Showing papers on "Phase (matter) published in 1969"
TL;DR: In this paper, the glass-liquid transition was exhibited thermally by both binary and ternary alloys, and the stability, ease of formation and glass transition temperature, Tg, of the glasses were all increased by the replacement of Pd with small concentrations of the noble metals.
416 citations
TL;DR: In this paper, the authors reviewed the available data from both alloy systems on the occurrence, the structure, the mechanism of formation, and the morphology of the phase and compared the effect of omega phase on the mechanical behaviour and on the superconducting properties.
Abstract: The omega phase is a metastable phase which forms in alloys of titanium and zirconium with most transition metals. In this paper the available data from both alloy systems on the occurrence, the structure, the mechanism of formation, and the morphology of the phase are reviewed and compared. The effect of omega phase on the mechanical behaviour and on the superconducting properties is then discussed. It is concluded that uncertainties still exist on the mechanism of the omega transformation during quenching and on the mechanism of the effect of omega on the mechanical properties.
371 citations
TL;DR: In this article, a theoretical technique to predict the thermal conductivity of heterogeneous solid mixtures has been developed, which does not require experimental data on the mean and standard deviations of the one dimensional porosity function describing the distribution of the discontinuous phase as is the case with Tsao's model.
337 citations
TL;DR: In this article, the metastable binary two-liquid region is defined, and a structural interpretation of the phase separation and the effects of small oxide additions on it is offered, and evidence for both classical and possible spinodal nucleation mechanisms during liquid segregation in this system is presented.
Abstract: Metastable glass-in-glass separation was observed on rapid quenching of A12O3-SiO2 melts containing from 10 to 50 mol% A12O3. Nucleation and subsequent crystallization of mullite within the high-alumina-dispersed glass phase may occur either during cooling from the melt or on reheating. The metastable binary two-liquid region is compositionally defined, and a structural interpretation of the phase separation and the effects of small oxide additions on it is offered. Evidence for both classical and possible spinodal nucleation mechanisms during liquid segregation in this system is presented.
230 citations
TL;DR: In this article, the zinc-rich solid phase in zinc-cadmium alloys has been studied after splat quenching to −196°C. Alloys containing from zero to 5 wt.% were examined by X-ray lattice parameter measurements.
227 citations
01 Jan 1969
211 citations
174 citations
01 Jan 1969
144 citations
Journal Article•
124 citations
TL;DR: In this paper, the growth and structural properties of thin-film polymorphs (amorphous, rhombohedral, and NaCl) of GeTe were investigated, and it was shown that the amorphous phase transforms very rapidly via random nucleation centers to the crystalline phase.
Abstract: As a part of our structural, optical, and electrical studies of amorphous versus crystalline GeTe films, this paper (Part I) reports on the growth and structural properties of the thin‐film polymorphs (amorphous, rhombohedral, and NaCl) of GeTe. When deposited above ∼130°C, the GeTe films are polycrystalline. Epitaxial or partially oriented growth of the rhombohedral phase is obtained on NaCl and mica at deposition temperatures ∼250°C. An electric field ∼4000 V/cm applied laterally on the substrate during deposition lowers the epitaxial temperature. At temperatures above 250°C, the high‐temperature NaCl structure grows epitaxially. Below a deposition temperature of ∼130°C, the films are amorphous. The amorphous phase transforms very rapidly via random nucleation centers to the crystalline phase at a well‐defined temperature of 145±3°C accompanied by the release of heat ∼1±0.2 kcal/mole (∼½kTm, where k is Boltzmann's constant and Tm is the melting point of GeTe). The transformation temperature increases li...
113 citations
TL;DR: In this paper, the external optical phonon modes in the ammonium and deuteroammonium halides have been studied through their intrinsic phase transitions in the temperature range 4 −290°K using infrared and Raman techniques.
Abstract: The external optical phonon modes in the ammonium and deuteroammonium halides have been studied through their intrinsic phase transitions in the temperature range 4–290°K using infrared and Raman techniques. The number of infrared and Raman active modes are in agreement with group theoretical predictions for the phases II, III, and IV, with the exception that no measurable anisotropic splitting of the out‐of‐phase mode in the tetragonal phase was observed in the infrared spectra. Whilst the frequency of the infrared reststrahlen modes showed only small discontinuities with temperature as the phase transitions were traversed, the phonon lifetimes of these modes showed distinct increases as the temperature was lowered through each phase transition. Estimates of the intrinsic ionic distortion present in NH4Cl and NH4Br are given. The compressibilities of NH4Cl and NH4Br at 4°K are calculated to be 3.86 × 10−12 and 6.79 × 10−12 cm2 dyn−1.
