Thin films of Wo3 deposited on quartz substrates at room temperature have been shown to be amorphous in structure. The optical absorption spectra of the amorphous and crystalline films have been measured in the temperature range 110° to 500°K. The fundamental absorption edge of an amorphous film occurs at 3800 A which on crystallization moves to 4500 A. On the high-energy side of the absorption edge several absorption peaks are resolvable in both types of film. The frequency dependence of the absorption coefficient below 104 cm−1 is described by an expression of the form K (v, T) = K 0 exp[− (β/kT) (E 0 − hv)] and above 104 cm−1 it follows a square law dependency. The temperature coefficient of the band edges was found to be − 5.0 × 10−4 eV/°K and the estimated band gaps at 0°K were found to be 3.65 and 3.27 eV for the amorphous and crystalline films, respectively. The electrical conductivity of a thin film has been measured in the temperature range 298–573°K and the activation energy was found t...

Optical and photoelectric properties and colour centres in thin films of tungsten oxide

The Binary Rare Earth Oxides.

Publisher Summary The physical properties given in this compilation are listed in the accompanying tabulation according to the table given in this chapter in which they can be found. Values for two quantities that have frequently been used in alloying theory studies, viz., the metallic radius and electronegativity, are not included here. Other properties, such as magnetic susceptibility, electrical resistivity, and thermal conductivity, which are generally of interest to those studying solids, are not included in this compilation primarily because such properties do not appear to be important in alloying theory. The derived properties and some interrelationships of the physical properties are examined and discussed in this chapter. Those subjects which also appear in tabulated form are listed in the accompanying tabulation. The initial goal in our alloy-theory program was a set of Gruneisen constants and a set of size factors. To calculate these quantities, almost all of the physical properties given herein are needed in the computations. Some of the other derived quantities are not only intermediate steps in the computations of the Gruneisen constant and size factor, but also serve as checks on the consistency of initial data (i.e., the measured physical properties of the elements). Some of the “constants” of the elements—that is, the Griineisen constant, entropy of fusion, etc., which have been derived for a few elements and then generally assumed to apply to all elements—are examined to see if this generalization is valid.

Physical Properties and Interrelationships of Metallic and Semimetallic Elements

Values for standard enthalpies of formation and dissociation energies for gaseous diatomic monoxides have been selected by critical assessment of experimental data from the literature. Gibbs energy functions, (−(G○T −H○298)/T), and enthalpy functions, (H○T −H○298), have been calculated from literature values for molecular parameters. Computer methods of storage, processing and retrieval are described and the resulting data are given in tables 4 to 11.

Thermochemical Data for Gaseous Monoxides

The actinyl ions exhibit an unusually robust covalent bond which has a profound influence on their chemistry. Their electronic structure has been unravelled by the use of a variety of optical measurements and by photoelectron spectroscopy, which together establish the composition and role of the valence orbitals. The experimental energy level scheme can be compared with the results of molecular orbital calculations of varying degrees of sophistication, the most successful being SCF calculations incorporating the effects of relativity. An important contribution to the bonding comes from the pseudo-core 6p shell, which is important in determining the linearity of the ions. A new concept, the Inverse trans Influence, is introduced in this context. There is some evidence that (d-orbital π-bonding is more important than σ-bonding. The remarkable strength of the actinyl bond can be attributed to the presence in the valence shell of both f and d metal orbitals, giving each actinide-oxygen bond a formal bond order of three.

Electronic structure and bonding in actinyl ions

The ionization potentials of Np(g) and NpO(g) were determined by electron impact utilizing mass−spectrometric measurements of vapor phase isomolecular equilibria. The results gave good agreement with surface ionization and spectroscopic data. (AIP)

The first ionization potentials of neptunium and neptunium monoxide

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R. J. Ackermann

Papers

The first ionization potentials of neptunium and neptunium monoxide

A thermodynamic study of the urania-uranium system

DETERMINATION OF LIQUIDUS CURVES FOR THE Th--W, Th--Ta, Zr--W, AND Hf--W SYSTEMS: THE ANOMALOUS BEHAVIOR OF METALLIC THORIUM.

Comments on pressure of uranium over uranium-uranium dioxide system

Measurements of the solubilities and derived thermodynamic properties of tungsten and tantalum in liquid thorium and uranium.