Preparation and dielectric properties of glass–ceramics in K2O–Al2O3–SiO2–CaO–CuO–TiO2 system

Glass–ceramics containing CaCu3Ti4O12(CCTO) crystalline phase were successfully prepared by air-quenching K2O–Al2O3–SiO2–CaO–CuO–TiO2 melts followed by heat treatment. X-ray diffraction, scanning electron microscopy and dielectric spectroscopy were used to characterize the samples. The results indicate that the as-synthesized samples are well crystallized upon the heat treatment. The main crystalline phases are KAlSi2O6, CCTO, CaTiO(SiO4), TiO2 and Cu2+1O. The dielectric constants of the as-synthesized samples increase with the total contents of CaO, CuO, TiO2. However, the dielectric constants of the heat treated samples is related to the formed CCTO crystalline phase, whose content is influenced by the glassy phase in the as-synthesized sample or re-melting of the KAlSi2O6 phase during the heat-treatment. The heat treated sample having the highest amount of CCTO phase shows the largest dielectric constant of 38. The dielectric losses (100 kHz, room temperature) of the samples are relatively smaller than the reported data in the literature.