The impact of anion ordering on octahedra distortion and phase transitions in SrTaO2N and BaTaO2N
Field | Value | Language |
dc.contributor.author | Wang, Chun-Hai | |
dc.contributor.author | Kennedy, Brendan J | |
dc.contributor.author | Menezes de Oliveira, Andre | |
dc.contributor.author | Polt, Julia | |
dc.contributor.author | Knight, Kevin S | |
dc.date.accessioned | 2019-02-21 | |
dc.date.available | 2019-02-21 | |
dc.date.issued | 2017-01-01 | |
dc.identifier.citation | Acta Cryst. (2017). B73, 389-398 https://doi.org/10.1107/S2052520617001123 | en_AU |
dc.identifier.uri | http://hdl.handle.net/2123/20040 | |
dc.description.abstract | In this work, we synthesized BaTaO2N and SrTaO2N using a two-step high temperature solid state reaction method and analysed the structural distortions, relative to the ideal cubic perovskite structure, according to group theory. From a complete distortion analysis/refinement using high resolution neutron diffraction data in the temperature range 8 K to 613 K, we identified tetragonal structures for BaTaO2N [P4/mmm (No 123)] and SrTaO2N [I4/mcm (No 140)]. In contrast to an anion-disordered cubic perovskite (Pm3 ̅m No 221) with Ta at the cell center, both systems show a site preference for oxygen anions in the two opposite corners (along the c axis) of the Ta-O/N octahedra rather than the four square corners in the ab plane (Γ3+ occupancy distortion), which induces a tetragonal elongation of the unit cell with the c axis being longer than the a axis. A further Ta-O/N octahedra displacement [R5-(a,0,0), rotation about the c axis] distortion was observed in SrTaO2N. This distortion mode is accompanied by an increased unit cell distortion that decreases as the temperature increases. Ultimately a second-order phase transition caused by the loss of the R5-(a,0,0) mode was observed at 400 – 450 K. | en_AU |
dc.description.sponsorship | Australian Synchrotron Australian Research Counci | en_AU |
dc.publisher | IUCr | en_AU |
dc.relation | ARC | en_AU |
dc.rights | CC by Attribution 4.0 International | en_AU |
dc.title | The impact of anion ordering on octahedra distortion and phase transitions in SrTaO2N and BaTaO2N | en_AU |
dc.type | Article | en_AU |
dc.identifier.doi | 10.1107/S2052520617001123 | |
dc.type.pubtype | Pre-print | en_AU |
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