Structure and Electrical Properties of BNKT-Based Ceramics

Abstract

In this work, the properties of lead-free 0.92(Bi0.5Na0.42K0.08)TiO3-0.08(BaNb0.01Ti0.99)O3 or 92BNKT-8BNbT ceramic has been investigated. The sample was fabricated by a solid-state reaction technique. The 92BNKT-8BNbT sample was well sintered and dense with high density value of 5.86 g/cm3. X-Ray diffraction (XRD) patterns showed a single perovskite phase with tetragonal symmetry and no impurity or secondary phases. The microstructure was analysed using a scanning electron microscopy (SEM). Average grain size was measured and calculated based on a mean linear intercept method. The ceramics had a cubic-like grain shape with an average grain size of 0.39 µm. The influence of temperature on the dielectric and ferroelectric properties of the ceramic was investigated. The dielectric curves exhibited broad transition peaks at Td and Tm, which were the characteristics of a diffuse phase transition. The polarization-electric field (P-E) hysteresis loop changed from well-saturated at room temperature (RT) to pinched-type loop at high temperature (HT) and the remanent polarization decreased from 21.25 µC/cm2 (at RT) to 5.96 µC/cm2 (at 150 °C).

Relationship between the Synthesis Method and the Magnetoelectric Properties of Bismuth Sodium-Potassium Titanate/Nickel Cobalt Ferrite Lead-Free Composites

“…Moreover, the typical relaxor behavior with frequency is clearly observed in sample BNKT-SS ( Figure 6 ). Broad peaks at T d and T m indicate the characteristics of a diffuse phase transition [ 52 , 53 ]. Interestingly, BNKT samples synthesized by the sol-gel method rendered high dielectric losses at low frequencies which could be associated with the low densification level, and the small grain size obtained after sintering at 975 °C.…”