TL;DR: In this article, low-angle X-ray diffraction has been used to characterize the two lyotropic mesomorphic phases (neat phase and middle phase) which are formed in the dodecylhexaoxyethylene glycol monoether + water system.
Abstract: Low-angle X-ray diffraction has been used to characterize the two lyotropic mesomorphic phases (neat phase and middle phase) which are formed in the dodecylhexaoxyethylene glycol monoether + water system. The occurrence of these two anisotropic mesomorphic phases does not affect the behaviour of the thermodynamic excess functions which have been interpreted in terms of solute-water interactions. Careful measurements of water vapour pressure have been necessary to establish the limited extent of the two phase co-existence regions which separate homogeneous mesomorphic phase regions from isotropic solution in this system. Volume and heat capacity measurements as a function of temperature across mesomorphic phase boundaries have confirmed that the neat phase/isotropic solution and the middle phase/isotropic solution transformations are first-order phase transitions with very small volume and enthalpy changes.
TL;DR: The phase relations in a portion of the 1375° isotherm of the system Sr-Ti-O were determined in this paper, where the broad absorption maximum shown in these spectra is attributed to Ti3+.
Abstract: The phase relations in a portion of the 1375° isotherm of the system Sr-Ti-O were determined. The following ternary phases were identified: Sr2TiO4, Sr3Ti2O7, Sr4Ti3O10, SrTiO3(ss), and what is believed to be SrTi12O19. The experimental techniques used in the determination of tha phase diagram are somewhat uncommon and are discussed in depth. Diffuse reflectance spectra were obtained for several compositions of SrTiO3(ss). The broad absorption maximum shown in these spectra is attributed to Ti3+.
TL;DR: In this article, phase equilibria have been studied at 20°C in the systems potassium caprylate-decanol-water, potassium caprate-octanol, and potassium olcatedecanol, water.
TL;DR: The liquidus isotherms in the Ga rich comer of the Ga-Al-As phase diagram have been determined from 800 to 1100°C and at 1000°C the corresponding solidus equilibrium isotherm was obtained as discussed by the authors.
TL;DR: In this article, it was shown that if small amounts of ionizable lipids, either anionic or cationic, are incorporated to a non-ionizable lipid, the lamellar phase takes up very large amounts of water, and the water in excess stays as a separate phase (lipids devoid of net charges).
Abstract: The lamellar phase of the lipid-water systems, when studied as a function of the water content, displays properties that belong to one of the following classes, according to the nature of the lipid. (a) The lamellar phase takes up an almost indefinite amount of water intercalated between the lipid layers (lipids bearing net electrical charges). (b) The maximum amount of intercalated water is rather small, and the water in excess stays as a separate phase (lipids devoid of net charges). (c) The amount of water in the lamellar phase is limited: further addition of water induces a transition to another liquid-crystalline phase (soaps and detergents). It is shown here that if small amounts of ionizable lipids, either anionic or cationic, are incorporated to a non-ionizable lipid, the lamellar phase takes up very large amounts of water, EW in the lipids of class (a): this phenomenon is not observed if the added lipids are an equinormal mixture of anionic and cationic species. These experiments stress ...
TL;DR: In this article, a detailed thermodynamic study of the Fe 1−x O phase has been carried out in the temperature range 700°-1350°C using solid state electrochemical techniques.
TL;DR: Phases and phase relations in the tungsten-oxygen, molybdenum-oxide, tantalum-oxide, and niobium-oxide systems are reviewed in this article.
Abstract: Phases and phase relations in the tungsten-oxygen, molybdenum-oxygen, tantalum-oxygen, and niobium-oxygen systems are reviewed.
TL;DR: In this article, the authors used a solution of potassium oleate (KO) in D2O to obtain a smectic mesophase at room temperature (20°C).
Abstract: OF the three types of liquid crystalline phases, the smectic type can be formed in some compounds by either varying the temperature (thermotropic mesophases) or the solvent concentration (lyotropic mesophases). The system we used belongs to the latter type and consisted of a solution of potassium oleate (KO) in D2O. According to Luzzati et al.1, a concentration above 72 per cent by weight of KO in water yields a smectic mesophase at room temperature (20° C). In such a system the soap-like molecules can form a lamellar domain structure, and in these domains the direction of the molecular maximum and minimum polarizability perpendicular to the molecular chains is at random. This results in an ordered structure with an optical uniaxial character having its optical axis perpendicular to the lamellae.
