Chemical diffusion of (La,Sr)CoO₃ and (La,Sr)FeO₃

Abstract

The present work reports equilibration kinetics for (La_0.8,Sr_0.2)CoO₃(LSC) and (La_0.72,Sr_0.18)FeO₃(LSF) in the temperature range 876–1114 K using a gravimetric method. Chemical diffusion determined in this way that depends on oxygen partial pressure, can be expressed by the following temperature dependence at low and high O₂), respectively, for LSC:

$$D_{chem} = 8.7 \times 10^{ - 3} {\text{exp}}\frac{{{\text{ - }}\left( {58.1 \pm 8.5} \right){\text{kJ/mol}}}}{{RT}}({\text{cm}}^{\text{2}} {\text{s}}^{{\text{ - 1}}} ){\text{ (1)}}$$

$$D_{chem} = 6.2 \times 10^{ - 3} {\text{exp}}\frac{{{\text{ - }}\left( {75.4 \pm 6.5} \right){\text{kJ/mol}}}}{{RT}}({\text{cm}}^{\text{2}} {\text{s}}^{{\text{ - 1}}} ){\text{ (2)}}$$

and for LSF:

$$D_{chem} = 3.05 \times 10^{ - 5} {\text{exp}}\frac{{{\text{ - }}\left( {30.3 \pm 2.8} \right){\text{kJ/mol}}}}{{RT}}({\text{cm}}^{\text{2}} {\text{s}}^{{\text{ - 1}}} ){\text{ (3)}}$$

$$D_{chem} = 6.3 \times 10^{ - 3} {\text{exp}}\frac{{{\text{ - }}\left( {82.7 \pm 10.2} \right){\text{kJ/mol}}}}{{RT}}({\text{cm}}^{\text{2}} {\text{s}}^{{\text{ - 1}}} ){\text{ (4)}}$$