Investigation of Co(OH)2 formation during cobalt electrodeposition using a chemometric procedure

AbstractThe mechanism of Co electrodeposition in sulphate solutions containing boric acid was investigated using the EQCM technique and potentiostatic measurements. The effects of solution composition, temperature and deposition potential were studied using factorial design as a chemometric procedure. The boric acid was used as a buffer to prevent pH changes due to the hydrogen evolution reaction (HER) during electrodeposition. The results showed that Co(OH)2 was formed as a parallel reaction to metallic Co formation under some experimental conditions. The analysis of the factorial design revealed that temperature and [Co2+:H3BO3] molar ratio were the critical variables that affect the mechanism of cobalt electrodeposition. At high temperatures (48°C) and using a 5:1 molar ratio of [Co2+:H3BO3], the formation of cobalt hydroxide was detected simultaneously with cobalt deposition

Organismos bentônicos bioindicadores da qualidade das águas da bacia do médio São Francisco.

bitstream/CNPMA/5839/1/organ_bentonicos.pd

Luminescence in anodic Zr'O IND.2' doped with Eu(III)ions

Photoluminescence and structure properties of anodically prepared ZrO2 oxide films doped with Europium (III) ions were investigated. Microstructural analysis reveals that the predominant crystallographic structure is the monoclinic phase with small quantities of tetragonal and cubic phases. Important crystallite size and isotropic strain are observed for the monoclinic phase and they are related to the incorporation of Europium (III) ions inside the oxide matrix. The photoluminescence spectrum reveals a broad emission band in the range between 350–650 nm related to the ZrO2. Emission lines corresponding to transitions from the lowest emitting 5D0 level of Eu(III) to several sublevels of the ground state level 7F0, 1, 2, 3, 4 were also observed.FAPESPCNP