Browsing by author "Kennedy, Brendan J"
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Complex 5d magnetism in a novel S = ½ trimer system, the 12L hexagonal perovskite Ba4BiIr3O12
Miiller, Wojciech; Dunstan, Matthew T; Huang, Zixin; Mohamed, Zakiah; Kennedy, Brendan J; Avdeev, Maxim; Ling, Chris DPublished 2013The 12L hexagonal perovskite Ba4BiIr3O12 has been synthesized for the first time and characterized using high-resolution neutron and synchrotron x-ray diffraction as well as physical properties measurements. The structure ...Open AccessArticle -
Direct observation of pressure-driven valence electron transfer in Ba3BiRu2O9, Ba3BiIr2O9 and Ba4BiIr3O12
Blanchard, Peter E R; Chapman, Karena W; Heald, Steve M; Zbiri, Mohamed; Johnson, Mark R; Kennedy, Brendan J; Ling, Chris DPublished 2016The hexagonal perovskites Ba3BiIr2O9, Ba3BiRu2O9 and Ba4BiIr3O12 all undergo pressure-induced 1% volume collapses above 5 GPa. These first-order transitions have been ascribed to internal transfer of valence electrons ...Open AccessArticle -
Experimental Observation and Computational Study of the Spin-gap Excitation in Ba3BiRu2O9
Ling, Chris D; Huang, Zixin; Kennedy, Brendan J; Rols, S; Johnson, M R; Zbiri, M; Kimber, S A J; Hudspeth, J; Adroja, D T; Rule, K C; Avdeev, Maxim; Blanchard, Peter E RPublished 2016Ba3BiRu2O9 is a 6H-type perovskite compound containing face-sharing octahedral M2O9 (M = Ir, Ru) dimers, which are magnetically frustrated at low temperatures. On cooling through T∗ = 176 K, it undergoes a pronounced ...Open AccessArticle -
The ferroelectric phase of CdTiO3. A powder neutron diffraction study.
Kennedy, Brendan J; Zhou, Qingdi; Avdeev, MaximPublished 2011-01-01The synthesis of bulk samples of polycrystalline CdTiO3 in both the rhombohedral ilmenite and orthorhombic perovskite forms is described and the structures of these have been refined using powder neutron diffraction data. ...Open AccessArticle -
The impact of anion ordering on octahedra distortion and phase transitions in SrTaO2N and BaTaO2N
Wang, Chun-Hai; Kennedy, Brendan J; Menezes de Oliveira, Andre; Polt, Julia; Knight, Kevin SPublished 2017-01-01In 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 ...Open AccessArticle -
The key role of bismuth in the magnetoelastic transitions of Ba3BiIr2O9 and Ba3BiRu2O9 as revealed by chemical doping
Blanchard, Peter E R; Huang, Zixin; Kennedy, Brendan J; Liu, Samuel; Miiller, Wojciech; Reynolds, Emily; Zhou, Qingdi; Avdeev, Maxim; Zhang, Z; Aitken, J B; Cowrie, B C C; Jang, L-Y; Li, Sean; Ling, Chris DPublished 2014The key role played by bismuth in an average intermediate oxidation state in the magnetoelastic spin-gap compounds Ba3BiRu2O9 and Ba3BiIr2O9 has been confirmed by systematically replacing bismuth with La3+ and Ce4+. Through ...Open AccessArticle -
Low temperature structure and the ferroelectric phase transitions in the CdTiO3 perovskite
Kennedy, Brendan J; Zhou, Qingdi; Zhao, Shipeng; Jia, Fanhao; Ren, Wei; Knight, Kevin SPublished 2017-01-01The paraelectric-ferroelectric transition in CdTiO3 has been monitored using high resolution neutron diffraction data. This necessitated preparing a sample enriched in 114Cd. A subtle, but significant, anisotropy in the ...Open AccessArticle -
Magnetic and structural studies of Sc containing ruthenate double perovskites A2ScRuO6 (A = Ba, Sr).
