High pressure densification and dielectric properties of perovskite-type oxynitride SrTaO2N

Perovskite-type SrTaO2N was densified using a belt-type high pressure apparatus at 2.5-7.7 GPa with and without sample heating. The relative density of the samples treated at 2.5 GPa was 64% and was increased to 75% in those treated at 7.7 GPa without sample heating. The color of the compact changed from orange to brown with densification and the crystals were fractured to nanometer size grains. The density was increased up to 86% with heating above 800 degrees C at 7.7 GPa and the sample color changed to black, accompanied by electrically conductive nature. The permittivity of compacts that were densified to a relative density of around 75% with heating at 600 degrees C and without sample heating were 200 and 90 at 100 Hz, respectively. (C) 2014 Elsevier Ltd. All rights reserved.