Investigation of luminescence characteristics of Tm3+ doped lithium borate (LiBO2): A first study

Abstract

Thulium-doped lithium borate (LiBO₂:Tm³⁺) phosphors were synthesized for the first time via a conventional solid-state reaction method. The structural and luminescence characteristics of the synthesized materials were investigated using X-ray diffraction (XRD), thermoluminescence (TL), and photoluminescence (PL) techniques. XRD patterns confirmed a well-crystallized host lattice, demonstrating that the crystalline structure remained stable upon Tm³⁺ substitution. The TL glow curves exhibited distinct overlapping peaks, indicating the presence of efficient trapping and recombination centers that are suitable for dosimetric applications. The kinetic parameters, including the activation energy (E), frequency factor (s), and kinetic order (b), were recorded using glow curve deconvolution based on the General-Order Kinetics (GOK) model. PL measurements under laser excitation revealed intense blue-to-green emissions in the 380-680 nm range, attributed to the characteristic intra-4f transitions of Tm³⁺ ions, specifically the ¹D₂ $\to$ ³H₆ and ¹G₄ $\to$ ³F₄ transitions. The spectral characteristics underscore the strong crystal field effects and high emission purity. These findings highlight that Tm³⁺-doped lithium borate phosphors combine robust structural integrity with superior luminescent and dosimetric performance, demonstrating their significant potential for environmental radiation dosimetry applications.