La2-xSrxCuO4-σ ceramics: synthesis, oxygen mobility and perspectives of catalytic applications

Abstract

ABSTRACTTwo special processing procedures based on freeze-drying synthesis have been developed in order to obtain fine (100nm) single phase LaSrCuO4−σ powders and dense ceramics. The rate of phase formation is strongly influenced by the composition of the salt precursor while the most crucial factors are heating rate and PO2 during decomposition. Studies of oxygen mobility in La2−xSrxCuO4−σ performed by dynamic-thermal O18-isotope exchange method revealed that all ceramic samples possess substantial catalytic activity in the isotope exchange reaction between oxygen molecules 32O2 and 36O2. Besides, substitution of La for Sr in La2−xSrxCuO4−σ (x =1) results in the decrease of oxygen release onset temperature from 460 to 380°C. Such a dependence correlates quite well with data on diffusion coefficients calculated for various x from the results of coulometric titration experiments. Samples with x=1 demonstrated also good catalytic activity in the reaction of CO oxidation.