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Professor Brendan J Kennedy


Contact Details

Professor of Chemistry and Third Year Coordinator
Room 458
School of Chemistry, Building F11
The University of Sydney, NSW, 2006, Australia
E: brendan.kennedy@sydney.edu.au
T: +61 (2) 9351-2742
F: +61 (2) 9351-3329

Career Profile

  • B.Ed. Melb. SC
  • Ph.D. Monash University
  • Postdoctoral Fellow, Oxford University and ANU
  • The University of Sydney (1998 to present)

Achievement and Awards

  • AINSE Gold Medal for Research Excellence 2003
  • ANZAAS 2005 Liversidge Lecturer

Areas of Interest

  • Solid State and Materials Chemistry
  • Crystallography - X-ray and Neutron Scattering
  • Structure and Bonding in Metal Oxides

Research

(a) Structural phase transitions in perovskite oxides

Perovskites are arguably the most important class of metal oxides.  We are using a combination of high resolution synchrotron and neutron diffraction studies to understand the response of perovskites to external stimuli, especially temperature and pressure. The delicate balance of simple factors such as ionic size and the degree of covalency of the cations leads to a rich variety of behavior in perovskite oxides. Some phase transitions simply involve tilting of the octahedral structural units in the crystal, while others, such as SrBi2Ta2O9, produce a ferroelectric form, which are of considerable scientific and technological importance.

(b) Heavy metals in inorganic hosts

Bone and teeth contain a large amount of a calcium hydroxy phosphate isostructural with the mineral apatite, Ca10(PO4)6(OH)2. We are interested in the interaction of such minerals with toxic heavy metals such as Pd or Cd in order to understand the fate of these metals in both the body and environment.  This work explores the structural response of minerals to a variety of heavy metals.

(c) Valence states in mixed 3d and 4d oxides

Replacing Sr with Ca in the mixed metal oxide SrRu0.5Mn0.5O3 induces a first order phase transition associated with the loss of the Jahn-Teller distortion of the Mn3+ cation.  Or so the story goes.  Analysis of the formal oxidation states of the Mn and Ru suggests complex redox equilibrium exists and that the Ca reduces the extent of electron transfer from the Ru to the Mn.  This results in both cations having a non-integer oxidation state.  The challenge is to quantify this using spectroscopic methods and suitable standards.

(d) Oxides for solid state memory devices

Ferroelectric oxides are being targeted for use in non-volatile memory devices.  We are working to extend the family of layered bismuth oxides that may be suitable for this application.  Bi4Ti3O12 is an attractive alternative to PbZr0.5Ti0.5O3 in ferroelectric devices, both since it does not contain any toxic lead and because of its large spontaneous polarization.  Substitution of both the Bi and Ti cations is likely to alter the polarization and this project will explore the synthesis, structure and properties of layers oxides such as Bi3SrNaNb3O12 and Bi2Sr2Nb2.67Zn0.33O12 as alternatives to Bi4Ti3O12.  Variable temperature structural studies are critical to establish the impact these substitutions have on the stability of the ferroelectric mode.

Publications (2009 - 2013)

  1. Noked, O; Melchior, A; Shuker, R; Livneh, T; Steininger, R; Kennedy, BJ and Sterer. E. Pressure-induced amorphization of La1/3TaO3. Journal of Solid State Chemistry, 202, 38-42, 2013. DOI: 10.1016/j.jssc.2013.03.007

  2. Awin, L; Kennedy, BJ and Avdeev, M. Structural and magnetic studies of A site doped LaRh1-xCuxO3(A=Ca2+, Sr2+, Pb2+ and Bi3+). Ceramics International, 39 (1), S233-S237, 2013. DOI: 10.1016/j.ceramint.2012.10.068

  3. Tan, T-Y; Martin, N; Zhou, Q; Kennedy, BJ; Gu, Q; Kimpton, JA; Zhang, Z and Jang, L-Y. Valence changes of manganese and structural phase transitions in Sr1-xPrxMnO3 (0.1 ≤ x ≤ 0.6). Journal of Solid State Chemistry, 201, 115-127, 2013. DOI: 10.1016/j.jssc.2013.01.034

  4. Prodjosantoso, AK; Zhou, Q and Kennedy, BJ. Synchrotron X-ray diffraction study of the Ba1-xSrSnO3 solid solution. Journal of Solid State Chemistry, 200, 241-245, 2013. DOI: 10.1016/j.jssc.2013.01.015

