A. Szlaferek

Magnetic characteristics of RNi4B compounds (R=Y, Pr, Sm, Tb, Ho and Er)

The magnetic properties of RNi4B compounds with R=Y, Pr, Sm, Tb, Ho and Er have been studied. These compounds crystallize in a hexagonal structure with the P6/mmm space group. YNi4B shows superconducting behavior below ∼12 K, while PrNi4B is paramagnetic but contains a contribution of a ferromagnetic impurity phase. For compounds with R=Sm, Tb, Ho and Er transitions to magnetically ordered state are visible at 38, 21, 6 and 12 K, respectively. A large hysteresis loop is observed for the SmNi4B compound with a coercive field HC>7.0 T, whereas the RNi4B compounds of the other rare earths are characterized by an HC lower than 0.06 T at 5 K.

Magnetic and resistivity investigation of Dy(Co1−xSix)2 (if0 < x ⩽ 0.2) compounds

Abstract The results of experimental investigations of the magnetic and transport (electrical resistivity) properties of Dy(Co 1− x Si x ) 2 , where x = 0.0, 0.1 and 0.2 compounds are presented. These systems crystallize in the whole concentration range of x , in the MgCu 2 Laves-phase-type crystal structure. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements were performed on the pseudobinary Dy(Co 1− x Si x ) 2 cubic compounds. The thermomagnetic cycle of ZFC and FC processes exhibits an irreversible behaviour. The composition dependence of the Curie temperature, 3d-magnetic moment and electrical resistivity is discussed.

Electronic Structure of GdNi4B Compound

The GdNi 4 B compound is studied both experimentally and theoretically by X-ray photoemission spectroscopy and self-consistent tight binding linear muffin-tin orbital calculations, respectively. The density of states at the Fermi level and the magnetic moments are obtained including the influence of various atomic positions in the unit cell. The calculated magnetic moment of Ni atoms is antiparallel to the magnetic moment of Gd and depends on the local environment.

X-ray photoemission spectra of UCo4B compound

Abstract The UCo4B compound crystallizes in the hexagonal CeCo4B-type structure, space-group P6/mmm. The electronic structure has been studied by combining X-ray photoemission spectroscopy (XPS) results with those obtained in the band structure calculations. The latter was carried out by using the self-consistent tight binding linear muffin-tin orbital (TB LMTO) method. Reasonable agreement between the experimental and calculated data has been achieved.

Effect of the poling temperature on the dielectric properties of oriented PVDF film

Abstract TSC and ϵ(T) was studied for SOLEF-25 μm polarized at various TP in EP=15-20 MV/m. Two high temperature TSC maxima were observed and related to the dipolar relaxation in α and β phases respectively. Increase of the ϵ after polarization is related to the nonpolar-polar transformation in α phase.

Magnetic properties of non-stoichiometric UFex compounds obtained by ball milling

Abstract The non-stoichiometric UFe x alloys were synthesized from the starting UFe 2 compounds with the iron excess in a conventional horizontal ball mill. X-ray patterns show that the mechanical alloying (MA) results in the formation of an amorphous iron reach UFe phase. The observed values of T c increase abruptly during the initial 65 h of MA and then more slowly up to 207 K when the milling period rises up to 230 h.

Spin phase diagrams and magnetic anisotropy in Nd2Fe14-xMxB compounds (M=Si, Cr and Cu)

Abstract Magnetic properties (saturation magnetization at 4.2 K, Curie temperature and spin reorientation temperature) of Nd2Fe14-xMxB systems (M = Si, Cr and Cu) are investigated. These compounds crystallize in a tetragonal Nd2Fe14B structure. Based on these measurements, the temperature-composition diagrams of spin arrangements appearing in Nd2Fe14-xMxB systems have been established.

High pressure impact on changes in potato starch granules

Abstract Air dry potato starch (84.9% d.s.) was subjected to pressurizing under the pressure of 50, 100, 250, 500, 750, 1000 and 2000 MPa for 1 h. The physical properties of pressurized starch, such as morphology, surface and crystalline structure, gelatinization parameters, were studied by means of scanning and atomic force microscopy (SEM/AFM), X-ray diffraction (X-ray), differential scanning calorimetry (DSC). The susceptibility to the amylolytic enzyme (α-amylase) was also measured. Application of pressure in the range of 50–2000 MPa results in an increase in the compressed potato starch bulk density, change in the contours of the granules from oval to polyhedral, increase in the roughness of the granule surface, vanishing of the X-ray reflexes generated by the orthogonal structure and weakening of the reflexes generated by the hexagonal structure, lowering of the enthalpy of starch gelatinization, and the enhancement of hydrolytic susceptibility of starch granules to the amylolytic enzyme.

Electronic Structure and Transport Properties of UFe_{2} System

The electronic structure of the UFe2 compound was studied by X-ray photoemission spectroscopy and ab initio self-consistent tight binding muffin tin orbital method. This compound crystallizes in a cubic Laves phase. The calculated valence band spectrum is characterized by two peaks due to U(5 f ) and Fe(3d) states. We have found a good agreement between the experimental valence band spectrum and theoretical ab initio calculations. The carrier concentration estimated from the Hall effect amounts to 10 22 cm -3 .