Influence of Ca in Mg ₂ FeVO ₆ Ceramic: Structure, Microstructure, Dielectric, and Electrical Properties for NTC Thermistor Application

In this communication, the synthesis (via solid-state reaction) and characterization (XRD, SEM, EDX, FTIR, and LCR measurements) of a novel Mg0.5Ca1.5FeVO6 ceramic are reported. Preliminary structural characterization verified the successful formation of a solid solution predominantly exhibiting a cubic phase (space group #Ia-3d). The Williamson–Hall analysis yielded an average crystallite size of 663.7 nm, a microstrain value of 0.00183, and a dislocation density of 2.27 × 1012 m−2. SEM micrographs revealed well-defined, densely packed grains with an average size of 0.84 µm, indicating enhanced grain connectivity and densification. Compositional analysis via EDX confirmed that the sample contained all constituent elements (Mg, Ca, Fe, V, and O) at 100% in both weight and atomic fractions. FTIR analysis confirmed the presence of characteristic Mg–O, Ca–O, Fe–O, and V–O vibrational modes in the synthesized sample. Dielectric studies revealed Maxwell–Wagner type interfacial polarization, exhibiting a high dielectric constant along with minimal energy loss. Impedance spectroscopy showed reduced grain boundary resistance and enhanced electrical conductivity, reflecting the negative temperature coefficient of resistance (NTCR) behavior. Electric modulus analysis revealed non-Debye relaxation, and AC conductivity studies confirmed thermally activated conduction. Furthermore, temperature-dependent resistance measurements confirmed the NTC thermistor behavior of Mg0.5Ca1.5FeVO6 ceramic, highlighting its potential for advanced temperature-sensing applications.