摘要：
During the process of developing commercial chips, the phosphors with single broadband emission are indispensable. In this report, a new ternary phosphate phosphor Na3Ba2Ca(PO4)(3):Eu2+ has been successfully synthesized by the high-temperature solid-state reaction (HSSR) method, which shows broad emitting band in the range of 350-600 nm centered at 436 nm (FWHM similar to 72.3 nm). The crystal structure of the Na3Ba2Ca(PO4)(3) and Eu2+ doped Na3Ba2Ca(PO4)(3) were determined by the Rietveld method, indicating the trigonal system with P31c space group. The selective two-site occupancy tendency of Eu2+ ions at Ba1O(9) and Ca2O(8) sites in the matrix was comprehensively revealed according to the split peaks (433 nm and 469 nm) at 298 K and 11 K, computational validation and fluorescence lifetime analysis of photoluminescence spectrum. Impressively, the optimal Na3Ba2Ca(PO4)(3):0.02Eu(2+) phosphor exhibits appropriate spectrum resemblance (SR) indexes (58.5% and 72.2%), proper thermostability (78.6%) and excellent chromaticity stability (Delta x = 8.68 x 10(-6) and Delta y = 3.64 x 10(-5)). Besides, the phosphor prepared by HSSR owns the higher internal quantum efficiency of 62.1% in comparison with that synthesized by polymerizable complex (PC) method. The new phosphor can serve as a potential broadband and blue-emitting phosphor for the application of solid-state lighting and plant growth.
摘要：
The new dual-emitting and color tunable single phase of Na2BaSr(PO4)(2):0.03Eu(2+), xMn(2+) (NBSP:0.03Eu(2+), xMn(2+)) phosphor are successful prepared in this work. The phase purity and photoluminescence properties are investigated. Regarding to the coordination, valence and cation radius, the Eu2+ ions occupy the Sr2 and Sr3 site and Mn2+ ions occupy the Sr3 site. According to the photoluminescence (PL) spectra of NBSP:0.03Eu(2+), xMn(2+) (x = 0-0.09), the strong energy transfer (ET) between Eu2+ and Mn2+ exists in these phosphors. The strong ET efficiency from Eu2+ to Mn2+ is as high as 92%, while the ET mechanism of Eu2+ and Mn2+ is quadrupole-quadrupole interaction. Moreover, the CIE coordinate of Eu2+ and Mn2+ co-doped Na2BaSr(PO4)(2) phosphors can realize the color tunable emission from blue to cold white. The temperature dependent photoluminescence intensity of NBSP:0.03Eu(2+), 0.05Mn(2+) phosphor still keeps 75.8% of that initial intensity when the temperature is 150 degrees C. In summary, the NBSP:0.03Eu(2+), xMn(2+) phosphors have a promising application in white light LED.
摘要：
Using functional phosphors that have a range of benefits, such as quick response to n-UV/blue light excitation, high quantum efficiency and low thermal quenching is crucial. In this work, we have utilized the traditional high-temperature solid-state reaction to synthesized Ce3+, Tb3+ single- and co-doped KBaBP2O8 (KBBPO) phosphors. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the luminescence properties and energy transfer process from Ce3+ to Tb3+ were investigated in details. Due to the Ce3+ can adequately sensitize Tb3+, the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The emission color chromaticity for the various KBBPO phosphors varies from dark blue to bright green with the increased concentration of Tb3+. The energy transfer mechanism between Ce3+ and Tb3+ is dominated by the exchange interaction, while the efficiency of the energy transfer is calculated as 59.29%. The optimal KBaBP2O8: 0.02Ce3+, 0.05 Tb3+ phosphor demonstrated low thermal quenching, which only reduces 19.3% of the initial intensity at 150 degrees C. The new KBaBP2O8: Ce3+, Tb3+ phosphor will be a potential candidate for widecolor-gamut display backlights.
