Тип публикации: статья из журнала
Год издания: 2011
Идентификатор DOI: 10.1016/j.jmmm.2010.09.057
Ключевые слова: Ludwigite structure, Magnetic susceptibility, Magnetic frustration, Mott conductivity, AC susceptibility, Cation distributions, Crystal data, Crystallographic sites, Electrical resistivity, Iron atoms, Low temperatures, Magnetic behavior, Magnetic frustrations, Magnetic system, Magnetic transitions, Mossbauer, Mossbauer effects, Mott hopping, Superexchange energy, Superexchange interaction, Temperature regions, Trivalent iron, Variable range, Cobalt, Electric conductivity, Magnetism, Mossbauer spectroscopy, X ray diffraction, Crystal structure
Аннотация: The crystal structure, cation distribution and exchange interactions in the Co2.25Fe0.75O2BO3 ludwigite have been explored through X-ray diffraction, electrical resistivity, ac-susceptibility and Mossbauer effect measurements. The crystal data have shown that iron atoms occupy the most symmetric crystallographic sites Fe4 and Fe2. Показать полностьюThe complex magnetic behavior with two magnetic transitions near 70 and 115 K at low temperatures was found. The Mossbauer data have displayed the trivalent iron states only. The values of superexchange energies have been estimated for Co3O2BO3 and Co2.25Fe0.75O2BO3 yielding a significant role of frustrations in the ludwigite magnetic system. Variable range Mott hopping conductivity law was proved to be valid in the wide temperature region, pointing out a localized character of charge carriers rather than collective. (C) 2010 Elsevier B.V. All rights reserved.
Журнал: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Выпуск журнала: Vol. 323, Is. 5
Номера страниц: 521-527
ISSN журнала: 03048853
Место издания: AMSTERDAM
Издатель: ELSEVIER SCIENCE BV