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Evidence of metastability and demixion/recombination process in fast oxide-ion conductor La1.92Ca0.08Mo2O8.96

Abstract : Unusual structural phenomena have been observed through high temperature X-ray diffraction in fast oxide-ion conductor La1.92Ca0.08Mo2O8.96. A demixion process occurs above 640°C, with calcium segregation leading to the formation of CaMoO4 impurity. It recombines at higher temperature to reform the pure cubic LAMOX phase (β-type disordered form). In addition, at lower temperature, a double reversed β/α/β phase transition (where α is the monoclinic ordered form) is observed. It is due to the metastability of the β-type structure at low temperature. Depending on the thermal history, La1.92Ca0.08Mo2O8.96 can therefore be obtained in either its α or its β form at room temperature. Sample shaping as a pellet with high relative density suppresses the low temperature phase transitions and stabilizes the cubic β form.
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https://hal-univ-lemans.archives-ouvertes.fr/hal-02135001
Contributeur : Gwenaël Corbel <>
Soumis le : lundi 20 mai 2019 - 21:30:33
Dernière modification le : samedi 3 août 2019 - 01:14:06

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A. Selmi, Gwenaël Corbel, A Lacorre. Evidence of metastability and demixion/recombination process in fast oxide-ion conductor La1.92Ca0.08Mo2O8.96. Solid State Ionics, Elsevier, 2006, 177 (35-36), pp.3051-3055. ⟨10.1016/j.ssi.2006.07.050⟩. ⟨hal-02135001⟩

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