LAUSR

Abstract Ionic conductivity of electrolyte is vital to decide efficiency and operating conditions of electrochemical energy conversion devices. Engineering electrolyte structure by strategically introducing elastic strain is rationalized approach to improve its ionic conductivity. In general, elastic strain in bulk material is introduced by doping effect; size-valence mismatch of dopant especially multiple valence dopant incorporate the local elastic strain. Dopant induced strain alter energy landscape near the local strained region and create un-equilibrium site; which provoke low potential ion diffusion path by modifying charge transfer barrier and thus ion conductivity. The accompanied changes in migration energy barrier, adsorption energy, dissociation barrier etc reduced diffusion kinetics. In the present attempt, we consider multiple-dopant effect in ceria systems to incorporate strain. The local straining effect is monitored by various spectroscopic probe like Extended X-ray Absorption fine Edge spectroscopy (EXAFS), Raman spectroscopy and X-ray absorption near edge spectroscopy (XANES). Dopant induced variation in local surrounding in terms of coordination number (CN) and interatomic spacing (IS) at nearest neighbour (NN) and next nearest neighbour (NNN)-site are revealed by EXAFS. The study exhibits detectable changes in CNs and IS at NN and NNN site. Raman spectra also depict dopant induced straining in ceria. High temperature Raman spectra reveal systematic disappearance of Raman modes associated with oxygen vacancies ordering. The XANES study exhibits existence of Ce in both oxidation state (Ce3+ & Ce4+); which is manipulated by dopant effect. The dopant modulated elastic straining effect enhanced conductivity of multiple doped ceria systems by one order as compared to singly doped ceria system at intermediate to low temperature range.