作者机构：
[Xie, Guodong; Si, Jiayong; Cai, Gemei] Coll Mech & Elect Engn, Cent South Univ Forestry & Technol, Changsha 410004, Hunan, Peoples R China.;[Si, Jiayong; Cai, Gemei; Li, Guihua] Sch Mat Sci & Engn, Cent South Univ, Changsha 410083, Hunan, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China<&wdkj&>College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
摘要：
Investigating the phosphors doped with single activators in a single component to realize white-light emission is urgently desired for phosphor-converted white-light-emitting diodes. In this work, on the basis of the chemical unit cosubstitution strategy, the new borophosphate phosphors Ba(3)CaK(PO(4))(3-x)(BO(3))(x):0.02Eu(2+) with a mixed anion group were prepared. Coupling structure refinement and photoluminescence analyses, Ba(3)CaK(PO(4))(3-x)(BO(3))(x) consists of five different cationic sites with different coordination environments, with Eu(2+) occupying the three sites for Ba(2+). In the process of partial substituting (BO(3))(3-) for (PO(4))(3-), because of the greatly distorted coordination field generated from the difference in the geometric configurations between the two anion groups, a red shift and broadening of the emission bands occurs, resulting in a color-adjustable emission from blue to white. A phosphor-converted light-emitting diode has been successfully fabricated with the incorporation of an as-prepared Ba(3)CaK(PO(4))(2.6)(BO(3))(0.4):0.02Eu(2+) phosphor and a 405 nm near-ultraviolet chip, which exhibits Commission International de I'Eclairage chromaticity coordinates of (0.31, 0.37) and a correlated color temperature of 6295 K. As demonstrated in the present work, an approach adopted from phosphate to borophosphate is conducted to develop high-quality phosphors.
期刊：
Journal of Alloys and Compounds,2022年927:167045 ISSN：0925-8388
通讯作者：
Jiayong Si<&wdkj&>Gemei Cai
作者机构：
[Si, Jiayong; Zhang, Jing] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Cai, Gemei; Huang, Junben; Li, Guihua] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Zhou, Tianliang] Xiamen Univ, Coll Mat, Xiamen 361005, Fujian, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China<&wdkj&>College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
摘要：
Exploring for red-emitting phosphor materials with supper property plays a key role in the development of white light-emitting diodes (WLEDs). Simultaneously, the crystal structure has a crucial effect on its lu-minescence properties. In this work, we synthesized a type of new red-emitting Li4Ca2B8O16: Eu3+ phosphor via the solid-state reaction. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the correspondence between local symmetry and luminescence properties were investigated in detail. Under the optimal 393 nm excitation, Li4Ca2B8O16: 0.33Eu3+ shows a strong red emission located at 612 nm ascribed to the 5D0 -> 7F2 transition of Eu3+. The calculated Judd-Ofelt parameters (& UOmega;2 and & UOmega;4) have clarified that Eu3+ has lower symmetry without an inversion center, resulting in the high value of R/O (the emission intensity ratio of 5D0 & RARR;7F2 to 5D0 & RARR;7F1) of 7.95 at x = 0.33 mol. The Li4Ca2B8O16: 0.33Eu3+ phosphor exhibits a high color purity of 94.99% with the chromaticity coordinates of (0.6547, 0.3449), perfect internal quantum efficiency (99.75%) and excellent thermal stability at high temperature (90.91% at 150 ?). The results indicate that this new Li4Ca2B8O16: Eu3+ phosphor can be used as the potential red component for pc-WLEDs.(c) 2022 Elsevier B.V. All rights reserved.
