Polymeric citrate precursor route to the synthesis of the high dielectric constant oxide, CaCu3Ti4O12

Abstract Using citric acid and ethylene glycol, a polymeric precursor of the above compound was obtained at low temperatures (135 °C) which on subsequent heat treatments led to pure CaCu 3 Ti 4 O 12 at 1000 °C. On sintering further at 1000 °C (20 h), the disks show high density (98%) and the dielectric constant was of the order of 3000 at 1 kHz. The dielectric loss varies between 0.3 and 0.35 (till 100 kHz) beyond that it increases sharply from 0.35 to 0.7 in the frequency range of 100–500 kHz. Our studies on dielectric properties of the above oxide, synthesized by the ceramic method and sintered under the same conditions, led to a dielectric constant of around 2200 at 1 kHz. The dielectric constant decreases with frequency in the oxides obtained by either of the above methods. Scanning electron micrographs (SEM) show much larger grains (nearly spherical) of 2–4 μm in the solid obtained by the ceramic route while the grains were much smaller (0.5–1.0 μm) in the oxide prepared by the polymeric citrate precursor route.