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1
Content available remote 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
Content available remote Electronic properties of ThCu5Sn and ThCu5In compounds
Werwiński M., Szajek A.
Materials Science Poland
|
2008
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Vol. 26, No. 3
724--727
EN
ThCu5In and ThCu5Sn alloys crystallize in an orthorhombic CeCu5Au-type structure with the Pnma space group. Ab-initio band structure calculations have been performed based on the full-potential localorbital (FPLO) method. The calculated densities of electronic states are used to obtain photoemission spectra. The spectra of valence bands are predominated by 3d electrons located on Cu atoms.
3
Content available remote Electronic structure of U5Ge4
Szajek A.
Materials Science Poland
|
2007
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Vol. 25, No. 2
513--517
EN
U5Ge4 crystallizes in a hexagonal Ti5Ga4 type structure with two inequivalent crystallographic sites occupied by uranium atoms. The band structure calculations were performed by the method of tight binding version of the linear muffin-tin orbital in the atomic sphere approximation (TB-LMTO ASA). The calculations showed that both types of uranium atoms can be magnetically ordered and then their spin magnetic moments are equal to 0.5 and -1.2 žB/atom, respectively.
4
Content available remote Electronic and electrochemical properties of Mg2Ni alloy doped by Pd atoms
Szajek A., Okońska I., Jurczyk M.
Materials Science Poland
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2007
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Vol. 25, No. 4
1251--1257
EN
The structure and electrochemical properties of nanocrystalline Mg2Ni and Mg2Ni/Pd nanocomposite have been studied. The materials were prepared by mechanical alloying. In nanocrystalline Mg2Ni powder, discharge capacities up to 100 mAźhźg-1 were measured. It was found that mechanically coated Mgbased alloys with palladium have effectively reduced the degradation rate of the studied electrode materials. Finally, the properties of nanocrystalline alloys and their nanocomposites were compared to those of microcrystalline samples. The electronic structure was studied by ab initio calculations, which showed that the 3b positions in the unit cell are preferred by the Pd impurities.
5
Content available remote The electronic and magnetic properties of Nd5Co19B6 and Nd5Co21B4 compounds
Szajek A.
Materials Science Poland
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2006
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Vol. 24, No. 3
843--848
EN
The Nd5Co19B6 and Nd5Co21B4 compounds were manufactured as promising systems suitable for fabrication of permanent magnets. They belong to the Rm+nCo5m+3nB2n family having the P6/mmm space group. The band structure calculations are performed by the tight binding version of the linear muffin-tin orbital method in the atomic sphere approximation (TB-LMTO ASA). The calculated magnetic moments on Co atoms depend on their local environment. The calculated values are compared with the bulk measurements.
6
Content available remote The electronic and magnetic properties of metastable Fe22PdB6 and Fe22PtB6 compounds
Szajek A., Kostyrya S.A., Idzikowski B.
Materials Science Poland
|
2006
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Vol. 24, No. 3
855--859
EN
Nanstructured soft magnets are example of materials made by partial crystallization of amorphous precursors. Fe22(Pt,Pd)B6 compounds which crystallize in the Cr23C6-type structure having four inequivalent sites (4a, 8c, 48h, 32f) for Fe, Pd and Pt atoms can form grains of several nanometers in diameter in residual amorphous matrix. Band structure calculations show that the local magnetic moments of Fe atoms depend on their local environments, and for 4a and 8c sites the resultant moments are enhanced up to about 2.5-3 žB/atom. The Pd and Pt atoms prefer location in 4a and 8c positions, respectively. Magnetic moments induced on the substituted atoms are equal to 0.45 žB/atom on Pt atom and 0.39 žB/atom on Pd one.
7
Content available remote Calculated magnetic moments and electronic structure of the compounds Rn+1Co3n+5B2n, R = Gd, Tb, n = 0, 1, 2, 3 and ∞
Szajek A., Morkowski J.A.
Materials Science Poland
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2006
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Vol. 24, No. 3
839--842
EN
The compounds of the Rn+1Co3n+5B2n family crystallize in a hexagonal structure having the P6/mmm space group. The ab initio spin-polarized band structure calculations have been performed based on the tight-binding linear muffin-tin orbitals method (TB LMTO) for the following five representatives of the family: RCo5, RCo4B, R3Co11B4, R2Co7B3 and RCo3B2, where R=Gd or Tb. The cobalt atoms occupying distinct sites have different types and numbers of neighbouring atoms and as a consequence the magnetic moments are different. The calculated values are compared with the bulk measurements.
8
Magnetism of nanocrystalline and bulk fexNi23-xB6 (x=0, 1, 22 and 23) alloys -- experiment and theory
Idzikowski B., Szajek A.
Materials Science
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2003
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Vol. 21, No. 1
73-82
EN
Formation of the nanostructure composed of a metastable magnetically ordered fcc-FexNi23-xB6 phase with large lattice constant (a=1.051-1.082 nm) from amorphous Fe81-y-zNiyZr7B12Auy (y=10-40, 64; z=0, 1) precursors due to the thermal treatment have been studied. Annealing of the y<=20, z=0 samples at temperatures 420-580°C leads to the increase of FexNi23-xB6 fraction embedded in amorphous matrix with grains sizes from few to few dozen nanometres. The structure transformations have been investigated by the DSC, XRD and TEM techniques. Magnetic behaviour of FexNi23-xB6 (x=0, 1, 22 and 23) phases have been studied theoretically using the spin polarized tight binding linear muffintin orbital (TB-LMTO) method. Anomalously high magnetic moments of Fe atoms have been found in some non-equivalent positions in the crystal structure.
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