Showing papers on "Amorphous solid published in 1968"
TL;DR: In this paper, a rapid and reversible transition between a highly resistive and a conductive state effected by an electric field was described in various types of disordered materials, particularly amorphous semiconductors covering a wide range of compositions.
Abstract: We describe here a rapid and reversible transition between a highly resistive and a conductive state effected by an electric field which we have observed in various types of disordered materials, particularly amorphous semiconductors1,2 covering a wide range of compositions. These include oxide- and boron-based glasses and materials which contain the elements tellurium and/or arsenic combined with other elements such as those of groups III, IV, and VI.
2,997 citations
TL;DR: In this article, the analysis of the infrared absorption bands in amorphous Ge which correspond to transitions between the three branches of the valence band has shown that the wave functions are delocalized over distances of the order 102A.
2,470 citations
TL;DR: In this paper, the glass transition phenomenon was found near 135°K with the sudden change of the heat capacity amounting to 35 J/(mol°K) and the drastic crystallization with the exothermic effect which amounts to 1.64 kJ/mol was then followed at this temperature.
Abstract: By making use of the vapor-condensation type calorimeter, the heat capacity measurements of amorphous, cubic and hexagonal ices were made between 20°K and 250°K. The glass transition phenomenon was found near 135°K with the sudden change of the heat capacity amounting to 35 J/(mol°K). The drastic crystallization with the exothermic effect which amounts to 1.64 kJ/mol was then followed at this temperature. The transformation of the cubic crystal to the hexagonal one was confirmed to occur in the temperature region from 160 to 210°K and to proceed in two steps with the activation energies of 21.3 and 44.7 kJ/mol, respectively. The amount of the exothermic effect accompanying this transformation was found to be about 160 J/mol.
401 citations
TL;DR: In this article, a glass-liquid transition in the Au0.77Ge0.136Si0.094 alloy was reported and the transition was manifested thermally by an abrupt rise of 5.5 cal/g•atom·°K in specific heat, Cp, as the alloy was heated from 285° to 297°K. The apparent glass transition temperature was increased by 1°−3° by increasing the heating rate by a factor of 16.
Abstract: Gold‐rich (73–81 at.% Au) alloys of gold–germanium–silicon were “splat” cooled to an amorphous solid form. Thermal and rheological evidence of a glass‐liquid transition in the Au0.77Ge0.136Si0.094 alloy is reported. The transition was manifested thermally by an abrupt rise of 5.5 cal/g‐atom·°K in specific heat, Cp, as the alloy was heated from 285° to 297°K. Just above 297°K, Cp starts to fall with increasing T on a reasonable extrapolation of the high‐temperature Cp–T relation of the liquid alloy. This thermal behavior could be repeated on the same sample after it had been carried through the transition and chilled again. The apparent glass‐transition temperature was increased by 1°–3° by increasing the heating rate by a factor of 16. The viscosity η of the amorphous alloy increases rapidly with falling temperature from 0.9 × 109 P at 305°K to 1.4 × 1013 P at 285°K and is described by the equation: η = 0.52 exp [136 / (T − 241.3)] P. The steady isothermal viscosity is independent of stress over the range...
336 citations
TL;DR: In this paper, the thermal behavior of amorphous hydrated zirconium oxide and its coprecipitates with other oxides was studied and a relation with the high-temperature solid solution was established.
Abstract: The thermal behavior of amorphous hydrated zirconium oxide and its coprecipitates with other oxides was studied. Solid solution with a limit of solubility seems to exist in the amorphous coprecipitates. A relation with the high-temperature solid solution was established. The structure of the amorphous zirconia was studied by X-ray and neutron diffraction; a thin plate model related to the structure of tetragonal zirconia is proposed. Heating the precipitates in an oxygen-free atmosphere produced a black nonstoichiometric oxide and stabilization of the tetragonal form.
316 citations
TL;DR: In this article, it was shown that boron-nitride films of up to 6000Aa thick have been deposited on a variety of substrates at 600 °-1000 °C by a reaction between diborane and ammonia in hydrogen or inert carrier gas.
