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Publicatii proprii
Anion substitution effects on structure and magnetism in the chromium chalcogenide Cr(5)Te(8) – Part I: Cluster glass behavior in trigonal Cr((1-x)) Q(2) with basic cell (Q = Te, Se; Te : Se=7 : 1)
The effect of substitution of the anion Te by Se in non-stoichiometric Cr(5)Te(8) has been investigated with respect to its crystal structure, magnetic properties, and electronic structure. The compounds Cr((1 + x))Q(2) (Q = Te, Se; Te:Se = 7:1; (1 + x) = 1.234(6), 1.264(6), 1.300(7)) were synthesized at elevated temperatures followed by quenching the samples to room temperature. The crystal structures have been refined with X-ray powder diffraction
Read moreLimitations of integral XMCD sum-rules for the early 3d elements
We report on XMCD measurements at the L2,3 edges of the early 3d transition metals, Ti, V and Cr, polarized by Fe. In contrast to the classical ferromagnets Fe, Co and Ni, the XMCD spectra reveal a complex and detailed fine structure. We analyze the experimental data with the help of full-relativistic ab initio calculations of the x-ray absorption cross section μ(E) that provide the energy-dependent XMCD spectrum and the correlated magnetic moments
Read moreDirect observation of the multisheet Fermi surface in the strongly correlated transition metal compound ZrZn2
The existence of flat areas of a Fermi surface (FS), predicted by electronic structure calculations and used in models of both magnetically mediated and phonon-mediated Fulde-Ferrell-Larkin-Ovchinnikov superconducting states, is reported in the paramagnetic phase of the ferromagnetic superconductor ZrZn2 using positron annihilation. The strongly mass-renormalized FS sheet, dominating the Fermi level density of states, is seen for the first time.
Read morePreparation, crystal structure, properties, and electronic band structure of TlTaSe3
TlTaSe3 was prepared from a fused mixture of Tl4Ta2Se11, Ta and Se in the molar ratio 1:2:1. The compound shows dimorphism with H-TlTaSe3, hexagonal, space group P6(3)/mmc, a = 7.2436(6), c = 5.9736(6) angstrom, c/a = 1.213 and O-TITaSe3, orthorhombic, space group Pnma, a = 9.554(13), b = 3.6244(6), c = 14.7271(17) angstrom. The crystal structure of H-TlTaSe3 is isotypic to BaVSe3 whereas that of O-TlTaSe3 is closely related to the NH4CdCl3-type.
Read moreCrystal structures, unusual magnetic properties and electronic band structures of Cr5-xTIxTe(8)
he effect of substitution of the cation Cr by Ti in Cr(5)Te(8) has been investigated with respect to its crystal structure, magnetic properties, and electronic structure. The compounds Cr(5-x)Ti(x)Te(8) (x = 0, 0.5, 1, 1.5, 1.85, 2, 3, 4, 5) were synthesized at elevated temperatures followed by slow cooling the samples to room temperature. The crystal structures have been refined with X-ray powder diffraction data with the Rietveld method. Three
Read moreStructural modifications of cellulose in heterogeneous acetylation process
Three cellulosic materials with crystalline structures of cellulose I, cellulose II and mixture of cellulose I and III, respectively, are acetylated in a heterogeneous system consisting of a mixture of acetic acid and toluene in order to decrease their hydrophilic character. Different degrees of acetylation are achieved by carrying out the process for various times of reaction. The variation of water affinity of the acetylated fibres estimated from
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