Cooling solid state

Figure 1 XRD analysis of Pf -(Cys)/nAu + reaction. 0.5 - 2.0 eq. of added to 1.0 eq. of Pt -(Cys), precipitated, and scanned on a Scintag Xj 0/0 automated powder diffractometer with a Cu target, a peltier-cooled solid-state detector, and zero background Si (510) sample support. Both line sets of standard diffractions are included for fee Pt (red lines) and Au (blue lines). Reaction sc heme for metathesis/transmetallation reaction between Pt -(Cys)/Au...

Figure 3.11. The schematic of the goniostat of a Scintag XDS2000 powder diffractometer with the horizontal axis and synchronized rotations of both the source and detector arms. This goniometer is equipped with a liquid nitrogen-cooled solid-state detector, which enables monochromatization of the diffracted beam by selecting a narrow energy window, thus registering only characteristic energy photons. R - is the radius of the goniometer.

D) Sealed x-ray tube source, Bragg-Brentano goniometer, radius 250 mm, cooled solid-state detector. 

In the formation of carbonaceous mesophase by thermolysis (pyrolysis) of isotropic molten pitch, the development of a liquid-crystalline phase is accompanied by simultaneous aromatic polymerization reactions. The reactivity o/pitch with increasing heat treatment temperature and its thermosetting nature are responsible for the lack of a true reversible thermotropic phase transition for the bulk mesophase in most pitches. Due to its glass-like nature most of the liquid-crystalline characteristics are retained in the super-cooled solid state. 

In sintering, the green compact is placed on a wide-mesh belt and slowly moves through a controlled atmosphere furnace (Fig. 3). The parts are heated to below the melting point of the base metal, held at the sintering temperature, and cooled. Basically a solid-state process, sintering transforms mechanical bonds, ie, contact points, between the powder particles in the compact into metallurgical bonds which provide the primary functional properties of the part. 

The austenite phase which can contain up to 1.7 wt% of carbon decomposes on cooling to yield a much more dilute solution of carbon in a-iroii (b.c.c), Fenite , together with cementite, again rather diaii the stable carbon phase, at temperatures below a solid state eutectoid at 1013 K (Figure 6.3). 

Phase transformations in the solid state (like those in iron), too, have latent heats. They may be small, but with sensitive equipment for measuring cooling curves or heating curves, they are easily detected. 

Fig. 4.6. Cross section of the front end of an SSD (solid-state detector), here Gold contact with a grooved Si(Li) crystal. Crystal and preamplifier are connected with a cooled copper rod and shielded by a case with an end cap and Be window [4.21, 4.29].

The energy-dispersive (EDX) solid state detector (SSD, Figs 4.6, 4.7) is made of lithium-drifted Si crystal (Si(Li)). Between a thin p-type and an n-type layer lies a high-resistivity Si crystal of centimeter dimensions. The front and end planes of the crystal are coated with Au and serve as electrodes. The crystal, cooled to 77 K by liquid nitrogen, represents a p-i-n diode (Fig. 4.7). An incident X-ray photon with... 

Freezing Point - Defined as the temperature at which a liquid changes from liquid to solid state. For example, liquid water changes to solid ice at 0 °C (32 °F). Some liquids solidify very slowly even when cooled below their freezing point. When liquids are not pure, their freezing points are lowered slightly. 

A number of other thermodynamic properties of adamantane and diamantane in different phases are reported by Kabo et al. [5]. They include (1) standard molar thermodynamic functions for adamantane in the ideal gas state as calculated by statistical thermodynamics methods and (2) temperature dependence of the heat capacities of adamantane in the condensed state between 340 and 600 K as measured by a scanning calorimeter and reported here in Fig. 8. According to this figure, liquid adamantane converts to a solid plastic with simple cubic crystal structure upon freezing. After further cooling it moves into another solid state, an fee crystalline phase. 

However, if we set the furnace temperature just slightly greater than T2, we would obtain a reaction limited to that of A - B, and thus could identily the intermediate reaction product, B. This technique is called isothermal thermogravimetry. Thus, we can follow a solid state reaction by first surveying via d3mamic TGA. If there are any intermediate products, we can isolate each in turn, and after cooling (assmning each is stable at room temperature) cam identify it by x-ray analysis. Note that we can obtain an assay easily ... 

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