Defect formation in Gd3Fe5O12-based garnets: a Mossbauer spectroscopy study
authors Waerenborgh, JC; Rojas, DP; Shaula, AL; Kharton, VV; Marques, FMB
nationality International
journal MATERIALS LETTERS
author keywords garnet; gadolinium ferrite; Mossbauer spectroscopy; defects; electron-hole conductivity; ionic transport
keywords YTTRIUM-ALUMINUM-GARNET; ELECTRICAL-CONDUCTIVITY; PROPERTY CORRELATIONS; CRYSTALS; OXIDES; TEMPERATURE; TRANSPORT; SYSTEM; YIG
abstract The Mossbauer spectroscopy of Gd2.2Pr0.8Fe5O12 garnet, which exhibits higher electronic conduction with respect to Gd3Fe5O12 due to the presence of Pe(4+) cations, showed that praseodymium, doping decreases the coordination of Fe3+ in octahedral sites. Penta-coordinated Fe3+ ions, in combination with small quantities of Fe4+, are also formed in the lattice of Gd2.5Ca0.5Fe5O12 where the variations of ionic and electronic transport properties indicate charge compensation via generation of oxygen vacancies and electron holes. The mechanisms of garnet lattice disorder, induced by acceptor- and donor-type doping, appear thus quite similar; in all cases, the ionic defect formation requires substantial structural reconstruction, probably associated with direct linking of iron-oxygen tetrahedra. Due to the low concentration of charge carriers and the important role of lattice relaxation in the oxygen ion migration processes, this behavior results in similar activation energies for the ionic conductivity in all Gd3Fe5O12-based garnets. (C) 2004 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-577X
year published 2004
volume 58
issue 27-28
beginning page 3432
ending page 3436
digital object identifier (doi) 10.1016/j.matlet.2004.05.081
web of science category Materials Science, Multidisciplinary; Physics, Applied
subject category Materials Science; Physics
unique article identifier WOS:000224449500013
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