Synthesis of single-phase polycrystalline Ca sub(2)Si powder and sintered compacts

Orthorhombic polycrystalline Ca sub(2)Si sintered compact bulk crystals were synthesized via a two-step treatment, and the experimental evaluation of the electrical and thermoelectric properties of Ca sub(2)Si is reported for the first time. First, single-phase Ca sub(2)Si powders were synthesized by the heat treatment of M sub(2)Si powders under a Ca vapor. Then Ca sub(2)Si sintered compacts were synthesized by the spark plasma sintering technique using the Ca sub(2)Si powders. It was found that single-phase Ca sub(2)Si sintered compacts were obtained when the sintering was carried out at temperatures lower than 673 K with high pressure of 300 MPa. The structural, electrical and thermoelectric properties of the Ca-silicide sintered compacts and their dependence on process conditions are discussed.