Materials Literature
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Abstract The reflectivity of CdO has been measured up to 13 eV on single crystals and polycrystalline material. Moreover the absorption of thin films was studied. The frequency dependence of the optical constants evaluated by Kramers‐Kronig analysis is discussed with regard to the band structure calculated by Maschke…
Measurements of the e.s.r. and optical spectra of the potassium and sodium molybdenum bronzes have been made. It is concluded that the observed e.s.r. signals arise from Mo5+ donor levels situated < 1 eV below the conduction band of the host MoO3 matrix. A model for the electronic structures of these compounds is prop…
Abstract The decay kinetics of sinusoidal surface profiles on copper annealed in a hydrogen atmosphere were investigated in the temperature range 600 to 1030 °C in order to determine the temperature dependence of the surface self‐diffusion coefficient, D s . Below 910 °C the surface profiles were found to be faceted r…
The syntheses and chemical properties of several new trisdicyano-1,2-dithiolene complexes of transition metals are described. These complexes have anions of the type [MS6C6(CN)6]z where M = Mn, Fe, Mo, and W and z=–2 and M = Fe and Co where z=–3. An improved synthesis of the known [CrS6C6(CN)6]2– is reported. The beha…
La structure magnétique de la variété rhomboédrique de Cr2S 3 (a = 5,94 Å ; c = 16,7 Å ; groupe R3) comprend trois sous-réseaux magnétiques : 3a et 3b parallèles et 6c anti-parallèle. La variation thermique légèrement différente de l'aimantation des sous-réseaux donne lieu à un faible ferrimagnétisme croissant de zéro…
Simplification of Ramsey's equation applied to the 195Pt chemical shift in square-planar platinum(II) complexes leads to an equation in which the paramagnetic shift is proportional to a linear combination of the wavelengths of two transitions in the absorption spectra of the complexes. The factor of proportionality de…
, containing small quantities of dissolved iron, is the only oxide formed in the oxidation of iron‐chromium alloys in the range 22–68% Cr in oxygen at 800°–1200°C; it is also formed, at least initially, on alloys containing 14 and 18% Cr. The oxide growth is diffusion‐controlled, with an apparent activation energy of…
Abstract The theory of transfer of electronic excitation energy between impurity molecules is developed without employing perturbation theory. The role of the lattice vibrations in the transfer process of the electronic excitation energy is taken into account. It is shown that the transfer time of electronic dipole ex…
SummaryThe behaviour has been examined of second-phase constituents in super-purity aluminium during etching in caustic soda, chemical brightening and anodizing in oxalic acid. Specimens containing large second- phase constituents were prepared using a carefully selected casting technique. Surfaces of specimens were m…
Adsorbed hydrogen on platinum-silica gives infra-red bands at 2040 and 2120 cm–1, and on platinum alumina at 2040 and 2110 cm–1. The 2110–2120 band is much enhanced by treatment by oxygen, and adsorption-desorption behaviour together with deuterium shift establish the band as due to weakly adsorbed hydrogen. It is pro…
The mode of action of ATP citrate lyase [EC 4.1.3.8] was investigated using a single homogeneous preparation from rat liver. First, the enzyme was incubated with labelled citrate and after incubation the protein portion was isolated through a column of Sephadex G-50. It was found that an enzyme-citrate complex is form…
By obtaining a clearer understanding of the mechanism of damping operating in manganese-copper alloys it may be possible either to improve damping properties at elevated temperatures or to select alternative systems with better ancillary properties. Electron-microscope, X-ray, and neutron-diffraction techniques have b…
Abstract Some series of solid solutions with perovskite‐type structure are synthesized and investigated, viz. the binary systems Nd 1− x , Me x MnO 3 where MeCa 2+ , Sr 2+ , Ba 2+ , and the ternary systems (Bi 1− x La x ) 0.5 Ca 0.5 MnO 3 and Bi 0.5 (Ca 1− x Me x ) 0.5 MnO 3 where MeSr 2+ , Pb 2+ , Ba 2+ . Distortio…
Blue oxophlorins are relatively strong bases and accept one proton (on nitrogen) to form green monocations; addition of a second proton (to the oxo-group) occurs in strongly acidic media to afford the dications derived from the tautomeric hydroxyporphyrins. Oxophlorins also form metal complexes derived from the hydrox…
The e.s.r. and electronic spectra and magnetic moments of Cu(NH3)2Ag(SCN)3 and [Cu(tren)NCS]SCN (tren = 2,2′,2″-triaminotriethylamine) are reported and compared with the previously reported data for trigonal bipyramidal complexes of the copper(II) ion. Theoretical expressions for the g-values for a copper(II) ion in a…
Abstract Two breaks are observed in the temperature dependence of both specific volume and logarithmic retardation time in isotactic polypropylene, indicating two glass transitions. In correspondence with two transitions, two loss peaks are found in isochronal measurement of dynamic mechanical loss at 3 Mc./sec. The l…
The results are described of some studies of a mechanism of energy dissipation due to strain-induced reorientation of tetragonality in binary manganese-copper alloys containing 60–90 wt.-% Mn. The dependence of the structure upon the progress of ageing and the temperature of observation is reported. A high damping cap…
Abstract not Available.
An aluminium-2% magnesium alloy solidified to a pronounced sub-structure shows, when tested in tension, at approximately 300°C an abrupt change in the mode of plastic deformation. Above this ‘transition’ temperature, where the flow stress maintains a steady value up to high strains, restoration is suggested to occur b…
Variable-temperature n.m.r. studies have proved the double alkoxide-bridged bi-octahedral (edge-shared) structure of the dimeric penta-alkoxides M2(OR)10, where M = Nb or Ta and R = Me, Et, or Bui. Rapid intramolecular double exchange of alkoxide groups occurs between (i) the two types of terminal group and (ii) the t…