects in phosphor-converted white light emitting diodes. Herein, a series of novel single-phase Tm3+/Dy3+ doped Na 5 Lu(WO 4) 4 phosphors were prepared. The detailed investigation of its luminescence behavior showed that Na 5 Lu(WO 4) 4 : x Tm3+, y Dy3+ achieved tunable luminescence through the energy transfer process of Tm3+→Dy3+ at 365 nm excitation. According to the concentration-dependent emission spectra results, the electric dipole-dipole interaction was dominant to be responsible for all the energy transfer processes within the singly- and doubly-doped scenarios. Temperature dependent photoluminescence spectra suggested the excellent thermal stability of Na 5 Lu(WO 4) 4 :9%Tm3+,5%Dy3+ phosphor, of which the luminescence intensity at 421 K and 471 K was only 13.4% and 18.63% lower than that at room temperature, respectively. Finally, Na 5 Lu(WO 4) 4 :9%Tm3+,5%Dy3+ phosphor was packaged with a 365 nm near-ultraviolet LED chip, which exhibited bright blue and yellow emission bands at various bias currents. This work suggests that the developed single-phase Na 5 Lu(WO 4) 4 :Tm3+,Dy3+ phosphors have potential application prospects in the daily lighting field. • Warm white emission color (0.33119,0.33132) is achieved by adjusting Tm3+/Dy3+ ratios in Na 5 Lu(WO 4) 4. • Energy transfer mechanisms between Ln3+ of phosphors are attributed to the electric dipole-dipole interaction. • High thermal stability up to 86% and 81% is observed at 421 K and 471 K, respectively. [ABSTRACT FROM AUTHOR]

Dynamically tuning the emission of circularly polarized luminescence (CPL) materials through external stimuli is fascinating because of their fundamental and application interests. In this work, light‐responsive and luminescence‐tunable CPL‐active materials are synthesized by mixing achiral helical polymer containing vibration‐induced emission (VIE) molecules and spiropyran (SP) with a chiral helical polymer. Through regulating the distinct emission of VIE molecules and the reversible photoisomerization of SP, the dynamic Förster resonance energy transfer (FRET) can be explored to reversibly control the emission color of CPL in different states after light‐controlled isomerization. This project is the first comprehensive investigation of CPL‐active materials with VIE properties. Finally, taking the advantage of the multistimuli responsive CPL signal in different states, an "INHIBIT" logic gate with CPL signal output based on the combination of control of UV/vis light irradiation time and state alternation is constructed. [ABSTRACT FROM AUTHOR]

Ce3+- or/and Dy3+-doped Mg2Al4Si5O18 phosphors have been fabricated via a sintering process at 1400°C for 5 h and their crystallinity and luminescence characteristics investigated. x-Ray powder diffraction analysis demonstrated that Ce3+/Dy3+ ions entered the Mg2Al4Si5O18 host and formed a solid solution. When excited at 345 nm, Ce3+-doped Mg2Al4Si5O18 phosphor emitted light in the blue region while Dy3+-doped Mg2Al4Si5O18 phosphor emitted light in the yellow region. When excited at 345 nm, emission bands located in both the blue and yellow regions were observed for the Ce3+/Dy3+-codoped Mg2Al4Si5O18 phosphor. Because of Ce3+ → Dy3+ energy transfers, the Ce3+/Dy3+-codoped Mg2Al4Si5O18 phosphor showed tunable luminescence, changing from the blue to yellow–green region through the white region with increasing Dy3+ concentration in the Ce3+/Dy3+-codoped Mg2Al4Si5O18 phosphor. The decay characteristics of the Ce3+ emission in the Ce3+/Dy3+-codoped Mg2Al4Si5O18 phosphors were also investigated. With increasing Dy3+ concentration, the lifetime of the Ce3+ emission decreased continuously, further confirming the occurrence of Ce3+ → Dy3+ energy transfer. [ABSTRACT FROM AUTHOR]