  5. Qasim, I; Kennedy, BJ and Avdeev, M. Synthesis, structures and properties of transition metal doped SrlrO3. Journal of Materials Chemistry A, 1 (9), 3127-3132, 2013. DOI: 10.1039/c3ta00540b

  6. Qasim, I and Kennedy, BJ. Structural characterization of the perovskite series Sr1-xLaxTi0.5Mn0.5O3. Journal of solid State Chemistry, 200, 39-42, 2013. DOI: 10.1016/j.jssc.2013.01.011

  7. Blanchard, PER; Liu, S; Kennedy, BJ; Ling, CD; Avdeev, M; Aitken, JB; Cowie, BCC and Tadich, A. Investigating the local structure of lanthanoid hafnates Ln2Hf2O7 via diffraction and spectroscopy. The Journal of Physical Chemistry C, 117 (5), 2266-2273, 2013. DOI: 10.1021/jp311329q

  8. Reynolds, E; Kennedy, BJ; Thorogood, GJ; Gregg, DJ and Kimpton, JA. Crystal structure and phase transitions in the uranium perovskite, Ba2SrUO6. Journal of Nuclear Materials, 433 (1-3), 37-40, 2013. DOI: 10.1016/j.jnucmat.2012.08.034

  9. Blanchard, PER; Clements, R; Kennedy, BJ; Ling, CD; Reynolds, E; Avdeev, M; Stampfl, APJ, Zhang, Z and Jang, L-Y. Does local disorder occur in the pyrochlore zirconates? Inorganic Chemistry, 51 (24), 13237-13244, 2012. DOI: 10.1021/ic301677b

  10. Reynolds, E; Kennedy, BJ; Thorogood, GJ; Gregg, DJ and Kimpton, JA. Crystal structure and phase transitions in the uranium perovskite, Ba2SrUO6. Journal of Nuclear Materials, 433 (1-3), 37-40, 2012. DOI: 10.1016/j.jnucmat.2012.08.034

  11. Zhou, Q; Blanchard, P; Kennedy, BJ; Reynolds, E; Zhang, Z; Miiller, W; Aitken, JB; Avdeev, M; Jang, L-Y and Kimpton, JA. Synthesis, structural and magnetic studies of the double perovskites Ba2CeMO6 (M = Ta, Nb). Chemistry of Materials, 24 (15), 2978-2986, 2012. DOI: 10.1021/cm301278a

  12. Kennedy, BJ; Qasim, I; Reynolds, E; Tan, T-Y and Zhou, Q. Synchrotron X-ray powder diffraction studies of structral phase transitions in perovskite oxides. Australian Journal of Chemistry, 65 (3), 229-235, 2012. DOI: 10.1071/CH11313

  13. Zhang, Z; Kennedy, BJ; Howard, CJ; Carpenter, MA; Miiller, W; Knight, KS; Matsuda, M and Miyake, M. Crystal structures, strain analysis, and physical properties of Sr0.7Ce0.3MnO3. Physical Review B, 85 (17), 174110, 2012. DOI: 10.1103/PhysRevB.85.174110

  14. Reynolds, E; Blanchard, PER; Zhou, Q; Kennedy, BJ; Zhang, Z and Jang, L-Y. Structural and spectroscopic studies of La2Ce2O7: Disordered fluorite versus pyrochlore structure. Physical Review B, 85, 132101, 2012. DOI: 10.1103/PhysRevB.85.132101

  15. Tan, T-Y; Kennedy, BJ; Zhou, Q; Ling, CD; Miiller, W; Howard, CJ; Carpenter, MA and Knight, KS. Impact of Jahn-Teller active Mn3+ on strain effects and phase transitions in Sr0.65Pr0.35MnO3. Physical Review B, 85 (10), 104107, 2012. DOI: 10.1103/PhysRevB.85.104107

  16. Tan, T-Y; Zhou, Q; Kennedy, BJ; Gu, Q and Kimpton, JA. Coupling of Jahn-Teller and tilting distortions in high temperature structural phase transition of the Ca0.2Sr0.6Nd0.2Mn1-xCrxO3; 0 ≤ x ≤ 0.2 perovskites. Solid State Sciences, 14 (4), 506-514, 2012. DOI: 10.1016/j.solidstatesciences.2012.01.027

