Materials Literature
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Abstract The problem of step motion during lateral growth in solid-solid phase transformations is re-examined. Results are obtained for the steady motion of an individual ledge when volume diffusion in the parent phase is the predominant contribution to the growth rate. A comparison is made between our results and the…
Essentially identical pretransitional smectic $A$ behavior is reported in both normal and reentrant nematic phases of mixtures of octyloxycyanobiphenyl (8OCB) and hexyloxycyanobiphenyl (6OCB). A phenomenological model which assumes an optimum density for smectic interactions explains quantitatively our correlation len…
Etch-decoration reveals that the rate of removal of carbon atoms exposed at monolayer steps on graphite surfaces depends on the population density of these edge atoms (the rate is higher at a low-density surface) and that carbon removal continues for a prolonged period after the oxygen supply in the gas phase has been…
All subgroups of the magnetic axial point groups are derived, and the invariant ones are indicated. These subgroups can be used in the determination of the symmetry of the low-temperature phase in phase transitions of crystals that are highly anisotropic in one direction (the ferroelectric transition of the chain-type…
The thermal expansion of VSe 2 from 40-1175K has been determined by X-ray diffraction. The lattice expansion is linear with temperature from 40 to about 300K with alpha a =18.6*10 -6 K -1 and alpha c =9.8*10 -6 K -1 . The behaviour alpha a > alpha c is anomalous for a layer compound. From the relation between the ther…
Abstract Ethinylbenzol ( 1 ) besitzt vier niederenergetische π‐Orbitale, die wegen ihrer Symmetrieeigenschaften differenziert auf Substitution im Alkinrest ansprechen. Der Verlauf der oberen π‐Ban‐den in den Gasphasen‐He(I)‐PE‐Spektren der Reihe 1‐13 (C 6 H 5 ‐ C C R) wird in Abhängigkeit von R untersucht. Relativ…
Abstract 4,5‐Dihydro‐7,9‐dimethyl‐3 H ‐benz[cd]azulen‐3‐on ( 1 ) sowie dessen N,N ‐Dimethyliminiumsalz 2 lassen sich durch Oxidation mit DDQ in die 3H ‐Benz[ cd ]azulenderivate 3 und 4 überführen. Das Salz 5 wird durch Alkylierung von 3 mit Triethyloxonium‐tetrafluoroborat erhalten, die Verbindung 6 aus 2 durch Reakti…
Infrared absorption spectra of various samples of hydrogen beta alumina are discussed with respect to the alternative concerning the existence of hydroxyl (OH - ) and oxonium (H 3 O + ) ions in this compound. Some results of inelastic and quasi-elastic neutron scattering are also given. It can be shown that the presen…
An effective medium theory is used to calculate the conductivity activation energy and the Seebeck coefficient for nearest-neighbour hopping in a band of Anderson localised states at the Fermi level. The results of these calculations are compared with experimental observations on cerium sulphide, fluorine-substituted…
New data are analyzed for the hard-sphere fluid at densities $\ensuremath{\rho}{\ensuremath{\sigma}}^{3}=0.95\ensuremath{-}1.08$ in the metastable range. In this region the diffusion coeffiecient behaves as in laboratory fluids, following a Doolittle equation with normal parameters rather than a Batchinski-Hildebrand…
The dominance of vacancy migration in grain boundary self-diffusion has been established by molecular-dynamics simulation of a bcc iron $\ensuremath{\Sigma}=5$ tilt boundary. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure dependent. Th…
Two structural phase transitions at 211 and 177 K are discovered and investigated in single crystals of cesium lithium molybdate by means of optical, dielectric, and X-ray methods. Spontaneous polarization and dielectric hysteresis loops are observed in both low temperature phases. Judging from X-ray powder data the s…
L'ordre magnétique dans LiCrO2 a été étudié sur monocristal par diverses techniques de diffraction neutronique. Grǎce à la méthode de Laue un vecteur de propagation unique k = [1/3, 2/3, 3/2] a été déterminé dans la maille multiple hexagonale (R3m). A l'aide d'un diffractomètre à quatre cercles, la mesure des intensit…
The technique of supersonic free jet spectroscopy can be used to study the structure and dynamics of molecules which have been cooled to far below their boiling points but which remain in the gas phase. Cooling of the internal degress of freedom, the molecular rotations and vibrations, produces a highly resolved and g…
Ferrite single crystals and the texture of polycrystalline BaFe12O19 samples, irradiated by fast neutrons are investigated by magnetic and neutronographic methods at 9 and 4.2 K. Antiphase helical ordering of the total magnetic moments of certain blocks of the unit cell is found to take place in the irradiated crystal…
We present a calculation of the wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ and the frequency ($\ensuremath{\omega}$)-dependent transverse dielectric function ${\ensuremath{\epsilon}}_{T}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}},\ensuremath{\omega})$ for a model semiconductor. Using the Penn m…
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. F. Jacobs and D. Shough, "Thermal expansion uniformity of Heraeus-Amersil TO8E fused silica," Appl. Opt. 20, 3461-3463 (1981) Export Citation BibTex…
Thin films of amorphous P, prepared by rf sputter deposition under conditions of variable substrate temperature, have been studied using x-ray diffraction and Raman scattering methods. The low-angle x-ray spectra indicate a peak at $k\ensuremath{\simeq}1.1$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, whose half-width and re…
A large red shift in the energy of the plasmon resonance in metallic V${\mathrm{O}}_{2}$ has been observed by decreasing the temperature near the metal-to-insulator phase transition (${T}_{c}=68$\ifmmode^\circ\else\textdegree\fi{}C). Below the transition temperature the plasmon resonance disappears. The plasmon resona…
Optical absorption and luminescence investigations performed on the system KCl-Eu${\mathrm{Cl}}_{2}$ revealed that, in addition to the precipitated phase which nucleates at temperatures below 100\ifmmode^\circ\else\textdegree\fi{}C and which has been ascribed to the Suzuki phase, three other Eu-precipitated phases can…