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Electron-beam was used for irradiation of amorphous precursors of (Fe64Co21B15)95P4Cu1 and (Fe64Co21B15)96P4 alloys and then by heat treatment nanocrystalline structure was created. Changes in microstructure were not observed under the doses of 4 MGy. All irradiated samples were compared with non-irradiated one. Samples were studied by Mossbauer spectroscopy and XRD. Irradiation had an influence on the volumetric fraction of the constituent phases and on their magnetic microstructure. After the heat treatment nanocrystalline sample prepared from irradiated precursor contained more crystalline phase than non-irradiated. This technology of prepare of nanocrystalline alloys indicates that irradiation of amorphous precursor has an influence on the final structure and properties of nanocrystalline alloy.

Nanocrystalline (Fe3Ni1)81Nb7B12 alloys were irradiated using different types of radiation and subsequently studied by Mossbauer spectroscopy. External magnetic field of 0.5 T, electron-beam irradiation up to 4 MGy, neutron irradiation up to 1017 neutrons/cm2 and irradiation with Cu ions were applied on the samples. All types of external factors had an influence on the magnetic microstructure manifested as a change in the direction of the net magnetic moment, intensity of the internal magnetic field and volumetric fraction of the constituent phases. The direction of the net magnetic moment was the most sensitive parameter. Changes of the microscopic magnetic parameters were compared after different external influence and results of nanocrystalline samples were compared with their amorphous precursors.

Tephra is a fragmental material produced by volcanic eruption. Here, volcanic tephra deposit from the northeast of China was used for our study. Samples of unaltered tephra are usually composed of feldspar, glass, pyroxene, and olivine. Moreover, these volcanic alteration products also contain Fe oxides, phylosilicates, sulfates, and amorphous Al-Si-bearing material. Six different samples of tephra obtained were analyzed by Mossbauer spectroscopy. A typical Mossbauer spectrum of tephra consists of magnetic and non-magnetic components (magnetic component represents about 11% and non-magnetic component about 89% of spectral area). According to the structural composition, it may be supposed that the magnetic component can be assigned to titanomagnetite. Non-magnetic components contain two quadrupole doublets (Fe2+ species) and one doublet containing Fe3+. According to the measured values of Mossbauer spectra, the first two doublets are very similar with pyroxene, olivine and the third to phylosilicate, alumi...

Meteorite fall was observed by the Kosice town in Slovakia in February 2010 and it was classified as an ordinary chondrite H5. The samples were prepared in powder form scratched from the surface. Mossbauer spectra were measured at room temperature and liquid nitrogen temperature. Spectra consist of components related to iron-bearing phases with different content. Non-magnetic part was fitted with three quadrupole doublets. According to its parameters, we identified olivine, pyroxene, and traces of Fe3+ phases. Magnetic part consists of an iron-rich Fe-Ni alloy with hyperfine magnetic field similar to kamacite α-Fe(Ni,Co) and troilite. Main elements were also determined by X-ray fluorescence spectroscopy.

Nanoperm, Hitperm and Finamet amorphous and nanocrystalline alloys were measured by Mossbauer spectrometry in a weak external magnetic field of 0.5 T. It was shown that the most sensitive parameters of Mossbauer spectra are the intensities of the 2nd and the 5th lines. Rather small changes were observed also in the case of internal magnetic field values. The spectrum of nanocrystalline Nanoperm showed the increase in A23 parameter (ratio of line intensities) from 2.4 to 3.7 and decrease of internal magnetic field from 20 to 19 T for amorphous subspectrum under the influence of magnetic field. Spectrum of nanocrystalline Finemet shown decrease in A23 parameter from 3.5 to 2.6 almost without a change in the internal magnetic field value. In the case of amorphous Nanoperm and Finemet samples, the changes are almost negligible. Hitperm alloy showed the highest sensitivity to the weak magnetic field, when the A23 parameter increased from 0.4 to 2.5 in the external magnetic fields. The A23 parameter of crystall...

We present a modified cluster expansion to describe single‐photon emitters in a semiconductor environment. We calculate microscopically to what extent semiconductor features in quantum dot‐wetting layer systems alter the exciton and photon dynamics in comparison to the atom‐like emission dynamics. We access these systems by the photon‐probability‐cluster‐expansion: a reliable approach for few photon dynamics in many body electron systems. As a first application, we show that the amplitude of vacuum Rabi flops determines the number of electrons in the quantum dot.

Aluminium based rapidly quenched alloys of nominal composition Al90Fe7Nb3 and Al94Fe2V4 were studied by Mossbauer spectroscopy. We have measured the recoil‐free fraction and thermal shift at room and liquid nitrogen temperature. The frequency modes of atomic vibrations were determined and consequently the characteristic Debye temperature was derived. Characteristic temperature calculated from f‐factor was lower than those fitted from second order Doppler shift. This indicates the presence of different frequency modes for amorphous and nanocrystalline states.