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Structural Changes in MgMn 2 O 4 at High Temperatures
Author(s) -
Mănăilă R.,
Păuşescu P.
Publication year - 1965
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19650090211
Subject(s) - tetragonal crystal system , ionic bonding , crystallography , cubic crystal system , diffraction , phase transition , activation energy , phase (matter) , materials science , chemistry , mineralogy , ion , condensed matter physics , crystal structure , physics , optics , organic chemistry
The distribution of cations in MgMn 2 O 4 is studied between 25 and 1000 °C by X‐ray diffraction. The values of the c/a ratio agree with the observed repartition of the cations. From the inversion of the distribution at high temperature the activation energy of the ionic migration is inferred: θ = 8100‐−18400 λ (°K). Around the tetragonal‐to‐cubic transition temperature there is a coexistence domain of both structures and an hysteresis of the proportion of the cubic phase. The appearance of the cubic phase seems to be facilitated by the inversion of the ionic distribution in the cubic nuclei.