Peculiar high-pressure behavior of BiMnO3
Alexei A Belik1, Hitoshi Yusa, Naohisa Hirao
1International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. Alexei.Belik@nims.go.jp
Inorganic Chemistry
|January 9, 2009
Summary
High-pressure studies reveal new structural phases in bismuth manganite (BiMnO3) perovskites. A monoclinic phase emerges at moderate pressures, transitioning to a stable orthorhombic phase at higher pressures.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Perovskite-type bismuth manganite (BiMnO3) exhibits complex structural behavior.
- Understanding high-pressure phase transitions is crucial for materials applications.
- Previous studies have explored ambient conditions, but high-pressure data is limited.
Purpose of the Study:
- To investigate the high-pressure structural properties of perovskite-type BiMnO3.
- To identify and characterize new phases under pressure.
- To compare high-pressure behavior with high-temperature and related perovskite data.
Main Methods:
- Synchrotron X-ray powder diffraction at room temperature.
- Variable pressure experiments up to approximately 8 GPa.
- Crystallographic analysis to determine phase symmetries and lattice parameters.
Main Results:
- A novel monoclinic phase (P2(1)/c symmetry) was identified between 1.5 and 5.5 GPa.
- The orthorhombic GdFeO3-type phase (Pnma symmetry) becomes stable above 8 GPa.
- Detailed crystal structure of the high-pressure orthorhombic phase was determined at 8.6 GPa.
Conclusions:
- BiMnO3 exhibits distinct structural phase transitions under high pressure.
- The high-pressure orthorhombic phase shows orbital ordering similar to LaMnO3 but with unique ac-plane arrangements.
- High-pressure behavior differs significantly from high-temperature behavior, suggesting unique pressure-induced phenomena.
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