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Crystal structure and phase transitions in Sr3WO6
Graham King1, Artem M Abakumov, J Hadermann
1Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210-1185, USA. gking@chemistry.ohio-state.edu
Inorganic Chemistry
|June 10, 2010
Summary
The study reveals distinct crystal structures for strontium tungstate (Sr(3)WO(6)) polymorphs, detailing their phase transition. These findings offer insights into complex perovskite structures and their atomic arrangements.
Area of Science:
- Solid-state chemistry and materials science.
- Crystallography and structural analysis of inorganic compounds.
Background:
- Strontium tungstate (Sr(3)WO(6)) exists in different polymorphic forms, notably beta and gamma phases.
- Understanding these polymorphs and their interconversion is crucial for materials design and application.
Purpose of the Study:
- To elucidate the crystal structures of the beta and gamma polymorphs of Sr(3)WO(6).
- To investigate the gamma<-->beta phase transition mechanism in Sr(3)WO(6).
- To analyze the structural distortions and atomic arrangements within these double perovskite phases.
Main Methods:
- Electron diffraction for structural determination.
- Synchrotron X-ray powder diffraction for high-resolution structural analysis.
- Neutron powder diffraction to probe atomic positions and magnetic structures.
Main Results:
- The gamma-Sr(3)WO(6) polymorph, stable above 470 K, adopts a monoclinically distorted double perovskite structure (space group Cc).
- A continuous phase transition occurs upon cooling to the triclinically distorted beta-Sr(3)WO(6) phase (space group C1).
- A unique feature is the non-cooperative rotation of WO(6) octahedra in the gamma phase, leading to edge-sharing with Sr cations, increasing coordination numbers.
Conclusions:
- Both Sr(3)WO(6) polymorphs exhibit a broken corner-sharing connectivity in their octahedral framework, characteristic of specific double perovskites.
- The gamma to beta phase transition involves unequal octahedral rotation angles and increased WO(6) distortions, reducing the overall symmetry.
- The study provides a detailed structural understanding of Sr(3)WO(6) polymorphs and their phase transition, contributing to the knowledge of complex perovskite materials.
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