PREPARATION, STRUCTURE, AND ELECTRONIC-PROPERTIES OF CA(11)MSB(9) (M=AL, GA, IN)

Two new Zintl compounds Ca(11)MSb(9) (M = Al, Ga) and the Zintl compou nd Ca11InSb9 have been synthesized in quantitative yields by reacting the elements in an 11:1:9 ratio at high temperatures (850 and 1000 deg rees C). Low-temperature (130 K) single-crystal X-ray diffraction data show that the Ca11GaSb9 compound is orthorhombic, space group = Iba2, Z = 4, a = 11.805(3) Angstrom, b = 12.463(3), c = 16.651(2) Angstrom, R1 = 2.50%, wR2 = 5.22%, and is of the Ca11InSb9 structure type. Powd er X-ray diffraction show that Ca11AlSb9 is also the Ca11InSb9 structu re type. Room-temperature lattice parameters from powder diffraction d ata are as follows: Ca11AlSb9, a = 11.832(3) Angstrom, b = 12.505(2) A ngstrom, c = 16.674(4) Angstrom; Ca11GaSb9, a = 11.839(2) Angstrom, b = 12.536(3) Angstrom, c = 16.716(1) Angstrom; Ca11InSb9 a = 11.899(2) Angstrom, b = 12.596(2) Angstrom, c = 16.722(3) Angstrom. Temperature- dependent resistivity measurements show that these materials are semic onducting.