Dielectric properties of Na1â€�?�ð�?�¥K$_x$NbO3 in orthorhombic phase

[摘要] Pellets of ceramic, Na_{1â€�?�ð�?��?}K_ð‘�?NbO₃ (ð‘�? = 0, 0.2 and 0.5), were prepared by conventional solid-state reaction method. Prepared samples were characterized using XRD and SEM. The frequency and temperature variation of dielectric constant, loss tangent and dielectric conductivity of prepared samples were measured in the frequency range from 10 KHzâ€�??1 MHz, and in the temperature range from 50â€�??250°C for ð‘�? = 0.2 and 0.5,and between 50 and 480°C for ð‘�? = 0 compositions. It was observed that the dielectric constant and loss tangent decrease, and conductivity increases with increasing frequency. Near the transition temperature the material shows anomalous behaviour for the observed properties, and the peaks of dielectric constant and loss tangent were observed shifting towards lower temperature with increasing frequency.

[学科分类] 材料工程

[关键词] Ferroelectrics;antiferroelectrics;perovskite;dielectric constant and loss;sintering;positive temperature coefficient of resistivity.