Os4+ Instability in the Pyrochlore Structure: Tl2–xBixOs2O7–y
| Autor: | Daniel Haskel, Jun Li, P. G. LaBarre, Arthur P. Ramirez, Elizabeth Sobalvarro Converse, Munirpallam A. Subramanian |
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| Rok vydání: | 2020 |
| Předmět: |
Valence (chemistry)
Absorption spectroscopy Chemistry Pyrochlore Valency engineering.material Inorganic Chemistry Condensed Matter::Materials Science Paramagnetism Crystallography Lattice constant Metastability engineering Condensed Matter::Strongly Correlated Electrons Physical and Theoretical Chemistry Solid solution |
| Zdroj: | Inorganic Chemistry. 59:1227-1233 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | Osmium-containing oxides are rare due to the difficulty in stabilizing complex structures with a fixed stoichiometry and metastability of the phases. Bismuth-substituted thallium osmate pyrochlore samples, Tl2-xBixOs2O7-y, were synthesized using solid-state reactions where the solubility limit was found to be approximately x = 1.4. Members of this solid solution were characterized by their structural, electronic, magnetic, and thermal properties to understand the influence of Bi3+ substitution on the ground state. The Os-containing pyrochlores crystallize in the ideal cubic pyrochlore structure (Fd3m), and the lattice parameter a was found to slightly increase as a function of Bi content. A possible interplay between structure and cation valence states was explored using both neutron powder diffraction and X-ray absorption spectroscopy, suggesting that a combination of Os4+/Os5+ and Tl1+/Tl3+ mixed valency throughout the solid solution allows for the stabilization of the pyrochlore structure. The system is metallic for the entire solid solution and predominantly exhibits temperature-independent paramagnetism. Specific heat measurements show an enhanced Sommerfeld coefficient, a possible flat-band signature. This system gave insight into the bonding preferences of Os, indicating a dependence on high oxidation states and mixed valence for the stability of complex structures. |
| Databáze: | OpenAIRE |
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