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Synthesis, crystal structure and physico-chemical properties of the new quaternary oxide Sr5BiNi2O9.6 |
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| Authors: | Mariya Novitskaya Ludmila Ivashkevich Holger Klein Jérémy David Mauro Gemmi Joke Hadermann |
| Institution: | a Department of Chemistry, Belarus State University, 14 Leningradskaya Str., 220030 Minsk, Belarus b Institute of Physicochemical Problems, Belarus State University, 14 Leningradskaya Str., 220030 Minsk, Belarus c Institut Néel CNRS and Université J. Fourier, BP 166, 38042 Grenoble Cedex, France d Center for Nanotechnology Innovation, NEST Istituto Italiano di Tecnologia, Piazza S.SIlvestro 12, 56127 Pisa, Italy e Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium |
| Abstract: | A new black quaternary oxide Sr5BiNi2O9.6 was synthesized by solid state reaction at 1200 °C. Its structure was solved by electron crystallography and X-ray powder refinement, yielding a tetragonal structure with space group I4/mmm, a=5.3637 (2) Å, c=17.5541(5) Å, Z=4. The structure can be described as a stacking of (Bi,Sr)-O rocksalt slabs and SrNiO3−δ perovskite slabs. The initial nickel valence is close to +3.1. Thermogravimetry and high-temperature oxygen coulometry showed that this compound has variable oxygen content as a function of temperature and oxygen pressure, and ultimately decomposes when heated in low oxygen pressure above 800 °C. It is a metallic conductor with n-type conduction. Its thermoelectric power was determined and found to be −20 and −38 μV/K at 300 and 650 °C, respectively. Magnetic measurements confirm the nickel valence close to +3 and show evidence of magnetic ordering at 20 K. |
| Keywords: | Perovskite Solid state synthesis Nickelates Oxygen vacancies |
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