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[en] The results of X-ray spectral investigation of praseodymium oxides and solid solutions in the PrO_x-YO_1.5 system are given. Chemical shifts (CS) in emission K-lines of praseodymium: K_α1, K_β1, K_β3 are measured. The values of x in the PrO_x formula are determined. The maximum x value (>1.95) is observed in solid solutions containing 40-50 mol.% PrO_x. The calculations revealed that decrease of 4f-state density takes place with growth of the degree of Pr oxidation (growth of x), at the same time density of 5d-states slightly increases. Certain correlation between 4f-, 5d-electron transitions in praseodymium and increase of electric conductivity of solid solutions in the inestigated system is established

[en] Investigations of electrical properties of (TbO_x)_y (YO_1.5)_1-y solid solutions in wide concentration range were conducted; isotherms of specific electric conductivity were constructed at 400, 600, 800, 1000, 1200, 1400 deg C. Various degrees of terbium oxidation in solid solutions with yttrium oxide, depending on terbium concentration was established. The method of X-ray spectral analysis was used to reveal the correlation of electrical properties of solid solutions with terbium oxidation degree, as well as with effective partial charges, occurring on terbium atom in result of solid solution formation. It is concluded that correlation between these parameters enables to control electrical properties of solid solutions in examined system by means of change of synthesis conditions (temperature, gaseous medium, the choice of optimal component concentrations)

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[en] Chemical shifts of the most intensive L-lines of thorium have been studied, and comparative analysis of experimental and theoretical data has been performed to elucidate the possibility of participating 5f-electrons in a chemical bond. Crystal diffraction X-ray spectrometer has been used for measuring chemical shifts of Lα₁, Lβsub(2,4), Lβsub(1.5) and Lγ₁ lines in ThO₂, ThBr₄, ThCl₄, ThF₄ and others with respect to metal and Kα₁ lines of bromine in ThBr₄, UBr₄, UBr₃, KBr and others with respect to Br₂⁰. The Hartree-Fock method has been used for evaluating the expected shifts of the same lines. It is shown that interpretation of the data in approximation of the Hartree-Fock method for isolated atoms and ions is possible if one assumes that in Thsup((4)) compounds 5f-states participate in the chemical bond. Effective charges in the compounds have been evaluated with due regard of the above data

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