Sohd metal lattice

Hydrides are compounds that contain hydrogen (qv) in a reduced or electron-rich state. Hydrides may be either simple binary compounds or complex ones. In the former, the negative hydrogen is bonded ionicaHy or covalendy to a metal, or is present as a soHd solution in the metal lattice. In the latter, which comprise a large group of chemical compounds, complex hydridic anions such as BH, A1H, and derivatives of these, exist. 

The coordination numbers of metal ions range from I. as in ton pairs such as Na CI in the vapor phase, (o 12 in some mixed metal oxides. The k>v limit, 1. Is barely within the realm of coordination chemistry, since the Na Cr km pair would not normally be considered a coordination compound, and there are few other examples. Likewise, the upper limit of 12 is not particularly important since k is rarely encountered in discrete molecules, and the treatment of sohd crystal lattices such as hexagonal BaTiOj and perovskite> as coordination compounds is not dc ie frequently. The lowest and highest coordination numbers found in typical coordination compounds are 2 and 9 with the intermediate number 6 being the most important. 

MetaUic behavior is observed for those soHds that have partially filled bands (Fig. lb), that is, for materials that have their Fermi level within a band. Since the energy bands are delocalized throughout the crystal, electrons in partially filled bands are free to move in the presence of an electric field, and large conductivity results. Conduction in metals shows a decrease in conductivity at higher temperatures, since scattering mechanisms (lattice phonons, etc) are frozen out at lower temperatures, but become more important as the temperature is raised. 

For nickel, cobalt, and hon-base alloys the amount of solute, particularly tungsten or molybdenum, intentionally added for strengthening by lattice or modulus misfit is generally limited by the instability of the alloy to unwanted CJ-phase formation. However, the Group 5(VB) bcc metals rely on additions of the Group 6(VIB) metals Mo and W for sohd-solution strengthening. 

Lithium Nitride. Lithium nitride [26134-62-3], Li N, is prepared from the strongly exothermic direct reaction of lithium and nitrogen. The reaction proceeds to completion even when the temperature is kept below the melting point of lithium metal. The lithium ion is extremely mobile in the hexagonal lattice resulting in one of the highest known soHd ionic conductivities. Lithium nitride in combination with other compounds is used as a catalyst for the conversion of hexagonal boron nitride to the cubic form. The properties of lithium nitride have been extensively reviewed (66). 

Sohd silver is more permeable by oxygen than any other metal. Oxygen moves freely within the metallic silver lattice, not leaving the surface until two oxygen atoms connect to form Og. This occurs at - 300° C. Below this temperature silver is an efficient catalyst for gaseous oxidative chemical reactions. Silver is also an extremely efficient catalyst for aqueous oxidative sanitation. 

When two metals A and B are melted together and the liquid mixture is then slowly cooled, different equilibrium phases appear as a function of composition and temperature. These equilibrium phases are summarized in a condensed phase diagram. The solid region of a binary phase diagram usually contains one or more intermediate phases, in addition to terminal solid solutions. In solid solutions, the solute atoms may occupy random substitution positions in the host lattice, preserving the crystal structure of the host. Interstitial soHd solutions also exist wherein the significantly smaller atoms occupy interstitial sites... 

The distinction between the two classes of materials considered in this Section pertains to the presence or absence of mixing at the molecular level. Thus in alloys, solid solutions of two or more semiconductors are formed where the lattice sites are interspersed with the alloy components. Semiconductor alloys, unlike their metallic counterparts, have a much more recent history and their development driver has been mainly optoelectronic (e.g., sohd-state laser) applications. In mixed semiconductor composites, on the other hand, the semiconductor particles are in electronic contact but the composite components do not undergo mixing at the molecular level. 

DOT Flanunable Solid, Label Flammable Sohd and Danger When Wet, UN 1427 Formula NaH MW 24.00 CAS [7646-69-7] Structure cubic lattice similar to the corresponding metal halide... 

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