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1

Photoemission spectra of some uranium compounds

Szajek A., Werwiński M., Morkowski J. A., Chełkowska G., Troć R.

Materials Science Poland

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2008

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Vol. 26, No. 4

995--999

EN

The electronic structure of some ternary uranium compounds (U2Ru2Sn and Ucu5M, M=Al, In, Sn) by theoretical (ab-initio calculations) and experimental investigations (X-ray photoemission) is studied. The band structure calculations have been performed based on the full-potential local-orbital (FPLO) method. The calculated densities of electronic states are used to obtain photoemission spectra, which are compared with experimental ones. Satisfactory agreement between the measured spectrum and that obtained from the calculated electronic structure has been achieved.

2

Electronic structure and electric properties of Gd(In1-xSnx)3 compounds

Kwiecień M., Chełkowska G., Betlińska A.

Materials Science Poland

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2007

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Vol. 25, No. 2

411--416

EN

Results of measurements of the electrical resistivity, crystal and electronic structure of Gd(In1-xSnx)3 compounds are reported. All these compounds crystallize in the cubic AuCu3 type structure. The effect of partial substitution of In by Sn atoms is reflected in a linear increase of the unit cell volume. The temperature dependence of the electrical resistivity ?strongly depends on the composition. For compounds with x ??0.1, the ??(T) behavior, observed at low temperatures, is untypical of metals. The electronic structure of all systems was studied by using X-ray photoelectron spectroscopy. The chemical shift of the 4f Gd peak to higher binding energy with the increase of Sn concentration was detected. The valence band near the Fermi level is dominated by hybridized 5d Gd and 5p In/Sn states.

3

Electronic properties of CeNi4Si compound

Falkowski M., Kowalczyk A., Toliński T., Chełkowska G.

Materials Science Poland

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2007

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Vol. 25, No. 2

321--326

EN

Temperature dependence of the specific heat for CeNi4Si was analyzed. These studies were supported by magnetic susceptibility, electrical resistivity and X-ray photoemission spectroscopy measurements.CeNi4Si is paramagnetic and follows the Curie-Weiss. This effective paramagnetic moment is lower than that for the free Ce3+. The f-occupancy nf and coupling between the f level and the conduction state are derived to be about 0.91 and 36 meV, respectively. Both the susceptibility data and the XPS spectra have shown that Ce ions are in intermediate valence state. The specific heat has been analyzed considering the electronic contribution, the Schottky anomaly, and the lattice contributions within the Debye model. The scheme of the energy levels created by the crystal electric field split is determined from the Schottky contribution to the specific heat.

4

Magnetic properties and electronic structure of YxGd1-xNi5 compounds

Bajorek A., Stysiak D., Chełkowska G., Deniszczyk J., Borgieł W., Neumann M.

Materials Science Poland

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2006

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Vol. 24, No. 3

867--874

EN

Measurements of the magnetic susceptibility, crystal and electronic structure for YxGd1-xNi5 (x=0.0, 0.2, 0.5, 0.8, 1.0) compounds with the CaCu5 type of crystal structure are reported. The substitution of Y for Gd atoms results in a decrease of the volume unit cell and the Curie temperature. In the paramagnetic range (300-650K) the DC susceptibility follows Curie-Weiss law for all investigated compounds. The effective moment deduced from the Curie constant decreases rapidly with Y concentration. The saturation magnetic moment for GdNi5 shows negative polarization of Ni 3d band induced by interactions with Gd 5d states. Both valence band and core level X-ray photoelectron spectra are analyzed. The presence of the satellite structure in Ni2p core level suggests the magnetic polarisation of Ni 3d states which dominate the valence band in all investigated compositions. The experimental investigations were completed with the band structure calculations. In all cases the calculations were based on KKR and KKR-CPA methods. Satisfactory agreement between the measured spectra and those obtained from the calculated electronic structure has been achieved.