Binary oxide

Entry number Oxide semiconductor Energy band gap, eV Comments Reference (s) 

1 wos 2.5-2.8 This material has been used as single crystals, thin films, powders and in mesoporous/ nanostructured form. Both virgin and doped samples studied. 339-350 

4 Sn02 3.5 Sb-doped single crystal samples used. Stable H2 and O2 evolution observed at Pt cathode and Sn02 photoanode respectively. 369,370 

5 NiO 3.47 A p-type semiconductor with indirect gap optical transition. 371, 372 

6 CdO - 2.3 A n-type semiconductor. Interestingly, Ru02-modified samples reduced the yield of O2 under irradiation. 373 

Some thermodynamic measurements on the reactions of sulphur dioxide and ammonia have been carried out.138 The reaction  

Pawlikowska-Czubak, A. Pomianowski, and J. Najbar, Z. anorg. Chem., 1974, 404, 284. 

Sulphates. Modifications to the automated photometric method for the determination of sulphate, which is based on decreasing the blue colour of the Ba-methylthymol blue complex by the precipitation of barium sulphate, have permitted150 determinations of 0—1.0 mg of SOT 1 with a 1.7% relative error. A flow cell was used with a high flow rate, produced by adding MeOH to the sample stream. A flow apparatus has also been used151 

Hejtmankova and C. Cerny, Coll. Czech. Chem. Comm., 1974, 39, 1787. 

Inorganic Chemistry of the Main-group Elements to study the thermodynamics of the hydration of NaHS04 in the temperature range 15—50 °C. From measured equilibrium decomposition pressures, the following thermodynamic functions were obtained for the compound NaHS04,H20 AH = -340.6 kcal mol1, AG = -294.7 kcal mol 1, and S° = 35.32 cal K 1 mol-1. The heat of the reaction  

---

There are numerous complex (ternary and quaternary) plutonium oxides. Their properties have been reviewed (30). Plutonium oxidizes readily to Pu(VI) from binary oxides to complex oxides such as Ba PuO. The best way to oxidize Pu to Pu(VII) is to prepare complex oxides such as Li PuO from Li20 and PUO2 iu flowing oxygen (85). 

Other important uses of stannic oxide are as a putty powder for polishing marble, granite, glass, and plastic lenses and as a catalyst. The most widely used heterogeneous tin catalysts are those based on binary oxide systems with stannic oxide for use in organic oxidation reactions. The tin—antimony oxide system is particularly selective in the oxidation and ammoxidation of propylene to acrolein, acryHc acid, and acrylonitrile. Research has been conducted for many years on the catalytic properties of stannic oxide and its effectiveness in catalyzing the oxidation of carbon monoxide at below 150°C has been described (25). 

The binary oxides and hydroxides of Ga, In and T1 have been much less extensively studied. The Ga system is somewhat similar to the Al system and a diagram summarizing the transformations in the systems is in Fig. 7.13. In general the a- and y-series have the same structure as their Al counterparts. )3-Ga203 is the most stable crystalline modification (mp 1740°) it has a unique crystal structure with the oxide ions in distorted ccp and Ga " in distorted tetrahedral and octahedral sites. The structure appears to owe its stability to these distortions and, because of the lower coordination of half the Ga ", the density is 10% less than for the a-(corundum-type) form. This preference of Ga "... 

The thermodynamic and other physical properties of binary oxides (e.g. A//f, AGf, mp, etc.) show characteristic trends and variations when plotted as a function of atomic number, and the preparation of such plots using readily available compilations of data can be a revealing and rewarding exercise. 

Table 14.14 Stmcture types for binary oxides in the solid state...

In all cases except Li3Nb04, phases similar to Li4Nb04F and Li4Ta04F were found. Pure binary oxides transform easily to modified structures characterized by ordered cation distribution, while oxyfluorides are more stable and require treatment at a high temperature, for an extended period of time, in order to be transformed into a state of ordered cation distribution. 

