Synthesis of nano-crystalline potassium sodium niobate ceramic using mechanochemical activation

Single phase nano-crystalline K0.5Na0.5NbO3 (KNN) ceramic has been successfully synthesized by the mechanochemical activation method. High energy ball milling was carried out on a mixture of K2CO3, Na2CO3 and Nb2O5 powders for different times (6 h, 12 h, 24 h and 32 h). The 32 h mechanically activated sample was calcined at 550 °C for 2 h. This is about 300 °C lower as compared with conventional solid state reaction. X-ray diffraction pattern of calcined sample revealed single phase perovskites structure with orthorhombic phase. Particle size of these powders was measured using DLS. The Morphology of mixture powder, before and after calcination, was examined under FEG-SEM. Dielectric, ferroelectric and piezoelectric properties were evaluated and compared with reported results using other competing techniques.