Photoconductive and optical properties of amorphous selenium
Electron and hole drift mobilities in photoconducting amorphous selenium
Woollam, J. A.↗
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Results for “Amorphization”
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Cell for measurement of basic electrical properties of amorphous and polycrystalline materials under pressure
Measuring instrument for amorphous and polycrystalline materials resistivity and Seebeck coefficient as function of temperature and pressure
Hadek, V.↗
Statistical mechanics of charged traps in an amorphous semiconductor
Coulomb interaction effect between charged traps in amorphous semiconductor, noting state density reduction at Fermi energy
Srinivasan, G.↗
High-resolution electron microscope observation of voids in amorphous Ge.
Electron micrographs have been obtained which clearly show the existence of a void network in amorphous Ge films formed at substrate temperatures of 25 and 150 C, and the absence of a void network in films formed at higher substrate temperatures of 200 and 250 C. These results correlate quite well with density measurements and predictions of void densities by indirect methods.
Donovan, T. M.↗
Search for anisotropic electrical properties in amorphous germanium.
Measurement of low-field and high-field resistivity in amorphous Ge in both the planar and transverse directions on the same samples, whose thickness ranged from 0.4 to 4 microns. No anisotropy was found, suggesting that the voids recently described by Galeener (1971) may not play a significant role in these transport processes.
Clark, A. H.↗
Reflection spectra of lunar dust grains with amorphous coatings.
The suggestion of Bibring et al. (1971) that the low albedos and reddish spectra observed in some lunar fines are caused by a low density amorphous substance which coats the fines is disputed. It is shown that these coatings have only a marginal effect on lunar reflectivity.
Hapke, B.↗
Residual conductivity in unannealed amorphous germanium.
An enhanced residual conductivity which persists long after cessation of illumination has been observed in amorphous germanium at 77 K. The effect may be thermally quenched by heating to 120 K, returning the sample to its initial condition.
Burke, T. J.↗
The chemisorption of H2O, HCOOH and CH3COOH on thin amorphous films of Al2O3
Investigation of the irreversible chemisorption of water, formic acid and acetic acid on a thin amorphous aluminum oxide film, using inelastic tunneling spectroscopy. All of the tunnel junctions employed were Al-Al2O3-Pb junctions with the adsorbate on the Al2O3 surface between the Al2O3 and the Pb electrode. The results obtained include the finding that all Al2O3 surfaces prepared by oxidation of Al have free CH groups present on them.
Lewis, B. F.↗
Thermomechanical behavior of amorphous tactic methacrylate polymers
Dynamic mechanical spectra of amorphous stereoregular poly(methyl methacrylate)s and poly(t-butyl methacrylate)s with assigned microtacticities are presented and discussed. An intermolecular argument is invoked to account for the higher glass transition temperature of syndiotactic vis a vis isotactic PMMA, in spite of the higher density of the latter at 30 C. An argument is presented to show that the ratio of glassy-region relaxation temperature to glass transition temperature is not only a measure of the degree of coupling of the beta and glass transition processes, but also of the degree to which intermolecular factors influence these processes. The greater extent of the low-temperature irreversibilities observed in the thermomechanical spectra of poly(t-butyl methacrylate)s is attributed to the brittle character induced by the bulky side groups which presumably weaken cohesive forces.
Kiran, E.↗
Amorphous ice on Saturnian rings and on icy satellites - Its formation, stability, and observability
Saturnian rings and icy satellites may be covered with amorphous rather than crystalline ice. Its likely source is water molecules sputtered by particles in the radiation belts, it may be stable, and its presence could be deduced from the rate of temperature drop in a shadow. Observation of this effect is, however, difficult, especially for the rings. A possible relation to the brightness anisotropy of ring A is pointed out.
Smoluchowski, R.↗
Plasma Deposition of Amorphous Silicon
Strongly adhering films of silicon are deposited directly on such materials as Pyrex and Vycor (or equivalent materials) and aluminum by a non-equilibrium plasma jet. Amorphous silicon films are formed by decomposition of silicon tetrachloride or trichlorosilane in the plasma. Plasma-jet technique can also be used to deposit an adherent silicon film on aluminum from silane and to dope such films with phosphorus. Ability to deposit silicon films on such readily available, inexpensive substrates could eventually lead to lower cost photovoltaic cells.