Novel borosilicate glasses containing Tb3+/Eu3+ co-doped KY 3 F 10 nanocrystals were manufactured via a traditional melt-quenching route and subsequent heat treatment. The nano-crystal structure was determined by X-ray diffraction (XRD) and its morphology directly observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Enhanced fluorescence intensity of the prepared samples can be obtained with a higher temperature heat treatment, which is ascribed to the embedding of Tb3+/Eu3+ co-doped KY 3 F 10 nanocrystals in the system glass. The effect of Eu3+ concentration on its luminescence was also carried out, and the energy transfer process between Tb3+ and Eu3+ was ascertained through emission spectra and decay curves. It was found that tunable luminescence from green to red can be obtained by controlling Eu3+ concentration in view of red emission of Eu3+ ion and energy transfer process from Tb3+ to Eu3+. The fluorescence relative intensity ratio (FIR) between 545 nm (Tb3+: 5D 4 →7F 5) and 615 nm (Eu3+: 5D 0 →7F 2) in the sample was also highly dependent on the temperature of the environment from measured temperature-dependent spectra, and high sensitivity of 0.24% K-1 can be achieved for the obtained glass ceramics (GCs). Their excellent properties in both chemistry-physics and sensing behavior render them a promising candidate for multicolor display and temperature sensor. [ABSTRACT FROM AUTHOR]

Summary: Supramolecular chemistry is progressively exploited as an effective design tool to organize different types of molecules into unique architectures with precisely controlled structures and functions. The development of luminescent materials constructed by assembly is one of the directions in which supramolecular chemistry plays an important role. The introduction of supramolecular approaches not only simplifies complicated design and time-consuming synthesis of complex and multifunctional molecules but it also endows the materials with the characteristics of luminescence tunability and stimuli responsiveness. Here, we highlight recent progress and emerging directions in the fabrication of artificial assembling systems with luminescence to enrich the concept of “assembling-induced emission.” We hope that this review functions as an aid to understand the emissive mechanism and construct a strategy for various emissive materials based on assembly systems.

In this work, we synthesized a series of novel carbon dots (CDs) by using phenylenediamines (three isomers: o‐phenylenediamine, m‐phenylenediamine, and p‐phenylenediamine) as starting materials via facile solvothermal approach. As‐prepared CDs could emit bright blue, green, yellow, orange, and red light with relatively high PLQY, individually. Optical properties could be controlled by simply varying reaction parameters. The luminescent mechanism was investigated and analyzed in detail. Finally, the blue‐emitting CDs and green‐emitting CDs showed many appealing properties, such as high sensitivity (limit of detection = 4.52 and 3.50 nmol/L), quick response (<2 minutes), broad response window (0‐70 nmol/L), and excellent selectivity for detecting Cr6+ and Al3+ cations, respectively. Thus, they have potential to be developed as the corresponding optical probes. While as‐prepared orange‐emitting CDs could be applied as a bio‐imaging reagent due to its long‐wavelength emission, relatively high PLQY, low toxicity, excellent water solubility, and good biocompatibility. [ABSTRACT FROM AUTHOR]

LaScO3:xBi3+,yTb3+,zEu3+ (x = 0 − 0.04, y = 0 − 0.05, z = 0 − 0.05) phosphors were prepared via high‐temperature solid‐state reaction. Phase identification and crystal structures of the LaScO3:xBi3+,yTb3+,zEu3+ phosphors were investigated by X‐ray diffraction (XRD). Crystal structure of phosphors was analyzed by Rietveld refinement and transmission electron microscopy (TEM). The luminescent performance of these trichromatic phosphors is investigated by diffuse reflection spectra and photoluminescence. The phenomenon of energy transfer from Bi3+ and Tb3+ to Eu3+ in LaScO3:xBi3+,yTb3+,zEu3+ phosphors was investigated. By changing the ratio of x, y, and z, trichromatic can be obtained in the LaScO3 host, including red, green, and blue emission with peak centered at 613, 544, and 428 nm, respectively. Therefore, two kinds of white light‐emitting phosphors were obtained, LaScO3:0.02Bi3+,0.05Tb3+,zEu3+ and LaScO3:0.02Bi3+,0.03Eu3+,yTb3+. The energy transfer was characterized by decay times of the LaScO3:xBi3+, yTb3+, zEu3+ phosphors. Moreover absolute internal QY and CIE chromatic coordinates are shown. The potential optical thermometry application of LaScO3:Bi3+,Eu3+ was based on the temperature sensitivity of the fluorescence intensity ratio (FIR). The maximum Sa and Sr are 0.118 K−1 (at 473.15 K) and 0.795% K−1 (at 448.15 K), respectively. Hence, the LaScO3:Bi3+,Eu3+ phosphor is a good material for optical temperature sensing. [ABSTRACT FROM AUTHOR]

