Cobalt , crystal

Promoters leading to increased cobalt dispersion. The addition of promoter elements may also lead to increased cobalt dispersion after preparation. In the absence of the promoters, relatively large cobalt crystals are formed, whereas, by adding these additives, smaller supported cobalt particles can be made. Such promotion effect is illustrated in Figure 3C. 

In the reaction of carbon monoxide on a cobalt crystal which could exist in two crystal structures depending on the temperature, the pattern of deposits followed the symmetry of the structure existing at the temperature of the reaction. 

Cobalt crystallizes in the HCP structure, which contains two atoms per unit cell. The atomic radius of the Co atom is 0.1253 nm. 

FIGURE 10.8 HRTEM images showing the behavior of two cobalt crystals covered by different number of graphitic shells under electron irradiation at 1000 K. It can be seen that while the smaller crystal on the left side is displaced rather rapidly, the larger crystal with initially one and then two graphitic shells shows almost no shrinking. (Adapted from Banhart, F., Redlich, Ph., Ajayan, P.M., 1998, Chem. Phys. Lett. 292, 554-560.)... 

Cobalt. - Crystal structures are reported for the phosphine substituted complex [Co2(C0)g(PMe3)2] and for the alkynyliron bridged species [Co2((t-PhCsCFp) (CO)g].240 studies of the radical anion [CO2(C0)2 (PF2)2NMe>3r indicate that the unpaired electron is in an intermetallic a molecular orbital mainly composed of cobalt orbitals.241 The coupling of alkylIdene with CO in complexes [Co2 /t-CHR)(jx-L)( -dppm)(CO)4] to yield ketenes has been studied under CO or S02. ... 

Cobalt chloride, C0CI2. Obtained as red crystals of CoCl2 6H20 from aqueous solution, CoCU HiO and C0CI2 are blue as is the (CoCU) " ion. No higher chloride is known although cobalt-haloammines, e.g. (Co(NH3)5C1) are stable. 

Kitakami O et al 997 Size effect on the crystal phase of cobalt fine particles Phys. Rev. B 56 13 849 Cullity B D 1978 Elements of X-ray Diffraction (Reading, MA Addison-Wesley)... 

Cobalt is a bluish silvery metal, exhibits ferromagnetism, and can exist in more than one crystal form it is used in alloys for special purposes. Chemically it is somewhat similar to iron when heated in air it gives the oxides C03O4 and CoO, but it is less readily attacked by dilute acids. With halogens, the cobalt(II) halides are formed, except that with fluorine the (III) fluoride, C0F3, is obtained. 

Tin-cobalt alloys Tin compounds Tin-copper alloys Tin crystals Tincture Tinctures... 

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. 

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

V-methyl aniline formed in the initial step to give the leuco base of methyl violet. Treatment with aqueous acid produces the dye. Because Michler s hydrol may also react with dimethyl aniline instead of the /V-methyl aniline to give crystal violet, commercial-grade methyl violet is usually a mixture. A cobalt complex has converted 4,T-dimethylaminodipheny1methane and dimethyl aniline in the presence of atmospheric oxygen to crystal violet in one step (50). 

Electrochemistry and Kinetics. The electrochemistry of the nickel—iron battery and the crystal stmctures of the active materials depends on the method of preparation of the material, degree of discharge, the age (Life cycle), concentration of electrolyte, and type and degree of additives, particularly the presence of lithium and cobalt. A simplified equation representing the charge—discharge cycle can be given as ... 

Titanate Pigments. When a nickel salt and antimony oxide are calcined with mtile titanium dioxide at just below 1000°C, some of the added metals diffuse into the titanium dioxide crystal lattice and a yellow color results. In a similar manner, a buff may be produced with chromium and antimony a green, with cobalt and nickel and a blue, with cobalt and aluminum. These pigments are relatively weak but have extreme heat resistance and outdoor weatherabihty, eg, the yellow is used where a light cadmium could not be considered. They are compatible with most resins. 

Nitroso-l-napbthol-4-sulfonic acid (3H2O) [3682-32-4] M 316.3, m 142-146°(dec), pK ,t -6.3 (OH). Crystd from dilute HCl soln. Crystals were dried over CaCl2 in a vacuum desiccator. Also purified by dissolution in aqueous alkali and pptn by addition of water. Reagent for cobalt. 

Cobalt (II) meso-5.10,15,20-tetraphenylporphine complex [14172-90-8] M 671.7. Brown crystals from Et20 or CHCl3-MeOH (cf iron chloride complex). Recrystd by extraction (Soxhlet) with CgHg. Sol in most organic solvents except MeOH and pet ether. [UV, IR J Am Chem Soc 70 1808 7948 81 5111 7959.]... 

Quite recently, Ciampolini and coworkers have reported the synthesis of two isomeric mked oxygen-phosphorus macrocycles and the crystal structures of their cobalt complexes. Synthesis of macrocycle 27 was accomplished by condensation of 1,2-bis-(phenylphosphino)ethane dianion with 2,2 -dichlorodiethyl ether in THE. The two isomers of 27 were isolated in 1.5% and 2% yield. The synthesis is formulated in Eq. (6.17), below. 

The effect of the CFSE is expected to be even more marked in the case of the heavier elements because for them the crystal field splittings are much greater. As a result the +3 state is the most important one for both Rh and Ir and [M(H20)6] are the only simple aquo ions formed by these elements. With rr-acceptor ligands the +1 oxidation state is also well known for Rh and Ir. It is noticeable, however, that the similarity of these two heavier elements is less than is the case earlier in the transition series and, although rhodium resembles iridium more than cobalt, nevertheless there are significant differences. One example is provided by the +4 oxidation state which occurs to an appreciable extent in iridium but not in rhodium. (The ease with which Ir, Ir sometimes occurs... 

CoNbOF5 [129] can also be considered an MeX3 type compound due to the steric similarity of cobalt and niobium ions. This compound crystallizes in tetragonal syngony with cell parameters a = 7.81 and c = 9.02 A (Z = 4 p = 3.19 g/cm3), and can be considered to have a distorted cubic Re03 structure. Both cobalt and niobium occur in the center of oxyfluoride octahedrons that are linked via their vertexes. 

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