Cation ratio

When ahovalent, ie, different valence, impurities are added to an ionic soHd, the crystal lattice compensates by forming defects that maintain both electrical neutraUty and the anion to cation ratio of the host lattice. For example, addition of x mol of CaO to Zr02 requires the formation of x mol of oxygen vacancies. 

The results of the extraction of metal cations are summarized in Table 3. The 4b showed the selectivity toward Fe " cation and cannot act as an extractant for Fe " at pH 2.2. The extraction of Fe cation with 4b was increased with increasing pH, but the Fe cation ratios at all pH decrease than that of 2b and 3b. The results suggested that the conformation of 4b and the C=0 groups in the polymer affected the extraction of Fe in this process. 

Since hydrofluoride synthesis is based on thermal treatment at relatively high temperatures, the possibility of obtaining certain fluorotantalates can be predicted according to thermal stability of the compounds. In the case of compounds whose crystal structure is made up of an octahedral complex of ions, the most important parameter is the anion-cation ratio. Therefore, it is very important to take in to account the ionic radius of the second cation in relation to the ionic radius of tantalum. Large cations, are not included in the... 

Table 15 summarizes anion-cation ratio for different types of fluorotantalates. Thermally stable compounds that can be prepared using the hydrofluoride method are noted in bold. 

Berndt, M.E., Seyfried, W.E. Jr. and Janeckey, D.R. (1989) Plagioclase and epidote buffering of cation ratios in midocean ridge hydrothermal fluids Experimental results in and near the supercritical region. Geochim. Cosmochim. Acta, 53, 2283-2300. 

Barne.s, H.L. and Czamanske, G.K. (1967) Solubilities and transport of ore minerals. In Barnes, H.L. (ed.). Geochemistry of Hydrothermal Ore Deposits. New York Holt, Rinehart and Win.ston, pp. 334-381. Berndt, M.E., Seyfried, W.E. Jr. and Janeckey, D.R. (1989) Plagiocla.se and epidote buffering of cation ratios in midocean ridge hydrothermal fluids Experimental results in and near the supercritical region. Geochim. Cosmochim. Acta, 53, 2283-2300. 

The electrodeposited Bi2Sr2CaiCu2Ox (BSCCO) precursor films were obtained by co-electrodeposition of the constituent metals using nitrate salts dissolved in DMSO solvent. The electrodeposition was performed in a closed-cell configuration at room temperature ( 24°C). The cation ratios of the electrodeposition bath were adjusted systematically to obtain BSCCO precursor compositions. A typical electrolyte-bath composition for the BSCCO films consisted of 2.0-g Bi(N03)3-5H20,1.0-g Sr(N03)2, 0.6-g Ca(N03)2-4H20, and 0.9-g Cu(N03)2-6H20 dissolved in 400 mL of DMSO solvent. The substrates were single-crystal LAO coated with 300 A of Ag. 

Fig. 2. Jensen cation plot for the classification of volcanic rocks in the Lac Cinquante region according to their Al, Mg, and Fe+Ti cation ratios.

As solvents, ionic liquids can be uniquely tuned to a particular purpose by adjusting the anion/cation ratio. To decaffeinate coffee, for example, you could create an ionic liquid that would just dissolve caffeine and nothing else. Current research suggests that ionic liquids can be recovered from solution and reused. 

The electrolyte concentration is very important when it comes to discussing mechanisms of ion transport. Molar conductivity-concentration data show conductivity behaviour characteristic of ion association, even at very low salt concentrations (0.01 mol dm ). Vibrational spectra show that by increasing the salt concentration, there is a change in the environment of the ions due to coulomb interactions. In fact, many polymer electrolyte systems are studied at concentrations greatly in excess of 1.0 mol dm (corresponding to ether oxygen to cation ratios of less than 20 1) and charge transport in such systems may have more in common with that of molten salt hydrates or coulomb fluids. However, it is unlikely that any of the models discussed here will offer a unique description of ion transport in a dynamic polymer electrolyte host. Models which have been used or developed to describe ion transport in polymer electrolytes are outlined below. 

Abstract world class unconformity-related U deposits occur in the Proterozoic McArthur Basin (Northern Territory, Australia) and Athabasca Basin (Saskatchewan, Canada). Widespread pre-to post-ore silicifications in the vicinity of the deposits, allow proper observation of paragenetically well-characterized fluid inclusions. We used a combination of microthermometry, Raman microspectroscopy and Laser Induced Breakdown Spectroscopy (LIBS), to establish the physical-chemical characteristics of the main fluids having circulated at the time of U mineralization. The deduced salinities, cation ratios (Na/Ca, Na/Mg) and P-T conditions, led to the detailed characterization of a NaCI-rich brine, a CaCl2-rich brine and a low-salinity fluid, and to the identification of mixing processes that appear to be key factors for U mineralization. 

The detailed synthesis of the IL s used here was described earlier (6). Two samples were prepared having R = butyl but the Al/cation ratio was 3/2 and 2 mol/mol. One sample each was prepared having R = ethyl, hexyl, octyl, and dodecyl for which the Al/cation = 2 mol/mol. 

Uniformly, within this group of cations, perchlorate ion accompanying the transition-element cation is replaced by nitrate (7,31), thiocyanate (7,52), or halide (7,6). Nitrate is probably replaced by thiocyanate, but a secondary change takes place in many systems, which makes direct comparison difficult (see below). If one then makes the further reasonable assumption that solvent interference can be used as an inverse measure of tendency to bind to the central metal cations, thiocyanate, whose competition with alcohol is less efficient (52) than that of chloride (6), should be somewhat replaceable with chloride. Comparisons between chloride and thiocyanate in acetonitrile show also that the formation of a complex with a given anion/cation ratio takes place much more readily with chloride than with thiocyanate (55, 34). By the same criterion, from experiments in alcoholic solution (55), bromide should replace chloride, and an extrapolation of the behavior to iodide seems reasonable. 

The AS-values increased with respect to those of the dehydrated samples (8), especially for the samples with high H20/cation ratios. This means that there is a distortion of the cationic hydration shell or a partial dehydration of the cations during migration (18). In other words, water around the migrating cations cannot be regarded water of hydration. In that respect, hydrated zeolites resemble concentrated cationic solutions (19). 

Table 21.3 Phase assemblage of glass-ceramics with constant cation ratios (16.5Y 56Si 27.5AI e/o) and increasing levels of nitrogen, N, and carbon, C, after heat treatment at 1200°C for 1 h (Hampshire and Ramesh, 1996) ...

Point defects are an important part of the work in this paper. There are many reasons for the formation of point defects in minerals and their presence can exert important perturbations on the properties of the material (4). Point defects are formed because of the thermally driven intrinsic disorder in a lattice, the addition of aliovalent impurities or dopants, the presence of metal-nonmetal nonstoichiometry, and the creation of nonideal cation ratios. The first three source of defects are well-known from binary compounds but the last is unique to ternary compounds. Ternary compounds are much more complex than the binary compounds but they also have gained a great deal of attention because of the variety of important behavior they exhibit including now the presence of superconductivity at high temperatures. The point defects can be measured by introducing probe ions into the lattice. 

Regarding size, it was apparent that particle size increased with the anion to cation ratio. The scatter of data, however, indicated that batch processing was generally quite unreliable. 

Table 5. Calculated values of stoichiometric coefficients as dependent on the anion/cation ratio (C/S). Data were obtained from 15 pooled samples the last two lines show variability between two separate runs...

---