Effect of γ-radiation on the phase transition temperature of Li0.5(NH4)0.5SO4

Polycrystalline lithium-ammonium sulphate samples were subjected to X-ray diffraction analysis for determining the lattice parameters of the prepared mixed crystals. The compositions of the samples were determined using X-ray microanalysis.

The Li_0.5(NH₄)_0.5SO₄ samples were irradiated with different doses of γ-radiation in order to investigate the effect of this ionizing radiation on the phase transition temperatures T_c1 and T_c2. The temperature dependence of the d.c. resistivity ρ_d.c. and dielectric constant of irradiated samples showed (i) a shift of T_c1 to higher temperatures; (ii) a shift of T_c2 to lower temperatures; and (iii) the appearance of a new anomaly near 128°C at moderately high γ-doses. The mechanisms giving rise to this behaviour are discussed.