Dielectric studies of 0.5 BaTiO3-0.5 Bi2/3Cu3Ti4O12 nanocomposite

A nanoceramic composite with a composition of 0.5 barium titanate (BaTiO3; BTO) and 0.5 Bi2/3Cu3Ti4O12 (BCTO) was synthesised using the solid-state method. Microstructural details were studied by X-ray diffraction (XRD) and scanning electron microscopy. XRD analysis confirmed the existence of both the BTO and BCTO phases. The average crystallite sizes obtained by the XRD analysis were found to be around 45 +/- 16 nm. The sample sintered at 950 degrees C for 12 h exhibited a very high dielectric constant (epsilon(r) = 43 459) at 100 Hz and at room temperature. The presence of semiconducting grains with insulating grain boundaries significantly contributes to such a high dielectric constant value, supporting the internal barrier layer capacitance mechanism operative in BTO-BCTO composites. The dielectric loss (tan delta) peaks observed for the BTO-BCTO composite with variation of frequency at few selected temperatures give an indication of the relaxation behaviour present in the composite.