Microstructure and electrical properties of nano-sized Ce_1-xGd_xO₂ (0 ≤ x ≤ 0.2) particles prepared by spray pyrolysis

Abstract

Nano-sized Ce_1-xGd_xO₂ (0 ≤ x ≤ 0.2) particles were prepared by spray pyrolysis process from the spray solution with ethylene glycol. The mean sizes of Ce_1-xGd_xO₂ (x = 0, 0.05, 0.1, 0.2) particles were each 46, 33, 29, and 28 nm. The mean crystallite size of pure CeO₂ was 33 nm. However, the Gd-doped CeO₂ had the mean crystallite size of 28 nm irrespective of the molar ratio of Gd to Ce components. The mean grain size of the sintered CeO₂ pellet was about two or four times larger than those of the Gd-doped CeO₂ pellets. The mean grain sizes of Ce_0.9Gd_0.1O₂ and Ce_0.8Gd_0.2O₂ pellets are about 0.5-0.4 μm. The pure CeO₂ pellet had low relative density of 80%. However, Ce_0.9Gd_0.1O₂ and Ce_0.8Gd_0.2O₂ pellets had the high relative densities above 95%. The Ce_0.9Gd_0.1O₂ and Ce_0.8Gd_0.2O₂ pellets had similar conductivities at all measuring temperatures. The Ce_0.9Gd_0.1O₂ pellet had conductivities of 4.73 × 10^-2 and 1.16 × 10^-1 Scm^-1 at measuring temperatures of 800 and 900°C respectively.