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Showing papers on "Valency published in 1977"


Journal ArticleDOI
TL;DR: In this paper, a simple valence bond model based on the electron requirement of the Mo 6 octahedron to form 12 covalent bonds is proposed to stabilize the structure and have a strong influence on the superconducting transition temperature.

66 citations


Journal ArticleDOI
TL;DR: In this article, the lattice constants of perovskite-type compounds (AA′)(BB′)O6 were verified from a series of compounds with known valency pairs.

52 citations


Journal ArticleDOI
01 Mar 1977-Nature
TL;DR: In this paper, the relativistic treatment becomes imperative to predict the chemical behaviour of the superheavy elements and the tetrahydride of the element 114 or eka-lead.
Abstract: RELATIVISTIC effects have a considerable influence on the chemical behaviour of the heavier elements. Our Dirac–Fock one-centre expansion calculations1–3 indicate that the X–H bond lengths, Re, suffer a relativistic contraction of about 5% for PbH4 (ref. 1) or AuH (ref. 2) and 7% for TlH (ref. 3). If the relativistic effects are included, however, these Re values mostly agree with experiment to within 2–3%. Relativistic effects also seem to be the main cause of the chemical difference between silver and gold2 and, possibly, of the dominant monovalency of thallium3. A relativistic treatment becomes imperative to predict the chemical behaviour of the superheavy elements. Following evidence for primordial superheavy elements4, we present here results for the tetrahydride of the element 114 or eka-lead. We believe that such a calculation gives a reasonable estimate for the covalent radius of this element. Although the dominant valency of 114 is expected to be 2, some tetravalent compounds are also expected to be stable7. As the latter valency is more convenient for calculations, having closed shells, we here consider (114)H4.

33 citations


Journal ArticleDOI
TL;DR: In this article, the characterization of Ir(CO)/sub 3/Cl, a one-dimensional highly conducting stoichiometric material in which chains containing short Ir metal-metal bonds of 2.844(1) A are stabilized without mixed valency or charge transfer to interstitial anions within the lattice, is reported.
Abstract: The characterization of Ir(CO)/sub 3/Cl, a one-dimensional highly conducting stoichiometric material in which chains containing short Ir metal-metal bonds of 2.844(1) A are stabilized without mixed valency or charge transfer to interstitial anions within the lattice, is reported. (LK)

31 citations


Journal ArticleDOI
TL;DR: A gas phase electron diffraction study of 1,3-dithiane, carried out at 100° C, has found no statistically significant evidence for the presence of any conformer in the vapor other than the chair, within an estimated uncertainty of 10% as discussed by the authors.

29 citations


Journal ArticleDOI
TL;DR: In this article, the χ(T) curves for 17 binary and 2 ternary ytterbium intermetallics have been found to have a common functional form with a characteristic temperature Tmax.
Abstract: Out of 17 binary and 2 ternary ytterbium intermetallics, in the five systems, YbGa2, YbCu2, YbAl2, YbAl3 and YbCuAl an intermediate valency was found. The χ(T) curves for these compounds have a common functional form with a characteristic temperature Tmax. No tendency to saturation is observed in the magnetization at 1.4 K in fields up to 330 kOe.

26 citations


Patent
25 Aug 1977
TL;DR: Gamma-butyrolactones are formed by reacting an olefin with a compound containing a carboxylate moiety having at least one hydrogen atom on the alpha carbon atom in the presence of an ion of manganese, cerium, or vanadium as discussed by the authors.
Abstract: Gamma-butyrolactones are formed by reacting an olefin with a compound containing a carboxylate moiety having at least one hydrogen atom on the alpha carbon atom in the presence of an ion of manganese, cerium, or vanadium, the ion being in a valency state higher than its lowest valency state.

23 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the valency fluctuations within the domain walls give rise to a relaxation process which obeys a logarithmic time law in magnetite (Fe3O4).

