• 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 D
      Published 2013
      The 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 Access
      Article
    • 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 D
      Published 2016
      The 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 Access
      Article
    • 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 R
      Published 2016
      Ba3BiRu2O9 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 Access
      Article
    • The ferroelectric phase of CdTiO3. A powder neutron diffraction study. 

      Kennedy, Brendan J; Zhou, Qingdi; Avdeev, Maxim
      Published 2011-01-01
      The 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. ...
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      Article
    • 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 S
      Published 2017-01-01
      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 ...
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      Article
    • 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 D
      Published 2014
      The 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 ...
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      Article
    • 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 S
      Published 2017-01-01
      The 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 Access
      Article
    • 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, Kazunari
      Published 2017-01-01
      Ruthenium 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 = ...
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      Article
    • Multi-scale Structural Analysis of the A-site and Oxygen Deficient Perovskite Sr11Mo4O2 

      King, Graham; Avdeev, Maxim; Qasim, Ilyas; Zhou, Qingdi; Kennedy, Brendan J
      Published 2017-01-01
      The 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 ...
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      Article
    • 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, Maxim
      Published 2017-01-01
      The 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 Access
      Article
    • 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 D
      Published 2019
      Having 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 ...
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      Article
    • 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, Zhang
      Published 2017-01-01
      The 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 Access
      Article
    • 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 J
      Published 2017-01-01
      The 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 Access
      Article
    • 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 D
      Published 2020
      Two 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 ...
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      Article
    • Synthesis-controlled polymorphism, magnetic and electrochemical properties of Li3Co2SbO6 

      Brown, Alex J; Xia, Qingbo; Avdeev, Maxim; Kennedy, Brendan J; Ling, Chris D
      Published 2019
      Li3Co2SbO6 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 ...
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      Article
    • 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 J
      Published 2017-01-01
      The 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 Access
      Article
    • 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, Masashi
      Published 2017-01-01
      The 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 Access
      Article
    • Tuning the Giant Magnetoelastic Transition in Ba3BiIr2O9 and Ba3BiRu2O9 

      Huang, Zixin; Avdeev, Maxim; Kennedy, Brendan J; Knight, Kevin S; Zhou, Qingdi; Ling, Chris D
      Published 2014
      We 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 ...
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      Article
    • YCa3(CrO)3(BO3)4: a Cr3+ kagomé lattice compound showing no magnetic order down to 2 K 

      Wang, Chun-Hai; Avdeev, Maxim; Kennedy, Brendan J; Kuepers, M; Ling, Chris D
      Published 2016
      We report a new gaudefroyite-type compound YCa3(CrO)3(BO3)4, in which Cr3+ ions (3d3, S = 3/2) form an undistorted kagomé lattice. Using a flux agent, the synthesis was significantly accelerated with the typical calcining ...
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      Article