Materials Literature
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Brillouin scattering from $a$-Si${\mathrm{O}}_{2}$ up to 17 GPa shows that an irreversible change in the longitudinal sound velocity takes place between 10 and 17 GPa and that this change is stable at atmospheric pressure. Raman spectra of the retrieved sample indicate that it is also amorphous but differ noticeably f…
Measurement of the fractal dimension, $D$, of colloidal aggregates of small silica particles is reported. We observe power-law decay of the structure factor $[S(k)\ensuremath{\sim}{k}^{\ensuremath{-}D}]$ by both light and x-ray scattering showing that the aggregates are fractal. $D$ is found to be 2.12\ifmmode\pm\else…
The new tetrachalcogenide compounds have a one-dimensional structure and two of these show transport properties which are characteristic of this type of conductor. The authors electron microscopy study permits them to show clearly and characterise the charge density waves which appear at 263 and 285K in (TaSe 4 ) 2 I…
We have used the theory developed in the previous paper to study the induced orientational order at simple models of a solid-liquid crystal (LC) interface. The LC is modelled by a Maier-Saupe type of anisotropic pairwise potential while the solid is modelled by an impenetrable wall which exerts an anisotropic external…
Molecular simulation calculations lead to strongly correlated data sequences for which the normal method of estimating the errors may lead to serious underestimates. The nature of the correlations are examined and superior methods of error estimation are identified.
By means of Penning-ionization electron spectroscopy the outermost surface layer of a pentacene film on a graphite substrate (cleavage plane) was selectively observed. Ultraviolet photoelectron spectroscopy was also applied to observe several layers from the surface. From the analyses of the two types of spectra the s…
Subharmonic steps in the dc $I\ensuremath{-}V$ characteristics are reported in the model compound Nb${\mathrm{Se}}_{3}$, when subjected to combined dc and ac drives. The steps occur at currents which correspond to frequencies ${\ensuremath{\omega}}_{\mathrm{int}}=(\frac{p}{q}){\ensuremath{\omega}}_{\mathrm{ext}}$, wit…
A series of twenty homogeneous ${\mathrm{Sr}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}\mathrm{Ti}{\mathrm{O}}_{3}$ mixed crystals has been measured dielectrically between 4.2 and 300 K. In the tetragonal phase, the dielectric constant perpendicular to the $c$ axis becomes peaked above ${x}_{c}=0.0018$, the quantum mechanic…
The T–x diagram of the CeH system is studied in the temperature range 100 to 470 K (2.05 ≦ x ≦ 2.82). Phase transitions are found in all the hydrides studied. Some phase transition lines are plotted in the T–x diagram. Transitions at x ⪅ 2.5 and T = 217 to 373 K are ascribed to hydrogen ordering on octahedral sites.…
The linear thermal expansion of SrTiO3 in the temperature range 10 to 150 K is measured with a relative accuracy of 5 × 10−7 by using a three-terminal capacitance dilatometer. The dilation δL/L of a single-domain crystal is converted to the ratio of the pseudo-cubic cell constants a(T)/a(Ta) by the equation a(T)/a(Ta)…
X-or W irradiation of Eu and Sm-doped CaSO4, produces a partial conversion from RE2+ to RE2+. Sm2+, Eu2+, and Eu3+ can be detected using radiophotoluminescence (RPL) and could be utilised for dosimetry. Preliminary measurements show that the minimum RPL detectable exposures using Eu and Sm doped phosphors are (155 ± 1…
This paper aims to clarify the conditions in which zero reflection from a dielectric film on metal substrate at oblique angles of incidence takes place. The numerical examples with experimental data show that the light absorption characteristics strongly depend on the film thickness. Therefore, it is useful to observe…
New Zealand has experienced two invasions of stilts, the first giving rise to the endemic Black Stilt (Himantopus novaezealandiae) and the second being that of the Pied Stilt (H. himantopus leucocephalus). The geographical separation of these forms was of insufficient duration for reproductive isolation to become comp…
Low temperature optical spectra of highly purified NaNO 2 crystals have been investigated in near u v region. The width of the zero-phonon absorption line at ν 00 due to the electronic transition 1 A 1 → 1 B 1 in NO 2 - is remarkably reduced in the purified crystal and three satellite absorption lines are observed sep…
The phase stability of Al as a function of pressure and the bulk properties at equilibrium are explored via a series of all-electron, non-muffin-tin, local-density-functional calculations for the fcc and bcc structures. The techniques used are the linear combination of Gaussian-type orbitals (LCGTO) techniques which w…
Fluorescence spectra have been analyzed at 4.2, 77, and 300 K and crystal field calculations have been performed on Na5Eu(MO4)4 (M=Mo, W) powders. The two sets of crystal field parameters are almost identical yielding a rms deviation of 5 cm−1. The values are (in cm−1): B20 =200 (180), B40 =−326 (−330), B44 =−863 (−85…
The sintering of ceramic oxide powders has been investigated using a high power CO2 laser as the heat source. The laser sintering method is very useful for the densification of oxides such as ZrO2, HfO2, and Y2O3 which have high melting points above 2000 °C. The new ceramic in the ternary system of (ZrO2-Y2O3-HfO2) pr…
The physical origin of eddy current losses in materials characterized by a very fine and complex domain structure is discussed, on the basis of a general statistical theory of losses developed in preceding papers. It is shown that the same process which is at the basis of the Barkhausen effect, namely the space-time c…
The generation of solitons and polarons and the decay of bipolarons into soliton-antisoliton pairs have been investigated with a self-consistent numerical calculation. The results are compared with the exact solutions at the continuum limit and justify the recent experimental suggestion of single-charge injection via…
In this paper we develop a modified self-consistent phonon approximation model which displays effects which indicate melting. The model is applied to hydrogen bond melting of poly (dG)⋅poly(dC) and predicts melting at 340 K. The calculation has no parameters adjusted to fit the melting, the hydrogen bond potentials ar…