Semi-metal

The detailed reactions of Si02 with the oxides of Ihe metals and semi-metals are of great importance in glass technology and ceramics... 

Hydrides of the types AnHi (An = Th, Np, Pu, Am, Cm) and AnHs (Pa —> Am), as well as ThaHis (i.e. ThHs.yj) have been so obtained but are not very stable thermally and are decidedly unstable with respect to air and moisture. Borides, carbides, silicides and nitrides (q.v.) are mostly less sensitive chemically and, being refractory materials, those of Th, U and Pu in particular have been studied extensively as possible nuclear fuels.Their stoichiometries are very varied but the more important ones are the semi-metallic monocarbides, AnC, and mononitrides, AnN, all of which have the rock-salt structure they are predominantly ionic... 

Many liquid alloys, in particular, the alkali-group IV alloys, exhibit (Zintl) anion clustering and show strong effects of compound formation. A typical example of such Zintl systems are sodium-tin alloys. In the solid NaSn crystal the Zintl anions Sn appear [1]. An interesting question is the stability of these anions in the liquid. Furthermore, the electrical conductivity of these alloys shows a strong dependence on composition [2] For the limiting (sodium-rich or tin-rich) cases a metallic (small) conductivity appears, but for the nearly equimolar compositions a semi-metallic behavior - with a considerably smaller conductivity - is observed. 

Some heavy metals and semi-metals are quite toxic (chromium, lead, and antimony) and expensive care is needed to prevent them from being dispersed in the environment. Lead in gasoline and paint has been... 

Cast iron is the standard material used to construct the cylindrical housing, but other materials may be used if corrosive conditions exist. The rotor is usually a continuous piece of steel that includes the shaft and is made from bar stock. Special materials can be selected for corrosive applications. Occasionally, the rotor may be a separate iron casting keyed to a shaft. On most standard air compressors, the rotor-shaft seals are semi-metallic packing in... 

A great deal of excitement has been generated by the assertion that some intercalation compounds of graphite possess a conductivity greater than that of copper (VIO, F13, Til). Much of this work was based upon earlier researches by Ubbelohde, who found that the a-axis conductivity of the semi-metal graphite increases, and develops a me-... 

Vibrational spectra of intra- and 18 inter-metal and semi-metal bonds (248)... 

Euln2P2 shows a rather low resistance at room temperature of 10 Q cm. The temperature dependence, shown in Pig. 11.4, is suggestive of a semi-metal. The resistivity decreases as a function of decreasing temperature until about 100 K, at which temperature it increases dramatically to a maximum coincident... 

Basic physical properties of sulfur, selenium, and tellurium are indicated in Table 1.3. Downward the sulfur sub-group, the metallic character increases from sulfur to polonium, so that whereas there exist various non-metallic allotropic states of elementary sulfur, only one allotropic form of selenium is (semi)metallic, and the (semi)metallic form of tellurium is the most common for this element. Polonium is a typical metal. Physically, this trend is reflected in the electrical properties of the elements oxygen and sulfur are insulators, selenium and tellurium behave as semiconductors, and polonium is a typical metallic conductor. The temperature coefficient of resistivity for S, Se, and Te is negative, which is usually considered... 

The metallic or semi-metallic character of many common sulfides implies the significance of electrochemical factors in the study of their oxidation, which is relevant to environmental, energy, and metallurgical issues, e.g., in connection with the direct electrochemical conversion of sulfide ores to metals, the pressure leaching of ore materials, or flotation processes. 

The Group III elements all have three electrons in their outer shell. Most of them form +3 ions by losing all three electrons. Because the boron atom is so small, its nucleus holds very tightly to all its five electrons. Boron usually combines with other elements which have electrons to share, just as carbon combines. It is called a semi-metal because it has some, but not all, of the metallic properties. 

Bismuth has the largest atom of any element of Group V, and it holds its electrons less tightly than the others do. It is a metal, but not a very good one. It is brittle and is also a poor conductor of electricity. Antimony and arsenic are semi-metals. Phosphorus and nitrogen are not metallic at all. Nitrogen exists in nature as a gas. 

The wide use of p-block and early transition metal chalcogenide materials for electronics applications (semiconductors, semi-metals, battery materials, etc.) has resulted in a large amount of work concerned with CVD using mixtures of metal halides and chalcogenoethers as dual source precursors and preformed complexes as single sources.166... 

Imino-fe(diorganophosphine chalcogenide)s and imino-fe(dialkoxy-/diary-loxy-phosphine chalcogenide)s, R2P(E)NHP(E)R2 (R = alkyl, aryl, alkoxy, aryloxy E = S, Se, Te) and their N-H deprotonated anionic forms, the dichalcogenoimidodiphosph(in)ates [R2P(E)NP(E)R2], have been extensively studied in the literature, mainly due to their wide-ranging coordination chemistry which has spanned almost all the metallic and semi-metallic members of the periodic table (see Section 5.3.8).72 78... 

A uniform monolayer surface depends upon it having been deposited on a flat electrode substrate. Impressive flatness can be achieved with the semi-metal graphite, a lamellar structure with weak van der Waals forces between the layers. A clean... 

Thompson [8]). Pure A and B are assumed to melt at 800 and 1000 K with the entropy of fusion of both compounds set to 10 J K-1 mol-1 (this is the typical entropy of fusion for metals, while semi-metals like Ga, In and Sb may take quite different values - in these three specific cases 18.4, 7.6 and 21.9 J K-1 mol-1, respectively). The interaction coefficients of the two solutions have been varied systematically in order to generate the nine different phase diagrams given in Figure 4.10. 

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