Materials Literature
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Barium borate glasses containing 0-35 mole% V 2 O 5 were found to be homogeneous. Optical absorption spectra indicated that only V 4+ of the lower valence states of vanadium was present. The molar volume data suggested that a change in the structure associated with vanadium ions occurred at around 22% V 2 O 5 . ESR sp…
We have studied the lattice dynamics of bcc Zr at 1400 K. We find that (a) the [111] longitudinal branch plunges rapidly to low frequencies in the vicinity of $q=\frac{2}{3}[111]$ indicating a nautral inclination for this metal to undergo a structural transformation to the $\ensuremath{\omega}$ phase, (b) the [110] lo…
The surface vibrational modes of atomic hydrogen adsorbed on W (100), observed by electron-energy-loss spectroscopy in off-specular directions, indicate bridge bonding at all coverages. The vibrational frequencies show a dependence on the W-H-W bond angle which changes due to reconstruction of the tungsten lattice. Th…
Abstract Data on the distribution of collagen fibril diameters in various connective tissues have been collected and analysed for common features. The diameter distributions of the collagen fibrils at birth and in the foetal stages of development are unimodal, whereas at maturity the mass-average diameter of the colla…
Refinement of the crystal structure is made for the room temperature phases of LaNbO4 and NdNbO4. The final R index is 0.0457 for LaNbO4 and 0.0342 for NdNbO4. From precise atomic parameters, the vectors of the shuffles for all atoms out of “the plane of shear” (010) are determined. Since the twins in the crystals are…
Stress-strain characteristics in silicon crystals are investigated as a function of the temperature, the strain rate, and the initial density of dislocations. Dislocation multiplication in the yield region is also observed by means of etch-pit technique. Specimens with lower initial densities of dislocations have high…
The effect oJ the electromagnetic Jorce on the solidified structure has beell studied Oil the Sn-IO % Pb alloy. I II the experiments, direct or alternative electric or magnetic current, anrl the currellts combined were applied into the molten metal. ['lIder the nine differellt exl)erimental conditions, the alloy was s…
Raman excitation profiles of copper tetraphenylporphyrin have been obtained and interpreted in terms of strong vibronic coupling. The Duschinsky mixing of normal modes in the excited Q electronic state has a dominant effect on the excitation profiles and the absorption spectrum. A general theoretical technique for cal…
A theory of ferroelectric phase transition in AgNa(NO 2 ) 2 is proposed on the basis of a two sublattice model. A model calculation is performed to obtain the temperature dependence of spontaneous polarization and the intensity of Raman scattering due to the symmetric bending mode of NO - 2 ions. The theoretical resul…
Optical absorption and photoelectron spectra of CsPbCl 3 and CsPbBr 3 have been studied. A sharp absorption peak is found at about 3 eV in CsPbCl 3 and 2.4 eV in CsPbBr 3 and its position shifts toward lower energy as the temperature decreases. XPS and UPS measurements of the materials suggest that this first peak is…
A classical model of the polarizability of π-bonded molecules is developed. The model is an extension of the atom dipole model which allows charge transfer within the molecule to reproduce the effect of delocalized π electrons. The model is applied to several test systems and is found to provide better agreement with…
Phonons in a metal have a finite lifetime due to the emission of electron-hole pairs. This process leads to an electron-phonon contribution ${W}_{\mathrm{ep}}^{p}$ to the thermal resistance, which limits the lattice thermal conductivity ${\ensuremath{\kappa}}_{p}$. We present a summary of the available experimental da…
Results of Raman scattering experiments associated with in-plane intercalate modes in graphite-bromine are reported. The spectra are interpreted in terms of models in which the molecular character of the bromine is retained and the molecular ordering of the intercalate layer is closely related to that in the layer str…
The shift of the optical-absorption edge when evaporated films are annealed at the glass-transition temperature is investigated in amorphous Ge${\mathrm{Se}}_{2}$, ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, and ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, and is related to structural studies described in the previous paper. A…
The structure of evaporated ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, and Ge${\mathrm{Se}}_{2}$ films, and the influence of annealing at the glasstransition temperature, are studied by extended x-ray-absorption fine structure (EXAFS) and by Raman spectroscopy. In addition, the topo…
The dielectric functions and optical conductivities of Cr${\mathrm{O}}_{2}$, Mo${\mathrm{O}}_{2}$, and W${\mathrm{O}}_{2}$ have been obtained from reflectivity measurements, and the results are interpreted on the basis of qualitative models proposed for the band structures of the transition-metal dioxide series. Cr${\…
Mössbauer spectra of the polycrystalline form of the square planar compound α,β,γ,δ-tetraphenylporphinato–iron (II) have been observed at a variety of temperatures. Analysis of the resulting spectra yield a positive electric field gradient interaction with quadrupole splitting ΔE=1.51 mm/s (4.2 K) and 1.52 mm/s (300 K…
An electronegativity scale is derived for the noble and transition metals, based on their electron-band theory description. The tendency of $d$-band electron and hole states to hybridize is used to estimate the propensity for a particular metal to gain or lose $d$-electron count and this, in turn, is used to provide t…
Ultraviolet optical absorption, emission, and excitation spectra are presented for 14-MeV neutron-irradiated high-purity crystalline ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$. Low-temperature polarized excitation spectra for the 3.8-eV luminescence correlated well with polarized absorption at 4.8 eV (both polarizations) a…
Experimental results are reported on S-state ions incorporated into PbFCl-type tetragonal single crystals. The spin Hamiltonian parameters of these ions are determined and correlated with structural and physico-chemical properties of the studied compounds. The experimental b 2 0 spin Hamiltonian parameters vary linear…