Thermally Activated Transport and Dielectric Dispersion in Tetragonal Hardystonite (Ca2ZnSi2O7) Ceramics

This work reports the successful synthesis of hardystonite ( Ca 2 ZnSi 2 O 7 ) via the solid-state reaction method using CaO, ZnO, and SiO 2 as precursor oxides. The phase formation and crystallization of the amorphous powder were investigated using X-ray powder diffraction (XRD), with Rietveld refinement confirming a phase-pure tetragonal structure (space group P-421m) without secondary phases. Fourier transform infrared spectroscopy (FTIR) further validated the structural evolution. Microstructural analysis via scanning electron microscopy (SEM) revealed the morphology of specimens sintered at 1250 °C for 2 hours. The electrical and dielectric properties of hardystonite were examined using complex impedance spectroscopy over a frequency range of 100–10 6 Hz. Conductivity measurements conducted between 40–400 °C demonstrated Arrhenius-type behavior, with activation energies of E a1 = 0.93 eV (high-temperature region) and E a2 = 0.14 eV (low-temperature region), suggesting polaron-assisted conduction. Electrical modulus spectroscopy revealed non-Debye relaxation, with grain-boundary effects dominating at lower frequencies. The dielectric constant exhibited frequency-dependent dispersion, decreasing with rising frequency while increasing with temperature. These findings highlight the structural and electrical characteristics of hardystonite, providing insights into its potential functional applications.