Minerals complex oxide

Principles and types of modular series have been summarized in a book by Ferraris et al. (2004). A hierarchical classification of structure has been introduced as well as the application of modularity to structure description and modelling. The order/disorder theory has been presented as fundamental to developing a systematic theory of polytypism, dealing with structures based on both ordered and disordered stacking of one or more layers. The structures of a great number of compounds (minerals, complex oxides, salts, etc.) have been described and discussed. 

Ytterby, a village in Sweden) Discovered by Mosander in 1843. Terbium is a member of the lanthanide or "rare earth" group of elements. It is found in cerite, gadolinite, and other minerals along with other rare earths. It is recovered commercially from monazite in which it is present to the extent of 0.03%, from xenotime, and from euxenite, a complex oxide containing 1% or more of terbia. 

The processing of tantalum and niobium begins with the fluorination of the raw material, which always consists of complex oxide compounds containing tantalum and niobium. The main types of tantalum- and niobium-containing minerals are discussed in Chapter 1, and typical compositions of such minerals are presented in Table 2. 

Site-binding constants have been determined for only a limited range of simple oxides with only one type of surface site. Multiple-surface site minerals occurring in the deep-well environment such as silicates, aluminosilicates, and complex oxides (such as manganese oxide) will require much more complex TLMs. 

The importance of the size of the solute relative to that of the solvent mentioned above is evident also from experimental determinations of the extent of solid solubility in complex oxides and from theoretical evaluations of the enthalpy of solution of large ranges of solutes in a given solvent (e.g. a mineral). The enthalpy of solution for mono-, di- and trivalent trace elements in pyrope and similar systems shows an approximately parabolic variation with ionic radius [44], For the pure mineral, the calculated solution energies always show a minimum at a radius close to that of the host cation. 

The Renison Bell tin mine is a large, but complex, oxide mineral deposit. Renison ore consists largely of pyrrhotite, quartz, dolomite, siderite and dorite. The chemical composition of the iron varies considerably. Some of the ore types are high in copper and silver. Table 21.5 shows the chemical analyses of various ore types. 

Schematic illustration on the specific adsorption on Fe-minerals of oxidants and reductants directly or through ligand bridges. The formation of these surface complexes (which is usually fast) facilitates the subsequent electron transfer.

Parks, G. A. (1967), "Aqueous Surface Chemistry of Oxides and Complex Oxide Minerals Isoelectric Point and Zero Point of Charge," in Equilibrium Concepts in Natural Water Systems, Advances in Chemistry Series, No. 67, American Chemical Society, Washington, DC. 

Clay minerals, oxides, and humic substances are the major natural subsurface adsorbents of contaminants. Under natural conditions, when humic substances are present, humate-mineral complexes are formed with surface properties different from those of their constituents. Natural clays may serve also as a basic material for engineering novel organo-clay products with an increased adsorption capacity, which can be used for various reclamation purposes. 

Terbium occurs in nature associated with other rare earths. It is found in minerals xenotime, a rare earth phosphate consisting of 1% terbia and in euxenite, a complex oxide containing about 1.3% terbia. It also is found in cerite, monazite, and gadolinite. Also, the element has been detected in stellar matter. Abundance of terbium in the earth s crust is estimated to be 1.2 mg/kg. 

Little is known concerning the chemistry of nickel in the atmosphere. The probable species present in the atmosphere include soil minerals, nickel oxide, and nickel sulfate (Schmidt and Andren 1980). In aerobic waters at environmental pHs, the predominant form of nickel is the hexahydrate Ni(H20)g ion (Richter and Theis 1980). Complexes with naturally occurring anions, such as OH, SO/, and Cf, are formed to a small degree. Complexes with hydroxyl radicals are more stable than those with sulfate, which in turn are more stable than those with chloride. Ni(OH)2° becomes the dominant species above pH 9.5. In anaerobic systems, nickel sulfide forms if sulfur is present, and this limits the solubility of nickel. In soil, the most important sinks for nickel, other than soil minerals, are amorphous oxides of iron and manganese. The mobility of nickel in soil is site specific pH is the primary factor affecting leachability. Mobility increases at low pH. At one well-studied site, the sulfate concentration and the... 

The pink or brick diatomite has been crushed, blended and pressed into bricks, which are calcined (burned) at temperatures greater than 900°C. During the process the mineral impurities form complex oxides and/or silicates. 

Aqueous Surface Chemistry of Oxides and Complex Oxide Minerals... 

Experimental Data. To provide a reference list of ZPC s for complex oxide minerals and coprecipitates and to obtain examples for studying the predictive usefulness of Equation 18, experimental data were collected. Owing to the diversity of observations from which ZPC s can be inferred, sources included the literature of colloid and soil science, sanitary engineering, and mineral engineering, especially froth flotation. A thorough search would require screening by mineral species as well as by topic and therefore was judged unwarranted. 

From a practical point of view, these compounds are models of crystalline matrices for nuclear waste disposal. One such storage material is SYNROC, a synthetic mineral whose major constituents are the complex oxides hollandite, zirconolite, and perovskite. We have chosen perovskite as a model structural family because of its efficient packing and its accommodation of a wide range of cations, both in size and oxidation state (5). 

The decreasing electropositive character of the elements across the series is shown in the typical minerals they form, and in the methods required to extract them. Early elements are found in oxide or complex oxide minerals (e.g., Ti02, CrFe03) and are known as lithophilic, whereas later elements are found... 

Attention will then be turned to the major oxide minerals MgO, AljOj, and SiOj and the binary transition-metal oxides of Ti, Mn, and Fe, with some brief discussion of the series of transition-metal monoxides (MnO, FeO, CoO, NiO) and complex oxides (FeCr204, FeTiOj, etc.), and of the problem of the calculation of Mossbauer parameters in iron oxides (and other compounds). 

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