Growth and Characterization of Ce- Substituted Nd2Fe14B Single Crystals

Single crystals of (Nd1-xCex)2Fe14B are grown out of Fe-(Nd,Ce) flux. Chemical and structural analysis of the crystals indicates that (Nd1-xCex)2Fe14B forms a solid solution until at least x = 0.38 with a Vegard-like variation of the lattice constants with x. Refinements of single crystal neutron diffraction data indicate that Ce has a slight site preference (7:3) for the 4g rare earth site over the 4f site. Magnetization measurements show that for x = 0.38 the saturation magnetization at 400 K, a temperature important to applications, falls from 29.8 for the parent Nd2Fe14B to 27.6 (mu)B/f.u., the anisotropy field decreases from 5.5 T to 4.7 T, and the Curie temperature decreases from 586 to 543 K. First principles calculations carried out within density functional theory are used to explain the decrease in magnetic properties due to Ce substitution. Though the presence of the lower-cost and more abundant Ce slightly affects these important magnetic characteristics, this decrease is not large enough to affect a multitude of applications. Ce-substituted Nd2Fe14B is therefore a potential high-performance permanent magnet material with substantially reduced Nd content.Comment: 11 Pages, 8 figures, 5 table

The current state of soil cover in Kazakhstan, problems and solution - Langfassung

This paper presents the research material gained during implementation of the international project led by the International Center for Agricultural Research in Arid Areas (ICARDA) entitled “Sustainable management of land resources in arid regions of Central Asia and Caucasus”. This project focused primarily on irrigation and degraded pastures in south and southeast Kazakhstan. Soils and forage crops were studied using conventional, proven methodological approaches and agro-chemical methods. The subjects of the study were: terrains, soil, water, cultivated and pasture plants (rice, triticale and winter wheat, wormwood-ephemeral, grass-shrub and cereal-grass communities)

The current state of soil cover in Kazakhstan, problems and solution

The main directions of scientific activity of the U.U.Uspanov Kazakh Research Institute of Soil Science and Agrochemistry is study of regularities in soil formation under anthropogenic pressure; rational use and increase of bio-productivity of soil resources; development of new technologies to improve soil fertility and crop productivity; assessment of the ecological state of soils in the conditions of anthropogenesis and development of measures for their improvement; provision of consulting and practical services for survey and preparation of agrochemical cartograms and map- schemes with various scales

Magnetic and structural transitions in La0.4_{0.4}Na0.6_{0.6}Fe2_2As2_2 single crystals

La$_{0.4}$Na$_{0.6}$Fe$_2$As$_2$ single crystals have been grown out of an NaAs flux in an alumina crucible and characterized by measuring magnetic susceptibility, electrical resistivity, specific heat, as well as single crystal x-ray and neutron diffraction. La$_{0.4}$Na$_{0.6}$Fe$_2$As$_2$ single crystals show a structural phase transition from a high temperature tetragonal phase to a low-temperature orthorhombic phase at T$_s$\,=\,125\,K. This structural transition is accompanied by an anomaly in the temperature dependence of electrical resistivity, anisotropic magnetic susceptibility, and specific heat. Concomitant with the structural phase transition, the Fe moments order along the \emph{a} direction with an ordered moment of 0.7(1)\,$\mu_{\textup{B}}$ at \emph{T}\,=\,5 K. The low temperature stripe antiferromagnetic structure is the same as that in other \emph{A}Fe$_{2}$As$_{2}$ (\emph{A}\,=\,Ca, Sr, Ba) compounds. La$_{0.5-x}$Na$_{0.5+x}$Fe$_2$As$_2$ provides a new material platform for the study of iron-based superconductors where the electron-hole asymmetry could be studied by simply varying La/Na ratio.Comment: 9 pages, 7 figures, to appear in Physical Review