Synthesis and crystal structure of the A6B5O18 perovskite-like compounds |
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| Institution: | 1. Taras Shevchenko University, 64/13, Volodymyrska Str., 01601 Kyiv, Ukraine;2. Ivan Franko State University, 40, Velyka Berdychivska Str., 10008 Zhytomyr, Ukraine;1. Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA;2. Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA;3. Illinois Institute of Technology, Chicago, IL 60616, USA;1. Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA;2. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei 430070, China;3. Department of Chemistry, Illinois Institute of Technology, Chicago, IL 60616, USA;1. Department of Physics, University of Kalyani, Kalyani, Nadia 741235, WB, India;2. Department of Engineering Physics, B. P. P. I. M.T., Kolkata 700052, WB, India |
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| Abstract: | New members of the AnBn?1O3n perovskite-like family (Ba5KNb5O18 and Sr6Nb4SnO18 compounds) with n = 6 have been synthesized and studied by the X-ray powder diffraction. Their crystal structures were found to belong to the Ba6Nb4TiO18-type with a = 0.57840(7) nm, c = 4.2532(5) nm and a = 0.5661(1) nm, c = 4.186(1) nm for Ba5KNb5O18 and Sr6Nb4SnO18, respectively. It was shown that Ba and K (A-atoms) are completely disordered in the crystal structure of Ba5KNb5O18 compound. But Nb and Sn atoms (B-atoms) in the crystal structure of the Sr6Nb4SnO18 compound are quite ordered with the preferred Sn+4 and Nb5+ cations localization in the center of perovskite-like block and on the boundaries of these blocks, respectively. Temperature and frequency dependencies of the real components of electric conductivity σI and dielectric permeability ?I; specific electric conductivity at the direct current σdc have been obtained by the impedance spectroscopy method for Sr6Nb4SnO18. |
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| Keywords: | Cation-deficient perovskite Layered structure X-ray powder diffraction |
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