Oxide Selenides

Minerals, electrochemistry of — Many minerals, esp. the ore minerals (e.g., metal sulfides, oxides, selenides, arsenides) are either metallic conductors or semiconductors. Because of this they are prone to undergo electrochemical reactions at solid solution interfaces, and many industrially important processes, e.g., mineral leaching and flotation involve electrochemical steps [i-ii]. Electrochemical techniques can be also used in quantitative mineral analysis and phase identification [iii]. Generally, the surface of minerals (and also of glasses) when in contact with solutions can be charged due to ion-transfer processes. Thus mineral surfaces also have a specific point of zero charge depending on their sur-... 

Besides filling in the missing links, it would be desirable to consider in addition the phosphorus oxide selenides. With their inclusion, the tendencies already detected in the oxides and oxide sulfides should become much more pronounced. Furthermore, one would introduce an additional probe atom (77Se) for NMR, a powerful analytical technique in this context. 

Several different functional groups can be introduced by selenenylation. The benzeneselenenyl ion tolerates a wide range of anionic groups. However, with differing anionic moieties the reactivity of the benzeneselenenyl ion varies greatly. All adducts can be subsequently converted to either allylic or vinylic moieties by the syn elimination of the corresponding selenoxide (oxidized selenide). 

Beryllium oxide, selenide, sulphide, and telluride, values of properties.. See Semiconductors Basis states, 5... 

Careful analysis of both powder X-ray dilfraction and EXAFS spectroscopic data located the cadmium sulfide as (CdS)4 cubes occupying the space within sodalite cages, with the Cd ions coordinated to framework oxygen atoms (Fig. 6.10). Furthermore, the clusters were observed to order between adjacent sodalite cages, to give superclusters or a superlattice structure. In subsequent work, a variety of compounds and elements have been prepared as well-defined clusters within zeolite frameworks, including metal oxides, selenides and phosphides, and these have been studied mainly with the view of determining the effects of cluster size on optical and electronic properties. 

U, Np, and Pu selenide and oxide-selenide molecular and cluster cations were synthesized by LA of dilute mixtures of An oxides in a selenium matrix (Gibson, 1999d) binary ions, AnSe +, and ternary cluster ions, An OmSe +, were observed, with the compositions of the mixed 0/Se clusters suggesting the aggregation of AnOm with Se , the presence of Se ions in analogy with 0 , or the presence of structures involving O—Se bonding. 

Under certain conditions, the action of H2Se on M2O3 gives oxide selenides as intermediate reaction products. These can be converted in a second reaction step into the 0-free M2Se3 or M3Se4 (see pp. 33 and 30), Obolonchik et al. [20, 21 ], also see Skripka [23], Skripka, Obolonchik [24]. 

YSe, like Y3Se4 and Y2Se3, is stable in dry air at room temperature. However, the slightest trace of water caused the surface of the selenide to turn black and, eventually, the entire sample would disintegrate. Selenium vapor evolves on heating in vacuum, probably around 650°C. Oxide selenides or selenates form superficially from YSei le temperatures above 400°C in poor vacuum, Norman [1]. 

C in a few days, Khodadad et al. [5]. On heating stoichiometric mixtures of M2028e and Al in a graphite boat at 10 " Torr to 1350 0, the oxide selenides react with Al corresponding to ... 

The reaction is complete in 4 h [1]. M2028e and especially La2028e combine with different metal selenides (for instance M = Ga, In, Ge, 8n, 8b, Or) to form quaternary oxide selenides with two metals, Guittard et al. [6]. 

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