Perovskite membranes by aqueous combustion synthesis: synthesis and properties

Abstract

The objective of this work is to identify optimum synthesis, compacting and sintering conditions in order to achieve a pure phase fully densified La0.8Sr0.2CrO3 (LSC) perovskite membrane. The aqueous combustion synthesis of LSC powders was investigated over a wide range of synthesis conditions by using the metal nitrates (oxidizer)‐glycine (fuel) system. The powders were pressed and sintered to create dense materials, which were characterized. It was shown that depending on fuel/oxidizer ratio, , the reaction can proceed in three different modes: Smoldering Combustion Synthesis (SCS), 0.7, with maximum temperature, Tm 600°C; Volume Combustion Synthesis (VCS), 0.71.2, 1150°CTm1350°C; Self-propagating High-temperature Synthesis (SHS), 1.2 1.6, 800°CTm1100°C. In turn, the characteristics of synthesized powders depend on the combustion mode. The crystalline structure of as-synthesized powders becomes more defined as increases (amorphous for SCS; crystalline for VCS and SHS). The specific surface area decreases slightly when mode changes from SCS ( 25 m 2 g − 1 )t o VCS (20 m 2 g −1 ), however, it increases substantially under SHS conditions (up to 45 m 2 g − 1 ). It was also shown that calcination is beneficial only for SCS powders, while VCS and SHS powders may be sintered directly as synthesized, thus bypassing the time and energy consuming calcination step. The measured oxygen permeation values for the membranes are comparable with the best candidate materials reported in the literature. © 2001 Elsevier Science B.V. All rights reserved.