Chromium effect crystal

However, as we have already pointed out, the value of Sgg — t2g is quite insensitive to the electronic configuration (2). Therefore, in the present paper, we approximated all of these effective crystal-field splittings by the value of eg — t2g Calculated in the ground state. On the other hand, the Racah parameters represent the electron-electron repulsion interaction and can be calculated by the radial part of the pure 3d atomic orbitals of the impurity chromium ion (1). After evaluating the value of these parameters, the multiplet structure of ruby can be obtained by diagonalizing the Tanabe-Sugemo matrices. 

Further purification of the carbonyl is effected by recrystallization from dry ether this is best accomplished by placing the crude product in the thimble of a Soxhlet extractor and extracting with dry ether. Pure chromium hexacarbonyl crystallizes on cooling it is filtered and washed as before. 

Early studies on oxide films stripped from iron showed the presence of chromium after inhibition in chromate solutionand of crystals of ferric phosphate after inhibition in phosphate solutions. More recently, radio-tracer studies using labelled anions have provided more detailed information on the uptake of anions. These measurements of irreversible uptake have shown that some inhibitive anions, e.g. chromateand phosphate are taken up to a considerable extent on the oxide film. However, other equally effective inhibitive anions, e.g. benzoate" pertechnetate and azelate , are taken up to a comparatively small extent. Anions may be adsorbed on the oxide surface by interactions similar to those described above in connection with adsorption on oxide-free metal surfaces. On the oxide surface there is the additional possibility that the adsorbed anions may undergo a process of ion exchange whereby... 

Chromium, (ri6-benzene)tricarbonyl-stereochemistry nomenclature, 1,131 Chromium complexes, 3,699-948 acetylacetone complex formation, 2,386 exchange reactions, 2,380 amidines, 2,276 bridging ligands, 2,198 chelating ligands, 2,203 anionic oxo halides, 3,944 applications, 6,1014 azo dyes, 6,41 biological effects, 3,947 carbamic acid, 2,450 paddlewheel structure, 2, 451 carboxylic acids, 2,438 trinuclear, 2, 441 carcinogenicity, 3, 947 corroles, 2, 874 crystal structures, 3, 702 cyanides, 3, 703 1,4-diaza-1,3-butadiene, 2,209 1,3-diketones... 

Eujii T, Suzuki D, Gunjii K, Watanabe K, Moriyama H, Nishizawa K (2002) Nuclear field shift effect in the isotope exchange reaction of chromium(III) using a crown ether. J Phys Chem A 106 6911-6914 Gale JD (2001) Simulating the crystal structures and properties of ionic materials from interatomic potentials. Rev Mineral Geochem 42 37-62... 

The high hardness of chromium oxide resulting from its crystal structure is exploited in polishing agents for metals and in brake linings. Addition of a small amount of chromium oxide to magnetic materials of audio and video tapes imparts a self-cleaning effect to the sound heads. 

These results indicate that alumina acts on CrgOg phase to prevent its clustering and segregation with high coordinate Cr + ions. This dispersive effect of the support provides a suitable environment for the formation on the surface of low coordinate chromium ions (ref. 2). However this effect of alumina tends to depress when the content of chromium exceeds 30 % at 410°C. This result seems to Indicate a saturation of the surface sites of the support which interact with the chromium (surface of alumina covered with a layer of chromium oxide). Then an excess of Cr O deposited leads to its clustering and crystallization. Consequently the coordination of chromium ions changes from tetrahedral (low coordination) to octahedral (high coordination). 

Bums, R. G. (1975b) Crystal field effects in chromium and its partitioning in the mantle. Geochim. Cosmochim. Acta, 39,857-64. 

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