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Search for Pnma materials with high-temperature structural phase transitions
1Fisika Aplikatua II Saila, Zientzia Fakultatea, Euskal Herriko Unibertsitatea, 644 Postakutxatila, Bilbao 48080, Spain. wmpigalj@lg.ehu.es
Acta Crystallographica. Section B, Structural Science
|August 6, 2000
Summary
Researchers identified pseudosymmetric inorganic structures likely to undergo high-temperature phase transitions. A maximal atomic displacement parameter (Delta) below 0.7 Å suggests a high probability for these structural phase transitions.
Area of Science:
- Crystallography
- Materials Science
- Solid-State Physics
Background:
- Pseudosymmetry in crystal structures suggests a higher-symmetry configuration.
- Small distortions in pseudosymmetric structures may lead to Landau-type phase transitions at higher temperatures.
Purpose of the Study:
- To systematically search for inorganic structures exhibiting pseudosymmetry.
- To identify compounds likely to undergo high-temperature structural phase transitions.
Main Methods:
- Systematic search of inorganic structures with space group Pnma from the Inorganic Crystal Structure Database.
- Identification of pseudosymmetric structures using a maximal atomic displacement parameter (Delta).
- Analysis of Delta values for compounds with known phase transitions and comparison with potential candidates.
Main Results:
- Pseudosymmetry was detected in inorganic compounds with known displacive Landau-type phase transitions.
- A maximal atomic displacement (Delta) below 1.0 Å was observed for most known phase transition compounds.
- 144 additional structures with pseudosymmetry features were identified, with 58 fulfilling a stricter Delta criterion (< 0.7 Å) for high transition probability.
Conclusions:
- Pseudosymmetry is a reliable indicator for identifying potential high-temperature structural phase transitions.
- A maximal atomic displacement parameter (Delta) below 0.7 Å effectively selects materials with a high probability of exhibiting such transitions.