Effect of particle size distribution on microstructure and piezoelectric properties of MnO2-added 0.95(K0.5Na0.5)NbO3-0.5BaTiO3 ceramics

The effect of particle size distribution on the microstructure and piezoelectric properties of MnO2-added 0.95(K0.5Na 0.5)NbO3-0.5BaTiO3 (KNN-BT) ceramics has been explored. It is known that the packing density of a green body is dependent on the ration of small to large particles present in the mixture. It was established that the rate of reaction is inversely proportional to the square of particle size. It was also suggested that commercial alkali powders require significant reduction in particle size before being used to form the green body to avoid agglomeration. It was observed that for KNN-BT ceramics, a higher density can be obtained by using higher content of smaller size particles in the green body. It was also proposed that enhanced piezoelectric properties in these lead-free ceramics can be achieved by using 100% particles of size less than 0.3 μm in the green body.