期刊：
Journal of Alloys and Compounds,2022年911:165092 ISSN：0925-8388
通讯作者：
Jiayong Si<&wdkj&>Gemei Cai
作者机构：
[Si, Jiayong; Zhang, Zhizhong; Tang, Jiamin] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Cai, Gemei; Li, Guihua] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Zhou, Tianliang] Xiamen Univ, Coll Mat, Xiamen 361005, Fujian, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China<&wdkj&>College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
摘要：
High thermal stability and quantum efficiency are the two very significant factors for phosphors when concerning all kinds of related applications. Therefore, it is still main research topics as long as referencing to the luminescence phosphors. It is well known that deep trap and large band gap are beneficial to excellent thermal stability. In this work, a series of Na2BaCa1-xSrx(PO4)2:0.03Eu(2+) phosphors have been prepared by traditional solid state reaction. When the Sr2+ content increases, the emission intensity exhibits a blue shift phenomenon with the highest peak around 448 nm caused by the varied centroid shift (epsilon(c)) and the crystal field splitting (epsilon(cfs)). The thermal stability of Na2BaCa0.2Sr0.8(PO4)(2):0.03Eu(2+) phosphor still approaches to 100.3% of that room temperature at 150 degrees C, while the external and internal quantum efficiency are greatly enhanced from 19.92% to 62.53%. It is due to the effect of the cation disorder by introducing the high level of Sr ion, which create the deep trap and broaden the bandgap, resulting in the anti-thermal quenching behavior and enhanced quantum efficiency. Moreover, Rietveld refinements, microstructure, decay curves and thermoluminescence are also adopted to shed light on related mechanism of luminous performance. Furthermore, a pc-WLED device has been fabricated through Na2BaCa0.2Sr0.8(PO4)(2):0.03Eu(2+) blue phosphor mixed with commercial yellow phosphor (SrSi2O2N2:Eu2+) and red phosphor (Sr2Si5N8:Eu2+), which performs a color temperature of 4721 K with a high color rendering index of Ra = 91.9. In view of zero thermal quenching and favorable quantum efficiency, this new phosphor is a prospect candidate for blue phosphors in WLED application. Further, the work provides a new method and reference for the great enhancement of thermal stability and quantum efficiency of luminescence materials. (C) 2022 Elsevier B.V. All rights reserved.
作者机构：
[Si, Jiayong; Fan, Xiaoyi; Tang, Jiamin] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Peoples R China.;[Cai, Gemei; Liu, Yijia; Li, Guihua] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>School of Materials Science and Engineering, Central South University, Changsha 410083, China
摘要：
A series of single Ce3+ doped and Ce3+ and Tb3+ co-doped Na2BaCa(PO4)(2) (NBCP) phosphors was synthesized by conventional solid-stated reaction method. The crystal structure, luminescence properties, thermal stability and energy transfer were carefully investigated. Ce3+ is inferred to substitute the Ba2+ site in NBCP lattice. The color-tunable emission from blue to green is observed by adjusting Tb3+ concentration among NBCP:0.03Ce(3+),yTb(3+) phosphors. The energy transfer behavior from Ce3+ to Tb3+ ions is both illustrated by co-doped PL spectra and decay curves. The energy transfer efficiency is as high as 91.5%. The mechanism of energy transfer is resonance type of dipole-dipole transition. In this work, the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150 degrees C. The Ce3+ and Tb3+ co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields. (c) 2021 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.
期刊：
Journal of Luminescence,2022年252:119291 ISSN：0022-2313
通讯作者：
Jiayong Si<&wdkj&>Gemei Cai
作者机构：
[Si, Jiayong; Tang, Jiamin; Wu, Di] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Cai, Gemei; Li, Guihua] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan, 410004, China<&wdkj&>School of Materials Science and Engineering, Central South University, Changsha, Hunan, 410083, China
摘要：
In order to investigated the new single-component white light emitting phosphate, Tm3+/Dy3+ doped KBaIn2(PO4)3 (KBIP) were successfully synthesized by solid state reaction. The structures of the compounds were investigated by XRD technique and Rietveld refinement methods. The luminescence properties were acquired and carefully analyzed. Meanwhile, the energy transfer process of Dy3+ and Tm3+ co-doped KBIP were inves-tigated in detail. The KBIP: 0.05Dy3+ phosphor can obtain the single neutral white with the chromaticity co-ordinate of (0.3218, 0.3307) and CCT value of 6018 K, while the emitting color of Dy3+ and Tm3+ co-doped KBIP could be adjusted from blue to near white. Furthermore, the overall integral intensity at 150 degrees C of 0.05 Tm3+ and 0.05Dy3+ co-doped KBIP is 80.5% of that at 25 degrees C. The results are indicate Dy3+/Tm3+ doped KBIP phosphors own potential application in future wLEDs.
作者机构：
[Si, Jiayong; Fan, Xiaoyi; Xu, Mengjie; Tang, Jiamin] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Cai, Gemei; Li, Guihua] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.
