Crystallographic Studies of Ba₁₂Nb_8-xTa_xCo₄O₃₆ (x=1,3,4,5,7)

Authors

W. Wong-Ng, National Institute of Standards and Technology
G. Liu, China University of Geosciences
I. Levin, National Institute of Standards and Technology
I. Williamson, Boise State University
A. Correa Hernandez, Boise State University
J. A. Kaduk, Illinois Institute of Technology
L. Li, Boise State UniversityFollow

Document Type

Article

Publication Date

9-2017

Abstract

Crystal structures and X-ray reference powder diffraction patterns have been determined for the Ba₁₂Nb_8-xTa_xCo₄O₃₆ (x = 1, 3, 4, 5, 7) series. Ba₁₂Nb_8-xTa_xCo₄O₃₆ crystallize in the cubic perovskite structure with a space group Pm3m (No. 221) and the lattice parameter increasing from a = 4.08732(3) Å to a = 4.08894 (2) Å as x varies from 1 to 7. The Goldschmidt distortion parameter for the entire series is about 1.05 (1.0488–1.0506), being similar to that of the cubic end member Ba₃Nb₂CoO₉. Transmission electron microscopy of the composition Ba₁₂Nb₄Ta₄Co₄O₃₆ (or Ba₃(NbTaCo)O₉) revealed nanoscale 1:2 ordering of Nb/Ta and Co, manifested in the presence of the diffuse superlattice reflections. As this ordering is limited to short range, the average structures were still refined assuming the ideal-perovskite cubic symmetry. X-ray powder diffraction patterns of the studied compounds have been submitted to the Powder Diffraction File (PDF).

Publication Information

Wong-Ng, W.; Liu, G.; Levin, I.; Williamson, I.; Correa Hernandez, A.; Kaduk, J. A.; and Li, Lan. (2017). "Crystallographic Studies of Ba₁₂Nb_8-xTa_xCo₄O₃₆ (x=1,3,4,5,7)". Solid State Sciences, 71, 3-7.