Thermodynamic properties of vitreous electrodes in a Ni/NiP glass-crystal Galvanic cell

Abstract

In the present paper, we present and discuss data on the thermodynamic properties of electrochemically deposited crystalline and vitreous metallic electrodes, focusing our attention on the model system of vitreous Ni/P alloys. Galvanic cells based on the glass→crystal transition are constructed and their electrochemical properties are analyzed as an alternative approach for the complete thermodynamic description of amorphous electron conductors. The EMF of the glass→crystal Ni/P–Ni battery when both crystalline Ni and the amorphous Ni/P layers electrodes placed in their native solution, gives ΔE(T) values from 0.120 to 0.140V in the temperature range from 293 to 333K. For the same system, we report a corrosion potential difference of ΔE=0.100V (at 298K, in a 1M H2SO4 electrolyte) between the glassy and the crystalline electrodes. The kinetic considerations of the deposition process provide a new way for interpretation of the mechanism of formation of amorphous deposits during electrodeposition and electroless formation of amorphous Ni3P layers based on a kinetic interpretation of Ostwald's Rule of Stages.