Phase and morphology evolution of (Na1-xKx)NbO3 powders related to calcinations and K2CO3 content

Abstract

Sodium-potassium niobate ((Na1-xKx)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 tohave 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 andlong dwell time clearly favored particle growth and the formation of large and hard agglomerates. All the (Na1-xKx)NbO3 powders showed a similar orthorhombic phase structure. The K2CO3 content significantlyaffected the calcination temperature and particle size and shape. Large particle size, cubic shape and a lower calcined condition were observed in (Na1-xKx)NbO3 powder with low K2CO3 content (x = 0.2).

Keywords

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