A phase-separated glass is designed to modulate the coordination environments of activators for achieving tunable luminescence in wide wavelength ranges. The luminescent properties and microstructures of Mn2+ doped glasses are carefully investigated. It is found that the luminescence center of Mn2+ is modulated to 620, 588 and 702 nm via the controllable precipitation of K 2 SiF 6 , KZnF 3 and ZnF 2 crystals from the glass networks, respectively. The emissions of Mn2+-Mn2+ dimers centered at 800 nm are also observed when Mn2+ ions are confined in the fluoride crystal coordination environments. The phase-separated glass possesses great potential for providing diverse coordination environments for Mn2+ and is beneficial for the formation of Mn2+-Mn2+ dimers. This glass not only provides a highly promising development of optical gain material for tunable fiber lasers, but the modulation strategy based on phase-separated networks also offers excellent opportunities for manufacturing a wide range of photonic materials featuring multiple-wavelength luminescence. [ABSTRACT FROM AUTHOR]

Double perovskite materials have become the first choice of luminescent matrix materials in recent years due to their advantages of more flexible, easy doping and stable performance. A series of Y 2- x - y Tm x Sm y MgTiO 6 (0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.2) phosphors were prepared by high temperature solid-state method using different concentrations of Tm3+ and Sm3+ as dopants. The X-ray diffraction spectrum (XRD), photoluminescence spectrum (PL), fluorescence lifetime curve and X-ray excitation luminescence spectrum (XEL) of the phosphors were measured. The measurement results show that the dopants Tm3+ and Sm3+ enter the host lattice and replace part of the position of Y3+. The Tm3+ -doped sample emits strong blue light (458 nm) under 360 nm excitation, and the Sm3+ -doped sample has obvious emission peaks at 568 nm, 605 nm, 652 nm and 715 nm under 409 nm excitation. The energy transfer behavior of Tm3+→Sm3+ exists in the double doped samples. The energy transfer mechanism is consistent with the mechanism of concentration quenching in the system. Tunable luminescence can be realized by changing the doping concentration and excitation wavelength, which has great application value in the field of LED lighting. The energy transfer process and energy transfer efficiency in the system can be determined from the fluorescence lifetime curve of the sample. The phosphor can be effectively excited by X-ray, and the sample has good heat resistance and radiation resistance, which can be applied to the field of X-ray imaging. In addition, the thermal excitation effects of temperature on the 4G 5/2 → 6H 5/2 (568 nm) and 4G 5/2 → 6H 7/2 (605 nm) characteristic transitions of Sm3+ are different. Optical temperature measurement can be realized by using the fluorescence intensity ratio of I 568 nm /I 605 nm. Good temperature measurement performance and temperature measurement range have obvious advantages in the field of non-contact optical temperature measurement. • Y 2- x - y Tm x Sm y MgTiO 6 phosphors were successfully prepared and their doping details and cell parameters were obtained. • The energy transfer and tunable luminescence of Y 2- x - y Tm x Sm y MgTiO 6 phosphors were confirmed. • Y 2- x - y Tm x Sm y MgTiO 6 phosphor has good thermal stability and radiation resistance. • Y 2- x - y Tm x Sm y MgTiO 6 phosphor can be used for optical temperature sensing with X-ray. [ABSTRACT FROM AUTHOR]