Calcote, H. F.↗
Production of bulk amorphous Pd/77.5/Si/16.5/Cu/6/ in a containerless low-gravity environment
Bulk amorphous spheres of Pd(77.5)Si(16.5)Cu(6), 1.5 mm in diameter, have been produced in free-fall containerless solidification. The experiments were conducted in the 32-m drop tube at Marshall Space Flight Center. The samples appear to be at least as stable (if not more so) as those produced during water quench.
Steinberg, J.↗
Amorphous ice and the behavior of cometary nuclei
The gradual heating of the nucleus of a comet approaching the sun may produce solid-state phase changes that are of particular importance for new comets, which may never have been heated before. The water-ice component of new comets is expected to be amorphous rather than crystalline, and its subsequent crystallization should produce gaseous tails and flareups at heliocentric distances about 70% greater than those expected for crystalline nuclei. These distances and the size of the flareups depend strongly on the inclination of the rotation axis and on the porosity of the ice. The effect should be weaker for older comets, but it may be related to the behavior of P/Schwassmann-Wachmann 1 if the layers of the crystallized ice peel off.
Smoluchowski, R.↗
Calculation of the critical cooling rate for amorphous Pd/77.5/Si/16.5/Cu/6/
The viscosity of the molten alloy Pd(77.5)Si(16.5)Cu(6) has been determined from 744 to 1000 C using an oscillating cup viscometer. Using these data (together with other pertinent physical data available for this alloy) in existing crystallization theory indicates that it could be made amorphous at cooling rates as low as 5-10 K/sec. This analysis assumes strictly homogeneous nucleation. Containerless solidification will be one good testing ground for the results of this analysis.
Steinberg, J.↗
The effect of grooves in amorphous substrates on the orientation of metal deposits. I - Carbon substrates
The graphoepitaxial alignment of vapor-deposited discrete metal crystallites is investigated in the nucleation and growth stages and during annealing by in situ UHV/TEM techniques. Various stages of nucleation, growth and coalescence of vapor deposits of Au, Ag, Pb, Sn, and Bi on amorphous, topographically structured C substrates are analyzed by advanced dark-field techniques to detect preferred local orientations. It is found that the topography-induced orientation of metal crystallites depends strongly on their mobility and their respective tendency to develop pronounced crystallographic shapes. Lowering of the average surface free energies and increasing the crystallographic surface energy anisotropies cause generally improved graphoepitaxial alignments.
Anton, R.↗
Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials
The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.
Miyoshi, K.↗
The ultraviolet absorber on Venus - Amorphous sulfur
It is pointed out that the identity of the chemical species responsible for the yellow coloration of the clouds of Venus and for the dark features which dapple the planet at ultraviolet wavelengths has long been a mystery. Independent pieces of evidence, discovered recently, suggest now that amorphous sulfur is the so-called UV absorber. A review of earlier ideas and controversies is presented, and attention is given to a new physical-chemical model of the Venus clouds which shows that sulfur should form there. A description is provided of physical characteristics of the cloud particles that, in comparison with model predictions, indicate the presence of sulfur. Optical data suggesting that elemental sulfur occurs in the clouds is discussed, and cloud morphological evidence for sulfur is considered.
Toon, O. B.↗
Laboratory studies of the condensation and properties of amorphous silicate smokes
The results of experiments intended for defining the vapor phase condensation of refractory materials are reported, and the usefulness of applying laboratory data to astrophysical conditions is assessed. The testing apparatus used produced Mg-SiO smokes by boiling powders in an evaporator. Critical temperatures for the onset of nucleation were measured for SiO-H2 and Mg-SiO-H2 systems. Spectroscopic examination of the grains produced were determined to be similar to the spectra obtained from both carbonaceous chondrites and several stratospheric micrometeorites. The experiments demonstrated that direct nucleation of refractory silicates from the vapor phase yielded amorphous, metastable particles, resembling more circumstellar grains than a chondritic matrix. It is suggested that the formation of SiO(x) may control nucleation in oxygen-rich stars.
Nuth, J. A.↗