  17. Miiller, W; Avdeev, M; Zhou, Q; Kennedy, BJ; Sharma, N; Kutteh, R; Kearley, GJ; Schmid, S; Knight, KS; Blanchard, PER and Ling, CD. Giant magnetoelastic effect at the opening of a spin-gap in Ba3sBilr2O9. Journal of the American Chemical Society, 134 (6), 3265-3270, 2012. DOI: 10.1021/ja211517h

  18. Miiller, W; Avdeev, M; Zhou, Q; Studer, AJ; Kennedy, BJ; Kearley, GJ and Ling, CD. Spin-gap opening accompanied by a strong magnetoelastic response in the S = 1 magnetic dimer system Ba3BiRu2O9. Physical Review B, 84 (22), 220406, 2011. DOI: 10.1103/PhysRevB.84.220406


  19. Qasim, I; Kennedy, BJ; Zhang, Z; Avdeev, M and Jang, L-Y. X-ray absorption near edge structure and crystallographic studies of the mixed valence oxide SrRu0.8Ni0.2O3. Journal of Physics: Condensed Matter, 23 (43), 435401, 2011. DOI: 10.1088/0953-8984/23/43/435401

  20. Thorogood, GJ; Zhang, Z; Hester, JR; Kennedy, BJ; Ting, J; Glover, CJ and Johannessen, B. Structure and cation ordering in spinel-type TcCo2O4. An example of a trivalent technetium oxide. Dalton Transactions, 40 (41), 10924-10926, 2011. DOI: 10.1039/c1dt10954e

  21. Kennedy, BJ; Zhou, Q and Avdeev, M. The ferroelectric phase of CdTiO3: A powder neutron diffraction study. Journal of Solid State Chemistry, 184 (11), 2987-2993, 2011. DOI: 10.1016/j.jssc.2011.08.028

  22. Zhou, Q; Kennedy, BJ and Avdeev, M. Thermal expansion behaviour in the oxygen deficient perovskites Sr2BSbO5.5 (B=Ca, Sr, Ba). Competing effects of water and oxygen ordering. Journal of Solid State Chemistry, 184 (9), 2559-2565, 2011. DOI: 10.1016/j.jssc.2011.07.019

  23. Kennedy, BJ and Avdeev, M. The structure of B-type Sm2O3. A powder neutron diffraction study using enriched 154Sm. Solid State Sciences, 13 (9), 1701-1703, 2011. DOI: 10.1016/j.solidstatesciences.2011.06.020

  24. Clements, R; Hester, JR; Kennedy, BJ; Ling, CD and Stampfl, APJ. The fluorite-pyrochlore transformation of Ho2-yNdyZr2O7. Journal of Solid State Chemistry, 184 (8), 2108-2113, 2011. DOI: 10.1016/j.jssc.2011.05.054

  25. Thorogood, GJ; Avdeev, M; Carter, ML; Kennedy, BJ, Ting, J and Wallwork, KS. Structural phase transitions and magnetic order in SrTcO3. Dalton Transactions, 40 (27), 7228-7233, 2011. DOI: 10.1039/c1dt10445d

  26. Kennedy, BJ; Zhou, Q and Avdeev, M. Neutron diffraction studies of Gd2Zr2O7 pyrochlore. Journal of Solid State Chemistry, 184 (7), 1695-1698, 2011. DOI: 10.1016/j.jssc.2011.04.003

  27. Thorogood, GJ; Kennedy, BJ; Avdeev, M; Peterson, VK; Hanna, JV and Luca, V. Cation disorder in NaW2O6+d ⋅nH2-zO post-ion exchange with K, Rb, Sr, and Cs. Journal of Physics and Chemistry of Solids, 72 (6), 692-700, 2011. DOI: 10.1016/j.jpcs.2011.02.018

  28. Zhou, Q; Kennedy, BJ and Kimpton, JA. The effect of disorder in Ba2YTaO6 on the tetragonal to cubic phase transition. Journal of Solid State Chemistry, 184 (4), 729-734, 2011. DOI: 10.1016/j.jssc.2010.12.011

  29. Avdeev, M; Thorogood, GJ; Carter, ML; Kennedy, BJ; Ting, J; Singh, DJ and Wallwork, KS. Antiferromagnetism in a technetium oxide. Structure of CaTcO3. Journal of the American Chemical Society, 133 (6), 1654-1657, 2011. DOI: 10.1021/ja109431t

