Development of a novel parallel synthesis by injection moulding and its application to study dielectric materials

摘要

A new parallel synthesis method by injection moulding technique has been developed for producing multi-component solid-state inorganic materials. The utility of the method has been illustrated by phase relationship investigation of the ternary system Fe2O3-TiO2-Al2O3. The consistency of phase relationship to the previous investigations by conventional means proved the reliability of the new combinatorial strategy. A further application of this parallel synthesis strategy was performed on another ternary system CuO-TiO2-CaO. The phase relations have been tentatively determined. From room-temperature dielectric property mapping at 10 kHz, giant dielectric constants (år >104) were observed for most of ceramic composites in the CuO-rich region and in the region along CuO-CaO binary line. The composites in the CaCu3Ti4O12-rich region were found to give a comparable giant dielectric constant when sintered at 1050°C. Composites with high år showed a particular microstructure of larger grains of a predominant phase surrounded by smaller grains of a secondary phase. In the representative composite with molar fraction of Cu/Ti/Ca of ~85/10/5, the frequency and temperature dependencies of permittivity and impedance were investigated. Strong hints suggested grain boundary effect as the most probable dielectric mechanism. Finally, the dielectric properties of the high-år composites prepared by sol-gel process revealed the qualitative reproducibility of the high-år composites.