Solid-liquid-vapor

Trentler T J ef a/1995 Solution-liquid-solid growth of orystalline lll-V semioonduotors an analogy to vapor-liquid-solid growth Science 270 1791... 

Is the stream single-phase (gas or vapor) or multiphase (vapor-liquid or vapor-liquid-solid) ... 

The critical point is unique for (vapor + liquid) equilibrium. That is, no equivalent point has been found for (vapor + solid) or (liquid + solid) equilibria. There is no reason to suspect that any amount of pressure would eventually cause a solid and liquid (or a solid and gas) to have the same //m, Sm, and t/m. with an infinite o and at that point. mC02 was chosen for Figure 8.1 because of the very high vapor pressure at the (vapor + liquid + solid) triple point. In fact, it probably has the highest triple point pressure of any known substance. As a result, one can show on an undistorted graph both the triple point and the critical point. For most substances, the triple point is at so low a pressure that it becomes buried in the temperature axis on a graph with a pressure axis scaled to include the critical point. 

The most important nanomaterial synthesis methods include nanolithography techniques, template-directed syntheses, vapor-phase methods, vapor-liquid-solid (VLS) methods, solution-liquid-solid (SLS) approaches, sol-gel processes, micelle, vapor deposition, solvothermal methods, and pyrolysis methods [1, 2]. For many of these procedures, the control of size and shape, the flexibility in the materials that can be synthesized, and the potential for scaling up, are the main limitations. In general, the understanding of the growth mechanism of any as-... 

Figure 6. Vapor-liquid-solid (plastic crystal) phase diagram of adamantane. The phase transition from plastic crystal to rigid crystal phase occurs at 208.6K (l/T = 0.004794K ). This diagram is based on the data of Table II.

The first major hazard in process plant is fire, which is usually regarded as having a disaster potential lower than both explosion and toxic release2. However, fire is still a major hazard and can under the worst conditions approach explosion in its disaster potential. Fire requires a combustible material (gas or vapor, liquid, solid, solid in the form of a dust dispersed in a gas), an oxidant (usually oxygen in air) and usually, but not always, a source of ignition. Consider now the important factors in assessing fire as a hazard. 

Figure 10.2. Vapor-liquid-solid growth of semiconductor nanowires.

Trentler, T. J. Hickman, K. M. Goel, S. C. Viano, A. M. Gibbons, P. C. Buhro, W. M. 1995. Solution-liquid-solid growth of crystalling III-V semiconductors—an analogy to vapor-liquid-solid growth. Science 270 1791-1794. 

Apparently, the direct transition from vapor to solid is less common than the double transition vapor — liquid — solid, see, e.g., Refs.158-160). From the rate of solidification of metal droplets (average diameter near 0.005 cm) at temperatures 60° to 370° below their normal melting points, the 7sl was concluded158) to be, for instance, 24 for mercury, 54 for tin, and 177 erg/cm2 for copper. For this calculation it was necessary to assume that each crystal nucleus was a perfect sphere embedded in the melt droplet the improbability of this model was emphasized above. 

Predicting Vapor-Liquid-Solid Equilibria in Multicomponent Aqueous Solutions of Electrolytes... 

It is evident from the title of this symposium that as a result of recent requirements to reduce pollutant levels in process wastewater streams, improved techniques for predicting the vapor-liquid-solid equilibria of multicomponent aqueous solutions of strong and/or weak electrolytes are needed. In addition to the thermodynamic models necessary for such predictions, tools have to be developed so that the engineer or scientist can use these thermodynamic models correctly and with relative ease. 

To illustrate the power of the general purpose tools we have developed, I will describe the application of our software to two systems. First, since most of the participants in this session are using it as an example, and because it is important, I will give some of our results for the NH3-CO2-H2O system. Secondly, to illustrate the prediction of combined vapor-liquid-solid... 

In developing the thermodynamic framework for ECES, we attempted to synthesize computer software that would correctly predict the vapor-liquid-solid equilibria over a wide range of conditions for multicomponent systems. To do this we needed a good basis which would make evident to the user the chemical and ionic equilibria present in aqueous systems. We chose as our cornerstone the law of mass action which simply stated says "The product of the activities of the reaction products, each raised to the power indicated by its numerical coefficient, divided by the product of the activities of the reactants, each raised to a corresponding power, is a constant at a given temperature. ... 

Despite these apparent weaknesses, within the context of a general purpose system for predicting the vapor-liquid-solid equilibria of multicomponent aqueous solutions, GCES as a tool succeeds remarkably well as will be seen in a few illustrations after the following description of the software structure and use. 

Using the ECES System for Vapor-Liquid-Solid Equilibria (FeCl -HCl-H90)... 

R. S. Wagner, and W. C. Ellis, Vapor—liquid—solid mechanism of single crystal growtti. Appl. Phys. 

M. K. Sunkara, S. Sharma, R. Miranda, G. Lian, and E. C. Dickey, Bulk synthesis of silicon nanowires using a low-temperature vapor-liquid-solid method, Appl. Phys. Lett. 19, 1546-1548... 

Almost defect-free GaSb whiskers are formed by the so-called VLS process vapor-liquid-solid) that was introduced by Ellis and Wagner [32]. Initially formed Ga droplets on the substrate, formed by pyrolysis of t-BusGa which is present in the gas phase to some extent due to the dissociation of the starting t-BusGa - SbRs adduct, catalyze the decomposition of t-BusGa and SbRs and... 

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