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Structural phase transitions in the LaMnO 3+λ system
Author(s) -
Bogush A. K.,
Pavlov V. I.,
Balyko L. V.
Publication year - 1983
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170180504
Subject(s) - orthorhombic crystal system , octahedron , phase transition , phase diagram , materials science , stoichiometry , phase (matter) , atmospheric temperature range , crystallography , transition temperature , trigonal crystal system , ferroics , condensed matter physics , crystal structure , chemistry , thermodynamics , quantum phase transition , physics , quantum critical point , superconductivity , organic chemistry
Structural phase transitions in the LaMnO 3+λ system are studied at various temperatures and with different Mn 4+ ion concentrations. Two structural phase transitions are established. The O′‐orthorhombic – O‐orthorhombic transition (O′O transition) is due to removing the cooperative Jahn‐Teller distortions and occurs in the Mn 4+ concentration range from 10 to 14% at room temperature. The temperature of this transition varies from 710 K for the stoichiometric LaMnO 3 to room temperature for LaMnO 3.07 . The O‐orthorhombic – rhombohedral transition (OR transition) is due to the change of the rotation axis of the undistorted MnO 6 octahedra from [100] and [110] to [ 11 1]. The temperature of this transition varies from 1010 K for LaMnO 3 to 230 K for LaMnO 3.135 . The structural phase diagram of temperature vs composition is plotted, indicating the existence of regions of the phase with different structures.