Oxygen ionic and electronic conductivity of La-doped BIMEVOX

Abstract

Doping by either lanthanum or nickel has been found to result in decreasing ionic conductivity and thermal expansion of the B i^ L a ^ .^ .C u ^ .N i.O , ,_ s (x = 0.10-0.20; у = 0-0.10; z = 0-0.20) ceramics. The infrared absorption spectroscopic data on Bi2_,La,Vl^v_.CuvN i.0 5 ,_ 8 have been shown to correlate with the conductivity and crystal structure of the oxides. The thermal expansion coefficients of the ceramics are (13.5-15.5) X 10~ft К at temperatures of 300-570 К and (14.8-18.6) X Ю-6 К 1 at 580-1050 K. Ion transference numbers of Bi2_ tLa>V0 y(,Cu„ 10O5 _,_R (x = 0.10-0.20) have been determined by Faradaic efficiency measurements at 720-800 К to vary in the range from 0.65 to 0.95. Doping by lanthanum results in increasing electronic conductivity. A new experimental arrangement to study Faradaic efficiency of oxygen ionic conductors has been suggested and verified.