Materials Literature
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A novel mechanism for spin-pairing at defect centres in amorphous silicon is proposed and discussed in terms of simple chemical bond arguments. Unlike the case of chalcogenide glasses (or amorphous arsenic), the presence of non-bonding (lone-pair) orbitals is found to be unnecessary in producing a negative effective H…
An in situ study of the electron spin resonance (ESR) of ultrahigh vacuum evaporated amorphous silicon is performed to define the characteristics of the signal as a function of preparation conditions. The influence of deposition rate, temperature of substrates, temperature of annealing, angle of incidence of the vapor…
Two methods for performing small-angle electron scattering (SAES) experiments in transmission electron microscopes are described: the long-camera-length method and the selected-area-diffraction method. It is shown experimentally that angular resolutions of a few microradians and a few tenths of milliradians, respectiv…
The optical properties of vacuum evaporated films of ZnS have been measured from 160 to 2000 A. The reflectance spectrum shows three maxima, at 1800, 1250, and 900 A. The first two are associated with interband transitions while the third is more of an atomic transition. To shorter wavelengths, the reflectance spectru…
Abstract The term “lead” pencil is a misnomer in that the pencil contains no lead but rather is composed of three primary ingredients in varying proportions: graphites, clays, and waxes [1]. Since its introduction during the 16th century, the pencil has become the most widely used writing instrument throughout the wor…
The thermal conduction of four niobium single crystals deformed at 77 K, 195 K 295 K and 470 K has been measured in the temperature region between 0·3 K and 20 K. From these measurements the thermal resistivity W pd due to plastic deformation was calculated in the temperature region below 5 K. After weak and medium de…
Solid insulators are used for support in many types of high voltage apparatus. Because these supports are often composed of high resistivity materials, static charges may be accumulated and held by them for extended periods of time. The electric field distribution in the vicinity of the insulator is then altered so th…
Fungi in the order Saprolegniales are known to contain varying proportions of sterols, such as cholesterol and fucosterol. In the caseAchyla, it has been found that fucosterol, the major sterol component, serves as the biosynthetic precursor of the hormones, antheriodiol and the oogoniols. Antheridiol is secreted by f…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.alpha.-Silyloxy and .alpha.-hydroxy manganese alkyls. Generation via a new five-membered metallocycleJ. A. Gladysz, J. C. Selover, and C. E. StrouseCite this: J. Am. Chem. Soc. 1978, 100, 21, 6766–6768Publication Date (Print):October 1, 1978Publication History Published onl…
Field desorption mass spectrometry requires ion emitters of reproducible high quality. A new method is described for producing field desorption emitters covered with carbon, metal or alloy dendrites within a few minutes. Their emission properties are as good as those of the well known carbon dendrite emitters produced…
Abstract With ZnO:Cu:H, ZnO:Cu:D, and ZnO:Cu:H:D IR‐active absorption line spectra composed of 20 absorption bands are observed. Regarding the values of the absorption coefficients one of the 20 absorption bands is prominent (“main peak”), 18 absorption bands lie on the high energy side of the main peak (“side bands”)…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntermolecular energy transfer between lanthanide complexes in aqueous solution. 1. Transfer from terbium(III) to europium(III) complexes of pyridinecarboxylic acidsHarry G. BrittainCite this: Inorg. Chem. 1978, 17, 10, 2762–2766Publication Date (Print):October 1, 1978Public…
The morphology of even-even nylons has been reexamined in order to determine whether crystallographic factors can exert a dominant influence on the morphology and growth behavior of polymeric spherulites. Directional solidification of these polyamides produces long oriented spherulites at zone velocities below ∼5 μm/m…
Emerging chick limb-buds at first grow only in length, not width. The growth parameters of limb mesoderm--cell shapes, distributions, division patterns and cleavage orientations--are incompatible with representations of this tissue as an elongating solid composed of proliferating but immobile cells. We observe that sa…
The morphological diversity in even-even nylons described in Paper I was found to be the result of crystallographic factors related to the high extent of hydrogen bonding. Among all spherulitic species in these polyamides, only positive spherulites crystallize in accordance with the phenomenological theory of Keith an…
Abstract X‐Ray diffraction orientation measurements have been made on a wide range of films blown from three high‐density polyethylenes, to determine more precisely the conditions which lead to the high‐stress crystallization type of orientation. The most extensive measurements relate to films from Hostalen GM 9955F;…
Magnetic properties and electrical conductivity of the YFe 2 O 4 single crystal were investigated. It was disclosed that YFe 2 O 4 is an antiferromagnet whose Néel point is 205 K, and the spin lies parallel to the hexagonal c axis. Below T N , the magnetization parallel to the c axis was not proportional to the magnet…
Abstract After X‐ray excitation of PbWO 4 /PbMoO 4 mixed single crystals at liquid nitrogen temperature two types of MoO ‐electron centres are observed by means of EPR. For low molybdenum concentration axial S 4 ‐symmetry centres are present, whereas in the case of crystals with high molybdenum content the centres und…
The paramagnetic susceptibility of potassium-tetracyanoquinodimethane (K-TCNQ) as a function of temperature is analyzed. K-TCNQ is considered to be in the strong to intermediate correlation regime of the Hubbard model. The magnetic properties are described in terms of a Heisenberg exchange Hamiltonian between localize…
The rheological behavior of PVC emulsion resin plastisols was investigated in steady shear flow. The shear rate dependence of the plastisol viscosity was influenced by (1) Brownian diffusion, (2) partial dissolution of the suspended resin, and (3) particle‐particle interactions. Partial dissolution of polymer from the…