Research Guides

I was an undergraduate student at the University of Bristol before coming to Oxford in 1976 to work as a graduate student with Tony Cheetham. I spent four further years in Oxford as a CEGB Research Fellow before moving to Leeds University as a Lecturer in 1984. I returned to Oxford as a University Lecturer in 1989, and was given the title of Professor of Chemistry in 2002; I am also a tutor at St. Catherine's College. I have held visiting professorships in Caen (1988) and Bordeaux (1995).

1. Electronic Properties of Solids Our research interests in this area cover a number of different topics. A theme common to all of them is the attempt to correlate crystal structure with electronic behaviour, particular emphasis being placed on the link between structure and magnetic properties. Here "structure" can mean the bulk crystal structure, as determined in X-ray and neutron diffraction experiments, or the local structure around defects in non-stoichiometric materials, as studied by EXAFS, Mössbauer spectroscopy and electron microscopy. Magnetic measurements are made over the temperature range 5<T/K<300 using a SQUID magnetometer, and we can measure electrical conductivity over the same range. The Inorganic Chemistry Laboratory has six X-ray powder diffractometers, including one which can be adapted for operation with sample temperatures of up to 800 °C. In addition EXAFS experiments are carried out at the Diamond Light Source at Rutherford Appleton Laboratory, which lies fifteen miles south of Oxford. Neutron diffraction is carried out at the Institut Laue Langevin at Grenoble, France, or at the Rutherford Appleton Laboratory. Mössbauer measurements are made in collaboration with Professors F. Grandjean and G. J. Long at the Université de Liège, Belgium. Compounds of particular interest include:

(a) oxides of elements from the 2nd and 3rd transition series (Ru, Rh, Ir, Pd, Pt) Compared to the oxides of the 1st transition series, compounds of 2nd and 3rd row transition metals have received very little attention. However, the use of 4d and 5d orbitals gives us the opportunity to increase the energy width of the valence band in oxide structures, thus moving from the localized electron regime (where compounds are insulators, often showing antiferromagnetic or ferromagnetic ordering at low temperatures) to the itinerant electron regime ( where compounds are metallic conductors and show no long-range magnetic order). We are particularly interested in preparing new compounds which lie on the border between localized and itinerant electron behaviour. In these cases we can observe the coexistence of ferromagnetism and a high electrical conductivity, both important properties in materials research.

(b) oxides containing two different d-block cations Compounds containing only one d-block cation usually order antiferromagnetically (i.e. no net magnetisation), although the spontaneous magnetisation associated with ferromagnetism is the sought-after property. The likelihood of ferromagnetic ordering is increased if two d-block cations with different numbers of unpaired electrons are incorporated into a compound, although other factors (spin frustration) have to be taken into account. A number of different structure types are under investigation at the present time. Members of the family Ln₁₈Li₈M₄M’O₃₉ (Ln = La, Pr, Nd; M, M’ = Ti, Mn, Fe, Co, Ru) adopt the crystal structure illustrated below. The presence of two distinct sites for the transition-metal cations (green and red octahedra in the picture) means that ferrimagnetism is likely to result if two different cations can be persuaded to occupy the two sites in an ordered manner.

(c) magnetically-ordered interstitial nitrides Nitrides that adopt a structure related to that of either manganese metal (β-Mn) or Fe₃W₃C are being studied. These compounds are capable of sustaining both magnetism (see M(H) curves below) and metallic conductivity, and our aim is to optimise their electronic properties by careful control of the relatively-complex chemical composition (e.g. Co₂Ge_0.3Ga_0.7Mo₃N) and the crystal structure.

2. Ruddlesden-Popper oxides as fuel-cell electrodes Oxides that adopt the K₂NiF₄ structure are under consideration for use as electrode materials in solid-oxide fuel cells. The research in this area is centred on the defect chemistry of the material, and the relative ease with which oxygen can be removed from the different sites within the structure under the reducing conditions found in a fuel cell. This is being investigated in neutron diffraction experiments carried out at high temperature under flowing hydrogen. This work is being carried out in collaboration with Dr. M. Bahout (Université Rennes 1) and Prof. C. Greaves (University of Birmingham). The figure below shows how the occupation factor of two distinct oxygen sites in La₂Sr₂CrNiO_8-δ varies as a function of temperature under hydrogen flow. Green and black squares represent the occupancy of the O1 (axial) and O2 (equatorial) sites during heating; blue and red triangles represent O1 and O2 on cooling. The blue line corresponds to the Ni (II) composition.

The influence of chemical composition on the magnetic properties of
Fe_1.5-xCo_xRh_0.5Mo₃N (0 ≤ x ≤ 1.5)
P. D. Battle, F. Grandjean, G. J. Long, and S. E. Oldham
J. Mater. Chem. 17, 4785 (2007)

Structural chemistry and magnetic properties of Nd₁₈Li₈Fe₅O₃₉ and Nd₁₈Li₈Co₄O₃₉; the interplay of cation and spin ordering
S. E. Dutton, P. D. Battle, F. Grandjean, G. J. Long and K. Oh-ishi
Inorganic Chemistry 47, 11212 (2008)

Structural chemistry and magnetic properties of Nd₁₈Li₈Fe_5-xM_xO₃₉ (M = Mn, Co)
S. E. Dutton, P. D. Battle, F. Grandjean, G. J. Long and P. A. van Daesdonk
Inorganic Chemistry 48, 1613 (2009)

Use of in situ neutron diffraction to monitor high-temperature, solid/H₂-gas reactions
F. Tonus, M. Bahout, P. F. Henry, S. E. Dutton, T. Roisnel, P. D. Battle
Chem. Commun. 2556 (2009)

Structural and magnetic properties of Pr₁₈Li₈Fe_5-xM_xO₃₉ (M = Ru, Mn, Co)
S. E. Dutton, P. D. Battle, F. Grandjean, G. J. Long, M. T. Sougrati, P. A. van Daesdonk, and E. Winstone
J. Solid State Chem. 182, 1638 (2009)

Magnetic ordering in nitrides with the η-carbide structure; (Ni,Co,Fe)₂(Ga,Ge)Mo₃N
L. A. Sviridov, P. D. Battle, F. Grandjean, G. J. Long and T. J. Prior
Inorganic Chemistry 49, 1133 (2010)

In situ neutron diffraction study of the high-temperature redox chemistry of Ln_3-xSr_1+xCrNiO_8-δ (Ln = La, Nd) under hydrogen
F. Tonus, M. Bahout, P. D. Battle, T. Hansen, P. F. Henry and T. Roisnel
J. Mater. Chem. 20, 4103 (2010)

Synthesis and structural chemistry of La₁₈Li₈Rh₄MO₃₉ (M = Ti, Mn, Ru)
P. D. Battle, S. E. Dutton, P. A. van Daesdonk
J. Solid State Chem. 183, 1620 (2010)

Structural chemistry and magnetic properties of Ln₁₈Li₈Rh_5-xFe_xO₃₉ (Ln = La, Nd)
P. D. Battle, S. E. Dutton, N. Thammajak, F. Grandjean, M. Sougrati, G. J. Long, K. Oh-ishi and S. Nakanishi
Inorganic Chemistry 49, 5912 (2010)