[en] In this lecture the positron annihilation method and the EXAFS method for detection of vacancies and lattice distortions are introduced. (TWO)

[en] The angular distribution of gamma radiation emitted from nuclei can show resonance signals under the influence of combined magnetic and electric quadrupole interactions acting as an intermediate state perturbation. An exploratory experiment shows the feasibility of this method. Perspectives of using these level mixing resonances on oriented nuclei (LMR/ON) are also discussed. (orig.)

[en] The microstructures of glassy and glass-ceramic telluride semiconductors are studied by the positron annihilation technique. The validity of some structural models for such materials is analysed. An identification technique of defects (positron trapping centers) in these semiconductors is proposed. Quantitative estimations of defect concentrations are made. Additional evidence for the co-existence of two phases in the Si-Te system over certain ranges of Te concentrations is presented. The characteristic sizes of microcrystalline inclusions in Ge-Te and Si-Te glass-ceramics are estimated. (author)

[en] Synchrotron radiation photoemission studies show that the Si(111)2x1-Sm interface has a complex morphology involving sequential formation stages with different Sm valence states. For metal coverages up to 2-3 A, Sm atoms appear only in a divalent state. At higher coverages (up to 10-15 A) the trivalent Sm configuration dominates and large chemical shifts of Si 2p and Sm 4f and 5p levels are observed. The Sm valence change is related to the onset of the reactive interdiffusion of Sm and Si. (author)

[en] The subject of the present work is the influence of Mo on the magnetic properties of amorphous (Fe, Mo)₈₀B₂₀ alloys as compared to its effect on crystalline b.c.c. Fe-Mo alloys. The combination of magnetization measurement and Fe-57 Moessbauer spectroscopy was used to obtain information about the contribution of both Fe and Mo atoms to the average magnetic moment of these amorphous alloys. The stiffness constants of spin waves depending on the composition were calculated from the low temperature behavior of the saturation magnetization. The amorphous character of the samples was confirmed by X-ray diffraction. The dependence of the saturation magnetization on temperature was measured with a vibrating sample magneto-meter. In these alloys, Mo atoms carried negligible magnetic moment. The decrease of the average magnetic moment per transition metal atom with increasing x is due to charge displacement in the 3d subband. (Kako, I.)

[en] Several ternary rare-earth compounds display long-range magnetic order in the superconducting state. When this order is antiferromagnetic, coexistence with superconductivity occurs over a wide temperature interval. Although simple ferromagnetic order destroys superconductivity, the competition between the magnetic and superconducting states produces a magnetic modulation of several hundred Angstroms wavelength which coexists with superconductivity. The modulated state, which has been studied by neutron scattering techniques in ErRh₄B₄ and HoMo₆S₈, exists over a narrow temperature range and is replaced by a ferromagnetic, normal conducting state at low temperature. Recent small-angle, neutron-scattering experiments with HoMo₆S₈ have established that the magnetic order in the modulated state is of long range. Although these experiments have proven that the modulated phase is not a vortex lattice no definitive microscopic description of the phase has yet been confirmed in either HoMo₆S₈ or ErRh₄B₄. Recent neutron scattering investigations which have attempted to elucidate the nature of the modulated phase are described. (Auth.)

[en] The NMR spectra of polycrystalline sample of zinc perchlorate were recorded in the temperature range 77-293 K on the spectrometer of broad lines working at the frequency 17,465 MHz. The values of the second moments of absorption lines were calculated on MERA-400 computer. The dependence of the second moment on the temperature is shown. (A.S.)

[en] The stoichiometric composition and stability constants of molecular complexes forming between some benzene derivatives and 2,4,6-trinitrotoluene were determined by NMR method. The obtained results are compared with the results of others. (A.S.)

[en] The magnetically induced anisotropy of the amorphous (Cosub(0.94)Fesub(0.06))sub(74.5)Sisub(13.5)B₁₂ alloy was investigated. The Moessbauer spectroscopic method was applied to examine the effect of annealing on the growth and release of the induced anisotropy. A sample was made by a single-roller quenching method in long ribbon form. The Curie temperature is 668 K, and the crystallization temperature is 799 K. The uniaxial anisotropy along the long direction of the ribbon existing in the as-prepared sample was removed by annealing. The growth of magnetic anisotropy by field-annealing was studied. The sample treated as mentioned above was annealed at 423 K in a magnetic field along the long direction of the ribbon (RD). Other samples were annealed in the fields along the width direction of the ribbon (RW), or perpendicular to the ribbon plane (RP). The Moessbauer spectra of the sample of the (423 K, 1500 Oe, RD)-annealing showed that the preferred orientation of magnetization axes rotated from a random distribution to the long direction of the ribbon. The sample of the (423 K, 1500 Oe, RW)-annealing gave a similar result. The sample of the (423 K, 1500 Oe, RP) annealing gave a result that the easy-plane anisotropy was still predominant. The rotation of the induced anisotropy by additional field-annealing in which a magnetic field was applied in the direction perpendicular to the preceding one was studied. The release of the induced magnetic anisotropy was investigated. The samples treated by the (423 K, 1500 Oe, RD)-annealing were additionally annealed at various temperature. The structural relaxation became active around 430 K. (Kato, T.)

[en] The electronic structure of Ni-B glasses was studied by means of gamma-ray Compton scattering and XPS. The Ni sub(100-x)B sub(x) alloy glasses were prepared by rapid quenching from melts in Ar atmosphere of 100 Torr. The Compton profile has been obtained, using a pure Ge solid state detector and the 59.54 keV gamma-ray emitted from a 1 Curie Am-241 isotope. The XPS measurement has been done, using the Mg-K(α) radiation equipped in an AEIES 2000-XPS spectrometer. By introducing the differential Compton profile from the observed Compton profile, it can be said that the d-like electrons increased at the expense of decreasing s, p-like electrons in Ni-B alloy glasses. The experimental XPS valence band spectra for Ni-B alloy glasses were mainly contributed from Ni 3d-band, but slightly modified to cause a small shoulder around -2 eV of the binding energy and a small hump around -10 eV. Discussion on the structure of Ni-B alloys is described. (Kato, T.)