Investigation of the structural, morphological, electrical and dielectric properties of Li₂CaGeO₄ compound

The synthesis of lithium calcium germanate ceramic powders was achieved through a conventional solid-state reaction method at high temperatures. The formation of the compounds was confirmed using X-ray diffraction and energy dispersive X-ray techniques. Using Scherrer’s formula and Williamson and Hall’s (W–H) method, the average size of the crystallite was found to be 55 nm and 85 nm, respectively. Impedance spectra were measured at temperatures ranging from 553 to 673 K, covering a frequency range of 10 Hz to 1 MHz. The AC conductivity displays frequency-dependent behavior following a variation of the universal power law described by this equation: σ_AC (ω) = σ_DC + Aω^S. By analyzing the plot of the pre-exponent S versus temperature, it was determined that the conduction mechanism in the system could be explained using the correlated barrier hopping model. Parameters such as hopping distance R_ω and localized state density N(E_F) were calculated. The behavior of permittivity (ε′, ε″) and the loss coefficient tan δ were attributed to Wagner’s Maxwell theory of interfacial polarization. Complex electric modulus studies confirmed that the relaxation process was thermally activated. Thermodynamic parameters, including the enthalpy ΔH and the change in entropy ΔS, were calculated. The negative value of ΔS indicated the presence of dipole–dipole interactions and the alignment of molecules in the activated state.