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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]

A series of color-tunable warm white-emitting phosphors Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+,Eu3+ were synthesized and characterized for their crystal structure, luminescence properties, thermal stability, fluorescence decay and energy transfer mechanism. The results show that the optimal excitation wavelength and doping concentration of Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+ phosphor are 350 nm and 0.05 mol%, respectively, and its concentration quenching is mainly caused by the interaction between nearest neighbor ions. Under the excitation at 350 nm, the Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+,Eu3+ phosphor showed prominent emission peaks at 471 nm, 576 nm and 622 nm. The photoluminescence spectrum and lifetime decay curves confirmed the presence of Dy3+→Eu3+ energy transfer in Ca 3 Y(AlO) 3 (BO 3) 4. The phosphor of Ca 3 Y 0·85 (AlO) 3 (BO 3) 4 :0.05Dy3+,0.1Eu3+ exhibited remarkable thermal stability and could maintain 87.68% of the emission intensity at 150 °C. By adjusting the doping ratio of Dy3+ and Eu3+ ions, the CIE coordinates and the related color temperature of Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+,Eu3+ phosphors can be adjusted. The w-LED device packaged with Ca 3 Y 0·85 (AlO) 3 (BO 3) 4 :0.05Dy3+,0.1Eu3+ phosphor can emit warm-white light (Tc = 3284 K, Ra = 72.7). These results suggest that Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+,Eu3+ phosphor can provide a potential alternative for the warm w-LED market. [Display omitted] • Synthesis of Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+, Eu3+ phosphors was successful. • The energy transfer between Dy3+ and Eu3+ in Ca 3 Y(AlO) 3 (BO 3) 4 was studied. • Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+, Eu3+ co-doped phosphors display exceptional thermal stability. • The CCT and color coordinates of warm white Ca 3 Y(AlO) 3 (BO 3) 4 :Dy3+, Eu3+ phosphors can be modified. [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]

Thermal quenching is a serious drawback that limits the application of phosphor-converted white light-emitting diodes (pc-WLEDs), because the operating temperature of phosphors tends to increase, resulting in emission loss due to non-radiative transitions. Herein,by introducing Lu3+ ions and Eu3+ ions into YBO 3 to create lattice distortion and cation disorder, a series of Lu 1-x Y 3 (BO 3) 4 : xEu3+ red phosphors have been designed to obtain novel phosphors with excellent thermal stability. The phosphors were synthesized by the traditional high-temperature solid-phase method. XRD results and EDS energy spectrum access the phase composite and crystal structure. Under 393 nm excitation, Lu 1-x Y 3 (BO 3) 4 : xEu3+ phosphors emit red light peaking at 594 nm, 613 nm, and 651 nm Lu 0.6 Y 3 (BO 3) 4 :0.4Eu3+ and Lu 0.2 Y 3 (BO 3) 4 :0.8Eu3+ can maintain 93% and 86% emission intensity respectively at 150 °C, and they can still maintain 90.2% and 78% respectively at 200 °C. Thermoluminescence spectroscopy proves that the Lu 0.2 Y 3 (BO 3) 4 :0.8Eu3+ phosphor has deep defects at 145 °C and 400 °C, which can release electrons to compensate for the emission intensity at high temperatures, thereby improving thermal stability.The prepared phosphor has extremely high thermal stability and particularly high color rendering purity (99.8%). Under the driving current of 120 mA, the color rendering index of the pc-WLED packaged with Lu 0.2 Y 3 (BO 3) 4 :0.8Eu3+ phosphor powder is 89.4, and the correlated color temperature is 4681K.All these results indicate that LuY 3 (BO 3) 4 :Eu3+ phosphors are promising for pc-WLED applications, especially for applications requiring high temperature operating conditions. • A novel red phosphor LuY 3 (BO 3) 4 :Eu3+ has been synthesized. Lu 1-x Y 3 (BO 3) 4 :xEu3+ phosphors were successfully synthesized. • Creating cation disorder and deep defects can enhance thermal stability. • The prepared phosphors have excellent thermal stability. • Lu 1-x Y 3 (BO 3) 4 :xEu3+ color purity can reach more than 99.8%. [ABSTRACT FROM AUTHOR]

