Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography.

ABSTRACT: An NMR crystallographic approach, involving the combination of ¹¹⁹Sn NMR spectroscopy, XRD, and DFT calculations, is demonstrated for the characterization of La₂Sn_2-x Ti _x O₇ ceramics. A phase change from pyrochlore (La₂Sn₂O₇) to a layered perovskite phase (La₂Ti₂O₇) is predicted (by radius ratio rules) to occur when x ≈ 0.95. However, the sensitivity of NMR spectroscopy to the local environment is able to reveal a significant two-phase region is present, extending from x = 1.8 to ∼0.2, with limited solid solution at the two extremes, in broad agreement with powder XRD measurements. DFT calculations reveal that there is preferential site subst

SUBMITTER: Fernandes A 

PROVIDER: S-EPMC5049937 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature