Synthetic exploration and characterization of zirconium-rich chalcogenides /
This dissertation presents the synthetic exploration of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739364481&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This dissertation presents the synthetic exploration of ternary zirconium chalcogenides incorporating both late transition metals and main-group elements. A family of compounds, Zr6MQ2 (M = Mn, Fe, Co, Ni. Ru, Pt; Q = S, Se, Te), were synthesized. The tellurides adopt the Zr6COA12- type structure while the selenides and sulfides adopt the Ta2P-type structure. Chains of condensed M-centered, tetrakaidecahedra of zirconium constitute the basic structural unit in all these compounds. Modes of cross- linking that give rise to the Zr6FeTe2 and Zr6Fel-xQ2+x structures and the influence of chalcogen size differences are discussed. The stabilization of these tellurides conferred by polar intermetallic Zr-Fe bonding is underscored by a bonding analysis derived from electronic band structure calculations. The investigation of Zr-Z-Te systems (Z = main- group elements) lead to the discovery of several compounds. Layers of edge-sharing of octahedral [Zr6As] clusters constitute the basic structural unit in Zro.29Zr2Te2As and Zr2TeAs. The replacement of included Zr ions in Zro.29Zr2Te2As by Na ions has been demonstrated. Structural relationships between Zro.29Zr2Te2As, Zr2TeAs, Zro.3ZrTe2 and ZrAs are presented. In the family of Zr(Sil-xAx)(AyTel-y) (A = Si, As, Sb; 0 < x, y < 1), ZrSio.66AS0.34Te is isostructural with ZrSiTe; arsenic in this material substitutes solely for silicon. ZrSio.5Aso.7Teo.8 and ZrSiO.5Sbo.7Teo.8 exhibit substitution for both Si and Te. Solid solutions of the type ZrSil-xGexTe were studied and revealed a smooth structural transformation from the 2-D ZrSiTe to the 3-D ZrGeTe. The new member ZrSnTe completes the 2-D to 3-D transformation on moving from ZrSiTe to ZrGeTe. Temary tellurides M,Zr3Te4 (MI = Na, K, Rb, Cs; 0.2 < x < 0.5) were synthesized and adopted a stuffed Nb3Te4-type structure. Zigzag Zr-Zr bonded chains are characteristic of the structure. Zr-Zr bond distances in these compounds are longer (- 0.5 A) than those of Nb3Te4 as expected for compounds with fewer electrons for metal-metal bonding. These compounds, like those mentioned above, are metallic with typical resistivities -10-4!a-cm. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvi, 171 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 154-161. |