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The potential and current oscillations during corrosion of NiCoAg alloy in Hank solution were studied. Detailed nonlinear fractal analyses were used to characterize complex time series clearly showing that the irregularity in these time series corresponds to deterministic chaos rather than to random noise. The chaotic oscillations were characterized by power spectral densities, phase space, and Lyapunov exponents. Electrochemical impedance was also applied the fractal dimensions for the corroded surface was obtained, and a corrosion mechanism was proposed.

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A new iron indium germanate has been prepared as polycrystalline powder material which crystallizes in the monoclinic system (S.G. C2=m, No. 12). The structure was characterized by X-ray powder diffraction and Rietveld refinement of the resulting diffraction pattern. The cell parameters are a ¼ 6:5124 (4) The structure contains R þ3 cations (R¼Fe, In) almost equally distributed in distorted RO 6 octahedral sites. These octahedra are joined by edge sharing forming a hexagonal arrangement on the ab planes. The RO 6 octahedra layers are held together by sheets of isolated Ge 2 O 7 diorthogroups constituted by a double tetrahedra sharing a common vertex. This compound has the thortveitite structure and keeps a strong relationship with the FeYGe 2 O 7 germanate, which presents two R þ3 sites with six-coordinated (R¼ Fe) and seven-coordinated (R¼Y) oxygens, corresponding to the different symmetry given by the monoclinic space group P2 1 =m (No. 11).