Preparation of ZnO/Eu mixed films by electrochemical precipitation

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• 作者：A. Goux ; T. Pauporté ; ; D. Lincot
• 关键词：Zinc oxide ; Europium oxide ; Potential-pH diagrams ; Electrodeposition
• 刊名：Electrochimica Acta
• 出版年：2007
• 期刊代码：30_00134686
• 类别：ch
• 出版时间：20 November 2007
• 卷：53
• 期：1
• 页码：50-58
• 文件大小：987 K

摘要

The electrochemical preparation of europium doped zinc oxide and europium oxide/hydroxide as thin films is investigated. First, a thermodynamic study of the Eu–Cl–H₂O system has been carried out at 25 and 70 °C in order to predict the electrochemical behaviour of Eu(III) dissolved in aqueous solution containing chloride ions. A comparison of the Eu–Cl–H₂O and Zn–Cl–H₂O systems indicates the possible coprecipitation of ZnO and Eu(OH)₃ from deposition solutions containing well-adjusted Eu(III)/Zn(II) concentrations ratio. The thermodynamic predictions have been confirmed experimentally by the electrochemical co-deposition of ZnO/Eu thin films on conducting electrode substrates at −1.4 V versus MSE. The presence of europium in the film is detected for Eu(III)/Zn(II) concentration ratio at (0.6 mM/5 mM) which is lower than the predicted value. Increasing Eu(III) concentration leads to the rapid appearance of two phases: dispersed zinc oxide nanorods and, at the bottom of the rods, a covering layer containing Eu(OH)₃ and zinc. The density of ZnO rods decreases and the rod size increases with increasing Eu(III) concentration in the bath. Above 1 mM EuCl₃, a dramatic fall in the current density is observed with the formation of a less conducting ZnO/Eu mixed deposit.