Reduced phases

Phases Formed in Pordand Cements. Most clinker compounds take up small amounts of other components to form soHd solutions (11). Best known of these phases is the C S soHd solution called aHte. Phases that may occur Hi Portiand cement clinker are given Hi Table 1. In addition, a variety of minor phases may occur Hi Portiand cement clinker when certain minor elements are present Hi quantities above that which can be dissolved Hi other phases. Under reducHig conditions Hi the kiln, reduced phases, such as ferrous oxide [1345-25-17, FeO, and calcium sulfide [20548-54-3] CaS, maybe formed. 

The ability of B, C and N as well as H to stabilize many of these reduced phases is at once a major preparative problem " and also a source of an... 

By contrast, ZrCl and ZrBr, also prepared by the high temperature reduction of ZrX4 with the metal, appear to be genuine binaiy halides. They are comprised of hep double layers of metal atoms surrounded by layers of halide ions, leading to metallic conduction in the plane of the layers, and they are thermally more stable than the less reduced phases. Zrl has not been obtained, possibly because of the large size of the iodide ion, and, less surprisingly, attempts to prepare reduced fluorides have been unsuccessful. 

Isopropanol is a colorless liquid having a pleasant odor it is soluble in water. It is more soluble in hydrocarbon liquids than methanol or ethanol. For this reason, small amounts of isopropanol may be mixed with methanol-gasoline blends used as motor fuels to reduce phase-separation problems. ... 

Aluminum forms a complete series of AlYX compounds (Y = S, Se, Te X = Cl, Br, I). Furthermore, a number of compounds with Se(IV) and Te(IV) are known, such as TeClJ AlClj (197) and SeClJ AICI4 (364), which are not considered here. A borderline case consists in the reduced phases found in the systems (TeCl4-(-4AlCl3)-Te and (SeCl4 + 4A1C13)-Se (88), e.g., Te (AlCl4-)2 (89), Te + (Al Clf)2 (89), Te + (AlCli-) (88), Se5+ (AlClj) (88), and Se + (AlClj)2 (87), which contain cyclic pol3dellurium and polyselenium cations. For a detailed review of homopolyatomic ions of the posttransition elements, see (86). 

This highhght examines several new hybrid layered structures in the hetero-metallic perrhenate and vanadate families, whereby the late transition-metals are incorporated and their roles probed in the structures of layered solids. From these two families, new structural principles have emerged that not only help us understand key stractural features and correcdy forecast new compositions, but equally, have yielded many surprises (chirality, reduced phases) that show some of the most exciting chemistry is still waiting to be discovered or even imagined ... 

In a reduced-phase diagram for a two-component system, T = 2 for a single phase and an area is the appropriate representation. F = 1 for two phases in equilibrium, and a curve that relates the two variables is the appropriate representation. As the composition of the two phases generally is different, two conjugate curves are required. 

Other two-component systems may exhibit either limited solubility or complete insolubility in the solid state. An example with limited solubUity is the silver-copper system, of which the reduced-phase diagram is shown in Figure 13.5. Region L represents a liquid phase, with F = 2, and S and 5s represent solid-solution phases rich in Ag and Cu, respectively, so they are properly called one-phase areas. S2 is a two-phase region, with F= 1, and the curves AB and DF represent the compositions of the two solid-solution phases that are in equilibrium at any... 

Figure 14.3. The reduced phase diagram at constant pressure for the two-component system diopside-anoithite, in which the pure sohds are completely insoluble in each other. Data from N. L. Bowen, Am. J. Sci. Ser. 4, 40, 161 (1915).

The interpretation of Equations (14.63) and (14.64) can be illustrated graphically by the reduced-phase diagram for a two-component system at constant pressure, as shown for the system diopside-anorthite in Figure 14.3. 

Figure 22 illustrates such plots with the r)0 data for aqueous xanthan solutions [128], where a reduced concentration L3 c instead of c is used for the abscissa. In agreement with the expectation, the data points for each sample almost follow a straight line. The vertical segments in the upper panel indicate the (reduced) phase boundary concentration Lfc) between the isotropic and biphasic regions. Similar linear plots have been obtained from q0 data for aqueous schizophyllan solutions [19,136,137],... 

Fig. Al. Comparison of the reduced phase boundary concentrations (ch cA) obtained by Chen s procedure [47] and the Onsager trial function procedures for f (a)...

These four equations of motion describe the dynamics of SHG in the fourdimensional phase space (Re04, Irnai, Rea2, Ima2). In practice, we can observe the motion only in the reduced phase space (phase surface). For example, with... 

Other semi-2-IPNs [52] processed by the freeze-drying method included IPN from 4,4 -bismaleimido diphenylmethane (BMI) and linear BTDA/3,4 -ODA polyamic acid that were dissolved in 1,3,5-trioxane (Fig. 16). The resulting semi-2-IPNs exhibited higher Tgs and reduced phase separation, and contained no plasticizing solvent. A comparison of unidirectional properties of composites prepared by the freeze-dry process to those by traditional solvent evaporation process is presented in Table 13. The freeze-drying method for the preparation of IPNs appears to be superior to previous technology. 

A reaction path can proceed in two principally different directions after it has crossed a phase boundary 1) (0juo/0j Bo)paih > (0//o /0 no)eq and 2) (0 o/0 Bo)paii. < (0/Wo/0 Bo)eq- In the second case, the reaction path will re-enter the field of the reduced phase which it just left and can then oscillate along the phase boundary line in Figure 7-8 for some length. A morphologically stable interface between the oxidized and the reduced phase can not develop in this case, and a part of the oxide layer is expected to consist of a mixture of two phases. 

There are several other methods of achieving stability in potentiostatic circuits. A capacitor may be added between the counter and reference electrodes to reduce phase shift in the critical frequency region. Some caution must be exercised since a low-resistance reference electrode then becomes the counterelectrode at high frequencies. A particularly interesting method is known as input lead-lag compensation a series RC is connected between the input terminals of the control amplifier, and a second resistor is connected between the noninverting input and common. This form of compensation has minimum effect on the slew rate of the control amplifier. Further details can be found in the book by Stout and Kaufman listed in the bibliography. 

The 600 blocks of positions and velocities represent an ensemble of 600 points in the phase space rN, of the entire system being studied or an ensemble of 6007V points in the reduced phase or p space of a single molecule. This approach was taken in calculating time-independent properties. For example, the mean square force on a molecule, , was given by... 

Problem 7 What is a two component system and how it is graphically represented Define reduced phase rule equation and condensed state. 

F=(C-P + 2)-l or F—C-P+1 This equation is known as condensed or reduced phase rule equation. 

Maudsley AA, Matson GB, Hugg JW, Weiner MW (1994) Reduced phase encoding in spectroscopic imaging. Magn Reson Med 31 645-651... 

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