Fluorite CaF

Fluorite. CaF,. and rutile. TiO,. are minerals in CaFj, each Ca is surrounded by eight F ions, each F by tour C r ions, while in TiO, ihe corresponding co-ordination numbers are 6 and 3. Co-ordination number is generally referred to the cation. 

The correlation of phosphate precipitation with decrease of conductivity (Wilson Kent, 1968), increase in pH (Kent Wilson, 1969) and hardness (Wilson et al, 1972) is shown in Figure 6.16. These results demonstrate the relationship between the development of physical properties and the underlying chemical changes, but there are no sharp changes at the gel point. Evidence from infrared spectroscopy (Wilson Mesley, 1968) and electron probe microanalysis (Kent, Fletcher Wilson, 1970 Wilson et al, 1972) indicates that the main reaction product is an amorphous aluminophosphate. Also formed in the matrix were fluorite (CaF ) and sodium acid phosphates. 

Penetration twins have an irregular composition plane, and the twin plane and the composition plane are not the same. As a representative example, the 111 twin of fluorite, CaF, is shown in Fig. 7.8. 

In laboratory tests of flotation, fluorite (CaF particles (range of particle diameters, 0.074-0.147 mm) with oleic acid as collector were aerated under three different conditions. These conditions and the percent CaF2 recovery after 10 min are as follows ... 

Crystals with the Rutile and the.Fluorite Structures Interionic Distances for Substances of Unsymmetrical Valence Type.—In a crystal of a substance of unsymmetrical valence type, such as fluorite, CaFs (Fig. 13-10), the equilibrium cation-anion interionic distance cannot be expected necessarily to be given by the sum of the crystal radii of the bivalent calcium ion and the univalent fluoride ion. The sum of the univalent radii of calcium and fluoride, 2.54 A, would give the equilibrium interionic distance in a hypothetical crystal with attractive and repulsive forces corresponding to the sodium chloride arrangement. 

Fig. I. Example of the temperature dependence of enthalpy relative to 25°C. Hi - Hyth is- anJ heal capacity. Cp. The data arc tor fluorite, CaF K K Kelly. 191)0). The discontinuities in the lines correspond In the a to p transition 11424 K> and the fusion 11691 K)...

The composition of the first successful glass, the so-called G200, is given in Table 6.1. It differs from modem glasses in that it is much higher in fluorite, CaF. As a consequence, its translucency is inferior, as is the franslucency of the cements prepared from it. 

Catti, M., Dovesi, R., Pavese, A., and Saunders, V.R. (1991) Elastic constants and electronic structure of fluorite (CaFs) an ab initio Hartree-Fock study, J. Phys. Condens. Matter 3, 4151- 4164. 

All the lanthanide elements form +3 oxides which are strongly basic. Cerium, Pr and Tb also form formally +4 oxides, but only the Ce oxide approaches 1 2 stoichiometry. The oxides of Pr and Tb are non-stoi-chiometric and approximate to the formulae Pr O, and Tb O, both showing oxygen deficiencies. The three dioxides have the fluorite (CaF,) structure with oxide ion vacancies. They are basic in character. Three of the lanthanide elements, Sm, Eu and Yt, form +2 oxides with sodium chloride structures. They are basic. 

TABLE 4.8 Fluorite (CaF ) and Anti-Fluorite (Na O) Types of Crystalline Substances after (Chiriac-Putz-Chiriac, 2005)... 

Fluorite CaF is found in many different colors. It occurs in veins, usually as a gangue mineral associated with lead, tin and zinc ores. It is the principal ore of fluorine, and... 

The most intense feature in the Raman microscopy spectrum of the ash specimen is at 475 cm Actinide oxides are known to crystallize at high temperature with a fluorite (CaFs) structure and space group Fm3m(Ol). This structure is predicted to possess a simple vibrational structure with one IR active phonon of T symmetry (302 cm for PUO2) and one Raman active phonon of T2g symmetry (478 cm for PUO2) at = 0 [88]. Therefore, the 475-cm Raman band can be assigned to the T2 mode of PUO2. 

Most substances that contain F are soluble. A common fluoride mineral is fluorite, CaF, which occurs in a variety of colors including purple, green, and yellow. Likewise, in rule 4, most substances that contain SO 4 are soluble, mostly with the exception of some of the alkaline earths and the lead ion. 

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