Materials Literature
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For pt.I see ibid., vol.8, no.12, p.1921 (1975). Samples of neutron-irradiated CaO examined at room temperature show EPR spectra from several defect species with S= 1 / 2 and g-values very close to the free-electron value. Spectra with S=1 have been associated with anion divacancy pairs along (100), (110) (NNN sites),…
The atomic arrangement in the basal plane of Ti is determined by analysis of low-energy electron diffraction (LEED) intensities. Twenty-five beams at four angles of incidence and at two azimuths have been measured and compared to calculations. Complications caused by the simultaneous presence on the surface of domains…
The frequency and infrared and Raman strength changes of lattice modes due to structural phase transitions of Landau type have been investigated. The lowest-order invariants in the thermodynamic potential describing the effect of interest have been determined by a group-theoretical method. It is shown that in the firs…
Extension of analyses of low-energy-electron-diffraction intensities to encompass structure determination of low-index semiconductor surfaces reveals that GaAs(110) is reconstructed. The As atoms protrude from the surface whereas the Ga atoms are displaced inward such that no nearest-neighbor bond lengths are altered.
Pieranski and Guyon (1973) describe a shear-induced instability in a nematic liquid crystal when the anisotropic axis is initially normal to the plane of shear, and present a simple calculation which supports their experimental results. A more detailed theoretical analysis of the stability of this flow arrangement to…
The variation in the film conduction during vapour deposition in UHV reflects the different growth stages: discontinuous structure; formation of stable metallic paths; and metallic continuous structure. If the deposition is stopped with R Square Operator 1 M Omega the resulting film is discontinuous with a temperature…
An order parameter theory is derived and used to explain the observed structural phase transformations in tetrathiafulvalene tetracyanoquinodimethane. It is shown that there should be three transitions. One set of chains orders at 54 K, the other at 47 K. The modulation wave vector in the ${\stackrel{\ensuremath{\righ…
A series of elements are tested for partial substitution in MnBi to form stable compounds suitable for magnetooptic memory applications. While MnBi1−xTex forms a stable NiAs-structure with higher c/a-ratio than the low temperature phase of pure MnBi, new stable compounds with low c/a-ratio are identified in the system…
Investigations of the system Mn5(Ge1-xSix)3, (with 0 ≦ X ≦ 1) show that a continuous series of solid solutions can be obtained over the complete concentration range. Curie temperature and magnetization measurements at 4.2 K show that the system is ferromagnetic in the concentration range 0 ≦ X ≦ 0.75. For X = 0.8 it b…
The structure, cation distribution, and cation valencies of the CuxMn3−xO4 spinel system are investigated by means of some selected experiments on specimens of this spinel system and some similar Cu and Mn containing spinels. Dilatation measurements reveal two important cation migration processes, namely the cation ex…
Structural and dielectric studies have been performed on CsH2PO4 for scrutinizing the validity of the previously reported structure. It is found that the symmetry in the paraelectric state is not orthorhombic as previously assumed but monoclinic with the space group of C. The net configuration of hydrogen bond and the…
A generalisation of Mott's model of an amorphous solid is used to investigate the characteristics of carrier transport by hopping in an extended temperature range. It is shown that three types of behaviour can be expected, the Mott T−-1/4 variable-range hopping at low temperatures, nearest-neighbour hopping at high te…
The molar hat capacity of GeTe, SnTe, and Pbte have been measured by the heat-pulse method from 0.9 to 60 K. No conclusive evidence was found for th effect o the soft TO phonon modes known to be presen in these mateials. An anomalous excess heat capacity previously reported near 3 K for GeTe was not confirmed. A deail…
We consider a set of dipole impurities randomly distributed in a nonpolar medium where the only interaction between the impurities is the dipole-dipole interaction. The dipoles are assumed to be oriented in the six equivalent (1,0,0) directions found experimentally to exist when O${\mathrm{H}}^{\ensuremath{-}}$ impuri…
The intensities of the electric dipole transitions of Ho3+ in three oxide glasses have been obtained from the absorption spectra in the visible and ir for tellurite glasses, and in the uv, visible, and ir parts of the spectrum for calibo and phosphate glasses. From the experimental values of the oscillator strengths a…
Optical constants were obtained by Kramers-Kronig analysis of normal-incidence reflectivities of Ni, Fe, concentrated FeNi alloys, and ordered and disordered ${\mathrm{Ni}}_{3}$Fe. Measurements were made from 2 to 27 eV and extended to 35 eV in Ni. Specimens were either thin evaporated films or bulk specimens that wer…
Detailed measurements and line-shape fits of the combined LO- and TO-phonon assisted electron-hole condensate luminescence lines from laser-excited, high-purity Si are reported in the temperature range from 2.2 to 13.0\ifmmode^\circ\else\textdegree\fi{}K. These data permit a determination of the liquid density $n$, ch…
Infrared studies of single crystals and thin films of the one-dimensional organic metal tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ) are presented. The frequency-dependent conductivity, ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$, and dielectric function, ${\ensuremath{\epsilon}}_{1}(\ensuremath{\omega}…
Reflectivity and wavelength-modulated reflectivity measurements on GaSe and $\mathrm{Ga}{\mathrm{S}}_{x}{\mathrm{Se}}_{1\ensuremath{-}x}$ mixed crystals are presented for energies ranging from 3 to 6 eV. Additional electroreflectance measurements are used to investigate the excitonic character of the structure at 3.4…
The geometry of stationary or mobile metallic and semiconducting domain configurations and their formation during the switching of a VO 2 single crystal are discussed. It is shown that the motion of narrow semiconducting domains in the sense of the electric current is driven by the Peltier effect at the two oppositely…