The electronic structure behaviour of Me,O, oxides (Me = Ti, V, Cr) has been determined from X P S valence band and core level measurements. From Ti to Cr sesquioxide the relative intensity of the 3d band increases systematically which can be explained by the (atomic) photoelectric cross section and the number of 3d electrons. Simultaneously the 3d-2p band separation decreases indicating a more stronger band overlap equivalent an enhanced covalent bonding component. The different electrical properties among the corundum structure oxides are determined by the trigonal field splitted and eg orbitals, their occupation and relative energy position at the Fermi level. The observations confirm the change from itinerant to more localized behaviour of d electrons caused by crystal structure parameter change (c/u ratio).

The K absorption edge of pure Fe and the pre-edge Fe K absorption of FeS, (pyrite), Fe20, (hematite), and FeCO, (siderite) are investigated with single crystal absorbers of these materials using linearly polarized synchrotron X-radiation. From the angular dependence of the pre-edge K absorption the existence of predominantly ligand-field-induced dipole transitions in Fe,O, and of quadrupole transitions in FeCO, is concluded. The multipole character and the mechanism of the pre-edge K absorption are discussed.Die K-Absorptionskante von reinem Fe und die Fe K-Vorkantenabsorption von FeS, (Pyrit), Fe,O, (Hamatit) und FeCO, (Siderit) werden a n einkristallinen Absorbern dieser Materialien mit linear polarisierter Synchrotron-Rontgenstrahlung untersucht. Aus der Winkelabhangigkeit der K-Vorkantenabsorption wird auf das Aaftreten von iiberwiegend ligandenfeldinduzierten Dipolubergangen im Fe,O, und von Quadrupoliibergangen im FeCO, geschlossen. Der Multipolcharakter und der Mechanismus der K-Vorkantcnabsorption werden diskutiert.

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From the angular correlation measurements of the positron annihilation radiation on cold rolled, polycrystalline Ni of purity 99.99% and 99.84% the curve‐shape parameters S are determined for treating the as‐deformed and annealed samples up to a thickness reduction of 90%. The trapping rate of the positrons can be determined for a thickness reduction up to 15 or 18% for the dislocations and for the vacancies as well. Using known relations for the hardening within range 2 the specific trapping rates are estimated for the dislocations, μd = 2.9 × 10−15 s−1, and for the vacancies, μv = 2.2 × 10−15 s−1. Estimated dislocation densities and vacancy concentrations vary between 108 and 1011 cm/cm3 and 1016 and 1019 cm−3, respectively. Both of them show a remarkable dependence on the purity of the samples. Ni of low purity exhibits formation of vacancy clusters after annealing.

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