title: Nanocrystalline gadolinium doped ceria: combustion synthesis and electrical characterization.
abstract: Twenty mol% gadolinium doped ceria powders were prepared by citrate-nitrate combustion synthesis technique. Two different sources of cerium viz. cerium nitrate and ammonium ceric nitrate were used in different oxidant-to-fuel ratios. The crystallite size of the synthesized powders ranged 5-27 nm was obtained depending on the preparation conditions with average particle size in the range 0.64-1.26 microm. Although, the powders were found to be agglomerated in nature, these powders were highly sinter-active as they showed very high sintered density (> or = 95%) when sintered at 1250 degrees C having grain size in the range of 200-500 nm. The electrical conductivity was found to depend on the temperature with two distinct regimes at a transition point of 350 degrees C. The grain boundary showed a significant role in the total conductivity with its activation energy dependent on the material preparation conditions. The activation energy of total conduction was found to be significantly low (-0.5 eV) in the temperature range of 400-700 degrees C, this property is unique for application as an electrolyte for solid oxide fuel cell operating in the low temperature range. It was found that a fuel-deficient combustion reaction using cerium nitrate as the oxidant yielded the best quality powder which showed a maximum electrical conductivity of -1.74 x 10(-2) S/cm at 600 degrees C.
authors.affiliation: Central Glass and Ceramic Research Institute, CSIR, Kolkata 700032, India.
authors.forename: Atanu
authors.initials: A
authors.lastname: Dutta
authors.forename: Saheli
authors.initials: S
authors.lastname: Patra
authors.forename: Vinila
authors.initials: V
authors.lastname: Bedekar
authors.forename: A K
authors.initials: AK
authors.lastname: Tyagi
authors.forename: R N
authors.initials: RN
authors.lastname: Basu