Abstract: Clear, vitreous films of boron nitride up to 6000Aa thick have been deposited on a variety of substrates at 600 °–1000 °C by a reaction between diborane and ammonia in hydrogen or inert carrier gas. Deposition rate may be readily adjusted to 50–1000 Aa/min. Most samples were made at either 600° or 800°, with some attendant variation in film properties. The 600° material contains some residual B‐H bonding. The film is essentially amorphous to electron diffraction. The refractive index is 1.7–1.8, the 1 MHz dielectric constant ~ 3 1/2, the dielectric strength , and the The band gap is 3.8 ev and the phonon temperature in the neighborhood of 2000°K. For semiconductor junction protection boron nitride has no advantage over silicon nitride. 600° deposition directly on Si has produced surface charges as low as , but there are room‐temperature drifts, and high‐field conduction also. BN deposited at 800° on Si is electrically similar to silicon nitride. Etching of BN film also presents the same problems as does silicon nitride. BN is not as good a barrier against sodium ion permeation. Attack by atmospheric moisture over a long period has varied from insignificant to extensive conversion to orthoboric acid.BN film on Si dopes the substrate with boron at temperatures above 900 °C in inert ambient. Uniform junction depths are produced. D‐C conductivity in 500–4000Aa films has been studied from room temperature to 270 °C. With fields ≥ 106 v/cm BN film shows stable, nonohmic conductivity which is independent of polarity. The 25 °C d‐c conduction is describable over at least seven decades of current by , , where , . The 600°‐deposited BN is the more conductive and can carry indefinitely. is linear, and the slope of the curve is in good agreement with the theoretical value for a Frenkel‐Poole conduction mechanism. Possible use of BN as a thin film varistor is discussed.
225 citations
TL;DR: In this article, the ion dose needed to form amorphous silicon as a function of the temperature of the silicon during bombardment was studied and it was shown that the bombarded regions exhibit various hues until eventually when they become completely amomorphous they appear "milky" due to the Rayleigh scattering of light.
Abstract: Thin films of single crystals of both n-type and p-type silicon contain disordered zones ∼ 50 A in diameter, discernible in the electron microscope after bombardment with ∼ 1013 Ne+ ions cm−2. As the dose increases these zones become more numerous until eventually (≳ 1014 ions cm−2) they overlap, creating a continuous surface layer which electron diffraction shows to be amorphous silicon. The individual zones disappear on annealing between 400 and 500°C, and at ∼630°C the amorphous layer recrystallizes epitaxially upon the underlying silicon, leaving an array of dislocation loops and dipoles. The bombarded regions exhibit various hues until eventually when they become completely amorphous they appear ‘milky’ due to the Rayleigh scattering of light. This appearance has been used as a convenient method to study the ion dose needed to form amorphous silicon as a function of the temperature of the silicon during bombardment.
202 citations
TL;DR: In this article, measurements were made of the dichroic ratios of a number of infrared bands for uniaxially deformed low-density polyethylene, and orientation functions were derived from the results on the conformationally sensitive amorphous bands at 1368/cm, 1352/ cm, 1303/cm and 1078/cm.
Abstract: : Measurements were made of the dichroic ratios of a number of infrared bands for uniaxially deformed low-density polyethylene. In order to characterize the amorphous orientation in the polymer, orientation functions were derived from the results on the conformationally sensitive amorphous bands at 1368/cm, 1352/cm, 1303/cm and 1078/cm. In conjunction with x-ray data and infrared dichroism data on the crystalline 1894/cm band, amorphous orientation functions were also derived from the 2016/cm band which appears to contain a normal amorphous component. The results indicate that extended trans sequences in the amorphous phase orient to a larger extent than isolated trans bonds flanked by gauche bonds. Results on the bands at 720 and 730/cm appear to show discrepancies when compared with the data from the other bands, and possible reasons for this apparent inconsistency are suggested. Amorphous orientation functions have also been derived from the CN stretching band at 2250/cm in a copolymer of ethylene and (2 weight percent) acrylonitrile. The bands at 2016/cm and 1894/cm were also analyzed for this copolymer, in addition to a C = O stretching band at 1740/cm due, apparently to thermal oxidation. Infrared dichroism results are also discussed for a copolymer of ethylene and (4.1 mole percent) methacrylic acid in which 70% of the -COOH groups are neutralized with sodium hydroxide. (Author)
141 citations
133 citations
TL;DR: In this paper, a theory was presented to explain the dependence of the superconducting transition temperature on the changes in the phonon frequency spectrum and electronic density of states which result from lattice disorder.
Abstract: A theory is presented to explain the dependence of the superconducting transition temperature ${T}_{c}$ on the changes in the phonon frequency spectrum and electronic density of states which result from lattice disorder. Numerical calculations of ${T}_{c}$ are presented for films composed of crystalline granules, for films composed of amorphous granules, and for homogeneous amorphous metals. The calculations are in good agreement with experimental values of ${T}_{c}$.
