Dilatometer studies on LAMOX based electrolyte materials for solid oxide fuel cells

The present study deals with the citrate complexion synthesis of LAMOX-based Solid Oxide Fuel Cell (SOFC) electrolyte materials (La_1.8Dy_0.2Mo_2-xW_xO₉ (x = 0, 0.1, 0.2, 0.5, and 1), La_1.8Dy_0.2Mo_2-xGa_xO₉ (x = 0.1 and 0.2), and La_1.8Dy_0.2Mo_2-xV_xO₉ (x = 0.025, 0.05, 0.1, and 0.2)) and their characterization to understand the sintering behaviour and phase stability. From the dilatometer studies, the linear shrinkage and shrinkage rate of the LDMW (x = 0, and 0.1) showed better shrinkage than LM and LDM. Gallium addition (LDMG) and Vanadium addition (LDMV) showed a negative impact on shrinkage behaviour. In the temperature range of 500–580 °C, the abrupt change in shrinkage rate showed the transition of phase from α to β for the LM. The modification of LM to LDM, LDMW, and LDMV suppressed the formation of the α phase. During thermal expansion behaviour study in the temperature range of 100–500 °C and 550–800 °C, the LM sintered pellet showed the coefficient of thermal expansion (CTE) values of 13.3 х 10⁻⁶/°C and 21.6 х 10⁻⁶/°C respectively. The LDM and LDMW sintered pellets showed the CTE values in the range of 14–15 х 10⁻⁶/°C and 16–19 х 10⁻⁶/°C, respectively. The relative density of the sintered pellets (1100 °C/5 h in air) (LM, LDM, LDMW, and LDMG (x = 0.1)) is found to be >90%. It provides the suitability of these materials for further investigation as electrolytes of SOFCs/SOECs.