TL;DR: X-ray K-absorption edge spectroscopy studies were performed on samples containing cupric ion supported on γ-alumina and it was found that a surface phase is present that resembles the structure of copper aluminate as discussed by the authors.
TL;DR: In this article, a single site-double site model was proposed to explain the Fe-Mg partitioning observed at different temperatures in the natural and experimental assemblages orthopyroxene-clino-pyroxene and orthopolyne-olivine, where the number of sites available within each phase and the exchange free energies between the intracrystalline sites, as well as an inter-phase exchange energy, temperature and composition were derived from the form of the partitioning curve.
TL;DR: In this article, a high pressure phase of MnTiO3 II was synthesized at high pressures and temperatures, which has the disordered ilmenite structure with the hexagonal lattice parameters of a = 5.2051 A, c = 13.699 A and V = 321.4 A.
TL;DR: The structure of the SiC phase in the system silicon carbide-boron carbide and carbon has been studied in the range 2200-2550°C as discussed by the authors and the solubility of boron in α-SiC at 2450-2500°C has been shown to be less than 0.2 wt.
TL;DR: In this paper, a study of the equilibrium shapes of small droplets of alloy liquid entrained within solid grains is presented, where factors affecting the attainment of equilibrium in such droplets are considered, and γ -plots are obtained for solid-liquid interfaces in the h. p. c. metals zinc and cadmium.
Abstract: Solid–liquid interfacial free energy is shown to be highly anisotropic in alloys of some h. c. p. metals and of two metalloids. This anisotropy is evaluated from a study of the equilibrium shapes of small droplets of alloy liquid entrained within solid grains. Factors affecting the attainment of equilibrium in such droplets are considered, and γ -plots are obtained for solid–liquid interfaces in the h. c. p. metals zinc and cadmium. In the magnesium alloys studied, spherical droplet shapes were observed, indicative of essentially isotropic interfacial energies. Droplet shapes were also analysed in some alloys of bismuth and of antimony. The results are related to current ideas of solid–liquid interfacial structure.
TL;DR: AgInTe 2, CuInS 2 and AgInS 3 transform at high pressures from the chalcopyrite structure to denser structures as mentioned in this paper, where the cations have octahedral or distorted co-ordination.
TL;DR: In this paper, the authors used differential thermal analysis and X-ray powder diffraction studies to determine the temperatures of phase transitions in each of these compounds, and observed a phase transition in CdSiP2 at 1098° C some 22° C below the melting point.
Abstract: ZnSnP2, ZnGeP2, ZnSiP2, CdGeP2 and CdSiP2 have been prepared in single or polycrystalline form by direct synthesis from the elements, combination of the group IV element with the II-V2 phosphide, vapour transport or solution growth. Differential thermal analysis and X-ray powder diffraction studies have been used to determine the temperatures of phase transitions in each of these compounds. Of particular interest is the observation of a phase transition in CdSiP2 at 1098° C some 22° C below the melting point. The thermal analysis studies of ZnSnP2 indicate a peak, the cause of which is uncertain, at 720° C which is well separated from the melting temperature of 930° C; further ZnSnP2 does not appear to be congruently melting and has a freezing point at 970° C. c/a ratios have been determined for all five compounds to 1 part in 2000.
TL;DR: In this paper, the properties of mixed hydroxides obtained by co-precipitation of FeCl2 or FeCl 2 with Na2SiO2 followed by ageing and purification were studied by X-ray diffraction, infra-red spectroscopy, and surface-area measurements.
Abstract: Summary
Several mixed hydroxides obtained by co-precipitation of FeCl2 or FeCl2 with Na2SiO2 followed by ageing and purification were studied by X-ray diffraction, infra-red spectroscopy, and surface-area measurements.
The compounds with molecular ratios SiO2/Fe2O3 ranging from 0·1 to 1·17 are essentially amorphous.
Silica, which is not to be considered as an integral part of the gel, is chemi-sorbed on the ferric or‘ferrosic’ phase.
The good agreement between IR, DTA, and surface-area measurements with increasing molecular ratios permits the distinction between two ranges of silica contents. In the first range, MR 0·1 range, silica polymerizes as a separate phase growing upon the‘ferrosic’ or‘ferric’ phase.