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Dislocation Structure of Epitaxial Ferrite‐Spinel Films
Author(s) -
Aleksandrov L. N.,
Mitlina L. A.,
Vasilyev A. L.,
Mikhailov V. A.
Publication year - 1986
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.2170210121
Subject(s) - ferrite (magnet) , materials science , spinel , beta ferrite , oxide , dislocation , crystallography , condensed matter physics , metallurgy , composite material , microstructure , chemistry , austenite , physics
The dislocation structure of ferrite‐spinel films obtained on the (001) plane of magnesium oxide has been studied. For the films of Mn and MgMn ferrites there has been found the formation of a cellular dislocation structure, complex dislocation clusters, for the Li ferrite the twinning. Experimental data are compared with the predictions of the theory of relaxation of internal stresses in heteroepitaxial structures. It has been shown that in the Li → Mn → MgMn ferrite the energy at the interface of magnesium ferrite and oxide ranges from 64 to 9 mJ · m −2 , the absolute magnitude of lattice mismatch at a synthesis temperature being 10.328 to 3.451 × 10 −3 and the critical thickness of a continuous film 0.02–0.1 μm. The formation of three‐dimensional islets‐nuclei hinders the obtaining of pseudomorphous continuous films. The critical radius ( R cr ) of a pseudomorphous islet in the same series of ferrites is 0.2–1.1 μm. For Li ferrite R exp > R er , for MgMn R exp < R er , that determines the prevailing types of defects. The process of relaxation of thermal stresses is associated with the overcoming of interaction barriers by dislocations and largely dependent on the film composition and temperature.