This work investigates the structural and dielectric properties of zinc molybdate (ZnMoO 4 ) and its composites with titanium dioxide (TiO 2 ) for applications in sub-UHF radiofrequencies (< 300 MHz). The ZnMoO4 (ZMO) matrix and composites with 10, 13, and 20 wt.% TiO₂ were synthesized via solid-state reaction. X-ray diffraction confirmed the formation of the pure ZMO phase and the incorporation of TiO 2 into the composites; Rietveld refinement revealed the absence of spurious phases, and scanning electron microscopy (SEM) showed structures formed by grains with different sizes and distinct microstructures. In the radio frequency range, the samples exhibit low values of relative permittivity (ε’ r ). Conductivity (σ) in the samples obeys Jonscher's power law and the normalization curves showed the presence of short-range movement of charge carriers, with a thermally activated relaxation process (formation of relaxation peaks). Ea values were calculated using the Arrhenius relation, utilizing the maximum peak frequency of the imaginary impedance and the conductivity. Good agreement was observed between the obtained values, suggesting a conduction process governed by the same type of charge carriers. The Nyquist diagram was used to examine the behaviors associated with grain and grain boundary effects in the ceramic samples. Temperature Capacitance Coefficient (TCC) was calculated, showing that ZMO, ZMT10, and ZMT13 transition around zero TCC in the 100 kHz – 1 MHz range. Therefore, it is valid to infer that the composites studied have potential for applications in sub-UHF electronic circuit components.
Martins et al. (Sun,) studied this question.