• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.368-372
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• 2006

The cobalt titanate, $CoTiO_3$ nanoparticles have been prepared by calcinations of precursor obtained from a mixture of $TiO_2$ and $Co(OH)_2$ in aqueous cetyltrimethylammonium bromide (CTAB) solution. The nanoparticles were investigated with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analysis (TGA/DTA) to determine the crystallite size and the phase composition. The spectroscopic characterizations of these nanoparticles were also done with UV-Vis spectroscopy and FT-Raman spectroscopy. XRD patterns show that $CoTiO_3$ phase was formed at calcinations temperature above 600 ${^{\circ}C}$. UV-Vis absorption spectra indicate that the $CoTiO_3$ nanoparticles have significant red shift to the visible region (400-700 nm) with $\lambda_{max}$ = 500 nm compared to pure $TiO_2$ powder ($\lambda_{max}$ = 320 nm). The new absorption peaks (absorption at 696, 604, 520, 478,456, 383, 336, 267, 238, 208 $c m ^{-1}$), which were not appeared in FT-Raman spectra of P-25, also confirm the formation of Ti-O-Co bonds at above 600 ${^{\circ}C}$ and just not the mixtures of titanium dioxide with cobalt oxides.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.933-941
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• 2008

The formation of $Co_nTiO_{n+2}$ compounds, i.e., $CoTiO_3$ and $CO_2TiO_4$, in a 5wt% $CoO_x/TiO_2$ catalyst after calcination at different temperatures has been characterized via scanning electron microscopy (SEM), Raman and X-ray photoelectron spectroscopy (XPS) measurements to verify our earlier model associated with $CO_3O_4$ nanoparticles present in the catalyst, and laboratory-synthesized $Co_nTiO_{n+2}$ chemicals have been employed to directly measure their activity profiles for CO oxidation at $100^{\circ}C$. SEM measurements with the synthetic $CoTiO_3$ and $CO_2TiO_4$ gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 $cm^{-1}$ appeared on 5wt% $CoO_x/TiO_2$ after calcination at $570^{\circ}C$ but not on the catalyst calcined at $450^{\circ}C$, and these peaks were observed for the $Co_nTiO_{n+2}$ compounds, particularly $CoTiO_3$. All samples of the two cobalt titanate possessed O ls XPS spectra comprised of strong peaks at $530.0{\pm}0.1$ eV with a shoulder at a 532.2-eV binding energy. The O ls structure at binding energies near 530.0 eV was shown for a sample of 5 wt% $CoO_x/TiO_2$, irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and $570^{\circ}C$ is the 532.2 eV shoulder which was indicative of the formation of the $Co_nTiO_{n+2}$ compounds in the catalyst. No long-life activity maintenance of the synthetic $Co_nTiO_{n+2}$ compounds for CO oxidation at $100^{\circ}C$ was a good vehicle to strongly sup port the reason why the supported $CoO_x$ catalyst after calcination at $570^{\circ}C$ had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the $CO_3O_4$ nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.

• Coupled systems mechanics
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• v.6 no.4
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• pp.465-485
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• 2017

In this paper, free vibration and static response of magneto-electro-elastic (MEE) beams has been investigated. To this end, a 3D finite element formulation has been derived by minimization the total potential energy and linear constitutive equation. The coupling between elastic, electric and magnetic fields can have a significant influence on the stiffness and in turn on the static behaviour of MEE beam. Further, different Barium Titanate ($BaTiO_3$) and Cobalt Ferric oxide ($CoFe_2O_4$) volume fractions results in indifferent coupled response. Therefore, through the numerical examples the influence of volume fractions and boundary conditions on the natural frequencies of MEE beam is illustrated. The study is extended to evaluate the static response of MEE beam under various forms of mechanical loading. It is seen from the numerical evaluation that the volume fractions, loading and boundary conditions have a significant effect on the structural behaviour of MEE structures. The observations made here may serve as benchmark solutions in the optimum design of MEE structures.