Mössbauer investigation of the europium state in fluoride glasses

The structure of glasses based on fluorides of alkaline-earth metals, aluminum, and europium, in which aluminum fluoride is partially replaced by aluminum nitride, is investigated by ¹⁵¹Eu Mössbauer spectroscopy. It is found that these glasses contain europium atoms in two oxidation states (+2 and +3). The isomer shifts of the Mössbauer spectra of Eu³⁺ and Eu²⁺ ions entering into the composition of the fluoride glasses are somewhat different from the isomer shifts of the Mössbauer spectra of EuF₃ and EuF₂ compounds. This difference is explained by the effect of the alkaline-earth metal and aluminum atoms (not bound directly to the europium atoms) on the electron density at the ¹⁵¹Eu nuclei. The broadening of the Mössbauer spectra of the Eu²⁺ ions in the fluoride glasses is explained by the nonuniform isomer shift.     

Determination of forms of element occurrence in samples of vanadium slag and slime

Complex research of technogenic raw material samples is carried out. Using the methods of X-ray diffraction and X-ray fluorescence analysis, the chemical and phase compositions of roasted vanadium slag and slime are established. The compounds of the base elements are extracted sequentially according to a three-stage scheme recommended by the European Commission. Their low mobility is recorded. Vanadium and manganese compounds possess higher mobility in the slag than in the slime. Iron and chromium form solid oxides and silicates that are disintegrated only under the action of HNO₃. The methods of microwave plasma atomic emission spectrometry (MP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) are used to determine the gross contents of V, Mn, Fe, Cr, Zn, Ni, Ba, Sr, Rb, Y, Ga, Ge, Mo, La, and Ce in the samples of slag and slime. It is shown that the total concentration of V, Mn, and Cr considerably exceeds the values of the maximum allowable concentrations (MAC) of these elements established for soils, objects with a sample base that is no less complex. Possible leaching of the forms of elements from solid samples of vanadium slime and slag with 0.1 M Na₂CO₃ solution and the mobile phase for reversed-phase high performance liquid chromatography (RP HPLC) is studied. Mostly, vanadium compounds are extracted under these conditions. Manganese compounds are extracted by 1–10%. An inconsistency is found between the time of retention during the chromatographic separation of V and Fe forms in the model mixtures and solutions obtained after the samples of vanadium slag and slime have been chemically treated.     

Hyperfine interactions of copper ions in the structure of high-temperature superconductors

Emission Mössbauer ⁶¹Cu(⁶¹Ni) spectra of simple MgO, NiO, Cu₂O, CuO oxides and superconducting La_{2 ? x} Sr _x CuO₄, Nd_{2 ? x} Ce _x CuO, and YBa₂Cu₃O_{7 ? x} copper metal oxides have been measured. It has been shown that emission Mössbauer spectroscopy on isotopes ⁶¹Cu(⁶¹Ni) makes it possible to determine the parameters of the electric gradient field tensor and magnetic field values in the copper sites of lattices of high-temperature superconductors and related materials.     

61Ni and 63Cu Hyperfine Coupling in Copper Sites of Superconducting Cupric Ceramic Metallic Oxides and Their Dielectric Analogues

Glass Physics and Chemistry - The 61Cu (61Ni) emission Mössbauer spectra of high-temperature superconducting ceramics are measured, as well as a number of dielectric and antiferromagnetic...     

Electric field gradient tensor in positions of rare-earth metals in RBa2Cu3O7 lattices

The parameters of the electric field gradient tensor (EFG) created in rare-earth metal (REM) sites of RBa₂Cu₃O₇ lattices (R = Nd, Sm, Gd, Dy, Y, Ho, Er, Tm) by crystal lattice ions have been determined by the method of emission Mössbauer spectroscopy on ⁶⁷Ga(⁶⁷Zn) and ¹⁵⁵Eu(¹⁵⁵Gd) isotopes. The EFG tensor has been calculated for REM sites in the approximation of the point charge model. It was shown that the agreement between the experimental and calculated parameters of the EFG tensor can be achieved if the holes are preferably localized in the chain oxygen sublattice.