High-Pressure Synthesis and Chemical Bonding of Barium Trisilicide BaSi(3)

BaSi(3) is obtained at pressures between 12(2) and 15(2) GPa and temperatures from 800(80) and 1050(105) K applied for one to five hours before quenching. The new trisilicide crystallizes in the space group I [Formula: see text] 2m (no. 121) and adopts a unique atomic arrangement which is a distorted variant of the CaGe(3) type. At ambient pressure and 570(5) K, the compound decomposes in an exothermal reaction into (hP3)BaSi(2) and two amorphous silicon-rich phases. Chemical bonding analysis reveals covalent bonding in the silicon partial structure and polar multicenter interactions between the silicon layers and the barium atoms. The temperature dependence of electrical resistivity and magnetic susceptibility measurements indicate metallic behavior.