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Series of NaBa 0.97 Ce 0.03 B 9 O 15 : x Tb3+, y Sm3+, z Dy3+ are synthesized by the traditional high temperature solid-state method. Ce3+ is used as a sensitizer to improve the spectral properties of Tb3+, Sm3+ and Dy3+ by the way of energy transfer which is proved by the fluorescence decay curves. And the mechanisms of energy transfer from Ce3+ to Tb3+, Sm3+ and Dy3+ are all determined as dipole-dipole interaction. The color of NBB:3%Ce3+, x Tb3+, 0.5%Sm3+ can shift from light violet thought white to yellow. And NBB:3%Ce3+, z Dy3+ can give out white light and move to green field. Moreover, the thermal stability makes NBB:3%Ce3+, 0.2%Dy3+ be a potential candidate for the self-referencing luminescent thermometry. Image 1 [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 Series of Ce3+/Eu2+, Ce3+/Mn2+ and Ce3+/Eu2+/Mn2+ doped Ba 3 Y(PO 4) 3 samples were synthesized by a high temperature solid state reaction method. Phase formation, energy transfer, luminescence properties and thermal quenching properties were investigated carefully. The energy transfer from Ce3+ to Eu2+ and Ce3+ to Mn2+ in Ba 3 Y(PO 4) 3 were verified and discussed detailed. When Ce3+ and Eu2+ are co-doped, the energy transfer process from Ce3+ to Eu2+ is confirmed with electric dipole-dipole interaction. For Ce3+/Mn2+ co-doped phosphors, the energy transfer process from Ce3+ to Mn2+ is proved with electric dipole-dipole interaction. Besides, due to the existence of defects, the phosphors show excellent thermal stability. For Ce3+/Eu2+/Mn2+ tri-doped Ba 3 Y(PO 4) 3 , the energy transfer Ce3+→Eu2+ (Mn2+) and Eu2+→Mn2+ are confirmed. The energy transfer priority among Ce3+, Eu2+ and Mn2+ is analyzed in detail basing on the change of emission intensity. The obtained tri-doped phosphors contain red, green and blue component, thus they can emit warm white light basing on the energy transfer. The results show that they may be novel white-light-emitting phosphors for ultraviolet white light emitting diodes. Graphical abstract fx1 [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]