Phase Evolution, Microstructure and Dielectric Properties of CaCu₃Ti₄O₁₂Ceramics Fabricated by Combustion Technique

Abstract

The effects of calcination temperature (750-1000 • C) and sintering temperature (1000-1125 • C) on phase evolution, microstructure and the dielectric properties of CaCu 3 Ti 4 O 12 (CCTO) ceramics were investigated. CCTO powders were synthesized by the combustion technique. The pure cubic perovskite phase of CCTO powders was detected above a calcination temperature of 950 • C and it was also obtained from the ceramics sintered below 1125 • C. The lattice parameter a of CCTO powder (7.3829-7.3870 Å) and ceramic (7.3721-7.3857 Å) increased with the higher firing temperatures. The increasing of the average particle size and the average grain size of samples was caused by the increase of firing temperatures. The highest density was ∼96% of the theoretical density, and was obtained from the sample sintered at 1100 • C for 2 h. This sample also exhibited a maximum dielectric constant of approximately 29664 and a low dielectric loss of about 0.0925. Most importantly, the combustion fuel (glycine) carried out an important role by reducing the dwell time and improving the density and dielectric properties.