Materials Literature
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A general symmetry argument is presented, and experiments on newly synthesized p-decyloxybenzylidene p'-amino 2-methyl butyl cinnamate are described, demonstrating that chiral smectic C and H liquid crystals are ferroelectric. Some of the properties of this new class of ferro-electrics are discussed.
The polarized reflectance of single crystals of tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) at 300 K is reported over the frequency range 300 to 4000 ${\mathrm{cm}}^{\ensuremath{-}1}$, with unpolarized data extending to 50 ${\mathrm{cm}}^{\ensuremath{-}1}$. A Kramers-Kronig analysis is used to obtain the fr…
The results from soft X-ray appearance potential spectroscopy (SXAPS), photon-induced Auger appearance spectroscopy h(cross) omega -APS), X-ray photoelectron spectroscopy (XPS) and ionization loss investigations on the carbon K level in graphite are compared. It is shown that plasmon excitation accompanies core hole c…
The effect of the grain size on unit-cell dimensions and dielectric properties has been studied in ceramic lanthana-substituted lead titanate of the general composition Pb1−αxLaxTiO3+x (1.5−α) with α = 1.20 and x = 0.07 (PLT7) and x = 0.18 (PLT18). The grain size ranges from 0.6 to 11 μm and the effects are most prono…
The interpolytypic transition from the IT to the 2H modification in the TaS2 system is shown to be a shear transformation. A transformation mechanism is proposed based on partial dislocation movement along successive glide planes. The same mechanism accounts for the observed simultaneous formation of polytypes other t…
Room-temperature pressure studies (3 kbar) on $a$-${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ reveal that both hole transport, as determined from time-of-flight experiments, and dark dc conductivity increase with hydrostatic pressure as $\mathrm{exp}(\ensuremath{\alpha}p)$, where $\ensuremath{\alpha}\ensuremath{\sim}0.45$…
The properties of real surfaces of (111) single-crystal Cu2O samples, prepared by quenching after equilibration at various oxygen pressures and at a temperature of 750 or 960 °C, were investigated using photoelectric emission, contact potential difference, and electrical conductivity measurements. The measurements yie…
On the base of results from the analysis of known the Judd-Ofelt expression for the line intensities of TR3+ ion spectra, some simple and quite reliable determination methods are given for the luminescent branching ratio connected with the radiative 4F3/2 → 4IJ transition and the redistribution of the intensities betw…
The attempt frequency for ion diffusion in the superionic conductors sodium and silver $\ensuremath{\beta}$-alumina is directly observed as a resonance in the far infrared dielectric response. Correlation of the measured attempt frequency with the observed diffusion coefficient suggests that the best conductors, Na an…
The transmission (ηT) and backscattering (ηR) of electrons with energies between 0.5 and 4 keV in thin films of Be, Al, Ge, Cu, and Ag, together with their secondary yields (δT, δR), were measured with a three-collector system. The SE efficiencies of backscattered electrons were 3 to 15 times greater than those of inc…
The intrinsic splay, twist, and bend deformations of nematic molecules are discussed. The intrinsic twist deformation leads to the cholesteric phase. On this molecular basis, the helical twisting power of cholesteric mixtures is discussed. The intrinsic splay and bend deformation cannot induce spontaneous deformation…
A recent proposal of Simmons and co-workers for the analysis of high-field thermally stimulated currents is extended to the case of thermoluminescence, with significant advantages for the study of continuous distributions of traps in bulk samples. The effect of the temperature smearing of the occupation function is al…
Rate coefficients have been determined in a drift tube-mass spectrometer apparatus for the oxidation reactions of Ti+ and Th+ ions in O2 and NO for ion mean energies ranging from thermal (300 K) to 5 eV. Formation of the first oxides of metal ions M+ in the reactions M+ + O2 (NO) → MO+ + O (N) is found to occur with r…
We have studied, both for the Kronig-Penney model and in general terms, the charge disturbance induced in a filled band of electrons by a solid surface. The existence of surface-charge quantization in a filled band is demonstrated and a division of energy bands into two types is made on this basis. The complementary r…
The LiD and LiH conductivities have been compared in the temperature range 300-900\ifmmode^\circ\else\textdegree\fi{}K. In both (LiD and LiH) the conductivity curve ${log}_{10}(\ensuremath{\sigma}T)=f(\frac{1}{T})$ shows three linear regions: (i) an intrinsic, (ii) a dissociation, and (iii) an association region. In a…
The valence-band structures of the light actinides thorium, uranium, and their dioxides have been investigated by means of x-ray photoemission spectroscopy. This study shows that the electronic structures of Th${\mathrm{O}}_{2}$ and U${\mathrm{O}}_{2}$ are quite similar, except for the presence of $5f$ electrons in U$…
The paraffin C33H68 undergoes three solid-solid phase transitions between room temperature and the melting point. The orthorhombic modification (A) stable at low temperatures is followed by two different monoclinic forms (B: 54.5°C < T < 65.5°C; C: 65.5°C < T < 68°C) and by the ``rotator ph…
We report a study of the infrared and Raman spectra of bulk glasses in the binary alloy system ${\mathrm{Ge}}_{1\ensuremath{-}x}{\mathrm{S}}_{x}$ ($0.90\ensuremath{\ge}x\ensuremath{\le}0.55$). The spectra are interpreted in terms of models based on covalent bonding in which the $8\ensuremath{-}N$ rule is satisfied; i.…
We describe the relation between the observed behavior of photoemission energy distributions vs frequency, angle, etc., and the quantum theory of photoemission as recently set forth formally by Caroli et al. We derive a Fermi's Golden-Rule formula for the angle- and energy-resolved photocurrent from an independent ele…
High-resolution electron diffraction patterns have been obtained from frozen, hydrated catalase crystals to demonstrate the feasibility of using a frozen specimen hydration technique. The use of frozen specimens to maintain the hydration of complex biological structures has certain advantages over previously developed…