Effect of tellurium content on the structural and dielectric properties of Se 100-x Te x alloys

This study systematically investigates the structural and dielectric properties of binary Se100-xTex alloys prepared via solid-state synthesis. Structural parameters and crystalline configurations were evaluated using traditional and modified Scherrer methods based on X-ray diffraction (XRD) profiles. The results demonstrate a significant compositional dependency; the Se₇₀Te₃₀ alloy exhibits the highest structural crystallinity of 89.07%. Modified Scherrer plot analysis revealed that the average crystallite size varies systematically from 32.22 nm down to 7.97 nm as a function of tellurium content. Smaller crystallites correlate with elevated dislocation densities (up to 0.01574 nm−²) and pronounced lattice distortion. Scanning electron microscopy (SEM) micrographs reveal a distinct polycrystalline morphology with a wide grain size distribution and internal porosity. Furthermore, dielectric relaxation spectroscopy conducted via LCR testing over a frequency range of 1 kHz to 1 MHz demonstrates a clear frequency dependence governed by space charge polarisation and hopping conduction mechanisms. The main novelty lies in decoupling size-induced and strain-induced lattice broadening via the modified Scherrer plot, directly linking these structural defects to the complex frequency-dependent dielectric relaxation phenomena across the composition range (x = 10–50) of Se100-xTex alloys.