High-performing lanthanide (Ln3+)-based luminescence thermometry is gaining widespread attention for its remote temperature reading, broad temperature range, high sensitivity, resolution, and stability in various applications. However, facile strategies for constructing multi-mode luminescence thermometry based on a simple material system are still challenging. Herein, we propose a dual-mode single-band ratiometric (SBR) luminescence thermometry based on the tunable Eu3+ luminescence in La 2 (WO 4) 3 (LaWO). Eu3+-doped La 2 (WO 4) 3 (LaWO:Eu) phosphor was synthesized by the high-temperature solid-state method. The rigid lattice of LaWO allows high content of Eu3+ doping without concentration quenching of luminescence, which endows high fluorescence intensity. In addition, in-situ and dynamic regulations of thermal-responsive luminescent properties of Eu3+ are systematically investigated, which enables the construction of SBR luminescence thermometry. At temperatures from 300 to 500 K, the maximum absolute and relative sensitivities reach 0.032 K-1 and 0.85% K−1, respectively. The high sensitivity and stability indicate that our results provide a facile and effective strategy for developing multi-mode luminescence thermometry and hold potential applications in various fields. [Display omitted] • Luminescence thermometry based on La 2 (WO 4) 3 :Eu3+ is reported for the first time. • Dual-mode SBR luminescence thermometry is realized simultaneously. • Tunable luminescence of Eu3+ enable high-performing luminescence thermometry based on a simple material system. [ABSTRACT FROM AUTHOR]

Cu+-activated aluminosilicate oxyfluoride glasses were successfully synthesized by melt-quenching method in air by adding Al powder as a reducing agent. Their luminescent properties were studied systematically via optical absorption, excitation, and emission spectra. Upon UV irradiation, a blue-emitting band of Cu+ was observed in glass with relatively low optical basicity. By increasing the optical basicity of glass, obvious redshifts of excitation (290 → 313 nm) and emission (435 → 470 nm) peaks were obtained. Through enhancing Cu+ content, the excitation and emission bands presented further redshifts, which shifted from 313 to 338 nm and 470 to 560 nm, respectively. It is proposed that the absorption band and emitting color of Cu+-doped glass can be tuned by changing the optical basicity of glass and Cu+ concentration. The highest quantum yield can reach 62.5%. More importantly, an investigation of the thermal stability showed that over 85% of the room temperature luminescent intensity is preserved at 200°C. These results imply that Cu+-activated aluminosilicate oxyfluoride glasses may be utilized for UV-converted W-LEDs.

In this study, high-quality single crystalline Mn-doped CdS nanosheets were synthesized by the chemical vapor deposition method and their photoluminescence (PL) properties were determined. Energy dispersive X-ray analysis, the non-uniform peak shifts in the Raman spectra, and micro-PL mapping demonstrated the presence of Mn ions in the nanosheets. The temperature-dependent (78–400 K) micro-PL spectra showed that the multi-peak emissions ranged from 455.302 to 749.901 nm. The band-edge emission exhibited a pronounced red shift (∼8 nm) as the temperature increased from 78 to 400 K due to the formation of exciton magnetic polarons (EMPs). The orange emission (597.621 nm) was due to the 4T 1 (4G) → 6A 1 (6S) d–d transition between the excited state and ground state of Mn2+. The shorter lifetimes compared with the forbidden d-d transition and deep traps due to structural relaxation confirmed that the red (670.832 nm) and near-infrared (749.901 nm) emissions were associated with localized EMPs. The PL emission centered at 471.780 nm appeared at 80 K due to free-exciton C (FXC). Emissions centered at 455.302 and 463.501 nm were detected for the first time in our samples. Interestingly, both of these emissions appeared on the higher energy side of FXC and unlike EMP, they did not follow the Varshni function. Therefore, we assigned these emissions to bound magnetic polarons. These novel emissions in dilute magnetic semiconductors could be beneficial for further applications in photovoltaics, full-color displays, and nanoscale devices. • Synthesis of Mn-doped CdS nanosheets via chemical vapor deposition. • Photoluminescence (PL) peaks from 455.3 to 749.9 nm covered blue to near-infrared. • PL peaks centered at 455.3 and 463.5 nm detected in CdS system for first time. • Both emissions on higher energy side of FXC and did not follow Varshni function. • Novel emissions in DMS could have applications in full color displays. [ABSTRACT FROM AUTHOR]

