Structural, Ferroelectric, and Electrical Properties of NiTiO3 Ceramic

The solid-state reaction route was used to prepare polycrystalline samples of NiTiO3. Basic x-ray structural analysis confirmed the formation of a single-phase compound with rhombohedral crystal structure. Study of surface morphology showed that the sample had well-defined grains with uniform distribution throughout the surface. The permittivity, tangent loss, electrical modulus, conductivity, and impedance of the material were obtained over wide ranges of temperature (25°C to 500°C) and frequency (1 kHz to 1 MHz). Strong correlation between the electrical parameters and microstructure (bulk, grain boundary, nature of charge carrier, etc.) of the material has been established. The dielectric parameters are found to be independent of temperature in both low and medium temperature ranges. The temperature-dependent bulk resistance and I–V characteristics exhibit negative temperature coefficient of resistance behavior of the material similar to that of semiconductors. The magnetic hysteresis loop revealed that the NiTiO3 ceramic displays antiferromagnetic behavior with weak ferromagnetism at room temperature. The frequency dependence of the electrical modulus and impedance of the material shows deviation from ideal Debye-type relaxation. The frequency and temperature dependence of the alternating-current (AC) conductivity and activation energy of the system obey Jonscher’s universal power law with non-Debye type of relaxation. The nature of the hysteresis loop shows that the material has ferroelectric characteristics at room temperature.