Study of structural, dielectric and electrical conduction behaviour of Gd substituted CaCu_3Ti_4O_(12) ceramics

摘要

Effect of Gd on microstructural, dielectric and electrical properties has been studied over wide temperature (300-500 K) and frequency range (100 Hz-1 MHz). Gd substitution in CCTO system results in decrease in the grain size and increase of Schottky potential barrier which causes lower value of dielectric constant. The dielectric constant remains nearly constant in temperature range 300-350 K. Doped samples show lower dielectric loss in middle frequency range (～ 10 kHz-1 MHz) at room temperature. The AC conductivity (σ_(ac)) obeys a power law, σ_(ac) = Af~n, where n is temperature dependent frequency exponent. The AC conductivity behaviour can be divided into three regions depending on conduction processes and the relevant charge transport mechanisms have been discussed.