114 citations
TL;DR: In this paper, the same level and temperature dependence of electrical conductivity in the interval 60-300 °K was observed for amorphous silicon layers and germanium layers.
01 Oct 1968
TL;DR: In this article, the effects of aqueous sodium aluminosilicate gels to zeolite were studied by means of sorption, and the effect of changing caustic concentration could be interpreted in terms of mass transfer of some dissolved species from the bulk of the gel medium to the surface of the crystal.
Abstract: Conversion of aqueous sodium aluminosilicate gels to zeolite. A was measured by means of sorption. Effects of SiO 2 Al 2 O 2 in the starting gel, caustic concentration, and stirring rate were studied. At excess silica, the gels were found to be unsuitable for kinetics studies because they tended to produce an amorphous by-product and addition to zeolite A. At excess alumina, the effect of changing caustic concentration could be interpreted in terms of mass transfer of some dissolved species from the bulk of the gel medium to the surface of the crystal. From the consideration of the effect of stoichiometry on growth rate, the diffusing species apears to contain two negative distribution of crystals showed a predominance of small particles. All observations are consistent with a diffusion mechanism of crystal growth.
TL;DR: In this article, the free volume concept is used to describe the temperature and the pressure dependence of the relaxation time for the micro-Brownian motion of amorphous chain segments, while the β relaxation due to local-mode motion of the frozen main chain shows weak dependence on temperature and pressure.
Abstract: The dielectric properties and the d. c. conductivity of poly(vinyl chloride), poly(vinyl acetate), polychlorotrifluoroethylene, and poly(ethylene terephthalate) were measured at temperatures above and below the glass transition temperature and at various pressures up to 3000 atm. The α relaxation associated with the micro-Brownian motion of amorphous chain segments depends strongly upon temperatures and pressure, while the β relaxation due to local-mode motion of the frozen main chain shows weak dependence on temperature and pressure. It is found that the free volume concept is valid for description of the temperature and the pressure dependence of the relaxation time for the α process. Activation energy and volume for both relaxation processes are determined from the experimental data. A simple relation between activation energy and volume for the α relaxation and pressure dependence of the glass transition temperature are derived. Temperature and pressure dependence of the d. c. conductivity in the rubbery state are notably different from those in the glassy state. Ionic conduction appears to be dominant in these polymers.
TL;DR: In this paper, a modified three-temperaturezone technique was used to vacuum-deposite GaAs onto GaAs and Ge single-crystal substrates, and the film properties were investigated by reflection electron diffraction (RED) and also optically.
Abstract: Epitaxial films of GaAs have been vacuum‐deposited onto GaAs and Ge single‐crystal substrates by a modified three‐temperature‐zone technique. The film properties have been investigated by reflection electron diffraction (RED) and also optically. At a deposition temperature of 375°C the films possess [100] fiber textures; below 375°C, the film properties follow those deposited on amorphous substrates. At 400°C the films become epitaxial with twinning on all (111) planes. Between 425° and 450°C, the films are highly ordered, twin free, on the b faces of GaAs and on Ge; in the same temperature range, thick films (> 10 000 A) and films deposited on a faces of GaAs exhibit extra reflections in RED and departures from the expected optical behavior. Films deposited above 450°C, under conditions for which excess Ga may exist, grow in an hcp modification; the reflectivity of these films agrees with bulk zinc blende GaAs.
Patent•
IBM1
TL;DR: A method of producing orIENTED CRYSTAL OVERGROWTH on a MONOCRYSTALLINE or AMORPHOUS SUBSTRATE wherein a FILM of Crayfish MATERIAL is DEPOSITED on the substrate and regions of the FILM are SELECTIVELY BOMBARDED with a LASER BEAM PULSE.
Abstract: A METHOD OF PRODUCING ORIENTED CRYSTAL OVERGROWTH ON A MONOCRYSTALLINE OR AMORPHOUS SUBSTRATE WHEREIN A FILM OF CRYSTALLINE MATERIAL IS DEPOSITED ON THE SUBSTRATE AND REGIONS OF THE FILM ARE SELECTIVELY BOMBARDED WITH A LASER BEAM PULSE.
TL;DR: In this article, the dielectric properties of four methacrylate polymers (methyl, ethyl, n-butyl and n-octyl) were studied in the frequency range 0.0001 cps-300 kcps at temperatures above and below the glass transition temperature and at various pressures up to 2500 atm.
