Synthesis of calcium copper titanate ceramics via the molten salts method

CaCu3Ti4O12 has a giant dielectric constant of up to 104 at room temperature and has great potential for various technological applications. In this work, CaCu3Ti4O12 ceramic powder was synthesized by heating a stoichiometric amount of CaCO3, CuO and TiO2 in molten NaCl–KCl and Na2SO4–K2SO4, 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 Na2SO4–K2SO4. 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 104 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 CaCu3Ti4O12 ceramics that were synthesized by the sol–gel method.