Sublimation temperature

Dyes for WORM-Disks. Regarding their memory layer, dye-in-polymer systems show advantages over metal layers in their higher stabiHty, lower toxicity, lower heat conductivity, lower melting and sublimation temperature, and simpler manufacturing technique (substrate coating by sublimation or spincoating). 

Table 1 Hsts the properties of several semiconductors relevant to device design and epitaxy. The properties are appropriate to the 2incblende crystal stmcture in those cases where hexagonal polytypes exist, ie, ZnS and ZnSe. This first group of crystal parameters appHes to the growth of epitaxial heterostmctures the cubic lattice constant, a the elastic constants, congment sublimation temperature, T. Eor growth of defect-free...

The maximum congment sublimation temperature, corresponds to the temperature above which the anion evaporation rate exceeds the cation evaporation rate from a (001) crystal surface in a vacuum. 

Along with the lattice constant the congment sublimation temperature is a useful guide as to which pseudobinary alloys, ( 0) (BC) or... 

Melting and sublimation temperatures are generally based on those given in Ref. 15. 

Vapor pressure data for soHd carbon dioxide are given in Table 2 (10). The sublimation temperature of soHd carbon dioxide, 194.5 K at 101 kPa (1 atm), was selected as one of the secondary fixed points for the International Temperature Scale of 1948. 

The equilibrium pressure when (solid + vapor) equilibrium occurs is known as the sublimation pressure, (The sublimation temperature is the temperature at which the vapor pressure of the solid equals the pressure of the atmosphere.) A norma) sublimation temperature is the temperature at which the sublimation pressure equals one atmosphere (0.101325 MPa). Two solid phases can be in equilibrium at a transition temperature (solid + solid) equilibrium, and (liquid + liquid) equilibrium occurs when two liquids are mixed that are not miscible and separate into two phases. Again, "normal" refers to the condition of one atmosphere (0.101325 MPa) pressure. Thus, the normal transition temperature is the transition temperature when the pressure is one atmosphere (0.101325 MPa) and at the normal (liquid + liquid) solubility condition, the composition of the liquid phases are those that are in equilibrium at an external pressure of one atmosphere (0.101325 MPa). 

Solution (a) The pressurep = 0.101 MPa is less than the vapor pressure of CCF at the triple point so that solid goes directly to gas. A pressure of 0.101 MPa is 1 atm. The temperature where the solid will sublime to form gas at p - 1 atm is the normal sublimation temperature of 194.70 K.q... 

Actually, the temperature does not change as heat is added to change the solid to gas at the equilibrium sublimation temperature. Hence, the heat capacity becomes infinite at this temperature, and the dotted line shown in Figure 8.12 should extend vertically to infinity. The compressibility and coefficient of expansion would show a similar behavior. 

B Carbon dioxide is liquid at 60 atm and 25° C. When it is released into a room at 1 atm and 25° C, as the pressure lowers, the system reaches the liquid-vapor boundary, at which pressure the liquid is changed to vapor. The vaporization absorbs sufficient heat to cool the C02 to below its sublimation temperature at 1 atm. As a result, fine particles of solid C02 snow are produced. 

Degree of furnace- temperature set- point dxjve material sublimation temperature. 

The above reaction shows that the oxychloride decomposes at the sublimation temperature into the volatile tetrachloride and the nonvolatile oxide. Reduction starts as soon as the chloride vapour contacts the molten magnesium, and this exothermic reaction raises the temperature of the reaction mixture. The temperature of the reduction crucible is maintained in the range of 800 to 875 °C. The process is carefully controlled by matching the sublimation rate of zirconium tetrachloride with the reduction rate. The conclusion of the reduction is indicated by a fall in temperature and pressure. 

Solid ammonium carbamate is stored in a compartment above the proportioning unit. The sublimation of solid blocks of ammonium carbamate is achieved by a local heater (spray or electrically warmed oil circulation). The sublimation temperature of ammonium carbamate is 60°C. The process being reversible, solid ammonium carbamate may be formed back for temperature lower than 60°C. 

These results clearly demonstrate the high potential of the single source precursor concept. In particular, the low deposition temperatures necessary for the stibinoalanes and the low carbon contents of the resulting material films are very promising results. However, the low vapor pressure of the heterocycles, which require sublimation temperatures about 130 °C, are a major drawback. 

The amount of energy necessary for the sublimation depends on the sublimation temperature, but between -10 °C and -40 °C the energy varies by less than 2 %. Furthermore energy is consumed to heat the vapor during the transport through the already dried prod-... 

If the freeze drying conditions are extreme namely small solid content, low sublimation temperature, e. g. ... 

The temperature at which a phase transition occurs is dependent on pressure (Figure 7). At atmospheric pressure (1 atm) the solid-to-liquid phase transition occurs at 0 °C and the liquid-to-gas phase transition occurs at 100 °C. If we increase the pressure, say to 100 atm, the solid-to-liquid phase transition occurs at a temperature slightly less than 0°C (—0.74°C) however, the liquid-to-gas phase transition occurs at a much greater temperature (312°C). If we decrease the pressure, say to 0.1 atm, the solid-to-liquid phase transition occurs at a temperature slightly greater than 0°C (0.004 °C) and the liquid-to-gas phase transition occurs at a lower temperature (46 °C). If we decrease the pressure further to below the triple point, there is no solid-to-liquid phase transition rather, the solid-to-gas phase transition occurs directly. At a pressure of 0.001 atm, the sublimation temperature is — 20.16°C. 

A volatile substance is one whose boiling point, or sublimation temperature, is such that it exists to a significant extent in the gaseous phase under ambient conditions. The following are volatile hydrocarbons that are commonly encountered ... 

For our part we have observed the production of Mo-nanoparticles starting from [Mo(CO)i5] directly on a carbon film deposited on a TEM grid at various sublimation temperatures and thus at various partial pressures of [Mo(CO)6] in the carrier... 

Table 9.5 Density and size of molybdenum particles deposited from [Mo(CO)6] at three different sublimation temperatures. (From Reference [13].)...

During combustion, strontium nitrate and strontium carbonate decompose to give strontium oxide whose spectrum is seen as a pinkish flame due to the positions of the emission bands and to the difficulty in obtaining a high concentration of strontium oxide vapour in the flame. This difficulty is due to the high sublimation temperature of the oxide which is in excess of 2500 °C. 

For example, the dye. Solvent Yellow 14 has a sublimation temperature of about 125 °C whereas its melting point is 134 °C. The reaction temperature of the chlorate-lactose composition is in excess of 500 °C, which often results in chemical reactions bringing about the destruction of a large proportion of the dye. For example, strong reduction brings about cleavage as shown in Scheme 10.2, whereas pyrolysis leads to decomposition as in Scheme 10.3 Hence, a typical orange smoke composition contains up to 50% of dyestuff in order to offset losses due to the above reactions. 

Occurs in two forms, alpha form—a colorless amorphous powder, and beta form—a reddish-brown crystal density 6.95 g/cm (alpha form) and 8.15 g/cm (beta form) decomposes on rapid heating at 900°C sublimation temperature 1,559°C insoluble in water and alkalis dissolves in mineral acids. 

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