Compounds in the Sr1-xBaxZrSe3 series, where 0 less than or equal to x less than or equal to 0.68, were prepared from SrSe, BaSe, Zr, and Se in evacuated and sealed silica ampules, at temperatures between 900 and 950 degrees C. An amorphous Zr-Se phase is competitively formed in the reaction thus synthesis mixtures require 20 and 40% mole excess of Zr and Se, respectively. The Sr1-xBaxZrSe3 compounds adopt the NH4CdCl3 structure type, containing columns of double edge-sharing ZrSe6 octahedra linked by distorted (Sr,Ba)Se-9 tricapped trigonal prisms. For 0.68 < x < 1.0, biphasic mixtures of CsNiCl3- and NH4CdCl3-type compounds are obtained. The x approximate to 1.0 phase is a commensurate mismatched chain compound of formula Ba1.07ZrSr3. The (Sr,Ba)Se-9 tricapped prisms show a marked decrease in bond distance anisotropy as the Ba2+ concentration increases in the Sr1-xBaxZrSe3 series. The structure of SrZrSe3 was determined from Rietveld profile analysis of the powder X-ray diffraction data whereas Sr0.74Ba0.26ZrSe3 and Sr0.32Ba0.68ZrSe3 were structurally characterized from single crystal X-ray studies. Crystallographic data for: (293 K)-orthorhombic, space group Pnma, a = 8.915(1), b = 3.965(1), and c = 14.514(2) Angstrom, V = 513.1(1) Angstrom(3), Z = 4, R = 5.39%, and R-wp = 6.55%; Sr0.74Ba0.26ZrSe3 (293 K)-orthorhombic, space group Pnma, a = 8.9305(2), b = 3.9796(13), and c = 14.611(2) Angstrom, V = 519.3(2) Angstrom(3), Z = 4, R(F-0) = 3.04%, wR(F-0(2)) = 5.95%; Sr0.32Ba0.68ZrSe3 (293 K)-orthorhombic, space group Pnma, a = 8.974(11), b = 4.0065(4), and c = 14.7868(12) Angstrom, V = 531.66(9) Angstrom(3), Z = 4, R(F-0) = 4.12%, wR(F-0(2)) = 9.94%. (C) 1997 Academic Press.
Xb116Times Cited:4Cited References Count:22