Microstructure and microchemistry of flash sintered K0.5Na0.5NbO3
Çorapcıoğlu, Gülcan and Gülgün, Mehmet Ali and Kisslinger, Kim and Sturm, Saso and Jha, Shikhar K. and Raj, Rishi (2016) Microstructure and microchemistry of flash sintered K0.5Na0.5NbO3. Journal of the Ceramic Society of Japan, 124 (4). pp. 321-328. ISSN 1882-0743 (Print) 1882-0743 (Online)
Official URL: http://dx.doi.org/10.2109/jcersj2.15290
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 250V/cm electric-field at 990°C. These conditions are ³100°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 coreshell 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  direction. Compositional equilibrium is achieved after a heat treatment at 1000°C for 4 h. The compositional variations appeared to have been linked to grain boundary melting during flash and consequent recrystallization as the sample cooled.
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