23 citations


Patent
04 Feb 1977
TL;DR: In this article, the compounds are useful in the treatment of atherosclerosis and are disclosed wherein R is hydrogen or C 1 to C 6 alkyl; R 2 and R 3 are each hydrogen or together form a valency bond; R 6 is carboxy or C 2 to C 8 alkoxy carbonyl; and R 7 and R 8 are each Hydrogen atoms or together formed a Valency bond.
Abstract: Compounds of the formula: ##STR1## or pharmaceutically acceptable salts thereof are disclosed wherein R is hydrogen or C 1 to C 6 alkyl; R 2 and R 3 are each hydrogen or together form a valency bond; R 6 is carboxy or C 1 to C 6 alkoxycarbonyl; R 7 and R 8 are each hydrogen or together form a valency bond; R 10 is carboxy or C 1 to C 6 alkoxycarbonyl and the dotted line represents two hydrogen atoms or a valency bond. The compounds are useful in the treatment of atherosclerosis.

6 citations



Book ChapterDOI
01 Jan 1977
TL;DR: In this paper, it was shown that in intermetallic compounds Yb as well as Ce can have two different valence states, i.e., intermediate between two integral values.
Abstract: It is well known that in intermetallic compounds Yb as well as Ce can have two different valence states. Recently indications were obtained that this is also the case for U. The valence adopted by these elements depends in general on the composition of the particular intermetallic compound, on the temperature and on the applied pressure. In some cases the valence state seems to be less clearly defined in that the elements mentioned show valences apparently intermediate between two integral values.

Patent
01 Jun 1977
TL;DR: In this paper, a higher valency salt of a desired metal or alloy is added to a fused salt electrolytic bath, reducing the higher valencies on a cathode electrode to a lower ones, and removing the so-produced lower valencies from the electrode surface.
Abstract: A high valency salt, such as TiCl 4 is reduced to a lower valency salt, such as TiCl 2 and/or TiCl 3 within a fused salt electrolytic bath via electrolysis so that an improved electrodeposition of a desired metal or alloy, such as Ti, occurs, from such adjusted bath. The process generally comprises adding a higher valency salt of a desired metal or alloy to a fused salt electrolytic bath, reducing the higher valency salt on a cathode electrode to a lower valency salt, removing the so-produced lower valency salt from the electrode surface and maintaining a predetermined amount of the lower valency salt within the electrolytic bath. Electrodeposition of a desired metal or alloy may then take place from such electrolytic bath containing a so-adjusted amount of the lower valency salt.


Book ChapterDOI
01 Jan 1977
TL;DR: Gschneidner and Smoluchowski as discussed by the authors analyzed the physical properties of the phases involved in the valence change and they concluded that about 0.5 to 0.67 of an electron per atom is transferred from the 4f level to the 5f level.
Abstract: Cerium was the first material found to undergo a valency change. X-ray studies in 1949–1950 revealed that when Ce was compressed to modest pressures (> 8 kbar at 300 K)1 or cooled to low temperature ( 12%) while the crystal structure remained the same. When these authors discussed this unusual behavior with their colleagues, both Zachariasen3 and Pauling4 independently suggested that this volume contraction corresponded to a valence change of 3 for γ-Ce to 4 for α-Ce, i.e. the 4f electron of γ-Ce was promoted to the valence band, leaving the 4f level of α-Ce empty. Several other authors subsequently reanalyzed the physical properties of the phases involved in the valence change and they concluded that about 0.5 to 0.67 of an electron per atom is transferred from the 4f level to the valence band.5 Today the consensus of scientists favors the 0.67 value. Furthermore, Gschneidner and Smoluchowski point out that the valences of the two phases involved (γ- and α-Ce) change with temperature and pressure. As a result of this valence change, the γ-α pressure-temperature phase boundary ends at a critical point. Ce is the only solid known to have a critical point.

Book ChapterDOI
31 Dec 1977

Journal ArticleDOI
TL;DR: In this paper, a pseudospin with S = 1 model for valence transition in rare-earth compounds is proposed and the saturation behavior of the magnetic susceptibility at low temperature is shown to be the consequence of tunnelling between the two pertinent configurations of the rare earth ion.

Journal ArticleDOI
TL;DR: In this article, the X-ray photoelectron spectra of α-Sb2O4 and BaBiO3 were analyzed and the mixed-valency character of these oxides was found only after careful pretreatment of the samples in situ.
Abstract: X-Ray photoelectron spectra of the metal(III)–metal(V) oxides α-Sb2O4 and BaBiO3 are reported. Indications of ‘mixed-valency’ character in the metal core-electron spectra could be found only after careful pretreatment of the samples in situ. Under normal conditions both compounds appear to have surface phases containing just the lower oxidation state.