Investigation on Structural and Thermoluminescence Properties of Ho3+ doped SrB4O7 Phosphor for dosimetry applications

Abstract A series of tissue equivalent novel Sr(1-x)B4O7:Hox (0 ≤ x ≤ 0.5 mol%) phosphors have been synthesized via solid state diffusion to investigate their structural and Thermoluminescence features. The rietveld refinement of XRD data confirms pure phase formation with an orthorhombic crystal structure. FTIR and Raman spectroscopy have been used to examine the vibration characteristics and bonding among each constituent of material. The analysis detected bending vibrations of bridging oxygen's within B-O-B bonds in BO3 trigonals, alongwith stretching vibrations of [BO4] tetrahedral. SEM was used to inquire the surface morphology as well as to record EDX patterns for authentication of the elemental composition in all the samples. The microphosphors possess a dense structure with irregularly shaped grains with an average grain size of 1.36-1.45μm. The TL glow curves have been recorded to evaluate the dosimetric properties of γ-exposed phosphors i.e. dose response, fading and reproducibility. Doped samples exhibit higher TL sensitivity as compared to pure samples. The critical holmium concentration for TL was found to be 0.5 mol%. Fading was examined and the TL intensity of the predominant dosimetric TL Peak of SB3 sample was determined to be a -12% decline after 15 days. Repetitive analysis demonstrates that SrB4O7 have high reproducibility. The phosphors exhibit a linear dose response and good reproducibility, with a standard deviation of ∼2%. The trapping parameters (viz. E, b and s) have been computed using PS, IR and Ilich methods. The dosimetric attributes of the novel fabricated phosphors acknowledge their adequacy for dosimetry applications.