Microstructure and electrical transport phenomenon of yttria alloyed nanocrystalline ceria solid solution synthesized by mechanical alloying

Abstract

This article reports the room temperature synthesis of nanocrystalline (4–20mol%) yttria (Y2O3) alloyed ceria (CeO2)-based solid solutions in open air employing a single step mechanical alloying technique. Structure and microstructure of these compounds have been investigated and the effect of yttria on the electrical transport phenomenon of these compounds is revealed. Structure and microstructure characterizations of all alloyed compounds are carried out in detail employing Rietveld refinement method by analyzing respective XRD patterns. Ionic conductivities of all these compounds are measured in open air in the temperature range 633–833K. For unsintered samples, conductivity increases continuously with increase in alloying concentrations up to 12mol% of Y2O3, which is higher than the alloying concentration synthesized by any other method. However, the total conductivity reaches maximum with 8mol% of Y2O3 when the samples are sintered and exhibits the highest conductivity of ∼3.8×10−3Ω−1cm−1 at 813K. Electrical relaxation process and transport phenomenon of all compounds are studied by impedance spectroscopy and complex modulus analysis. Presence of thermally activated relaxation and hopping mechanism in the system are also confirmed and correlated with the microstructure. Present findings indicate the possible application of these compounds as oxygen ion conductors in many electrochemical devices at quite low temperature range of 673–873K.