Ba3SiI2, a Double Salt of Barium Iodide and the Zintl Phase Ba2Si

Reacting Ba2X (X=Si, Ge) with a melt of BaI2, new compounds of the composition Ba3I2X were found. These are the simplest representatives of double salts between Zintl phases and halides. The isotypic structures were refined by single-crystal X-ray data (Fddd, a=10.057(2), b=14.064(3), c=29.526(4) ?, R/Rw=0.04/0.07 for X=Si, and a=10.064(2), b=14.082(2), c= 29.605(4) ?, R/Rw=0.03/0.07 for X=Ge). Magnetic measurements show Ba3I2Si to be diamagnetic with a mol susceptibility of 7.7×10-5cm3/mol. This is in accordance with conductivity measurements and LMTO band structure calculations which show a semiconducting behavior with an electronic band gap of about 0.4 eV.