通讯机构：
[Jiayong Si] C;[Gemei Cai] S;College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan, 410004, People’s Republic of China<&wdkj&>School of Materials Science and Engineering, Central South University, Changsha, Hunan, 410083, People’s Republic of China
摘要：
The development of novel single-component white-emitting phosphors with high thermal stability is essential for improving the illumination quality of white light-emitting diodes. In this work, we synthesized a series of Ce3+, Tb3+, Mn2+ single- and multiple-doped Ca9La(PO4)7 (CLPO) phosphors with β-Ca3(PO4)2-type structure by the simple high-temperature solid-state reaction. The crystallization behavior, crystal structure, surface morphology, photoluminescence performance, decay lifetime and thermal stability were systematically investigated. The PL spectra and decay curves have evidenced the efficient energy transfer from Ce3+ to Tb3+ and from Ce3+ to Mn2+ in the CLPO host, and corresponding energy transfer efficiency reaches 41.8% and 54.1%, respectively. The energy transfer process of Ce3+→Tb3+ and Ce3+→Mn2+ can be deduced to the resonant type via dipole-dipole and dipole-quadrupole interaction mechanism, and corresponding critical distance were determined to be 12.23 and 14.4 Å, respectively. Based on the efficient energy transfer, the white light emission can be successfully achieved in the single-component CLPO:0.15Ce3+, 0.10Tb3+, 0.04Mn2+ phosphor, which owns CIE chromaticity coordinates of (0.3245, 0.3347), CCT of 5878 K, internal and external quantum efficiency of 84.51% and 69.32%. Especially, compared with the emission intensity at 25 °C, it still remains 98.5% at 150 °C and 92.0% at 300 °C. Based on these results, the single-component white light emission phosphor CLPO:0.15Ce3+, 0.10Tb3+, 0.04Mn2+ is a potential candidate for UV-converted white LEDs.
作者：
Xu, M. J.;Si, J. Y.*;Li, G. H.;Liu, Y. J.;Cai, G. M.*;...
期刊：
Journal of Luminescence,2020年221:117115 ISSN：0022-2313
通讯作者：
Si, J. Y.;Cai, G. M.
作者机构：
[Si, J. Y.; Xu, M. J.] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Liu, Y. J.; Cai, G. M.; Li, G. H.] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Zhang, J.] Southwest Petr Univ, Sch Mat Sci & Engn, Chengdu 610500, Sichuan, Peoples R China.
通讯机构：
[Si, J. Y.; Cai, G. M.] C;Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.
作者机构：
[陈龙; 司家勇; 刘松浩; 廖凯] College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha;410004, China;[陈龙; 司家勇; 刘松浩; 廖凯] 410004, China
通讯机构：
College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, China
摘要：
A new phosphate Ba3In4(PO4)(6) has been discovered in the exploration of novel host materials for color-tunable phosphors in BaO-In2O3-P2O5 system. The crystal-structure determination using powder XRD data reveals it belongs to the cubic langbeinite structure type (S.G. P2(1)3), unlike Mg3In4(PO4)(6) crystallizing the triclinic system (S.G. P (1) over bar). The existence of PO4 has been verified by IR spectra of the title compound. DTA and experimental indicate that this new phosphate has a high melting point of similar to 1293 degrees C. Combined with calculated electronic structure and experimental UV-Vis diffuse reflectance spectrum, it has a wide direct energy band gap which is favorable for host materials. The site symmetry of Eu3+ ions and the cross relaxation of Tb3+ ions in this matrix have been clarified according to their luminescence properties. Red-pink-green tunable emission can be realized adjusting the Eu3+ and Tb3+ contents. The quantum yields of representative phosphors under the excitation of 370-392 nm ultraviolet radiation have been measured and discussed. The PL intensity of Ba3In4(PO4)(6): 0.02Eu(3+), 0.015Tb(3+) phosphor at 423 K of is about 67% of that at 298 K. Present results indicate that the Ba3In4(PO4)(6)-based phosphors are valuable for the multicolor and stable thermal performance in the display and lighting fields. (C) 2019 Elsevier B.V. All rights reserved.
