Ce4+Ce3+ redox equilibrium in Na2O-B2O3 melts by linear sweep voltammetry

✍ Scribed by Akira Sasahira; Toshio Yokokawa

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 758 KB
• Volume: 29
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(84)87105-4

✦ Synopsis

New semi-empirical equations were presented to study the redox equilibria of transition metal ions in molten oxides by Iinear sweep voltammetry. These equations gave the relation between the peak potential and the polacographic half-wave potential, and contained the Randlm&vcik equation as an extreme case. The measurements of C&+/C?+ equilibrium in several Na#-BzO, melts were used to verify the equations. The agreement between the electrochemically estimated value of the equilibrium and the other estimated from the chemical analysis of the quenched sample was quite satisfactory. The relation between the Ce4*/Ce3+ equilibrium and the composition of the melt was discussed as the functions of the basicity. NOMENCLATURE E(O*, sample melt) E(O,, std melt) E"(M, sample melt) &it x3 XMax Electrode potential characterized by the reaction (A) in a sample melt &+4e-*202-(A) Electrode potentialcharacterized by the reaction (A) in the standard melt, 33 Na,0.67 SiO,, in 1 atm O2 Standard redox potential of the reaction (B) in the sample melt MY+ +(y-x)e-=M"+ (B) Initial potential of the workingelectrade, identical with E(O,, &nple melt) at the equilibrium condition Peak potential of the voltammo-gr=n Polarographic half-wave potential Bulk concentration ratio OF the oxidized species to the reduced species square root of the ratio of the diffusion coefficient of the oxidized species to that of the reduced species Current function and its maximum value, which is related to current i by i = nFAC&,/(nDO,nFv/RT)~