Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1610727 | Journal of Alloys and Compounds | 2014 | 6 Pages |
Abstract
The effects of the oxygen deficiency, δ, on the electrical and magnetic properties of Sr2âxLaxVO4âδ were investigated. For this objective, single-phase polycrystalline materials of Sr2âxLaxVO4âδ (x = 0, 0.04, 0.1, 0.2, 0.8 and 1) were synthesized. The value of δ was determined by thermo-gravimetric-analysis. The δ of Sr2âxLaxVO4âδ (x ⩽ 0.2) was almost the same value, â¼0.2. The δ of x = 0.8 was 0.05 and that of x = 1 was â¼0. Electrical resistivity measurement showed that all the samples were semiconductive. For the low magnetic field (â¼0.002 T) measurement, the spin-glass-like behavior was clearly observed for larger δ samples (x = 0.04, 0.1 and 0.2). This behavior became weak for smaller δ samples (x = 0.8 and 1). It is considered that the random distribution of the oxygen vacancies in the two-dimensional VO2 plane lead to this result. From the high magnetic field (1 T) measurement, it was found that the Curie-Weiss term, Ïcw, dominated in the magnetic susceptibility, Ï, of Sr2âxLaxVO4âδ (x ⩽ 0.2, δ â¼Â 0.2). The Ïcw considerably reduced for x = 0.8 (δ = 0.05) and almost disappeared for x = 1 (δ â¼Â 0) i.e., SrLaVO4. Thus, the Ïcw is considered to be originated from oxygen vacancies. Hence, it is revealed that the δ is critical to the properties of Sr2âxLaxVO4âδ, in addition to x. It is worthy to note that almost temperature independent Ï of SrLaVO4 is anomalous, because in this material, all the V are V3+ with S = 1. The almost temperature independent susceptibility may be due to the spin fluctuation enhanced by the strong two-dimensionality of the crystal structure, quantum fluctuation or the spin frustration in VO2 square lattice.
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
N. Suzuki, T. Noritake, T. Hioki,