Тип публикации: статья из журнала
Год издания: 2015
Идентификатор DOI: 10.1016/j.jmmm.2015.03.016
Ключевые слова: Phase transition, Magnetic structure, Pyroxene, Magnetic properties, Calorimetric measurements, Antiferromagnetism, Calorimetry, Crystallography, Lithium, Phase transitions, Magnetism, Silicate minerals, Single crystals, Spin fluctuations, Vector spaces, Calorimetric investigations, Collinear antiferromagnetic structure, Crystal and magnetic structure, First-order phase transitions, Structural and magnetic properties, Superstructure reflections, Crystal structure
Аннотация: The possibility of cation substitution in pyroxenes allows the investigation the gradual change of structural and magnetic properties under doping in these compounds. Here, Na0.5Li0.5FeGe2O6 was prepared by the standard solid-phase reaction method and has been investigated using X-ray and neutron powder diffraction, and further chaПоказать полностьюracterized by magnetic and calorimetric measurements. The crystal structure of Na0.5Li0.5FeGe2O6, at 300 K is monoclinic C2/c (a-10.0333(1), b=8.8136(1), c =5.5295 (9) angstrom, beta = 108.921(1)degrees). Calorimetric investigations indicate a displacive first order phase transition at T=271 +/- 1 K which is accompanied by the appearance of superstructure reflections in the X-ray patterns. At this transition Na0.5Li0.5FeGe2O6 undergoes a space group change from C2/c to P2(1)/c (a-9.9692(3), 6-8.8545 (3), c-5 4752(2) angstrom. (3=108.494(1)). Magnetic order has been found below the Neel temperature T-N approximate to 18 K and has been refined from neutron diffraction. The quasi-low-dimensional magnetic spin system Na0.5Li0.5FeGe2O3 exhibits a collinear antiferromagnetic structure with the space group Pa2(1)/c and the doubling of the unit cell along the crystallographic a-axis of the pyroxene crystal (propagation vector k = (1/2, 0, 0)). The critical modes which are responsible for the phase transition from C21c to P21/c symmetry and for the magnetic transition from paramagnetic to antiferromagnetic state have been determined and their role in the transition is described. They are also the relevant mechanism driving the magnetic order in LiFeGe2O6. (C) 2015 Elsevier By. All rights reserved.
Журнал: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Выпуск журнала: Vol. 385
Номера страниц: 243-249
ISSN журнала: 03048853
Место издания: AMSTERDAM
Издатель: ELSEVIER SCIENCE BV