Dense KSr2Nb5O15 ceramics with uniform grain size prepared by molten salt synthesis

Dense KSr2Nb5O15 (KSN) ceramics with various grain-size distributions were prepared by the conventional solid-state sintering under different conditions, e.g. one-step and two-step techniques. Bi2O3 (2 mol%) was added as sintering aid. KSN powder crystals prepared by the molten salt synthesis was used as raw materials. Varying temperature from 1250 degrees C to 1350 degrees C at one-step sintering technique were found to enhance abnormal grain growth. For two-step sintering technique, presintering at 1250 degrees C followed by higher sintering temperature of 1350 degrees C controlled abnormal grain growth and obtained a dense KSN ceramics with uniform grain size (an average grain size of 3 mu m). The effect of KSN powder crystals on promoting densification and presintering technology on controlling abnormal grain growth were discussed. The correlation of microstructure with dielectric properties was investigated. (C) 2014 Elsevier B.V. All rights reserved.