Analysis of the Parameters of the Mössbauer Spectra and the Spectra of Nuclear Quadrupole Resonance of the Superconducting Ceramic YBa2Cu3O7

Electronic defects in lattices of YBa2Cu3O7 and La2 − xSrxCuO4

“…It is possible to just compare the theoretical and experimental parameters of the lattice EFG tensor to determine the effective charges of atoms (Marchenko et al 2018a;2018b;Terukov et al 2018). If the electron shells of the probe atom are completely (or half ) filled, then the electron cloud can be considered as consisting of several concentric spheres.…”

“…The discovery of the high-temperature superconductivity phenomenon in copper metal oxides (Bednorz, Muller 1986) resulted in a large number of studies of nuclear quadrupole interaction (NQI) in typical materials of this kind-YBa 2 Cu 3 O 7 − x and La 2 − x Sr x CuO 4 -through nuclear quadrupole resonance (NQR) method with probe nuclei 17 O (Ishida et al 1991;Takigawa et al 1989), 63 Сu (Ohsugi et al 1994;Pennington et al 1989), 137 Ва (Shore et al 1992), 139 La (Ohsugi 1995), as well as through absorption Mössbauer spectroscopy (MS) with probe nuclei 57 Fe, 119 Sn, 151 Eu, 155 Gd, 161 Dy, 166 Er, 169 Тm, 170 Yb (Masterov et al 1995) and emission MS with probe nuclei 67 Cu( 67 Zn) and 67 Ga( 67 Zn) (Marchenko et al 2018a;2018b;Terukov et al 2018). NQI tensor parameters (the quadrupole interaction constant and the asymmetry parameter) provide information on the spatial distribution of electronic defects in various sublattices within high-temperature superconductors (HTSC).…”

“…In crystal lattices with high chemical bond ionicity, which includes copper metal oxides YBa 2 Cu 3 O 7 − x and La 2 − x Sr x CuO 4 , two sources of the electric field gradient (EFG) on probe nuclei can be distinguished: crystal lattice ions (lattice EFG) and nonspherical valence shells of the probe atoms (valence EFG). The total EFG on the probe nucleus is determined by the parameters (Marchenko et al 2018a;2018b) ( )…”