Synthesis and characterisation of rare earth element doped lithium borate phosphor

Rare earth element terbium doped lithium borate phosphor was synthesized by conventional solid-state reaction method for the first time. X-ray diffraction (XRD) analysis, radioluminescence (RL) and thermally stimulated luminescence (TSL) techniques were used to investigate structural and luminescence properties of terbium doped lithium borate phosphors. XRD patterns confirm that the lithium borate phosphors sintered at 1200 °C exhibit monoclinic structure. RL spectrum of synthesized terbium doped lithium borate phosphor revealed that terbium ions represent in trivalent oxidation states. RL measurements shows that the series of emission state 5D4→7F6, 5D4 →7F5, 5D4→7F4 and 5D4→7F3, corresponding to the typical 4f-4f infra-configuration forbidden transitions of Tb+3, are appeared and major emission peak is around at 541 nm. The TSL kinetic parameters of a newly synthesized terbium doped lithium borate phosphor have been calculated. The LiBO2:Tb3+exhibits two TSL glow curves at around 90 and 155 °C. The kinetic parameters, namely activation energy (trap depth) and frequency factor (s) associated with the main glow peak (155 °C) of the material were determined using peak shape (PS) and various heating rates (VHR) methods.