Effect of Annealing Temperature on Gamma‐Induced Thermoluminescence in NaLi ₂ PO ₄ –Na ₃ Ce(PO ₄ ) ₂ : Insights for Radiation Dosimetric Applications

The thermoluminescent (TL) dosimetric behavior of a NaLi 2 PO 4 –Na 3 Ce(PO 4 ) 2 (a dual‐phase phosphate material) synthesized via solid‐state reaction in ambient air was systematically studied. X‐ray diffraction analysis confirmed the presence of both constituent crystalline phases. Field emission scanning electron microscopy revealed agglomerated clusters with irregular morphology and nonuniform grain distribution, exhibiting an average particle size of ≈0.72 µm. EDS verified the elemental composition, predominantly comprising Na, P, O, and Ce. FTIR and Raman spectroscopies identified characteristic vibrational modes of the (PO 4 ) 3− group. UV–visible absorption spectra showed a prominent band at 295 nm, corresponding to the 4f → 5d transition of Ce 3+ ions. The TL response of the material was examined under varying annealing conditions and γ‐ray doses from a 60 Co source. Optimal TL intensity was achieved after annealing at 700°C/1 h and irradiation at 40 Gy, exhibiting a dominant glow peak at 239°C. The phosphor demonstrated a linear TL dose response over the 0–40 Gy dose range. Deconvolution of the TL glow curve at 40 Gy revealed four distinct peaks, and kinetic parameters were determined using Chen's peak shape method. These findings suggest that the NaLi 2 PO 4 –Na 3 Ce(PO 4 ) 2 composite is a promising candidate for TL dosimetric applications.