The Defect Chemistry of LaMnO3+δ: 5. Thermodynamics

✍ Scribed by J.A.M. van Roosmalen; E.H.P. Cordfunke

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 199 KB
• Volume: 110
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1144

✦ Synopsis

The temperature dependence of the relationship between composition and oxygen partial pressure has been described for (\mathrm{LaMnO}{3+\delta}) and (\mathrm{LaMnO}{3-\delta}) on the basis of an assessment of literature data obtained by TGA by several authors. The thermodynamics of defect formation is calculated on the basis of these results. For the formation of lanthanum and manganese vacancies in (\mathrm{LaMnO}{3+\delta}), it has been determined that (\Delta H{\mathrm{V}}^{\circ}=(-380 \pm 6) \mathrm{kJ} \cdot \mathrm{mole}^{-1}), and (\Delta S_{\mathrm{V}}^{\circ}=(-266 \pm 5) \mathrm{J} \cdot \mathrm{mole}^{-1} \cdot \mathrm{K}^{-1}). For the formation of oxygen vacancy clusters in (\mathrm{LaMnO}{3-\delta}, \Delta H{\mathrm{V}}^{\circ}=(349 \pm 6) \mathrm{kJ} \cdot \mathrm{mole}^{-1}), and (\Delta S_{\mathrm{V}}^{\circ}=(96.4 \pm 4.9) \mathrm{J} \cdot \mathrm{mole}^{-1} \cdot \mathrm{K}^{-1} . \quad 1994) Academic Press, Inc.