A series of Ce3+/Tb3+/Eu3+ singly doped, codoped and tri-doped Ca 2 MgSi 2 O 7 phosphors were prepared by a solid state reaction. The XRD patterns suggest that the rare earth ions have doped into Ca 2 MgSi 2 O 7 hosts entirely and formed phosphors with a single phase. To investigate the energy transfer of Ce3+ → Tb3+ → Eu3+, the excitation and emission spectra of the prepared Ce3+/Tb3+/Eu3+ singly doped, codoped and tri-doped Ca 2 MgSi 2 O 7 phosphors were measured. The excitation and emission spectra of Ce3+/Tb3+/Eu3+ singly doped Ca 2 MgSi 2 O 7 phosphors show that the Ce3+ emission band overlaps with the excitation bands of Tb3+ and Eu3+, and the emission bands of Tb3+ overlap with the excitation bands of Eu3+. The emission spectra of Ce3+/Eu3+, Ce3+/Tb3+ and Tb3+/Eu3+ codoped phosphors demonstrate that the Ce3+ → Eu3+ energy transfer is forbade but the Ce3+ → Tb3+ and Tb3+ → Eu3+ energy transfers occur. The emission spectra of Ce3+/Tb3+/Eu3+ tri-doped Ca 2 MgSi 2 O 7 phosphors demonstrate the energy transfer from Ce3+ to Eu3+ could be obtained through the Tb3+ chain. [ABSTRACT FROM AUTHOR]

The influence of the nature of linear acrylic polymers differing in the concentration of hydroxyl groups on the spectral-luminescent properties of a hybrid compound, the molecule of which combines two different luminophore fragments, namely, hydroxy-substituted 2,4,5-triarylimidazole and 8-azomethine-7-hydroxycoumarin, and model compounds corresponding to these fragments, is studied. The optimum conditions for the preparation of acrylic polymers containing the luminophores under study by photocuring are selected. The dependence of the luminescent properties of the materials on the number of hydroxyl groups is established. [ABSTRACT FROM AUTHOR]

A novel rare-earth (RE) free feldspar glass-ceramic phosphor has been designed by a fast sintering route, following a conventional ceramic process. In this work, it is studied how subtle chemical modifications of structural elements may affect luminescence behaviour in this novel matrix. These cation additions acting as glass network former and as modifiers, 1 wt % of SiO 2 and CaCO 3 or Na 2 CO 3 , respectively, produce a photoluminescence enhancement up to 200%. Whereas, addition of Al 2 O 3 , a glass network former, decreases the photoluminescence emission. Raman spectroscopy evinces a correlation between photoluminescence emission and the Al,Si disorder at microscopic scale. These findings open a new challenge in order to obtain larger structural disorder to make this RE free glass-ceramic much more powerful for future optical applications, highlighting for security markers or light emitting glasses. This new phosphor might be considered as a more sustainable and low-cost alternative to RE phosphors. [ABSTRACT FROM AUTHOR]

Abstract Sc 2 W 3 O 12 is an important host matrix for rare-earth doped luminescence. However, the conventional method to prepare the material is solid-state reaction, which results into coarse and irregular morphologies. In this work, Eu3+ doped Sc 2 W 3 O 12 phosphors with high crystallinity and pure phase were successfully synthesized via one-step hydrothermal method. It was found that the crystalline phase changed from Sc 2 W 3 O 12 phase to Na 4 Sc 2 (WO 4) 5 phase when the molar ratio between Sc(NO 3) 3 and Na 2 WO 4 decreased. The temperature-dependent X-ray diffraction analysis was performed to prove the negative thermal expansion property of Sc 2 W 3 O 12. A systematic study on the effect of reaction time, temperature and Eu3+ doping concentration was explored. It was also found that the as-prepared samples displayed tunable emission colors, ranging from blueish white to orange red. Particularly, the white light emission with the chromaticity coordinate of (0.3395, 0.3289) can be realized in Sc 2 W 3 O 12 : 5% Eu3+. What's more, the photoluminescence properties of the samples were investigated under different ambient temperatures between 97 and 280 K. The result clearly showed energy transfer between Eu3+ and WO 4 2−. The above results suggested that Sc 2 W 3 O 12 :Eu3+ can be excellent candidate for solid-state lasing, panel display and WLEDs. [ABSTRACT FROM AUTHOR]

