Electrical and dielectric properties of Na1/2La1/2Cu3Ti4O12 ceramics prepared by high energy ball-milling and conventional sintering

We report on the measurements of the electrical and dielectric properties of Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramics prepared by high energy ball-milling and conventional sintering without any calcination steps. The x-ray powder diffraction analysis shows that pure perovskite-like CCTO phase is obtained after sintering at 1025 degrees C-1075 degrees C. Higher sintering temperatures result in multi-phase ceramics due to thermal decomposition. Scanning electron microscope observations reveal that the grain size is in a range of similar to 3 mu m-5 mu m for these ceramics. Impedance spectroscopy measurements performed in a wide frequency range (1 Hz-10 MHz) and at various temperatures (120 K-470 K) are used to study the dielectric and electrical properties of NLCTO ceramics. A good compromise between high epsilon' (5.7 x 10(3) and 4.1 x 10(3) at 1.1 kHz and 96 kHz, respectively) and low tan delta (0.161 and 0.126 at 1.1 kHz and 96 kHz, respectively) is obtained for the ceramic sintered at 1050 degrees C. The observed high dielectric constant behavior is explained in terms of the internal barrier layer capacitance effect.