Chalcogenides, transition metal

Li J, Badding ME, DiSalvo FJ (1992) New layered ternary niobium teUurides Synthesis, structure, and properties of NbMTe2 (M = Fe, Co). Inorg Chem 31 1050-1054 Tremel W, Kleinke H, Derstroff V, Reisner C (1995) Transition metal chalcogenides New views on an old topic. J Alloy Compd 219 73-82... 

Perspectives for fabrication of improved oxygen electrodes at a low cost have been offered by non-noble, transition metal catalysts, although their intrinsic catalytic activity and stability are lower in comparison with those of Pt and Pt-alloys. The vast majority of these materials comprise (1) macrocyclic metal transition complexes of the N4-type having Fe or Co as the central metal ion, i.e., porphyrins, phthalocyanines, and tetraazaannulenes [6-8] (2) transition metal carbides, nitrides, and oxides (e.g., FeCjc, TaOjcNy, MnOx) and (3) transition metal chalcogenide cluster compounds based on Chevrel phases, and Ru-based cluster/amorphous systems that contain chalcogen elements, mostly selenium. 

Binary systems of ruthenium sulfide or selenide nanoparticles (RujcSy, RujcSey) are considered as the state-of-the-art ORR electrocatalysts in the class of non-Chevrel amorphous transition metal chalcogenides. Notably, in contrast to pyrite-type MS2 varieties (typically RUS2) utilized in industrial catalysis as effective cathodes for the molecular oxygen reduction in acid medium, these Ru-based cluster materials exhibit a fairly robust activity even in high methanol content environments of fuel cells. 

With respect to non-noble and non-Ru catalysts, transition metal chalcogenides with spinel and pyrite structures have been investigated and shown that these can also be active to oxygen reduction processes. The motivation in the present case is that chalcogen addition might enhance the stability and activity toward the ORR... 

Solorza-Eeria O, EUmer K, Giersig M, Alonso-Vante N (1994) Novel low-temperature synthesis of semiconducting transition metal chalcogenide electrocatalyst for multielectron charge transfer Molecular oxygen reduction. Electrochim Acta 39 1647-1653... 

Alonso-Vante N, Tributsch H, Solorza-Eeria O (1995) Kinetics studies of oxygen reduction in acid medium on novel semiconducting transition metal chalcogenides. Electrochim Acta 40 567-576... 

Schbllhom R, Meyer H (1974) Cathodic reduction of layered transition metal chalcogenides. Mater Res Bull 9 1237-1245... 

K. Mitchell, J. A. Ibers, Rare-erath transition-metal chalcogenides. Chem. Rev. 102 (2002) 1929. 

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... 

Jaegermann, W., and H. Tributsch (1988), "Interfacial Properties of Semiconducting Transition Metal Chalcogenides", in S. G. Davison, Ed., Progress in Surface Science 29, Pergamon Press, New York. 

In a transition metal chalcogenide or oxide, positive guests like Li occupy sites surrounded by negative chalcogen or oxygen ions, and distance themselves as far as possible from the positive transition metal ions. Since Li has a filled outer core of electrons (unlike the transition metal ions in many of the hosts), the geometry of the site is not important as long as the anions are distributed evenly around the site. Thus y" surrounded by four anions would prefer the anions to form a tetrahedron rather than a square. 

Atomic Eorce Microscopy Studies of Transition Metal Chalcogenide Deposition Using Translationally Hot Atoms (from Spain, 1997)... 

Coleman, R. V., Giambattista, B., Hansma, P. K., Johnson, A., McNairy, W. W., and Slough, C. G. (1988). Scanning tunneling microscopy of charge-density waves in transition metal chalcogenides. Adv. Phys. 37, 559-644. 

The pyrite (FeS2) structure (C2) consists of molecular ions (Fig. 1.8). The structure is closely related to NaCl from which it may be derived by replacing Na by Fe and Cl by S , with the centre of the S ion occupying the chloride position. Each iron is octahedrally coordinated but each sulphur is tetrahedrally surrounded (one S and three Fe). Several transition metal chalcogenides crystallize in this structure. 

Several insulating inorganic solids possessing sheet structures, for example, silicates belonging to the pyrophyllite family (Thomas, 1982), and acid phosphates (Alberti Constantino, 1982 Clearfield, 1981) of some tetravalent metals form intercalation compounds with a variety of donor molecules in these cases, intercalation does not involve a redox process, unlike in the cases of transition metal chalcogenides and... 

There are many non-stoichiometric compounds in the 3d transition metal chalcogenides. Among them, the NiS phase with the NiAs-type structure has been investigated in detail from both chemical and physical viewpoints. Let us adopt this compound as a typical example of a non-stoichiometric compound. 

Accordingly over all the composition range from MX to MX2, either the NiAs- or Cdl2-type structure is stable at higher temperatures. A number of papers have been published on 3d-transition metal chalcogenides from the viewpoint of order-disorder of metal vacancies. A study of the V-S system from this point of view is described here. 

Table 4.2.4. Lattice energies (in kJ mol 1) of some alkali metal halides and divalent transition metal chalcogenides...

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