Thermogravimetric investigations of nickel-oxide thin films and powders

Classical TC analysis of films supported on micro-cover glasses was performed in order to determine the appropriate processing temperature to achieve electrochemically active NiOxHy thin films. As deposited films made from three different precursors (Ni-acetate, nitrate and sulphate) and their corresponding powders were also investigated. From dynamic TG measurements the onset decomposition temperature could be determined. It was found out that the starting temperature of the mass change of thin films is approximately 30 degrees lower than that of the powders. A broader decomposition range was also observed for thin films. Furthermore, the isothermal treatment of films deposited on conducting substrate at 270 and 300 degrees C was performed and by cyclic voltametry the importance of temperature and time of heating was proved. Films obtained at higher temperatures (>300 degrees C) are electrochemically inert because of the NiO phase formation.