Influence of escaping of Na & K on physical properties in lead-free Na_0.92K_0.08NbO₃ ceramic

Abstract

Lead-free Na_x K_1–xNbO₃ (NKN) ceramic with x = 0.08 was prepared by a conventional solid-state reaction method to investigate the influence of the Escaping of Na & K on their physical properties. It has been found that the NKN ceramics with x = 0.08 exhibit pure perovskite (ABO₃) structure. The pure phase NKN was achieved for all sintering temperatures of 1100 °C, 1150 °C, 1200 °C and 1250 °C. Change in microstructure, indicates that the grain size increases with the increasing sintering temperatures. The dielectric constant was dependent of the Escaping of Na & K. From the analyses, we suggest that the high dielectric constant for the NKN ceramics near sintering temperature 1150 °C are closely related to their low escaping of Na & K and microstructures of uniformly distributed large grains rather than the widely believed morphotropic phase boundary effect of lattice parameter discontinuity.

Keywords:

• Escaping of Na & K
• sintering
• dielectric constant and grain size

Acknowledgements

The authors are thankful to Prof. N. S. Panwar, Head, Department of Instrumentation Engineering-USIC, SOET, HNB Garhwal University, Srinagar (Garhwal), for his kind suggestion. Prof. N. S. Panwar is also thankfully acknowledged for providing laboratory facilities.