Determination of the effect of composition on microstructure and electrical properties in k0.5bi0.5tio3-batio3-na0.5bi0.5tio3 based powders

Piezoelectric materials are a special class of materials with a wide range of applications, from sensors to actuator, energy storage to ultrasonic motors. However, commonly used lead-based piezoelectric ceramics are very toxic for the natural life and therefore, it is necessary to develop environment-friendly lead-free piezoelectrics ceramics has become extremely important. Lead-free Sodium Bismuth Titanate (NBT) containing piezoelectric materials are the best candidates instead of lead containg piezoelectric materials shown by researchers. Among the NBT-containing lead-free piezoceramics, K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 solid solution attracts to much attention especially in material development studies for actuator applications due to its high piezoelectric coefficient, high coupling coefficient, low energy loss and high depolarization temperature. In this study, matrix powders with high dielectric, piezoelectric and ferroelectric properties (1-x)(K0.5Bi0.5TiO3-BaTiO3)-xNa0.5Bi0.5TiO3 (KBT:BT=2:1) system, were produced using the conventional solid oxide mixing technique in the compositions of x = 0,5, x = 0,6, x = 0,7, x = 0,8 and x = 0,9. The powders were calcined at 880°C for 3 hours according to the results of TG-DTA and XRD analysis. Then, matrix powders, which were pressed into pellets, and sintered at 1125°C for 4 hours according to the results of TMA analysis. It was observed that the ceramics, which were analyzed by SEM, had homogeneous grain distribution and compact structure. As a result of these studies, it was determined that the composition of x = 0.8 stands out. From the electrical measurement results of the sample of this composition, permanent polarization was determined as 8,1 µC/cm2, coercive field 9,96 kV/cm, piezoelectric coefficient (d33) value 133 pC/N and depolarization temperature (Td) 198°C. Keywords: Piezoelectricity, Ferroelectricity, Matrix powder, Sodium bismuth titanate based, Electrical properties.