Characterization and electrochemical behaviour of nanostructured calcium samari...

• Author(s): Barrocas, B. ; Sério, S. ; Rovisco, A. ; Nunes, Y. ; Sá, A. I. Correia de ; Pereira, M. I. da Silva ; Jorge, M. E. Melo
• Date: 2014
• Persistent ID: http://hdl.handle.net/10400.9/2546
• Origin: Repositório do LNEG
• Subject(s): Manganites electrodes; Cyclic voltammetry; Magnetron sputtering; Electrochemical impedance spectroscopy; Electrode roughness
• Document Type: Article
• Language: English

Description

Ca1-xSmxMnO3(0 . x . 0.4) films were successfully fabricated on Indium Tin Oxide (ITO) coated quartzglass substrates by radio frequency magnetron sputtering technique (RF- magnetron sputtering) fromcompacted nanosized powder targets, and subsequent annealing at 800.C in air, for 6 h. X-ray diffrac-tion shows a pure typical perovskite phase for x . 0.1. Scanning electron microscopy and atomic forcemicroscopy revealed that the films surface is dense, with low roughness, depending on the Sm content, even though a few cracks were observed. Crystallite size was found to decrease with the Sm content. Theelectrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The oxide electrode fs capacitance was estimated using both techniques and the corresponding roughness factors evaluated. The values obtained from the two methods show a good agreement. A com-parison between the voltammetric data and those referred in the literature allowed finding out that theredox reaction occurring at the electrode surface involves the pair Mn4+/Mn3+. EIS measurements con-firm the voltammetric data and they also give additional information about the film porosity and the charge transfer resistance. This last parameter is associated with the oxidation and reduction of the pairMn3+/Mn4+and after normalized by the roughness factor shows an increase with samarium content.