Phosphides mixed-metal

Phosphides. Compounds of phosphoms containing the more electropositive elements are generally called phosphides. A large number of binary phosphides as well as many ternary mixed-metal phosphides, metal phosphide nitrides, etc, are known. Some binary phosphides, such as those of nickel, exhibit a variety of stoichiometries (Ni P, Ni P2, Nq2P5, Ni2P, Ni P, NiP, NiP2, NiP ), whereas others, such as aluminum, form only one (AlP). Metalloids such as B and Si also form phosphides. 

As in the parent binary phosphides MV, the metal 2p3 p XPS spectra for the mixed-metal phosphides M XM XV exhibit asymmetric lineshapes originating from final state effects [34] involving the metal-metal bonding network. Virtually no changes in BE are observed relative to the binary phosphides MV or the elemental metals... 

The XPS and XANES investigations of MnP-type binary phosphides MP and mixed-metal phosphides M XM XP discussed above have revealed some of the factors that influence BEs and absorption energies. In particular, a charge redistribution can take place within the metal-metal bonding network when two different... 

However, with the improved resolution of modem XPS instruments, BE shifts as small as 0.1 eV can be detected and may be significant. These shifts can be interpreted, to a first approximation, by changes in the atomic charge (an intraatomic effect), but to account for more subtle differences, as seen in the mixed-metal phosphides M aM P and mixed arsenide phosphides MAsi -VP>, the role of next-nearest neighbours cannot be neglected. These interatomic effects, as incorporated into the charge potential model, help explain the unusual trends in BE observed in these series. 

Almost all metals form phosphides, and over 200 different binary compounds are now known. In addition, there are many ternary mixed-metal phosphides. These phosphides consist of metal cations and phosphide anions. In addition to some simple anions (P3-, P -, P ), there are many polyphosphide anions that exist in the form of rings, cages, and chains, as shown in Fig. 15.3.4. 

The most widely used method for the preparation of solid materials is by reaction of solid components in the correct molar proportions at elevated temperature over a long period. Many mixed metal oxides, chalco-genides (sulfides, selenides and tellurides) and pnictides (phosphides and nitrides) have been prepared using this method. Accurate weighing of... 

Transition-Metal Arsenides, MAs, and Mixed Arsenide Phosphides, MAsi yPy... 

Fig. 23 Dependence of metal and pnicogen charges on level of P substitution (y) in a mixed arsenide phosphide series MAsi yPy. The average pnicogen charge, qpn = yqP + l-y)q s, shown by the dashed line, balances the metal charge. Reprinted with permission from [61], Copyright Elsevier...

No, the editor didn t know what this name meant either.) It means salts of the triva-lent anions of Group V, restricted in [1] to arsenides, antimonides and bismuthides and prepared by reaction of sodium pnictides with anhydrous halides of transition and lanthanide metals. This violently exothermic reaction may initiate as low as 25°C. Avoidance of hydrated halides is cautioned since these are likely to react uncontrollably on mixing. Another paper includes a similar reaction of phosphides, initiated by grinding [2], Nitrides are reported made from the thermally initiated reaction of sodium azide with metal halides, a very large sealed ampoule is counselled to contain the nitrogen [3],... 

The Badische AniKn- und Soda-Fabrik prepared a nitride of undetermined composition by heating a mixture of silica and carbon in an atm. of nitrogen. The reaction proceeds at a relatively low temp, if a hydroxide or salt of a metal be added. The product contains silicon nitride mixed with the nitride of the metal. The Badische Anilin- und Soda-Fabrik also removed many of the impurities—iron, carbon, silicates, carbides, silicides, and phosphides—by treatment with acids or mild oxidizing agents which do not affect the silicon nitride. A. S. Larsen and O. J. Storm prepared the nitride by the action of nitrogen on molten silicides—e.g. ferrosilicon. 

---