Development of new oxygen ion conductors based on Nd4GeO8 and Nd3GaO6

作者：Purohit RD; Chesnaud A; Lachgar A; Joubert O; Caldes MT; Piffard Y^*; Brohan L

来源：Chemistry of Materials, 2005, 17(17): 4479-4485.

DOI：10.1021/cm050537h

New oxygen ion conductors have been prepared by substituting Ga3+ for Ge4+ in Nd4GeO8, Zn2+ and Mg2+ for Ga3+ in Nd3GaO6, and Ca2+ and Sr2+ for Nd3+ in Nd3GaO6. A combustion technique using ethylenediamine tetraacetic acid has been developed to synthesize these materials at similar to 900 degrees C, leading to powders with spherical particles of about 100-200 nm. The green pellets obtained through the combustion-synthesized powders could be sintered to similar to 98% at 1250 degrees C. It was found that Nd4Ge1-xGaxO8-x/2 are formed up to x = 0.10, Nd3Ga1-xMxO6-x/2 (M = Zn, Mg) up to x = 0.03, and Nd3(1-x)M'3xGaxO6-3x/2 up to x = 0.03 and 0.015 for M' = Ca and Sr, respectively. These relatively small substitution rates induce a significant increase in oxygen ion conductivity (sigma(800 degrees C) = 0.2 x 10(-2) S cm(-1) for Nd4Ge0.9Ga0.1O7.95; sigma(800 degrees C) = 0.5 x 10(-2) and 0.4 x 10(-2) S cm(-1) for Nd3Ga0.97M0.03O5.985 with M = Zn and Mg, respectively, and sigma(800 degrees C) = 0.6 x 10(-2) and 0.7 x 10(-2) S cm(-1) for Nd2.91Ca0.09GaO5.955 and Nd2.955Sr0.045GaO5.9775, respectively) with respect to pure Nd4GeO8 (sigma(800 degrees C) = 2.8 x 10(-4) S cm(-1)) and pure Nd3GaO6 (sigma(800 degrees C) 2.7 x 10(-4) S cm(-1)).

• 出版日期2005-8-23