Kayser, Paula; Injac, Sean; Ranjbar, Ben; Kennedy, Brendan J; Avdeev, Maxim; Yamaura, KazunariPublished 2017-01-01Ruthenium containing double perovskites A2ScRuO6 have been synthesized as polycrystalline powders and structurally characterized using a combination of synchrotron X-ray and neutron powder diffraction methods. When A = ...Open AccessArticle -
Multi-scale Structural Analysis of the A-site and Oxygen Deficient Perovskite Sr11Mo4O2
King, Graham; Avdeev, Maxim; Qasim, Ilyas; Zhou, Qingdi; Kennedy, Brendan JPublished 2017-01-01The long range average crystal structure, as well as the short and medium range structural features, of the A-site deficient and oxygen deficient perovskite Sr11Mo4O23 have been determined. Rietveld refinement of synchrotron ...Open AccessArticle -
Revisiting the cubic crystal structures of Sr4Nb2O9 and Sr5Nb2O10
Ling, Chris D; Kennedy, Brendan J; Wang, Chun-HaiPublished 2021We have synthesized polycrystalline and single crystal samples of Sr4Nb2O9 and Sr5Nb2O10 and revisited the crystal structure of the high-temperature cubic phase. By careful analysis of single-crystal X-ray diffraction ...Open AccessArticle -
Spin-orbit coupling controlled ground state in the Ir(V) perovskites A2ScIrO6 (A = Ba or Sr)
Kayser, Paula; Kennedy, Brendan J; Ranjbar, Ben; Kimpton, Justin; Avdeev, MaximPublished 2017-01-01The structural and magnetic properties of the two Ir(V) perovskites Ba2ScIrO6 and Sr2ScIrO6 have been established. The structures were refined using a combined neutron and Synchrotron data set. At room temperature the ...Open AccessArticle -
Squeezing electrons out of 6s2 lone-pairs in perovskite-type oxides
Wang, Chun-Hai; Kayser, Paula; Kennedy, Brendan J; Maynard-Casely, H E; Gu, Qinfen; Ling, Chris DPublished 2019Having identified a set of conditions that predispose a solid-state ionic compound to a pressure-induced valence transition, we investigated a series of Bi(III) perovskite oxides. We found such a transition below 10 GPa ...Open AccessArticle -
Structural and magnetic properties of the osmium double perovskites Ba2-xSrxYOsO6
Kayser, Paula; Injac, Sean; Kennedy, Brendan J; Vogt, Thomas; Avdeev, Maxim; Maynard-Casely, Helen; Zhaoming, ZhangPublished 2017-01-01The crystal and magnetic structures of double perovskites of the type Ba2-xSrxYOsO6 have been studied by synchrotron X-ray and neutron powder diffraction methods, bulk magnetic susceptibility measurements and X-ray absorption ...Open AccessArticle -
Structure and Magnetism in Sr1-xAxTcO3 Perovskites. The importance of the A-site cation.
Reynolds, Emily; Avdeev, Maxim; Thorogood, Gordon J; Poineau, Frederic; Czerwinski, Kenneth R; Kimpton, Justin A; Yu, Michelle; Kayser, Paula; Kennedy, Brendan JPublished 2017-01-01The Sr1-xBaxTcO3 (x = 0, 0.1, 0.2) oxides were prepared and their solid-state and magnetic structure studied as a function of the temperature by x-ray and neutron powder diffraction. The refined Tc moments at room temperature ...Open AccessArticle -
Structure evolution of Na2O2 from room temperature to 500 oC
Ling, Chris D; Kennedy, Brendan J; Avdeev, Maxim; Wang, Chun-HaiPublished 2020Na2O2 is one of the possible discharge products from sodium-air batteries. Here we report the evolution of the structure of Na2O2 from room temperature to 500 oC using variable-temperature neutron and synchrotron X- ray ...Open AccessArticle -
Synthesis and crystal structures of two polymorphs of Li4–2xMg1+xTeO6
Brown, Alex J; Liu, Jiatu; Marlton, Frederick P; Avdeev, Maxim; Kennedy, Brendan J; Ling, Chris DPublished 2020Two polymorphs of lithium magnesium tellurate Li4–2xMg1+xTeO6 have been prepared by solid-state reactions and their crystal structures characterised by powder X-ray and neutron diffraction. For x 0, a monoclinic C2/m ...Open AccessArticle -
Synthesis-controlled polymorphism, magnetic and electrochemical properties of Li3Co2SbO6
Brown, Alex J; Xia, Qingbo; Avdeev, Maxim; Kennedy, Brendan J; Ling, Chris DPublished 2019Li3Co2SbO6 is found to adopt two highly distinct structural forms: a pseudohexagonal (monoclinic C2/m) layered O3-LiCoO2 type phase with “honeycomb” 2:1 ordering of Co and Sb; and an orthorhombic Fddd phase, isostructural ...Open AccessArticle -
Thermal Expansion Behavior in TcO2. Towards breaking the Tc-Tc bond.
Reynolds, Emily; Zhang, Zhaoming; Avdeev, Maxim; Thorogod, Gordon J; Poineau, Frederic; Czerwinski, Kenneth R; Kimpton, Justin A; Kennedy, Brendan JPublished 2017-01-01The structure of TcO2 between 25 and 1000 °C has been determined in-situ using powder diffraction methods and is found to remain monoclinic in space group P21/c. The thermal expansion in TcO2 is highly anisotropic with ...Open AccessArticle -
Thermal Expansion in BaRuO3 Perovskites – an unusual case of bond strengthening at high temperatures
Kayser, Paula; Injac, Sean; Kennedy, Brendan J; Menezes de Oliveira, Andre; Shirako, Yuichi; Hasegawa, MasashiPublished 2017-01-01The temperature dependence of the structures of three polytypes of BaRuO3 have been investigated between room temperature and 1000 °C using high resolution Synchrotron X-ray diffraction. The structural studies reveal a ...Open AccessArticle -
Tuning the Giant Magnetoelastic Transition in Ba3BiIr2O9 and Ba3BiRu2O9
Huang, Zixin; Avdeev, Maxim; Kennedy, Brendan J; Knight, Kevin S; Zhou, Qingdi; Ling, Chris DPublished 2014We have experimentally investigated the effects of pressure on the magnetoelastic transitions associated with the opening of spin-gaps in Ba3BiIr2O9 and Ba3BiRu2O9. For both compounds, reducing the unit cell volume by ...Open AccessArticle
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