Materials Literature
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Single crystals of the wide bandgap semiconductor stannic oxide, SnO2, have been grown and studied electrically. A chemical vapor deposition technique using chlorine transport, no inert carrier gases, and low pressure has been used to grow stannic oxide crystals of higher purity and with almost an order-of-magnitude h…
Refined structures of eight natural garnets [Cr-pyrope, almandine, spessartine, Mngrossular, grossular, uvarovite, goldmanite, and andradite] are compared with that of synthetic pyrope to determine the effects of the substituent cations on polyhedral interactions,bond lengths, and angles. The Si-O bonds in these garne…
A rectangular prism with edges in principal crystal directions is prepared with electrodes on the corners of one face. Voltage-current ratios for opposite pairs of electrodes permit calculation of components of the resistivity tensor. The method can use small samples, and is best suited to materials describable by two…
Nonohmic properties of ZnO ceramics with five additives of Bi 2 O 3 , CoO, MnO, Cr 2 O 3 , and Sb 2 O 3 are studied in relation to sintering temperature, additive content, and temperature dependence. The observation of electron photomicrographs and X-ray microanalysis proves a ceramic microstructure such that ZnO and…
An ion-beam deposition technique has been developed and was used to deposit thin films of insulating carbon on room-temperature substrates. It was established that the carbon films deposited using this technique are insulating and have the following characteristics similar to that of carbon in the diamond form: (1) tr…
Vitreous carbon, one of the most important materials based on graphite carbon, is outstanding in its high mechanical strength, resistance towards aggressive media, and imperviousness to gases. Because of these unique properties, there has been a rapid growth in the range of articles made of vitreous carbon and in the…
Vapour bubble collapse problems lacking spherical symmetry are solved here using a numerical method designed especially for these problems. Viscosity and compressibility in the liquid are neglected. Two specific cases of initially spherical bubbles collapsing near a plane solid wall were simulated: a bubble initially…
The olfactory nerve of the garfish, Lepisosteus, is about 1 millimeter in diameter and about 20 centimeters long, depending on the size of the fish; it is easily prepared by breaking off successive scored segments of the rostrum. It consists of a relatively homogeneous population of about 10(7) nonmyelineated nerve fi…
Abstract Der aus dem Holz der Edelkastanie ( Castanea sativa ) und der Eiche ( Quercus sesseliflora ) isolierte Gerbstoff Vescalin besitzt die Struktur 2a und ist damit anomer zu Castalin. Die Struktur wird bewiesen durch die saure Hydrolyse zu Flavogallonsäure ( 1a ) und D ‐Glucose sowie durch NMR‐ und Massenspektren…
Abstract In the transmission electron microscope, as shown in figure 1 (Nixon 1962), the electron gun at the top illuminates the specimen with the beam angle controlled by the condenser lens. The lenses below the specimen are used to magnify the image of the specimen which is viewed on the final screen at many thousan…
Abstract The various modes of specimen signal acquisition presently available on the scanning electron microscope permit both morphological and analytical studies to be carried out on the specimen. The advantage of the scanning electron microscope is that it provides an information-rich image at resolutions determined…
Abstract Unter verschiedenen Zustandsbedingungen wurde die Temperaturabhängigkeit der thermischen Schädigung von Nylon 6.6 und Nylon 6.10 vergleichend untersucht. Die erheblich größere thermische Unbeständigkeit von Nylon 6.6 läßt sich auf die Ringschlußtendenz des Adipinsäurebausteines zurückführen. In Gegenwart von…
Abstract A scanning microscope is described which is capable of a point resolution of 0.5 nm. We have demonstrated that it can produce the same kinds of micrographs as a conventional microscope. However, by using several detectors to produce signals corresponding to different groups of transmitted electrons we are abl…
An anomalously large magnetostriction has been found in ${\mathrm{Fe}}_{2}$Ti${\mathrm{O}}_{4}$. The magnetostriction constants ${\ensuremath{\lambda}}_{100}$ and ${\ensuremath{\lambda}}_{111}$ are (4.7 \ifmmode\pm\else\textpm\fi{} 0.4) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}3}$ and (1.3 \ifmmode\pm\e…
First measurements of double-photon elastic scattering performed on liquids with centrosymmetric molecules yield good agreement with statistical molecular theory of nonlinear light scattering. Studies of this new scattering are shown to allow determination of the third-order molecular polarizability as well as its ani…
The specific heat of YbFe${\mathrm{O}}_{3}$ in the range 1.5-15 K exhibits spin-reorientation and Schottky anomalies. The magnetic field dependence of the reorientation anomalies is consistent with phenomenological descriptions which predict that two second-order phase transitions occur in the reorientation process. T…
A novel application of the Born-Oppenheimer approximation is made which predicts the strength and nature of the singular threshold structure associated with plasmon satellites for a wide class of experiments involving the interactions of photons or fast electrons with solids.
The crystal structure and internal defects of equiatomic TiNi martensites have been studied using the techniques of electron microscopy, electron diffraction, and X-ray diffraction. The crystal structure may be described as of distorted B19 type with a monoclinic unit cell, the lattice parameters of which are a = 2.88…
High values of electro-optic coupling and second-harmonic generation coefficients have been found in m-nitroaniline; Miller's Δ coefficients are higher than any previously reported. The shape of the absorption band rather than a favorable bond-orientation geometry appears to be responsible.
Raman spectra of aqueous gadolinium nitrate solutions, and complementary infrared spectra, have been obtained for a wide range of compositions. Detailed intensity analyses indicate that the predominant species in solutions with nitrate:gadolinium ratios less than two is Gd(NO3)2+ (β2 = 4.6 ± 0.2 at 25°C). Small concen…