  30. Rodriguez, EE; Poineau, F; Llobet, A; Kennedy, BJ; Avdeev, M; Thorogood, GJ; Carter, ML; Seshadri, R; Singh, DJ and Cheetham, AK. High temperature magnetic ordering in the 4d perovskite SrTcO3. Physical Reveiw Letters, 106 (6), 067201 (4pp), 2011. DOI: 10.1103/PhysRevLett.106.067201

  31. Kennedy, BJ and Avdeev, M. The structure of C-type Gd2O3. A powder neutron diffraction study using enriched 160Gd. Australian Journal of Chemistry, 64 (1), 119-121, 2011. DOI: 10.1071/CH10310

  32. Ting, J and Kennedy, BJ. Structure and properties of manganese-substituted bismuth titanates. Journal of Physics: Conference Series, 251 (1), 012029 (4pp), 2010. DOI: 10.1088/1742-6596/251/1/012029

  33. Macquart, RB; Kennedy, BJ and Avdeev, M. A primitive tetragonal intermediate in the orthorhombic-cubic phase transition of perovskite-type strontium niobate Sr0.92NbO3. Journal of Solid of Solid State Chemistry, 183 (10), 2400-2405, 2010. DOI: 10.1016/j.jssc.2010.08.001

  34. Kaur, N; Singh, B and Kennedy, BJ. Dissolution of Cr, Zn, Cd, and Pb single- and multi-metal-substituted goethite: Relationship to structural, morphological, and dehydroxylation properties. Clays and Clay Minerals, 58 (3), 415-430, 2010. DOI: 10.1346/CCMN.2010.0580311

  35. Thorogood, GJ; Kennedy, BJ; Griffith, CS; Elcombe, MM; Avdeev, M; Hanna, JV; Thorogood, SK and Luca, V. Structure and phase transformations in the titanosilicate, sitinakite. The importance of water. Chemistry of Materials, 22 (14), 4222-4231, 2010. DOI: 10.1021/cm100727h.

  36. Zhou, Q; Kennedy, BJ and Avdeev, M. Structural studies of the disorder and phase transitions in the double perovskite Sr2YTaO6. Journal of Solid State Chemistry, 183 (8), 1741-1746, 2010. DOI: 10.1016/j.jssc.2010.05.018

  37. Thorogood, GJ; Avdeev, M and Kennedy, BJ. Structural studies of the aeschynite-euxenite transformation in the series Ln(TiTa)O6 Ln = Lanthanide. Solid State Sciences, 12 (7), 1263-1269, 2010. DOI: 10.1016/j.solidstatesciences.2010.02.036

  38. Ricciardo, RA; Cuthbert, HL; Woodward, PM; Zhou, Q; Kennedy, BJ; Zhang, Z; Avdeev, M and Jang, L-Y. Structure and properties of Sr1-xCaxMn0.5Ru0.5O3 perovskites: Using chemical pressure to control Mn/Ru mixed valency. Chem. Mater., 22 (11), 3369-3382, 2010. DOI: 10.1021/cm903848h

  39. Ting, J; Kennedy, BJ; Zhang, Z; Avdeev, M; Johannessen, B and Jang, L-Y. Synthesis and structural studies of the transition-metal-doped Rh perovskites LaMn0.5Rh0.5O3 and LaCu0.5Rh0.5O3. Chem. Mater., 22 (5), 1640-1646, 2010. DOI: 10.1021/cm902718r

  40. Ling, CD; Kennedy, BJ; Zhou, Q; Spencer, JR and Avdeev, M. Synthesis, structures, and phase transitions of barium bismuth iridium oxide perovskites Ba2BiIrO6 and Ba3BiIr2O9. Journal of Solid State Chemistry, 183 (3), 727-735, 2010. DOI: 10.1016/j.jssc.2010.01.017

  41. Macquart, RB; Kennedy, BJ and Avdeev, M. Neutron diffraction study of phase transitions in perovskite-type strontium molybdate SrMoO3. Journal of Solid State Chemistry, 183 (1), 249-254, 2010. DOI: 10.1016/j.jssc.2009.11.005

  42. Kaur, N; Singh, B and Kennedy, BJ. Copper substitution alone and in the presence of chromium, zinc, cadmium and lead in goethite (a-FeOOH). Clay Minerals, 44 (3), 293-310, 2009. DOI: 10.1180/claymin.2009.044.3.293

  43. Carpenter, MA; McKnight, REA; Howard, CJ; Zhou, Q; Kennedy, BJ and Knight, KS. Characteristic length scale for strain fields around impurity cations in perovskites. Physical Review B, 80 (21), 214101 (8 pages), 2009. DOI: 10.1103/PhysRevB.80.214101