The stoichiometry of transition metal oxides is more variable. Iron, for example, forms three binary oxides. In FeO the iron atoms have lost two electrons each (Fe, O ), and in Fc2 O3 they have lost three electrons each... 

C04-0114. Ruthenium forms four different binary oxides R112 O3, R11O2, R11O3, and R11O4. Write a... 

C04-0115. Nitrogen forms the binary oxides NO, N2 O, NO2, N2 O4, and N2 O5. Write a baianced chemicai equation for O2 reacting with N2 to form each of these oxides, and determine how many eiectrons a nitrogen atom ioses in each case. 

Ir catalysts supported on binary oxides of Ti/Si and Nb/Si were prepared and essayed for the hydrogenation of a,P-unsaturated aldehydes reactions. The results of characterization revealed that monolayers of Ti/Si and Nb/Si allow a high metal distribution with a small size crystallite of Ir. The activity test indicates that the catalytic activity of these solids is dependent on the dispersion obtained and acidity of the solids. For molecules with a ring plane such as furfural and ciimamaldehyde, the adsorption mode can iirfluence the obtained products. SMSI effect (evidenced for H2 chemisorption) favors the formation of unsaturated alcohol. 

Not all binary oxides fall clearly into the category of acidic or basic oxides. For example, the oxides of Zn and A1 have the ability to react as either acid or base, depending on the other reactant. This is illustrated in the following equations. 

Chalcogen Binary oxides Compound Symmetry Mixed oxides Compound Symmetry... 

TABLE 4.1. Properties of Selected Binary Oxide Gate Dielectrics1,9,10... 

In many instances several different compositions of the binary oxide and chloride compounds are available. In each case we designate as most common the particular compound that is least expensive and available in the largest quantities from common suppliers,4 as summarized in Table 4.1. Included with each entry is the number (eu) of unpaired electrons determined from magnetic-susceptibility measurements. 

These are derived by subtraction of the standard molar enthalpy of formation of the binary oxides, since standard enthalpies of individual reactions can be combined to obtain the standard enthalpy of another reaction. Thus,... 

Whereas the enthalpy of formation of A12Si(>5 from the elements is large and negative, the enthalpy of formation from the binary oxides is much less so. Af ox m is furthermore comparable to the enthalpy of transition between the different polymorphs, as shown for A SiOs in Table 1.5 [3], The enthalpy of fusion is also of similar magnitude. 

ArV is not necessarily positive, and to compare the relative stability of the different modifications of a ternary compound like AGSiOs the volume of formation of the ternary oxide from the binary constituent oxides is considered for convenience. The pressure dependence of the Gibbs energies of formation from the binary constituent oxides of kyanite, sillimanite and andalusite polymorphs of A SiOs are shown in Figure 1.10. Whereas sillimanite and andalusite have positive volumes of formation and are destabilized by pressure relative to the binary oxides, kyanite has a negative volume of formation and becomes the stable high-pressure phase. The thermodynamic data used in the calculations are given in Table 1.7 [3].1... 

The binary systems we have discussed so far have mainly included phases that are solid or liquid solutions of the two components or end members constituting the binary system. Intermediate phases, which generally have a chemical composition corresponding to stoichiometric combinations of the end members of the system, are evidently formed in a large number of real systems. Intermediate phases are in most cases formed due to an enthalpic stabilization with respect to the end members. Here the chemical and physical properties of the components are different, and the new intermediate phases are formed due to the more optimal conditions for bonding found for some specific ratios of the components. The stability of a ternary compound like BaCC>3 from the binary ones (BaO and CC>2(g)) may for example be interpreted in terms of factors related to electron transfer between the two binary oxides see Chapter 7. Entropy-stabilized intermediate phases are also frequently reported, although they are far less common than enthalpy-stabilized phases. Entropy-stabilized phases are only stable above a certain temperature,... 

For a binary oxide like Fe203 the reaction in question is... 

Let us initially look at a semiconducting binary oxide Ai gO in a chemical gradient an oxygen potential gradient. Reduction takes place on the low oxygen... 

---