Structure and magnetic properties of amorphous and nanocrystalline Fe85.4Hf1.4B13.2 alloy

Purpose: The forming of magnetic properties of the nanocrystalline Fe-based are different than those in conventional ferromagnetic materials that is: the soft magnetic properties increase with decreasing of grain size of crystalline phase Design/methodology/approach: The nanocrystalline Fe-based alloys could be obtain by many different methods, in this work first amorphous ribbons were obtained by planar-flow casting method and after that amorphous precursor were heat treated. The changes of structure associated to crystallization was investigated by X-ray diffractometry, the analysis of Mössbauer spectra made it possible to determine the average hyperfine field and volume fractions of α Fe crystalline phase. The changes of coercive force (Hc) of tapes were investigated using coerciometer with the terrestrial magnetic field compensation. Findings: The obtained results of investigations shows that crystallization process of amorphous Fe85.4Hf1.4B13.2 allowed to form nanocrystalline structure. This crystallization process has two-stages character and exhibit redistribution of the phases stages. The changes of magnetic properties has been observed with increasing the temperature annealing of investigated alloy. The coercive force is decreasing and minimum Hc is obtained at temperature 523 K. The obtained results showed clearly that for examined alloy is possible to determine the specific thermal treatment conditions (Top) causing an improvement of the magnetic properties. Practical implications: The possibility of optimization of soft magnetic properties is obtaining by the use of controlled crystallization of amorphous alloys. Originality/value: It has been found that the Fe85.4Hf1.4B13.2 alloys consisting of a mostly single bcc structure with nanoscale grains exhibit much better soft magnetic properties than in example well-known nanocrystalline Fe73.5Cu1Nb3Si13.5B9 . The group of Fe – M – B alloys is called NANOPERMTM. From a viewpoint of industrial application they are very attractive materials especially because of the highest BS among the nanocrystalline alloy

Factors affecting the level of damage by wild boar in farmlands in north-eastern Poland

Frąckowiak, W., Gorczyca, S., Merta, D., Wojciuch-Płoskonka, M

Reproductive parameters, birth date-effect and body condition of wild boars (Sus scrofa) inhabiting forest and forest-farmland environments in Poland

Merta, D., Albrycht, M., Frąckowiak, W., Furtek, J., Mamok, T

Wild boar population at the Vistula Spit – management of the species in forested and urban areas

Bobek, B., Frąckowiak, W., Furtek, J., Merta, D., Orłowska, L

Pulsar shadow as the origin of double notches in radio pulse profiles

We present the model of eclipsing a rotating, spatially extended source of directional emission by a central absorber, and apply it to the pulsar magnetosphere. The model assumes the radially extended inward radio emission along the local direction of the magnetic field, and the pulsar as the absorber. The geometry of the magnetic field lines of the rotating dipole is favourable for the double eclipse events, which we identify with the double notches observed in pulse profiles of nearby pulsars. For pulsars with large dipole inclinations 70 <~ alpha <~ 110 deg the double notches are predicted to occur within a narrow phase range of 20 to 30 deg before the main radio peak. Application of the model to PSR B0950+08 establishes it as a nearly orthogonal rotator (alpha =~ 75 deg, beta =~ -10 deg) with many pulse components naturally interpreted in terms of the inward radio emission from a large range of altitudes. The inward components include the intermittently strong, leading component of the main pulse, which would traditionally have been interpeted as a conal emission in the outward direction. The model also identifies the magnetic field lines along which the radially extended inward radio emission occurs in B0950+08. These have a narrow range of the footprint parameter s close to 1.1 (closed field line region, near the last open field lines). We describe directional characteristics of inward emission from the radially extended region and compare them with characteristics of extended outward emission. Our work shows that pulse profiles of at least some pulsars may be a superposition of both inward and outward emission.Comment: 28 pages, 13 figures, accepted by ApJ, high-quality figures are available from http://www.ncac.torun.pl/~michalf/inward1_figs

57Fe Mössbauer spectroscopy of annealed metamict davidite

This paper reports preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) studies of metamict davidite samples (La,Ce,Ca,Th)(Y,U,Fe)(Ti,Fe,Mn)20(O,OH)38 after high temperature annealing in an argon atmosphere. The Mössbauer spectra show a gradual decrease of quadrupole splitting and line width values of an Fe3+ doublet with increasing annealing temperature. Rather unexpected feature of these spectra for an Fe2+ doublet is a considerable increase of the line width with progressive crystallinity and a simultaneous decrease of both quadrupole splitting and isomer shift values. Changes of the hyperfine parameters as a function of the annealing temperature appeared as sensitive indicators of the thermal recrystallization process of metamict davidite similar to metamict silicates