Studies of structural, dielectric and electrical characteristics of nickel-modified barium titanate for device applications

In the present report, an attempt has been made to develop (via synthesis and characterization) a lead-free multifunctional material by introducing Ni in BaTiO3 of a composition of (Ba0.5Ni0.5)TiO3 for the temperature sensor and bandwidth applications. The phase analysis using X-ray diffraction data reveals the mono-phase nature of the developed system in the tetragonal crystal symmetry. The variation of structural parameters such as lattice constant, unit volume, change in tetragonality ratio from 1.0082 to c/a = 1.5792, are evidence of structural distortion generated in the unit cell of BaTiO3 on the addition of nickel at its Ba-site of the parent compound. This distortion significantly affects the dielectric, ferroelectric, impedance, and conductivity characteristics of barium titanate. The electron microscopic studies of the material show the compactness and uniform distribution of grains almost the same size over the surface of the pellet sample. The frequency-temperature-dependent studies of the material exhibit that ferroelectric-paraelectric phase transition temperature (Tc) of BaTiO3 (~ 120 °C) has been diffused or shifted, and hence no phase transition or dielectric anomaly is observed in the experimental temperature range (30–500 °C) in Ni-rich barium titanate (i.e., Ba0.5Ni0.5)TiO3. The relative permittivity even at 450 °C is found to be in the order of 103 with conductivity in the order of 10–4 Ω cm−1. However, room temperature hysteresis loop provides the saturation polarization of (Ps = 3.1416 μC/cm2), remnant polarization (Pr = 0.8478 μC/cm2) and coercive field (EC = 87.76 kV/cm). The analysis of various electrical data (parameters), such as relative permittivity, loss tangent, impedance as a function of temperature and frequency has provided dielectric relaxation and conduction mechanism in the material. Based on the above parameters, it may be concluded that the material can be a suitable candidate for multifunctional applications like temperature sensors, bandwidth, etc.