Pornsuda Bomlai, Winai Saengchote, Supasarote Muensit and Steven J. Milne

pp. 441 - 448

Abstract

Sodium-potassium niobate ((Na_1-xK_x)NbO₃) powders with x = 0.2, 0.4, 0.6 and 0.8 were prepared following the conventional mixed oxide method and characterized by TG-DTA, XRD and SEM techniques. The effects of calcination temperature, dwell time and K₂CO₃ content on phase formation behavior and
morphology of the powders were investigated. The calcination temperature and dwell time were found to have a pronounced effect on the phase formation of the calcined sodium-potassium niobate powders. It was found that the crystallized phase depended on calcination conditions. The high calcination temperature and
long dwell time clearly favored particle growth and the formation of large and hard agglomerates. All the (Na_1-xK_x)NbO₃ powders showed a similar orthorhombic phase structure. The K₂CO₃ content significantly affected the calcination temperature and particle size and shape. Large particle size, cubic shape and a lower calcined condition were observed in (Na_1-xK_x)NbO₃
 powder with low K₂CO₃ content (x = 0.2).

Keywords

• sodium-potassium niobate
• lead-free piezoelectric material
• phase formation
• morphology evolution