Abstract This paper demonstrates that a highly thermal stable and tunable-luminescence phosphors Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ with efficient energy transfer, which is prepared by the high-temperature solid-state reaction. First-principles method is performed to analyze the electronic structures, band structure, density of states and formation energy of Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+. For high luminescence output, Y 3- x Al 2 Ga 3 O 12 : x Tb3+ and Y 3- y Al 2 Ga 3 O 12 : y Eu3+ with high concentration quenching (x = 0.5 and y = 0.7) are achieved. The effect of energy transfer from Tb3+ to Eu3+on emission color tuning and luminescence thermal stability is studied. The energy transfer efficiency from Tb3+ to Eu3+ reaches as high as 74.2% and emission color can be tuned from green, yellow and red by adjusting the ratio of Tb3+/Eu3+. What's more, Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ phosphor exhibits a good thermal stability, of which emission intensity still keeps 60% at 150 °C. Highlights • The color-tunable emission is obtained by adjusting the ratio of Eu3+ and Tb3+. • The energy transfer mechanism of Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ is discussed in detail. • Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ phosphor show high thermal stabilities. [ABSTRACT FROM AUTHOR]

Abstract A series of Ca 5 (BO 3) 3 F: Tb3+/Eu3+ phosphors have been prepared via solid-state reaction. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements. The emission intensity of Ca 5 (BO 3) 3 F: Tb3+ with Li+, Na+, K+ as charge compensators are remarkably enhanced, and the sample in presence of Na+ exhibits the strongest emission intensity. The emission spectra and fluorescence decays confirm the presence of efficient energy transfers from Tb3+ to Eu3+ in Ca 5 (BO 3) 3 F: Tb3+/Eu3+ phosphors. The energy transfer mechanism between Tb3+ and Eu3+ has been proven to be resonant type via the electric dipole-dipole interaction. The thermal quenching temperature T 50 obtained from the temperature-dependent emission spectra is 478 K, demonstrating a high thermal stability of the as-obtained Ca 5 (BO 3) 3 F: Tb3+/Eu3+ phosphors. Moreover, by increasing the molar ratio of Eu3+ to Tb3+, the emission colors of Ca 5 (BO 3) 3 F: Tb3+/Eu3+ phosphors can be tuned from green to orange, and then to red. These results demonstrate that the as-obtained Ca 5 (BO 3) 3 F: Tb3+/Eu3+ phosphors may have potential applications in solid-state lighting fields. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract In this work, a series of photoluminescent materials have been synthesized based on optically transparent and chemically stable glasses of the nominal composition Na 3 Al 2 (PO 4) 2 F 3 (NaF–Al 2 O 3 –P 2 O 5 system) doped with 1 wt% of europium. It has been shown that the synthesis conditions (mainly the temperature and duration of the melting stage under reducing conditions) strongly affected the photoluminescence spectra of the material. This effect has been ascribed to varying proportions between Eu3+ and Eu2+ ions concentrations, imposed by the synthesis conditions, which was confirmed by XPS, absorption and decay times measurements. As both Eu3+ and Eu2+ centers exhibit photoluminescence in different ranges of the visible spectra (Eu3+ – red, and Eu2+ – mainly blue) the possibility, shown by us, to control relative proportions of the oxidation states of europium and consequently to control the photoluminescence spectra, may be advantageous from the viewpoint of potential applications of such materials as novel phosphors for white LEDs with the emission spectra resembling natural light. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract In this work, Pr3+ and Tb3+ coactivated Na 5 Gd(WO 4) 4 (NGW) phosphors have been synthesized by high-temperature solid-state reactions and the scheelite crystal structure was determined for the first time. A color-tunable emission in NGW: Pr3+, Tb3+ phosphors can be realized by the modulation of excitation wavelengths, namely, the fluorescence intensity ratio of Pr3+ to Tb3+ in this material could be changed by different excitation. With increasing temperature, the luminescence of NGW: Pr3+, Tb3+ phosphor decreases almost linearly with the CIE coordinate variation from (0.306, 0.392) to ((0.375, 0.465) and result in the color of the photoluminescence variation from the blue-green to yellow. These results demonstrated that the investigated phosphors are attractive for application in display lighting and optical temperature sensing. Highlights • A novel phosphor Na 5 Gd(WO 4) 4 : Pr3+, Tb3+ has been synthesized. • The scheelite crystal structure of Na 5 Gd(WO 4) 4 was determined for the first time. • The color-tunable emission properties of Na 5 Gd(WO 4) 4 : Pr3+, Tb3+ have been realized. • Na 5 Gd(WO 4) 4 : Pr3+, Tb3+ phosphor shows high thermostability. [ABSTRACT FROM AUTHOR]

