Structural, electric modulus and complex impedance analysis of ZnO/TiO2 composite ceramics

ZnO/TiO2 composite ceramics have been prepared by solid-state reaction technique at 900°C. The X-ray diffraction results revealed the formation of secondary phases referred to as spinel Zn2TiO4 and hexagonal ZnTiO3. The structural analysis showed that all the composites that have been prepared have a polycrystalline nature and a hexagonal wurtzite structure. The complex modulus (M) and electric impedance of the samples have been investigated by broadband dielectric spectroscopy in a wide range of temperature (40°C-110°C) and frequency (0.1 Hz to 10 MHz). The modulus plots (M′′, M′) illustrate the presence of non-Debye type of relaxations attributed to the effects of interfacial and dipolar polarizations. The real and the imaginary parts of the impedance are well fitted to equivalent circuit models. At high temperatures, Z″max varies from 0.03 × 106 to 4.9 × 106 Ω when the TiO2 doping concentration increases from 1 to 7 wt%. From the obtained results, the secondary phase ZnTiO3 plays an important role in the electrical properties.