Abstract: Dielectric properties of four methacrylate polymers (methyl, ethyl, n-butyl and n-octyl) were studied in the frequency range 0.0001 cps–300 kcps at temperatures above and below the glass transition temperature and at various pressures up to 2500 atm. At temperatures well above Tg a single relaxation peak (α′ peak) was observed in the case of the higher n-alkyl methacrylates. However, this peak was split into two peaks, α and β, with decrease in temperature or increase in pressure. The molecular motions corresponding to the α and the β relaxation processes are the micro-Brownian motions of amorphous main chains and of flexible side chains, respectively. From the temperature and the pressure dependence of the average dielectric relaxation time of these polymers the single relaxation process (the α′ process) was attributed to the micro-Brownian motion of the main chain coupled with that of the side chain. The effects of temperature and pressure on the d.c. conductivity of these polymers were also studied.
TL;DR: In this paper, an inverse power-law approximation for the interaction potential between a fast-moving projectile and the atoms of an amorphous target into which it penetrates was proposed.
Abstract: By using an inverse power-law approximation for the interaction potential between a fast-moving projectile and the atoms of an amorphous target into which it penetrates, it is possible to calculate...
TL;DR: In this paper, an adiabatic Nernst-type calorimeter with a cell for condensing a sample vapor as an amorphous state was constructed, and the heat capacities of the glassy, supercooled liquid, and crystalline states of methanol were measured from 20°K to 120°K.
Abstract: An adiabatic Nernst-Type calorimeter with a cell for condensing a sample vapor as an amorphous state was constructed. By making use of this calorimeter, the heat capacities of the glassy, supercooled liquid, and crystalline states of methanol were measured from 20°K to 120°K. It was found that the state of methanol deposited on the chilled substrate at about 95°K from its vapor state shows a glass transition phenomenon at about 103°K accompanied with the sudden increase of heat capacity, ΔCP, amounting to 26 J/(mol°K). The drastic crystallization with the exothermic effect coming to 1.54 kJ/mol was observed near 105°K. The residual entropy for the glassy methanol was found to be 7.07 J/(mol°K). Based on these results it seems very plausible to propose that any non-crystalline solid deposited on the chilled substrate from the vapor state will show the glass transition phenomenon.
TL;DR: In this paper, a combination of low-energy electron diffraction and retarding potential measurements was employed to study gaseous adsorption on atomically clean (001) and (110) Mo single crystal surfaces.
TL;DR: In this article, the authors used the technique of vapor deposition to obtain homogeneous glass films of several BaO-SiO2 compositions in the region of the metastable miscibility gap.
Abstract: : The technique of vapor deposition was used to obtain homogeneous glass films of several BaO-SiO2 compositions in the region of the metastable miscibility gap. The films were electron beam heated in the electron microscope and the process of phase separation was observed. At low BaO contents, the separation was characterized by the appearance of discrete, amorphous, second-phase particles. For compositions near the center of the miscibility gap, the separation process resulted in two continuously interconnected phases similar to those found in the corresponding bulk glasses. In the thinnest of these films the process was observed to proceed by the coalescence of isolated particles into the interconnected second-phase submicrostructure. At high BaO contents, rapid crystallization of the films prevented study of the separation process. Two processes which could lead to the coalescence of discrete second-phase particles into an interconnected submicrostructure are discussed. It is suggested that coalescence may take place when either of these processes results in the particles approaching within some small distance of each other. The results indicate that observations of final phase-separated morphologies are inadequate for specifying the processes by which those morphologies arose. (Author)
TL;DR: In this paper, experimental results on the behavior of discontinuous metal films on amorphous substrates of carbon and silicon monoxide are extended and reviewed in terms of possible mechanisms to account for the experimental behavior.
Abstract: Experimental results on the behavior of discontinuous metal films on amorphous substrates of carbon and silicon monoxide are extended and reviewed. These results are discussed in terms of possible mechanisms to account for the experimental behavior. The mechanism of island motion with subsequent coalescence is selected, for it agrees best with the observed results. This mechanism is used as a basis for a calculation in which the behavior of the islands is treated by statistical methods. Solutions predict the time and temperature dependence for the mean radius and dispersion of the island distribution. Comparison to experiment is favorable and yields a quantity which corresponds to the binding energy of gold islands to carbon or to silicon monoxide substrates. For the gold‐carbon case, the binding energy is 1.29±0.04 eV, while the gold‐silicon monoxide case yields 1.52±0.23 eV.
