Materials Literature
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Experiments on the transport of thermal energy through aggregates of small particles at low temperature are discussed. A transition to a weakly-temperature-dependent thermal conductivity, or plateau, appears at the temperature at which the thermal phonon wavelength equals the particle size. This is interpreted as evid…
Evidence from a number of previous experiments is found for Ag-cluster vibrations in enhanced Raman scattering from a Ag surface. By the analysis of the conditions specific to such experiments, the most likely identity of these clusters has been revealed to be ${\mathrm{Ag}}_{4}$${\mathrm{}}^{+}$. To further confirm t…
The reflective and absorptive contributions to the optical modulation in sputter-deposited thin films of crystalline LixWO3 have been determined as a function of lithium concentration (0<x<0.5). The magnitude of the reflective response increases with increasing substrate temperature (Ts) during depositio…
The one-dimensional Schr\"odinger equation with multiple scattering potentials is transformed to a discrete (tight-binding) form exactly. For a random configuration of potentials in which all the states are localized, it is shown (not argued) that the resistance \ensuremath{\rho} behaves as \ensuremath{\rho}\ensuremat…
We propose a simple decoration of the Penrose tiling to produce a two-dimensional quasi-crystalline model. We have used molecular dynamics simulation to invesigate the stability and the phase transitions of this system. Stable with pair potentials, it undergoes a first-order transition to the liquid phase. Its enthalp…
55 Mn spin-echo NMR spectra of RMn 2 compounds (R=heavy rare-earth) and their external field dependence have been measured in their magnetically ordered states. From the analysis of the 55 Mn hyperfine field, the Mn magnetic moments have been estimated as 2.6 and 2.5 µ B for GdMn 2 and TbMn 2 , respectively, whereas a…
Theoretical predictions for various neutral and charged forms of polyaniline are presented and discussed. The MNDO semiempirical method is used to predict geometries which serve as input for valence effective Hamiltonian (VEH) calculations of the electronic band structure. The VEH calculations provide predictions for…
Electron energy loss spectroscopy (EELS) has been used to study the adsorption of nitric oxide on Rh(111). NO adsorbs in twofold bridge sites at all coverages. The dissociation rate of NO on this surface at low coverage has been measured directly using EELS. The first order dissociation rate parameters are Ea =19.2±0.…
Les deux composes cristallisent dans le systeme orthorhombique, groupe PcaB. Coordination bipyramidale rhomboedrique et pyramidale rhomboedrique autour de En et Cu respectivement
NdDyFe14B shows a spin reorientation around TS =92 K which is lower than that obtained for Nd2Fe14B (150 K). Neutron diffraction on powder specimen indicates a preferential occupation for Dy atoms of the 4 f sites, but does not reveal the spin reorientation.
Angle-resolved valence photoemission spectra have been obtained for W(011) and W(001) using Al K\ensuremath{\alpha} and Mg K\ensuremath{\alpha} excitation and with both normal and off-normal emission directions. The angular resolution was \ensuremath{\lesssim}\ifmmode\pm\else\textpm\fi{}1.0\ifmmode^\circ\else\textdegr…
Initial steps in the photodissociation of nitrosyl ferrous and ferric heme complexes have been investigated by calculation of the ground and excited states and electronic spectra as a function of iron-ligand bond lengthening. The method used is an all valence semi empirical INDO-SCF-CI procedure with transition metal…
A b initio self-consistent field and configuration interaction (SCF-CI) calculations with a minimal basis set are carried out on a few lower π→π* states of free base porphin and free base chlorin. Excitation energies and oscillator strength of these states are calculated and are compared with observed values. For the…
Using an rf-magnetron sputtering method, highly c-axis-oriented La-modified PbTiO3 (PLT) thin films with compositions of Pb1−xLaxTi1−x/4O3, where x=0.05, 0.10, and 0.15, have been obtained on MgO single-crystal and epitaxial Pt thin-film substrates under conditions of low gas pressure and low deposition rate. The degr…
The broadband luminescence of isolated Cr+3 ions in the title lattices is investigated. The 4T2g lowest excited state is found to undergo Jahn–Teller distortion in the eg coordinate, in addition to expanding along the a1g. Quantitative determination of these displacements is made by analysis of extremely rich fine str…
Calculations of the electronic structure, the Fermi surface, and the momentum density of annihilation photon pairs are presented in preparation for an experimental study of the half-metallic ferromagnet NiMnSb with the aid of the two-dimensional angular correlation of annihilation radiation technique. The band structu…
The free energy of a polmyer solution is derived by a consideration of the monomer density fluctuations and incorporating three-body interactions. Explicit interpolation formulas are obtained for the concentration dependence of the correlation length for arbitrary strengths of two- and three-body interactions within t…
A universal but unexplained characteristic of glasses is the temperature-independent region or plateau in the thermal conductivity for temperatures 1--30 K. Examination of low-temperature thermal conductivity data for a wide variety of glasses indicates that the mean free path of the average thermal phonon becomes les…
The thermal conductivities of glassy solids, when scaled by material parameters, have a similar magnitude and temperature dependence, from the lowest temperatures yet measured, to the melt. Both empirical results and theoretical models are reviewed briefly. It is emphasized that the thermal conductivity of an amorphou…
Measurements of the elastic and inelastic neutron scattering from vitreous silica in the frequency range 0.3 to 4 THz and with scattering vectors in the range 0.2 to 5.3 A${\r{}}^{\mathrm{\ensuremath{-}}1}$ are analyzed in conjunction with heat-capacity measurements on the same samples to provide a microscopic descrip…