| An investigation into the binary ZrI(,4)-Zr and ternary CsI-Zr-ZrI(,4)^systems has produced several new compounds which were^synthesized via high temperature techniques and characterized^by x-ray diffraction. The new binary compounds include two^polymorphs of ZrI(,2) ((alpha) and (beta)) as well as a new understanding of a^phase described earlier as "ZrI(,1.8)". (alpha)-ZrI(,2) forms as black lath-like^crystals by vapor phase transport reactions between Zr and ZrI(,4)^from 700 to 825(DEGREES)C. Its structure was refined in the monoclinic space^group P2(,1)/m with a = 6.821(2), b = 3.741(1), c = 14.937(3) (ANGSTROM) and^(beta) = 95.66(3)(DEGREES), Z = 4 (R = 0.064). This phase is isoelectronic and^isostructural with (beta)-MoTe(,2), a distorted CdI(,2)-type structure in which^the zirconium atoms are displaced 0.440 (ANGSTROM) from the centers of the^octahedra along a to form zig-zag metal chains (d(,Zr-Zr) = 3.182(3) (ANGSTROM))^parallel to b. (beta)-ZrI(,2) is similarly formed as black gem-like crystals^between 800-975(DEGREES)C, crystallizing in the trigonal space group R3(' )^with hexagonal axes a = 14.502(2) and c = 9.966(2) (ANGSTROM), Z = 18^(R = 0.109). This phase contains a Zr(,6)I(,12) cluster as; (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI); (d(,Zr-Zr) = 3.20 (ANGSTROM)) and is isostructural with Sc(,7)Cl(,12) = Sc('3+)Sc(,6)Cl(,12)('3-) save for the isolated cation. Guinier x-ray powder diffraction data previously reported for "ZrI(,1.8)" has now been found to arise from (alpha)-ZrI(,2) intergrown with an orthorhombic ZrI(,2) phase (perhaps isostructural with WTe(,2)) plus an unknown phase.; The ternary compounds include Cs(,2)ZrI(,6), Cs(,3)Zr(,2)I(,9) and CsZr(,6)I(,14). The first is isostructural with K(,2)PtCl(,6). Cs(,3)Zr(,2)I(,9) is formed from the reaction of CsI, ZrI(,4) and Zr between 700-900(DEGREES)C as black gem-like crystals which crystallize in the space group P6(,3)/mmc with a = 8.269(1) and c = 19.908(3) (ANGSTROM), z = 2. This phase was found to have a Cs(,3)Cr(,2)Cl(,9)-type structure, d(,Zr-Zr) = 3.134(4) (ANGSTROM) (R = 0.087). CsZr(,6)I(,14) forms both rod and gem crystals by the same reaction with more metal between 900-950(DEGREES)C. It crystallizes in the orthorhombic space group Ccmb with a = 14.275(4), b = 15.880(4) and c = 12.953(4) (ANGSTROM) (R = 0.062). This phase also contains a Zr(,6)I(,12) cluster as; (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI); (avg. d(,Zr-Zr) = 3.31 (ANGSTROM)) and is isostructural with Nb(,6)Cl(,14) and Ta(,6)I(,14) except that an additional cesium occupies a hole in the binary structure.; ; ('1)DOE Report IS-T-958. This work was performed under Contract W-7405-eng-82 with the Department of Energy. |
