Germanium binary compounds

A major and growing use of the minor metalloids is in semiconductor fabrication. Germanium, like silicon, exhibits semiconductor properties. Binary compounds between elements of Groups 13 and 15 also act as semiconductors. These 13-15 compounds, such as GaAs and InSb, have the same number of valence electrons as Si or Ge. The energy gap between the valence band and the conduction band of a 13-15 semiconductor can be varied by changing the relative amounts of the two components. This allows the properties of 13-15 semiconductors to be fine-tuned. 

Like carbon and silicon, and to a lesser extent, germanium and tin. lead forms binary compounds with metals, such us NajPh and Nu Pb.i. These materials are essentially salt-like, ami contain polypluinbide anions. They are of theoretical interest, because they are intermediate m character between stoichiometric ctimpounds idaltonidc compounds) and intermediate phases. The two compounds cited dissolve in liquid ammonia, electrolyze in such solutions to give the metals, and apparently form ions such as [Fh-r 1J and (Ph.,)4- which readily form amine complexes. 

A major portion of the effort on semiconductors has been expended on the binary compounds having the zinc blende or wurtzite structure. These are commonly classified by the A group numbers such as III-V (InAs) and II-VI (CdTe) and have what may loosely be described as a 1 to 1 cation-anion ratio. However, another series of compounds that has become of increased interest can be generally classified as the IV-VI compounds. Specifically, these are the chal-cogenides of germanium, tin, and lead. In this discussion, we present some experimental observations on the tellurides of these group IV A elements. 

Use the group structure of the periodic table to predict the empirical formulas for the binary compounds that hydrogen forms with the elements germanium, fluorine, tellurium, and bismuth. 

This Table names a large number of homoatomic and binary compounds and species, and some heteropolynuclear entities, and thus may be used as a reference for names of simple compounds and a source of examples to guide in the naming of further compounds. It may be necessary to browse the Table to find (families of) compounds that match those of interest. For example, all the oxides of potassium are named corresponding compounds of the other alkali metals, not included here, are named analogously. Several silicon and germanium hydride species are named names for corresponding tin and lead species are not necessarily included. 

Group 14 (Ge, Sn, Pb). Germanium reacts with tungsten at elevated temperature only under increased pressure (77kbar, 1500-2500 °C). Two binary compounds are known WsGes and WGe2- No solid solubility exists between the two metals and the solubility of W in molten Ge is negligible. 

Intermetallic clathrates were first discovered in the coiu se of investigations on the thermal decomposition of the binary compounds hltTti [48,49], where M = alkali metal and Tt = group 14 element. Systematic investigations carried out in the seminal work by Cros et al. [1-3,50-52] demonstrated that a variety of alkali metal silicon and germanium-based compositions are prepared via this route, which continues to be employed for preparation of clathrate materials in contemporary investigations [53-64]. 

The phase-field distribution in the isothermal section at 870 K (fig. 79) is characterized by existence of ten ternary compotmds. Maximum solubilities of germanium in the binary compounds of the Sm-Pd system are lOat.% for SmPd and 5 at.% for SmPd3-2.3. Solubility of samarium in the palladium germanides was fotmd to be negligible. As reported by Barakatova (1994), SmPd2Ge2 (2) and Sm(Pd,Ge)2 (9) dissolve 15 at.% Ge and 10 at.% Ge respectively. 

The ternary phase diagram is characterized by the existence of eleven ternary compounds and by the formation of solid solutions based at the H02C017 and H0C05 binary compounds where the maximum solubility of germanium is lOat.%. The HosGej phase dissolves 8 at.% Co. 

The ternary systems with two rare-earth metals and germanium are characterized by the formation of compounds with compositions (R,R )5Ge4, (R,R )iiGeio, (R,R )Ge and (R,R )2Ge which crystallize with the structure types of binary compounds and their superstructures. This is caused by the similarities in the electronic structure of R elements. 

They are formed from the binary compounds by substitution of S or Se by a second non-metal, frequently arsenic, silicon, germanium, or tellurium. Such a choice of elements is evidence of the covalent character of the bonding in the rare earth sulfides and selenides. 

In addition to the binary compounds discussed above, there are a few examples of discrete lead-nitrogen46, lead-phosphorus, lead-arsenic and lead-antimony bonds in various compounds, but they are considerably more rare than the corresponding compounds of tin, germanium and silicon. 

For the binary alkaline earth sihcide SiSr, two different structures have been reported. One contains one-dimensionally extended zigzag chains beside isolated Si" atoms [73]. Schafer et al. prepared a modification with the same composition, which instead contained isolated sUicide units of ten atoms. In these units, planar hexagons are substituted in the 1-, 2-, 4-, and 5-ring positions by four additional Si atoms. An isostructural compound was found for germanium as well, but showing defects in this unit in the positions 1, 2, 4, and 5. Both materials could not be obtained from stoichiometric approaches, and their formation obviously is coupled to strontium excess [69] (Fig. 3). 

Germanes hydride, 2 76 reactivity of, 2 87 Germanium anionic cluster, 24 227 azides, preparation, 9 138 properties, 9 135-136, 139, 141 binary carbide not reported, 11 211 carbides, preparation of, 11 163 chalcogenide halides, 23 390 chlorides, mass spectra of, 18 248, 249 complexes, xenon fluoride reactions, 46 85 compounds, see also Organogermanium compounds... 

Two factors combine to lend a greater diversity in the stereochemistries exhibited by bivalent germanium, tin and lead compounds, the increased radius of Mn compared with that of Mw and the presence of a non-bonding pair of electrons. When the non-bonding pair of electrons occupies the isotropic valence level s orbital, as in, for example, the complex cations Pb[SC(NH2)2]6+ and Pb[antipyrine]6+, or when they are donated to conductance band levels, as in the binary tin and lead selenides or tellurides or the perovskite ternary phases CsMX3 (M = Sn, Pb X = Cl, Br, I), then the metal coordination is regular. However, in the majority of compounds an apparent vacancy in the coordination sphere of the metal is observed, which is usually ascribed to the presence of the non-bonding pair of electrons in a hybrid orbital and cited as evidence for a stereochemically active lone pair . 

Germanium, tin, and lead give alloy-type binaries of the alkali metals of variable stoichiometry, but when dissolved in ammonia with the alkali metals they produce colored Zintl-type anions see Zintl Compounds) in solution which can be... 

Epitaxial films frequently have superior characteristics than either polycrystalline or amorphous films. The epitaxial growth concerns a large number of materials silicon, silicon-germanium alloys, III-V compounds, binary and ternary composites, metals, etc. 

All the components, if possible, are made of silicon. The next important materials are germanium and gallium arsenide as well as some other III-V compounds such as GaP, InSb, InAs and GaN and their ternary mixed compounds. Furthermore, binary and ternary IV-VI compounds like PbSnTe have been found to be very useful... 

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