The parameters d the elearic field gradient (EFG) tensor at the copper sites in the La2,Sr,Cu04 lattice !the principal component of the EFG tensor eq and the asymmetly parameter 11) were determined experimentally by emission Mdssbauer spectroscopy with "Co("Fe) and mCu~7Zn) isotopes. No qualitative conformity was found between the experimental data and the values of eq calculated in a p i n t charge model. This disagreement is attributed to an uncertainty in the values of Sternheimer coefficients for Zn2+ and Fe3+ ions and in the charge scaling of the &-,SrxCu04 lattice. A comparison of the experimental and calculated dependences d eq onx shows that the holes arising from the SubstitUtion d La3+ by SFc are localized mainly at the oxygen sites in the Cu-02 plane.
α‐In2Te3, ß‐In2Te3, and Ga2Te3 crystals doped with iron or tin are studied. Both, iron and tin are found in divalent states in ß‐In2Te3 and Ga2Te3 by Mössbauer spectroscopy. Their electrical inactivity is explained by a compensation effect of In+ or Ga+ ions which pins the Fermi level to the middle of the energy gap. In α‐In2Te3 doped with iron or tin some impurity enriched regions which results in an additional conductivity at low temperature are found.
It has been shown that temperature dependences of the gravity centres of 67 Cu( 67 Zn) and 67 Ga( 67 Zn) emission Mössbauer spectra of Nd 1.85 Ce 0.15 CuO 4 , La 1.85 Sr 0.15 CuO 4 and Tl 2 Ba 2 Ca 2 CuO 8 superconductors are described by the second-order Doppler shift in the temperature range T > T c , and Bose condensation of Cooper pairs should be taken into account at T < T c (T c is the superconducting transition temperature). The spatial nonuniformity of the electron density created by the Bose condensate has been observed in La 1.85 Sr 0.15 CuO 4 .
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