Structural, dielectric properties and electrical conduction behaviour of Dy substituted CaCu_3Ti_4O_(12) ceramics

摘要

Dy substituted CCTO ceramics were synthesized using solid state reaction method. Effect of Dy on structural, microstructural, dielectric and electrical properties has been studied over a wide temperature (300-500 K) and frequency range (100 Hz-1 MHz). Rietveld refinement, carried out on the samples, confirmed single phase formation and indicated overall decrease in lattice constant. Microstructure showed bimodal distribution of grains in CCTO with bigger grains surrounded by smaller grains. Dy substitution reduced grain size. Dy substitution in CCTO reduces the dielectric constant which may be attributed to increase of the Schottky potential barrier. The dielectric constant remains nearly constant in temperature range 300-400 K. The AC conductivity obeys a power law, σ_(ac)=A f~n where n is the temperature dependent frequency exponent. The AC conductivity behaviour can be divided into three regions, over entire temperature range, depending on conduction processes. The relevant charge transport mechanisms have been discussed.