Structural Characterization and Influence of Defects on the Optical Properties of the Oxygen-Deficient Perovskite Ba3LiNb2O8.5□0.5
Résumé
A new oxygen-deficient perovskite Ba(3)LiNb(2)O(8.5)□(0.5) was synthesized via a conventional solid-state route and compared to the already known perovskite Ba(3)Li(0.75)Nb(2.25)O(9). The structure of Ba(3)LiNb(2)O(8.5)□(0.5) was investigated by means of X-ray and neutron diffraction, TEM, NMR, and XPS. The study of its thermal behavior revealed an unexpected color change when heated to 1400 °C in a sealed platinum tube, with conservation of the initial X-ray structure. First-principles calculations have been performed in order to better understand these observations. The geometry optimizations and the optical spectra simulations highlight the role of both Nb/Li distribution and oxygen-vacancy location.
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