Abstract The Sr (1- x) Al 2 O 4 : x Eu3+ (0 ≤ x ≤ 5.0%) phosphors were synthesized by solid state reaction method. They crystallized in monoclinic structure and well consistent with that of JCPDS No.34–0379. Thermal and compositional analysis was described in detail. The photoluminescence excitation spectra were recorded monitoring the emission at 612 nm corresponding to the Eu3+: 5D 0 → 7F 2 transition. The photoluminescence excitation spectrum of undoped SrAl 2 O 4 consists of a broad band with maximum at 278 nm, while the Eu3+ -doped phosphors contain similar broad band of lower intensity and Eu3+ characteristic bands. The photoluminescence properties were analyzed by exciting the studied phosphors at 278 nm (within the host) and at 395 nm (within the Eu3+) wavelengths. The SrAl 2 O 4 :Eu3+ phosphors show bluish-pink luminescence at 278 nm excitation and concentration dependent luminescence at 395 nm excitation. The local site symmetry of the host material around the Eu3+ ions was studied by calculating the Judd-Ofelt intensity parameters using the Eu3+: 5D 0 → 7F J (J = 1, 2 and 4) transitions. The experimental results show that the SrAl 2 O 4 : Eu3+ phosphors are potential for solid state lighting and display devices. Highlights • SrAl 2 O 4 :Eu3+ phosphors were crystallized into monoclinic structure. • SrAl 2 O 4 :Eu3+ phosphors exhibit bluish-pink luminescence at 278 nm excitation. • SrAl 2 O 4 :Eu3+ phosphors exhibit tunable luminescence at 395 nm excitation. • SrAl 2 O 4 : Eu3+ phosphors are potential for solid state lighting and display devices. [ABSTRACT FROM AUTHOR]

Abstract A series of isostructural lanthanide metal-organic frameworks (LnMOFs), [Eu x Tb 1-x L(DMF) 2 (NO 3)] (Tb-MOF for x = 0; Eu-MOF for x = 1; Eu x Tb 1-x -MOF for x = 0.001, 0.005, 0.01, 0.05, 0.07 and 0.09, H 2 L =2, 2′- bipyridine-4, 4′-dicarboxylic acid) have been obtained under solvothermal conditions by adjusting the ratio of Eu3+ to Tb3+. The emission colors of the series of LnMOFs have been tuned from green to red due to the energy transfer from Tb3+ to Eu3+ ions. Furthermore, the luminescent sensing performances of the LnMOFs for hazardous phenolic compounds and pH values were studied. The results revealed that the LnMOFs can be used as luminescent sensors for selective detection β-naphthol and pH in the range of 6–1. The sensing mechanism for β-naphthol may be due to the absorption competition of the energy between the LnMOFs and β-naphthol. The different protonation levels of the uncoordinated pyridine nitrogen atom with varying pH may be the reason for the pH dependent effect. In addition, the photocatalytic activities of the LnMOFs for degradation of Rhodamine (RhB) were also studied. The results demonstrate that the LnMOFs have the efficient photocatalytic performances under UV light irradiation and show good stabilities. Graphical abstract The LnMOFs can be used as luminescent sensors for selective detection β-naphthol and pH in the range of 6–1. In addition, the LnMOFs display the high photocatalytic activities for degradation of RhB under UV light irradiation. fx1 [ABSTRACT FROM AUTHOR]