Effect of Ag substitution on ferroelectricity in KNbSi2O 7

The ferroelectric properties of AgxK1_xNbSi2O7 (x = 0??0.10) single crystals were evaluated to understand the effect of Ag substitution on ferroelectricity in KNbSi2O7. Millimeter-sized plate-like AgxK1_xNbSi2O7 single crystals were fabricated by crystallization of the glass phase. The remanent polarization of AgxK1_xNbSi2O7 decreased with increasing the amount of Ag, meaning that the ferroelectricity of KNbSi2O7 is reduced by Ag substitution. Such a tendency was also confirmed by first-principles calculations for KNbSi2O7 and AgNbSi2O7. The displacement of Nb from the center of gravity of the NbO6 octahedron and the rotation of the NbO6 octahedron around the c-axis were smaller in AgNbSi2O7 than in KNbSi2O7. These may be due to the larger electronegativity and smaller ionic radius of Ag. The similarities between the AgxK1_xNbSi2O7 and AgxK1_xNbO3 were also discussed. ??2022 The Ceramic Society of Japan. All rights reserved.