Phosphors are regarded as the crucial functioning part of white light-emitting diodes (WLEDs). Silicate-based phosphors have enjoyed numerous attentions for decades due to their varied crystal structures and high chemical stability, as well as their great application potentials. In this work, a novel cyan-emitting phosphor Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ is synthesized via a high-temperature solid-state method. The phase purity was first verified by X-ray diffraction (XRD) analyses, and its structure was further solved by Rietveld refinement. The photoluminescence characteristics were investigated in detail by employing diffuse reflectance spectroscopy (DRS), fluorescence spectroscopy, and other characterization methods. The results evidence that the optimal doping concentration of Eu2+ is ∼4 mol%. The fundamental band gap of Ba 2 La 8 (SiO 4) 6 O 2 :4mol%Eu2+ is estimated to be approximately 2.91 eV, which provides sufficient space to accommodate activators like Eu2+. The CIE coordinates lie in the cyan region, which allows Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ to efficiently fill into the missing cyan emission in conventional WLED devices. As a proof-of-concept experiment, a prototype WLED device was then assembled, which suggests that the introduction of Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ could lead to an increased color rendering index from 87 to 92. These results imply that the Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ phosphors show great potential in full-spectrum WLEDs application. • The novel cyan-emitting phosphor Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ was obtained via a typical high-temperature solid-state method. • The structure of Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ phosphor, including the incorporation sites of Eu2+ into the host, were investigated. • The optical properties of Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+ cyan-emitting phosphor were investigated carefully. • Thanks to the additional cyan component from the Ba 2 La 8 (SiO 4) 6 O 2 :Eu2+, the color rendering index of the WLED has boosted. [ABSTRACT FROM AUTHOR]

Thermal quenching is one of the most critical challenges for the application of materials under high temperatures. Particularly, BaMgAl 10 O 17 :Eu2+ (BAM) has been well considered the preferred blue-emitting phosphor in tricolor fluorescent lamps, plasma display panels (PDP), and many other lighting and display devices due to its excellent luminescence efficiency and satisfactory chromaticity. However, its wide application range is still constrained by two major problems. Firstly, the synthesis temperature for BAM is too high. Commercial BAM materials are typically prepared with high-temperature solid-phase methods over 1550°Ctemperatures. Secondly, co-solvent, which is added during the synthetic process to dissolve the solid phases, is prone to thermal deterioration. To tackle these problems, we propose the cationic substitution method combined with co-solvent-assisted sintering to improve the thermal stability of BAM. In the end, we obtained a novel BAM material with a comparably lower synthesis temperature and satisfactory thermal stability. In our work, the thermal stability of BAM synthesized with 5% boric acid substituted by 0.08 mol Ca2+ was significantly higher compared with that synthesized without calcium substitution. Additionally, the activation energies (Δ E) of Ba 0.92 Ca 0.08 MgAl 10 O 17 :Eu2+ and Ba 0.92 Sr 0.08 MgAl 10 O 17 :Eu2+ were calculated to be approximately 0.26 eV and 0.35 eV, respectively, indicating that the BAM substituted with Sr2+ is more thermally stable. • Cationic substitution combined with co-solvent assisted sintering method is used to decrease the thermal deterioration. • The synthesis temperature of the as-prepared materials is reduced by nearly 300°, which can save a lot of energy consumption and cost for production. • By replacing Ba2+ with Ca2+ and Sr2+,the luminescence intensity of the fluorescent sample was greatly improved. [ABSTRACT FROM AUTHOR]

• K 3 ScF 6 :Cr3+ can be excited by blue light, leading to a broadband NIR emission. • K 3 ScF 6 :Cr3+ retain 87.3% of their initial emission intensity at 150 °C. • The fabricated NIR-LED based on K 3 ScF 6 :Cr3+ has good photoelectric efficiency. • NIR-LED based on K 3 ScF 6 :Cr3+ can be applied in night vision imaging systems. Broadband near-infrared light (NIR) near 800 nm has broad application prospects in food detection and night vision monitoring. Compared with NIR chips, NIR phosphors have distinct advantages, including low cost, a mature synthesis process, and tunable combination. However, at present, oxide NIR phosphors have some disadvantages, such as a narrow full width at half maximum (FWHM), poor thermal stability, and low photoelectric efficiency. Herein, K 3 ScF 6 :Cr3+ NIR phosphors with a cubic structure were synthesized using the hydrothermal method. These phosphors can be effectively excited by blue light (430 nm) and red light (630 nm), leading to a broadband Cr3+ emission from 650 nm to 950 nm with a large FWHM of 430 nm. They also exhibit excellent thermal stability and retain 87.3% of their initial intensity at 150 °C. Under a driving current of 100 mA, their photoelectric efficiency can reach 9.315% of that of fabricated NIR light-emitting diodes (NIR-LED). An NIR-LED device based on this phosphor can thus be implemented in night vision imaging systems. [ABSTRACT FROM AUTHOR]