  44. Zhou, Q; Kennedy, BJ; Avdeev, M; Giachini, L and Kimpton, JA. Structural studies of the phases in Ba2LaIrO6 – New light on an old problem. Journal of Solid State Chemistry, 182 (11), 3195-3200, 2009. DOI: 10.1016/j.jssc.2009.08.026

  45. Kennedy, BJ; Saines, PJ; Ting, J; Zhou, Q and Kimpton, JA. Structural characterisation of the perovskite series SrxCa1-x-yNdyMnO3: Influrence of the Jahn-Teller effect. Journal of Solid State Chemistry, 182 (10), 2858-2866, 2009. DOI: 10.1016/j.jssc.2009.07.041

  46. Zhou, Q; Kennedy, BJ; Zhang, Z; Jang, Ling-Yun and Aitken, JB. X-ray absorption near edge structure and crystallographic studies of the mixed valence oxides CaRu1-xMnxO3. Chemistry of Materials, 21 (18), 4203-4209, 2009. DOI: 10.1021/cm9007238

  47. Macquart, RB; Zhou, QD and Kennedy, BJ. Structural investigation of Sr2LiReO6. Evidence for a continuous tetragonal-cubic phase transition. Journal of Solid State Chemistry, 182 (7), 1691-1693, 2009. DOI: 10.1016/j.jssc.2009.04.010

  48. Kaur, N; Grafe, M; Singh, B and Kennedy, BJ. Simultaneous incorporation of Cr, Zn, Cd, and Pb in the goethite structure. Clays and Clay Minerals, 57 (2), 234-250, 2009. DOI: 10.1346/CCMN.2009.0570210

  49. Goodwin, AL; Kennedy, BJ and Kepert, CJ. Thermal expansion matching via framework flexibility in zinc dicyanometallates. Journal of the American Chemical Society, 131 (18), 6334, 2009. DOI: 10.1021/ja901355b

  50. Ting, J; Kennedy, BJ; Withers, RL and Avdeev, M. Synthesis and structural studies of lanthanide substituted bismuth-titanium pyrochlores. Journal of Solid State Chemistry, 182 (4), 836-840, 2009. DOI: 10.1016/j.jssc.2008.12.030

  51. Kennedy, BJ; Ting, J; Zhou, QD; Zhang, ZM; Matsuda, M and Miyake, M. Structural characterisation of the perovskite series Sr0.9-xCaxCe0.1MnO3: Influence of the Jahn-Teller effect. Journal of Solid State Chemistry, 182 (4), 954-959, 2009. DOI: 10.1016/j.jssc.2008.12.032

  52. Saines, PJ; Kennedy, BJ and Smith, RI. Structural phase transitions in BaPrO3. Materials Research Bulletin, 44 (4), 874-879, 2009. DOI: 10.1016/j.materresbull.2008.09.013

  53. Thorogood, GJ; Kennedy, BJ; Peterson, VK; Elcombe, MM; Kearley, GJ; Hanna, JV and Luca, V. Anomalous lattice parameter increase in alkali earth aluminium substituted tungsten defect pyrochlores. Journal of Solid State Chemistry, 182 (3), 457-464, 2009. DOI: 10.1016/j.jssc.2008.11.014

  54. Zhang, ZM; Howard, CJ; Kennedy, BJ; Matsuda, M and Miyake, M. Crystal structures and phase transition in (Sr0.8Ce0.2)(Mn1-yCoy)O3 (y=0 and 0.2): the influence of Jahn-Teller distortion. Journal of Physics-Condensed Matter, 21 (12), 124218, 2009. DOI: 10.1088/0953-8984/21/12/124218

  55. Kaur, N; Singh, B; Kennedy, BJ and Grafe, M. The preparation and characterization of vanadium-substituted goethite: The importance of temperature. Geochimica et Cosmochimica Acta, 73 (3), 582-593, 2009. DOI: 10.1016/j.gca.2008.10.025

  56. McKnight, REA; Kennedy, BJ; Zhou, Q and Carpenter, MA. Elastic anomalies associated with transformation sequences in perovskites: II. The strontium zirconate-titanate Sr(Zr, Ti)O3 solid solution series. Journal of Physics-Condensed Matter, 21 (1), 015902, 2009. DOI: 10.1088/0953-8984/21/1/015902