Yu. P. Kostikov

X-ray phase analysis of structure of water-salt systems: NaCl-H2O and KCl-H2O

Aqueous solutions of sodium and potassium chlorides were studied by a diffraction method. The effect of cations on the structure of water was considered from the viewpoint of this method. The size of supramolecular structures and the number of water molecules per salt formula unit in solution were estimated.

Valence States of Lead and Bismuth Atoms in the High-Temperature Superconductor BaPb1-xBixO3

X-ray photoelectron spectra of valence bands and core levels of BaPb0.8Bi0.2O3, PbO, PbO2, BaPbO3, BaBiO3, NaBiO3, and Bi2O3 were studied. Comparison of the electron binding energies of the Pb 4f7/2 or Bi 4f7/2 core levels for all the oxides studied showed that the high-temperature oxide superconductor BaPb0.8Bi0.2O3 contains simultaneously two different valence forms of lead atoms (PbIV and PbII) and two different valence forms of bismuth atoms (BiV and BiIII). Parameters of the X-ray photoelectron spectra of the valence bands do not contradict the conclusion on heterovalent states of lead and bismuth atoms in BaPb0.8Bi0.2O3.

Structural microheterogeneites in strontium perchlorate solutions of posteutectic concentrations

Aqueous solutions of strontium perchlorate were studied in a wide range of concentrations at room temperature by X-ray diffraction, thermogravimetry, and calorimetry. The features of the solubility polytherm of strontium perchlorate, that distinguish it from those of other Group II metal perchlorates, were explained in terms of two coexisting interconverting crystal hydrates.

On the Possibility of Using SPARK-1M Portable X-ray Spectrometer for Studying the Chemical Bond

The possibility of using SPARK-1M spectrometer for studying the shift of emission lines belonging to the K series of X-ray spectra of transition metals (chemical shift of the lines) was studied. The possibility of using the spectrometer for measuring the chemical shift and evaluating the relative amounts of transition metals in different oxidation states is analyzed.

Role of core and valence atomic orbitals in the formation of chemical bonds

The general principles of the electronic structure of molecules and complexes are discussed. An analysis of photoelectron and x-ray photoelectron spectra reveals that in most cases, the interaction of the valence AOs results in the formation of delocalized MOs, which are populated by electrons, but are not bonding according to their energies (molecules with small atomic cores are exceptions). These MOs do not make a positive contribution to the exothermic effect of chemical bonding. The delocalization of the valence electrons in such MOs reduces their charge density in the region of the atomic cores and lowers the energy of the inner “atoms-in-molecules” levels as a result of the reduction of the internal shielding; the ESCA shifts of the inner electronic levels confirm this stabilization. In accordance with the virial theorem, the lowering of the energy of the core levels of the central atoms (with simultaneous, generally small changes in the energy of the core levels of the ligands and despite the significant destabilization of the delocalized MOs in comparison to the valence orbitals of the corresponding free atoms) makes up the main contribution to the energy of chemical bonds.

The effect of thermal stresses in the heterogeneous BaTiO3-MgO system on the Curie point of barium titanate

SummaryIt is shown by electron probe analysis that MgO does not form a solid solution with barium titanate. The effect of added magnesia on the Curie point of BaTiO3 can be explained in terms of thermal stresses which arise, upon thermal treatment, in heterogeneous samples composed of substances having substantially different thermal expansion coefficients.ZusammenfassungDie Elektronenstrahlmikroanalyse zeigt, daß MgO keine Festlösung mit Bariumtitanat bildet. Der Einfluß von Magnesiazusätzen auf die Verschiebung des Curie-Punktes von BaTiO3 läßt sich aufgrund der Wärme-spannungen erklären, die bei thermischer Behandlung in heterogenen Prüflingen entstehen, deren Komponenten wesentlich verschiedene Wärmedehnzahlen haben.

The oxidation state of manganese in its oxides and some other compounds, from the fine structure of the Kβ1β′-lines

SummaryThe X-ray Kβ1β′-emission spectra of the lower oxides of Mn have been studied. From this study it is concluded that Mn is present in the bi-, ter- and quadrivalent states in the oxides of apparently tervalent manganese, in approximately equal proportions.ZusammenfassungAus den KKβ1β′-Linien der Röntgenemissionsspektren der niederen Manganoxide ergibt sich, daß das Mn in den Oxiden seiner scheinbar dreiwertigen Form in annähernd gleichen Mengenverhältnissen als Mn(II), Mn(III) und Mn(IV) vorliegt.

A rapid method of quantitative electron microprobe analysis: The homologue method

SummaryA rapid method of quantitative electron microprobe analysis is suggested, for the determination of the molar ratio between elements in homologous phase systems with one of the sample homologues being used as reference standard. A criterion for applicability and an error evaluation are given. The method suggested is shown to be promising for determining the ratio between elements in thin films.ZusammenfassungEine Schnellmethode der quantitativen Elektronenstrahlmikroanalyse wurde vorgeschlagen, die für die Ermittlung des molaren Verhältnisses zwischen Elementen in homologen Systemen bestimmt ist, wobei eine der vorhandenen homologen Verbindungen als Bezugsstandard dient. Ein Kriterium der Anwendbarkeit dieser Methode sowie ein Verfahren zur Ermittlung ihres Fehlers wurde angegeben. Sie dürfte für die Ermittlung des Verhältnisses zwischen Elementen in Dünnschichten besonders gut geeignet sein.

A new method for measuring the chemical shifts of X-ray emission lines and its application in electron microprobe analysis

SummaryA new formula for calculating the chemical shift of X-ray lines is theoretically derived. A test of the method is given as well as its application in electron microprobe analysis for the purpose of obtaining some crystal-chemical characteristics of solids.ZusammenfassungEine neue Formel für die Berechnung der chemischen Verschiebung von Röntgenlinien wurde theoretisch abgeleitet. Die Prüfung der Methode und ihre Anwendung in der Elektronenstrahlmikroanalyse für die Ermittlung einiger kristallchemischer Kennzahlen von Festkörpern wurde beschrieben.