Binary preparation

C. M. Grill, Closed-loop recycling with periodic intra-profile injection a new binary preparative cliromatograpliic technique , J. Chromatogr. 796 101 -113 (1998). 

III-V compound semiconductors with precisely controlled compositions and gaps can be prepared from several material systems. Representative III-V compounds are shown in tire gap-lattice constant plots of figure C2.16.3. The points representing binary semiconductors such as GaAs or InP are joined by lines indicating ternary and quaternary alloys. The special nature of tire binary compounds arises from tlieir availability as tire substrate material needed for epitaxial growtli of device stmctures. 

Figure C2.16.2 shows tire gap-lattice constant plots for tire III-V nitrides. These compounds can have eitlier tire WTirtzite or zincblende stmctures, witli tire wurtzite polytype having tire most interesting device applications. The large gaps of tliese materials make tliem particularly useful in tire preparation of LEDs and diode lasers emitting in tire blue part of tire visible spectmm. Unlike tire smaller-gap III-V compounds illustrated in figure C2.16.3 single crystals of tire nitride binaries of AIN, GaN and InN can be prepared only in very small sizes, too small for epitaxial growtli of device stmctures. Substrate materials such as sapphire and SiC are used instead.

Nitrogen does form a number of binary compounds with the halogens but none of these can be prepared by the direct combination of the elements and they are dealt with below (p. 249). The other Group V elements all form halides by direct combination. 

The properties of a copolymer can be viewed as hybrids of the properties of the separate homopolymers. Because of this, a good deal of refinement can be introduced into these properties by the use of copolymers. The situation is analogous to the use of pure liquids or binary solutions as solvents. The number of binary combinations, n(n - l)/2 as noted above, greatly exceeds the number of pure liquids, and any one of these combinations can be prepared over a range of compositions. Just as mixed solvents offer a wider range of properties than... 

Thousands of compounds of the actinide elements have been prepared, and the properties of some of the important binary compounds are summarized in Table 8 (13,17,18,22). The binary compounds with carbon, boron, nitrogen, siUcon, and sulfur are not included these are of interest, however, because of their stabiUty at high temperatures. A large number of ternary compounds, including numerous oxyhaUdes, and more compHcated compounds have been synthesized and characterized. These include many intermediate (nonstoichiometric) oxides, and besides the nitrates, sulfates, peroxides, and carbonates, compounds such as phosphates, arsenates, cyanides, cyanates, thiocyanates, selenocyanates, sulfites, selenates, selenites, teUurates, tellurites, selenides, and teUurides. 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

Alloys. Many Ge alloys have been prepared and studied. Most have been made by melting Ge with another metal, much as germanides are made. Collections of binary phase diagrams and comments about many Ge alloys are available (25—28). 

Xenon dichloride [13780-38-6], XeCl, and xenon(II) chloroduoride [73378-52-6], XeClE, have been prepared by photochemical and electric discharge methods and have been examined at low temperatures by matrix-isolation techniques (39,40). The dichloride has a linear stmcture like that of XeE2. Evidence for the existence of XeCl2, XeBr2, and xenon tetrachloride [14989-42-5], XeCl, has been obtained from Mn ssbauer studies (41,42). Owing to thermal chemical instabiUties, no dihaUde other than the binary duorides has been prepared in macroscopic amounts. 

Halides. AH of the anhydrous and hydrated binary haUdes of iron(Il) and iron(Ill) are known with the exception of the hydrated iodide of iron(Ill). A large number of complex iron haUdes have been prepared and characterized (6). 

Phosphoms forms weU-defined halogen compounds of the types PX, PX, POX, and PSX, all of which except the pentaiodide and the oxy- and sulfoiodides are known. In addition to the binary haUdes, a few of the many possible mixed haUdes, eg, PX2Y and PX2Y2, have been prepared. The commercially important phosphoms haUdes are phosphoms trichloride [7719-12-2] phosphoms oxychloride [10025-87-3] phosphoms pentachloride [10026-13-8] and phosphoms sulfochloride [3982-91-0]. A few other phosphoms haUdes, eg, PI, PR13) marketed as reagent... 

Other Phosphorus—Nitrogen Compounds. Of the binary phosphoms—nitrogen compounds, only triphosphoms pentanitride [12136-91 -3] 3 5 been obtained in a pure state. It can be prepared by treatment of P S q with ammonia and subsequent heating of the intermediate... 

There are numerous complex (ternary and quaternary) plutonium oxides. Their properties have been reviewed (30). Plutonium oxidizes readily to Pu(VI) from binary oxides to complex oxides such as Ba PuO. The best way to oxidize Pu to Pu(VII) is to prepare complex oxides such as Li PuO from Li20 and PUO2 iu flowing oxygen (85). 

Plutonium trichloride, PUCI3, is the only known binary chloride of plutonium. No higher chloride in the soHd state has been prepared so far. The trichloride is a blue-green soHd and can be prepared from the reaction of Pu metal or PUO2, and HCl gas at elevated temperatures, and can be purified by sublimation and zone melting. The yellow complex chloride, CS2PUCI3, is stoichiometric, stable, and can be used as a primary analytical standard for plutonium (156). 

Alkoxides. Zirconium alkoxides are part of a family of alcohol-derived compounds (219). The binary zirconium compounds have the general formula ZRX — (OR). They are easily hydrolyzed and must be prepared under anhydrous conditions. They are prepared by the reaction of zirconium tetrahahdes and alcohols ... 

Metallic Antimonides. Numerous binary compounds of antimony with metallic elements are known. The most important of these are indium antimonide [1312-41 -0] InSb, gallium antimonide [12064-03-8] GaSb, and aluminum antimonide [25152-52-7] AlSb, which find extensive use as semiconductors. The alkali metal antimonides, such as lithium antimonide [12057-30-6] and sodium antimonide [12058-86-5] do not consist of simple ions. Rather, there is appreciable covalent bonding between the alkali metal and the Sb as well as between pairs of Na atoms. These compounds are useful for the preparation of organoantimony compounds, such as trimethylstibine [594-10-5] (CH2)2Sb, by reaction with an organohalogen compound. 

Anhydrous metal borates may be prepared by heating the hydrated salts to 300—500°C, or by direct fusion of the metal oxide with boric acid or B2O2. Many binary and tertiary anhydrous systems containing B2O2 form vitreous phases over certain ranges of composition (145). 

Ghromium(VI) Gompounds. Virtually all Cr(VI) compounds contain a Cr—O unit. The cbromium (VT) fluoride [13843-28-2], CrF, is the only binary halide known and the sole exception. This fluoride, prepared by fluorinating Cr at high temperature and pressure, easily disproportionates... 

The graphics capabiUties of the CAD/CAM environment offer a number of opportunities for data manipulation, pattern recognition, and image creation. The direct appHcation of computer graphics to the automation of graphic solution techniques, such as a McCabe-Thiele binary distillation method, or to the preparation of data plots are obvious examples. Graphic simulation has been appHed to the optimisation of chemical process systems as a technique for energy analysis (84). 

Chapter 12 discusses the distribution software BETA for preparing event tree analysis from a work processor table. BETA allows the use of binary conditionals so the nodal probabilities in a vertical line are not necessarily equal but depend on preceding events. 

---