Asian Journal of Chemistry Vol. 21, No. 10 (2009), S013-016 Synthesis and Characterization of Nanocrystalline Gd Doped CeO 2 KALPANA NAGDE ANUSHREE KHANDALE and SHYAMSUNDAR BHOGA Department of Physics, R. T. M. Nagpur University, Nagpur-44033, India Email: msrl1@hotmail.com Nano-sized gadolinia doped ceria prepared by combustion method lowers sintering temperature. The dopant concentration dependent lattice distortion is correlated with the electrical properties and grain size. The linear thermal expansion coefficient study suggests enhancement in it by doping. Key Words: Solid electrolyte, X-ray powder diffraction, Solid oxide fuel cells INTRODUCTION Ceria based solid solutions have been regarded as the most promising solid electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFC) due to their ionic conductivity higher than YSZ 1 . Amongst various cations viz. Ca 2+ , Sr 2+ , Y 3+ , La 3+ , Gd 3+ , and Sm 3+ doped ceria the gadolinia and the samaria doped ones have emerged as promising solid electrolytes. In fact, according to literature densification of ceria-based ceramics below 1600°C has been difficult 2, 3 . The severe sintering conditions make it difficult to co-fire with other components of SOFC thereby expensive manufacturing of SOFCs 4, 5 . Generally, the reduction in particle size facilitates obtaining requisite dense ceramic at considerably low sintering temperatures. The present study was focused on grain size effect on packing density and conductivity. EXPERIMENTAL The solid solutions Gd x Ce (1-x) O 2 , where x = 0.05 and 0.1, were prepared by combustion route 6 . An appropriate molecular stochiometric amount of cerium, samarium and gadolinium in the form of hexahydrated nitrates (99.99% pure, Sigma USA) along with glycine fuel were dissolved in the distilled water and charred at 550°C. The foamy, pale yellow in color, residue was crushed and sintered at 800°C for 7 hrs in air. The pellets of dimensions 9mm diameter and 1-2 mm thickness were sintered at various temperatures in the range from 800 to 1300°C for 7 hours. The samples were characterized by the X-ray powder diffraction. The complex impedance in the temperature and frequency ranges 100–600°C and 10mHz to 1MHz, respectively was measured using Solartron 1255B FRA. The details of