Synthesis,structure and optical properties of two new Perovskites: Ba2Bi2/3TeO6 and Ba3Bi2TeO9 |
| |
| Affiliation: | 1. College of Science, Northwest A&F University, Yangling, Shaanxi, 712100, PR China;2. School of Chemistry and Environmental Science, Xiangnan University, Chenzhou, Hunan, 423043, PR China;3. College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China;4. Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, Xiangnan University, Chenzhou, Hunan, 423043, PR China;1. Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany;2. Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan;3. Max Planck Institute for Solid State Research, Stuttgart 70569, Germany;1. Inorganic Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QR, UK;2. EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium;3. Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW2234, Australia;4. School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia;5. School of Physical, Environmental and Mathematical Sciences, UNSW Canberra at the Australian Defence Force Academy, Canberra, BC 2610, Australia;1. Department of Physics, Faculty of Engineeing (ITER), Siksha ‘O’ Anusandhan Deemed to be University, Bhubaneswar, Odisha, India;2. Department of Physics, GIET, Gunupur, Raygada, Odisha, India;3. Depatment of Physics, Central Institute of Technology, Kokrajhar, BTAD, Assam, India;4. Department of Chemistry, Faculty of Engineeing (ITER), Siksha ‘O’ Anusandhan Deemed to be University, Bhubaneswar, Odisha, India;1. School of Chemistry and Chemical Engineering, Weifang University, Weifang, Shandong 261061, China;2. Department of Physics, Pukyong National University, Busan 608-737, Republic of Korea |
| |
| Abstract: | Two new ordered Perovskite compounds, Ba2Bi2/3TeO6 and Ba3Bi2TeO9, have been synthesized and structurally characterized from neutron powder diffraction data. Ba2Bi2/3TeO6 is cubic (space group=Fm3̄m; a=8.4836(2) Å), with a 1:1 rock salt ordering of Te6+ and Bi3+ on the octahedral sites. To maintain charge balance the bismuth site is only 2/3 occupied. Ba3Bi2TeO9 is trigonal (space group=P3̄c1; a=6.18313(6) Å, c=14.8645(2) Å), with a 2:1 ordering of Bi3+ and Te6+, and out-of phase tilting of the octahedra about all three pseudocubic axes (Glazer tilt system a-a-a-). The two structures also differ from each other in the local coordination of Bi3+. This ion is shifted toward an octahedral face in Ba3Bi2TeO9, whereas ideal octahedral coordination is observed in Ba2Bi2/3TeO6. This shift is driven by the valency requirements of oxygen and aided by the stereoactive lone electron pair on Bi3+. These structural changes lead to a distinct change in the optical band gap, from ∼2.8 eV in Ba2Bi2/3TeO6 to ∼2.3 eV in Ba3Bi2TeO9. Substitutional doping studies were carried out in the hope of increasing conductivity. Although the dopants appear to be homogeneously distributed, the resulting compositions were found in each case to be electrically insulating. Extended Hückel band structure calculations were performed in order to obtain a qualitative understanding of the optical and electrical properties. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
