Microstructure and microchemistry of flash sintered K 0.5Na 0.5NbO 3
Journal of the Ceramic Society of Japan
In this paper, flash sintering experiments were performed, for the first time, on sodium potassium niobate (KNN) ceramics. A theoretical density of 94% was achieved in 30 s under 250 V/cm electric-field at 990°C. These conditions are ~100°C lower and faster than the conventional sintering conditions. Grains tended to grow after 30 s. flash sintering duration under constant electric-field. Detailed microstructural and chemical investigations of the sample showed that there was inhomogenous Na, K distribution and it resembles a core–shell structure where K is more in the shell and Na is more in the core region. The inhomogenous distribution of Na and K was correlated with the doubling of the unit cell within the grain along 002 direction. Compositional equilibrium is achieved after a heat treatment at 1000°C for 4 h. Finally, the compositional variations appeared to have been linked to grain boundary melting during flash and consequent recrystallization as the sample cooled.
Corapcioglu, Gulcan; Ali, Gulgun Mehmet; Kisslinger, Kim; Sturm, Saso; Jha, Shikhar K.; and Raj, Rishi, "Microstructure and microchemistry of flash sintered K 0.5Na 0.5NbO 3" (2016). Mechanical Engineering Faculty Contributions. 18.