TL;DR: In this paper, an optical density of states in amorphous Ge derived from photoemission measurements was derived, and it was shown that the maximum in the valence-band density was shifted 1.5 eV to higher energy with respect to the crystalline density.
Abstract: An optical density of states in amorphous Ge derived from photoemission measurements shows that the maximum in the valence-band density of states is shifted 1.5 eV to higher energy with respect to the crystalline density of states. No structure is observed in the conduction-band density of states for the amorphous material, whereas strong structure is present in the crysalline density of states. Changes observed in the optical properties of Ge on disordering can be explained using these results.
TL;DR: Sputtering efficiency is defined in this article as the fraction of bombarding ion energy leaving a crystal via sputtering and backscattering, and is defined for the case of perpendicular incidence on a crystal.
Abstract: Sputtering efficiency is denned as the fraction of bombarding ion energy leaving a crystal via sputtering and backscattering. This quantity is calculated for the case of perpendicular incidence on ...
TL;DR: The radial distribution function for an electrodeposited amorphous nickel-phosphorus (149 wt% P) alloy has been determined in this article, and the atomic distribution was found to be similar to that in a liquid metal.
Abstract: The radial distribution function for an electrodeposited amorphous nickel‐phosphorus (149 wt% P) alloy has been determined The atomic distribution was found to be similar to that in a liquid metal, and more disordered than that observed in an amorphous nickel‐phosphorus alloy produced by chemical deposition Two transformations (both exothermic) were observed in this alloy; the first of which occurred at 280°±2°C with an energy of 185 cal/g (960 cal/g atom) and the second at 410°±5°C with an energy of 60 cal/g (310 cal/g atom) As deposited, the alloy exhibits only a very weak small‐angle x‐ray scattering, apparently not due to the presence of the phosphorus
TL;DR: In this paper, it was shown that the amorphous structure is characterized by rotations about the valence bond directions, and these rotations are restricted to two "rotationisomers" of a two-tetrahedra “molecule”: the trans-configuration and the cisconfiguration.
TL;DR: In this article, the properties of amorphous Ge and Si are reviewed: short-range order, electrical conductivity, Hall effect, thermoelectric power, rectification and injection in junctions with single crystals, photoconductivity and non-ohmicity in high electric fields.
TL;DR: In this paper, a P, v, T equation of state for polyethylene of arbitrary crystallinity is constructed by constructing, separately, equations of state, for purely crystalline and purely amorphous polyethylenes and then combining the two according to the degree of crystallinity.
Abstract: A P, v, T equation of state is theoretically constructed for polyethylene of arbitrary crystallinity. This is done by constructing, separately, equations of state for purely crystalline and purely amorphous polyethylene and then combining the two according to the degree of crystallinity. Very little experimental data is used in constructing either the crystalline or amorphous equations of state. Comparisons of the predicted P, v, T relations with experiment are quite favorable.
TL;DR: In this article, the structure of vanadium dioxide films was determined by x-ray diffraction, reflection electron diffraction and electron microscopy of carbon replicas of the film surfaces.
Abstract: Reactively sputtered vanadium dioxide films have been analyzed to determine the relation between their electrical and structural properties. The structure of the thin films was determined by x-ray diffraction, reflection electron diffraction, and electron microscopy of carbon replicas of the film surfaces. The various substrates which were evaluated for thin film VO2 deposition were amorphous glass, glazed ceramic, and single-crystal sapphire and rutile. Electrical conductivity measurements were made to correlate film perfection with the conductivity ratio between the semiconducting and metallic states. Films deposited on amorphous substrates such as glass and glazed ceramic are polycrystalline in structure with small grain size. Conductivity ratios of approximately 102 were observed with a very broad transition region centered at 68 °C. These films, in addition to VO2, exhibit an extra x-ray line at d = 2.25, tentatively identified as VO1.87. On sapphire substrates, highly textured films were obtained wh...
TL;DR: In this article, the Ramaman spectra for CER-VIT, fused silica, ULE glass, and a Corning heat-absorbing glass are presented.
Abstract: Raman spectra, with polarizations, are presented for CER–VIT, fused silica, ULE glass, and a Corning heat-absorbing glass. The spectra of the three amorphous glasses are quite similar. The spectra of these glasses indicate a small scattering unit of low symmetry, perhaps a distorted SiO4 tetrahedron. The spectrum of CER–VIT differs from that of crystalline quartz and from those of the amorphous glasses.