NEW TERNARY CLATHRATE COMPOUNDS IN THE SY STEMS BARIUM INDIUM ZINC/CADMIUM GERMANIUM - ZINTL COMPOUNDS WITH PHASE WIDTH/

By systematic investigations in the systems barium-indium/zinc/cadmium -germanium we found couple of new electrovalent ternary compounds with A(8)X(46) clathrate (I) type structures. They crystallize cubically i n space-group Pm3n. For Ba8In16Ge30 (a = 1075.8 pm), Ba8Zn8Ge38 (a = 1 082.0 pm) and Ba8Cd8Ge38 (a = 1096.0 pm) the structures were verified by X-ray single crystal diffraction data. According to valence and bou nding distances the new clathrates should be Zintl compounds. Measurem ents of the temperature dependence of the electrical resistivity prove d, that they are indeed semiconductors. A part of the 2B/3B metal atom s can be substituted by germanium. Charge balance will be retained by creation of vacancies in the A(8)X(46) type structures. By phase analy sis the limits of the composition range were determined as Ba8In4Ge9[] Ge-3(30) (a=1084.9pm), Ba8Zn4Ge10[]Ge-2(30) (a = 1073.6 pm) and Ba8Cd4 Ge10[]Ge-2(30) (a = 1082.0 pm).