Cobalt lattice structure

Another example of phase change is the one exhibited by electrodeposited cobalt. In this case the transformation is from fee- to hep-tj pe lattice structure as a result of hydrogen inclusion during depKJsition on the one hand and subsequent out-diffusion on the other hand. 

The dispersion relation Fig. 3(b) clearly shows that the upper lying band takes over the nature of the Kagome lattice structure hidden in the triangular lattice of cobalt ions (see Fig. 4) despite of the presence of tdd, l and t2. Therefore, it is of crucial importance to study the effect of the Kagome lattice structure to clarify the electronic state in the C0O2 layer. 

The Kagome lattice structure clearly explains the non-symmetric nature of the band structure of the C0O2 layer. When the effect of the Kagome lattice becomes dominant, the bottom band, i.e., the flat band as shown in Fig, 3(a) will play a crucial role on the electronic state. Mielke [32] has shown that the flat band with the Coulomb interaction has the ferromagnetic ground state at around half filling. A prospective system for the ferromagnet will be dl transition metal oxides, i.e., the layered titanates with iso-structure of the cobalt oxides. 

HCP (hexagonal close packing) A type of crystal lattice structure found in zinc, titanium, and cobalt, for example. 

Thermal decomposition is the process wherein the structure of the catalyst is formed by the heat treatment of the precursor after volatile components are decomposed or chemical water associated with the lattice structure of the solid is removed. Examples of such a phenomenon are the decomposition of metal nitrate, hydroxide, carbonate, chloride, sulfate, phosphate, hydroxy salts, or oxy salts to corresponding oxides. The following equation shows the decomposition of cobalt nitrate coupling with partial oxidation of Co ... 

Manganese, iron, and cobalt have structures different from the other members of their columns, which is generally attributed to magnetism. Nonmagnetic manganese and iron would be expected to be hep and cobalt would be expected to be fee crystal lattice. 

The equilibrium, room temperature structure of pure cobalt is hep. The fee structure is stable at high temperatures (422 °C to 1495 °C) and has been retained at room temperature by rapid solidification techniques [101], X-ray diffraction analysis was used to probe the microstructure of bulk Co-Al alloy deposits containing up to 25 a/o Al and prepared from solutions of Co(II) in the 60.0 m/o AlCfi-EtMelmCl melt. Pure Co deposits had the hep structure no fee Co was observed in any of the deposits. The addition of aluminum to the deposit caused a decrease in the deposit grain size and an increase in the hep lattice volume. A further increase in the aluminum content resulted in amorphization of the deposit [44], Because the equilibrium... 

What is the structure of this Co-Mo-S phase A model system, prepared by impregnating a MoS2 crystal with a dilute solution of cobalt ions, such that the model contains ppms of cobalt only, appears to have the same Mossbauer spectrum as the Co-Mo-S phase. It has the same isomer shift (characteristic of the oxidation state), recoilfree fraction (characteristic of lattice vibrations) and almost the same quadrupole splitting (characteristic of symmetry) at all temperatures between 4 and 600 K [71]. Thus, the cobalt species in the ppm Co/MoS2 system provides a convenient model for the active site in a Co-Mo hydrodesulfurization catalyst. 

The total surface areas determined by the N2 BET method for the calcined, supported catalysts are listed in Table II. The X-ray diffraction (XRD) results showed diffraction peaks from a cubic lattice with a unit cell distance of 6.1 A were present on all of the calcined catalysts. Both C03O4 and C0AI2O4 have structures consistent with that lattice spacing, making assignment of the type of crystalline cobalt species present on the alumina supports difficult. 

The spinel ferrites were fabricated by solid state reaction technique. Cobalt and Zinc ferrites CoxZnyFe204,(x=0.7,0.3,0.4,0.2 and y=0.3,0.7,0.6,0.8) were prepared by solid state reaction technique. The crystalline structure of the sample was investigated by X-ray diffraction(XRD). All samples show cubic spinel structure. The lattice parameter decreases with increasing cobalt content. Magnetic properties shows that the prepared sample exhibit ferromagnetic behaviour at room temperature. The saturation magnetization increases with increasing cobalt content. Curie temperature... 

Spectra of the mixed spinels are interpretable in terms of X-ray diffraction studies of the same samples by Azdroff (16). Cobalt appears to be in the divalent condition, based upon the location of the principal maximum. Manganese appears in a higher valence state. The extended fine structure, which is supposed to be determined by the lattice, appears identical for all the spectra of Figs. 14 and 15 which are of truly cubic spinels, namely CosOi,... 

Figure 1 shows Fourier transforms of EXAFS spectra of a few samples prepared. The radial distribution functions of these samples are different from that of nickel oxide or cobalt oxide [7]. All the Fourier transforms showed two peaks at similar distances (phase uncorrected) the peak between 1 and 2 A is ascribed to the M-0 bond (M divalent cation) and the peak between 2 and 3 A is ascribed to the M-O-M and M-O-Si bonds. The similar radial distribution functions in Figure 1 indicate that the local structures of X-ray absorbing atoms (Ni, Co, and Zn) are similar. No other bonds derived from metal oxides (nickel, cobalt and zinc oxides) were observed in the EXAFS Fourier transforms of the samples calcined at 873 K, which suggests that the divalent cations are incorporated in the octahedral lattice. 

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