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The coexistence mechanism of Eu2+ and Eu3+ ions in YAl3(BO3)4 host under different reducing conditions is investigated and confirmed in great detail, which can be described by three aspects as following. First, Eu3+ is protected by the layered structure of YAl3(BO3)4. Second, the number of the interstitial defects ((Al)i...,(Y)i...) increases with increasing Eu2+ to maintain the charge balance of the system. And these defects can capture free electrons which are used for the reduction of Eu3+. Finally, free holes become more and more with the number of nonequivalent substitution defects (EuY') increasing, which make the 5d electrons of Eu2+easily escape to the conduction band and Eu2+ convert to Eu3+. This work will be of great significance to research coexistence of multiple valence ions in the structure of borate and defect motion with nonequivalent substitution. [ABSTRACT FROM AUTHOR]

A series of color-tunable NaBa1−zSrzB9O15:Ce3+,Mn2+ phosphors were synthesized by a high temperature solid state method. Luminescence property, energy transfer, thermal stability and cation substitution were investigated in detail. Due to energy transfer, NaBaB9O15:Ce3+,Mn2+ presents violet to green luminescence and manifest a broad excitation range from 200 to 350 nm. The energy transfer mechanism of Ce3+–Mn2+ is identified as a dipole–dipole interaction. NaBa1−zSrzB9O15:Ce3+,Mn2+ displays both Ce3+ violet and Mn2+ green and orange emissions under ultraviolet excitation. It is observed that Sr2+ partial substitution for Ba2+ could adjust the ratio of Mn2+ emission intensity in different cation sites, which results from preferred sites’ occupation with modification of the crystal structure. Furthermore, increase in temperature can enhance the energy transfer from Ce3+ to Mn2+, which enhances the Mn2+ emission intensity sharply. The highly thermal-sensitive property of NaBa1−zSrzB9O15:Ce3+,Mn2+ makes it feasible for its potential application in luminescent ratiometric thermometers with wide temperature range. [ABSTRACT FROM AUTHOR]

A series of color-tunable NaBa1−zSrzB9O15:Ce3+,Mn2+ phosphors were synthesized by a high temperature solid state method. Luminescence property, energy transfer, thermal stability and cation substitution were investigated in detail. Due to energy transfer, NaBaB9O15:Ce3+,Mn2+ presents violet to green luminescence and manifest a broad excitation range from 200 to 350 nm. The energy transfer mechanism of Ce3+–Mn2+ is identified as a dipole–dipole interaction. NaBa1−zSrzB9O15:Ce3+,Mn2+ displays both Ce3+ violet and Mn2+ green and orange emissions under ultraviolet excitation. It is observed that Sr2+ partial substitution for Ba2+ could adjust the ratio of Mn2+ emission intensity in different cation sites, which results from preferred sites’ occupation with modification of the crystal structure. Furthermore, increase in temperature can enhance the energy transfer from Ce3+ to Mn2+, which enhances the Mn2+ emission intensity sharply. The highly thermal-sensitive property of NaBa1−zSrzB9O15:Ce3+,Mn2+ makes it feasible for its potential application in luminescent ratiometric thermometers with wide temperature range. [ABSTRACT FROM AUTHOR]

A new Dy(III) complex, [KDy(sbtc)(H2O)2]·2H2O (1) (KH3sbtc: 5-sulfo-1,2,4benzenetetricarboxylic acid potassium salt), has been synthesized by solvothermal reaction of Dy2O3and KH3sbtc, and characterized by single crystal X-ray diffraction studies, elemental analysis, and FTIR. Single crystal X-ray diffraction reveals that1has a 3-D architecture, and there is only one crystallographically independent Dy(III) and K(I) in1. The coordination geometry of Dy(III) is a distorted monocapped tetragonal antiprism and K(I) is also a distorted monocapped tetragonal antiprism. The whole sbtc4−is aμ8-bridge linking four different Dy(III) cations and four different K(I) cations, giving a 3-D network structure. Thermal stability and solid luminescence of1were also investigated. [ABSTRACT FROM AUTHOR]

A series of Na 1-z K z Ba 1-y Sr y B 9 O 15 :Eu2+ were synthesized by the high temperature solid state method. H 3 BO 3 excess makes it easier for Eu2+ to enter Na+ site, and the single-phase "blue + green" double emission band can be observed, which is proved by thermoluminescence and the change of crystal structure. Moreover, there exists an intense energy transfer from the blue-emitting center to the green-emitting center, which is proved by the decay curve. The occupation of Eu2+ can be tuned by the introduction of Sr2+ and K+ in NaBaB 9 O 15. Further, the highly thermal-sensitive property of NaBaB 9 O 15 : 1%Eu2+ makes it feasible for its potential application in luminescent ratiometric thermometers with wide temperature range. In addition, the disorder degree of matrix cations increases with the incorporation of K+, which improves the thermal stability. Image 1 • Eu2+ can enter into Na+ site with the excessive H 3 BO 3 and muti-band emission is achieved. • Sr2+/K+ can adjust the occupied radio of Eu2+ in Ba2+ and Na+ site. • K+ can improve the thermal stability of NBB:Eu2+ due to the disorder degree of matrix cations. • NBB:1%Eu2+ could be a versatile solid-state probe. [ABSTRACT FROM AUTHOR]

Abstract Luminescence mechanism of self-activated phosphor Ca 0.75 Sr 0.2 Mg 1.05 Si 2 O 6 (CSMS) originating from oxygen vacancy defects has been deeply investigated by regulating synthesis temperature. The results demonstrate that the luminescence comes from three different oxygen defects in the crystal structure. For Ce3+ doped CSMS (ICSD#68180), two concentration quenching phenomena can be observed at x = 0.03 and 0.12 as the result of the formation of new substance CaMgSi 2 O 6 (ICSD#17043), which leads to the actual concentration of Ce3+in CSMS (ICSD#68180) is far less than the doping concentration since part of Ce3+ ions enter CaMgSi 2 O 6 (ICSD#17043). The emission spectra of CSMS: x Ce3+ shifts from 388 nm to 405 nm with increasing Ce3+ content, which mainly should be due to the 5d energy center of Ce3+ shifting down and the crystal field split. Graphical abstracts fx1 [ABSTRACT FROM AUTHOR]