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Low-temperature vacuum reduction of BiMnO3
Alexei A Belik1, Yoshitaka Matsushita, Masahiko Tanaka
1International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. Alexei.Belik@nims.go.jp
Inorganic Chemistry
|July 14, 2011
Summary
Researchers prepared oxygen-deficient BiMnO(2.81) via low-temperature vacuum reduction. This new phase exhibits a cubic perovskite structure with ordered oxygen vacancies and MnO(5) pyramids, though it is unstable in air.
Area of Science:
- Materials Science
- Solid State Chemistry
- Crystallography
Background:
- Stoichiometric BiMnO(3) is a known perovskite material.
- Controlling oxygen stoichiometry is crucial for tuning material properties.
- Low-temperature synthesis routes are desirable for preserving complex structures.
Purpose of the Study:
- To synthesize a novel oxygen-deficient bismuth manganate phase.
- To characterize the crystal structure and oxygen vacancy ordering of the new phase.
- To investigate the stability of the oxygen-deficient phase.
Main Methods:
- Low-temperature vacuum reduction of stoichiometric BiMnO(3) at 570-600 K and <10(-3) Pa.
- Synchrotron X-ray powder diffraction for structural analysis.
- Analysis of crystal structure, including space group and lattice parameters.
Main Results:
- Successfully prepared oxygen-deficient BiMnO(2.81) in bulk form.
- BiMnO(2.81) crystallizes in a cubic perovskite-type structure (space group I-43d) with a 4a(p) superstructure.
- Ordered oxygen vacancies lead to the formation of MnO(5) pyramids, and the material is unstable in air.
Conclusions:
- Low-temperature vacuum reduction is an effective method for creating oxygen-deficient BiMnO(2.81).
- The ordered oxygen vacancies significantly alter the crystal structure, forming MnO(5) pyramids.
- The synthesized BiMnO(2.81) phase exhibits instability in ambient conditions, readily re-oxidizing.
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