Synthesis of calcium copper titanate ceramics via the molten salts method

Abstract CaCu 3 Ti 4 O 12 has a giant dielectric constant of up to 10 4 at room temperature and has great potential for various technological applications. In this work, CaCu 3 Ti 4 O 12 ceramic powder was synthesized by heating a stoichiometric amount of CaCO 3 , CuO and TiO 2 in molten NaCl–KCl and Na 2 SO 4 –K 2 SO 4 , respectively. The synthesis temperature was decreased from 1000 °C (required by conventional solid-state reactions) to 750 °C for NaCl–KCl or to 850 °C for Na 2 SO 4 –K 2 SO 4 . The flux type has a larger influence on the phase compositions and morphology of the resultant powders than the synthesis temperature does. The dielectric constant of the resulting ceramics is more than 10 4 over the wide frequency range from 100 Hz to 100 kHz. The dielectric loss tangent of the resulting ceramics is lower than 0.2 in the frequency range from 100 Hz to 100 kHz. The dielectric behavior of both samples is similar to the results obtained for CaCu 3 Ti 4 O 12 ceramics that were synthesized by the sol–gel method.