Dr Daniel J Price

Department of Chemistry
University of Glasgow
Glasgow G12 8QQ
Scotland

Telephone: +44 (0) 141 330 8794
FAX: +44 (0) 330 4888
email: d.price@chem.gla.ac.uk



Biography

Born in Bristol Daniel Price attended St Katherine's School and Sixth Form. In 1991 he graduated from the University of Sheffield with BSc honours in Chemistry. He obtained a PhD (Sheffield) for research into hydrogen bond induced mesomorphism, (a project supervised by Professor Duncan Bruce). He subsequently moved to France to take a postdoctoral position with the late Professor Olivier Kahn at the ICMCB in Bordeaux. This time researching a different aspect of phase behaviour; cooperative magnetism in transition metal coordination networks. In 1995 he returned to the UK as a postdoctoral fellow working with Professor Annie Powell and Dr Paul Wood at the University of East Anglia. Here many new coordination network materials were discovered using hydrothermal methods, many of which showed complex magnetic behaviour. Daniel Price was awarded an EPSRC Advanced Research Fellowship in 1999 to develop synthesis for hybrid inorganic-organic materials, which can have unusual electronic and magnetic properties. The Fellowship initially commenced at Edinburgh University before being transferred to Southampton University in 2000. In 2004 he was appointed to a lectureship in chemistry at the University of Glasgow.

Research Interests

Keywords: Hybrid materials, condensed matter physics, coordination networks, magnetic interactions, spin frustration, magnetic ordering, cooperative phenomena, phase behaviour, low dimensional systems.

Current Interests

Most generally we are interested in the complex behaviour of many body systems having different types of interactions. In other words we are interested in cooperativity, phase structures and phase behaviour, or to put it another way, we are interested in symmetry, structure, patterns, textures, order and disorder, phase transitions and order parameters. This is a very far-reaching field of science, and theories of phase behaviour are applied to such diverse things as the early history of the universe, superconductors, fluid flow, protein folding, liquid crystals, as well as boiling water for your cup of tea.

Roman mosaic - Pompeii. Three-fold symmetry can result in magnetic spin frustration and the suppression of conventional order.

We enter this field as magnetochemists, using magnetic moments from atoms with unpaired electrons as objects that can interact with each other through a magnetic exchange interaction. We are interested in spatial and temporal magnetic structures and the magnetic phase behaviour.

Both the detailed nature of the moments, and the coupling interaction are important, as is the network dimension and topology. These things can be controlled to some extent by using a "crystal engineering" approach, building specific arrays of transition metal ions and linkers to mediate the coupling interaction.Our aims are to form new materials which both test the current theories of solid-state (condensed matter) physics and to form materials where very interesting and unusual physical behaviour is expected.

An example of this is the humble antiferromagnetically coupled chain of spins. Even such a simple system can show some bizarre behaviour. For a chain of antiferromagnetically coupled S=1/2 ions theory says that no long-range order can exist above absolute zero, and at low temperatures you have a compressible 1-D spin liquid like order. By contrast if we replace the magnetic moments with an S=1 ion, the behaviour is qualitatively different. Such a system can undergo a phase transition to an incompressible 1-D spin liquid state, where there is quantum coherence, and a curious combination of long-range and liquid-like order (known as hidden string order) not seen elsewhere in nature. By contrast for the S = 2 case we know very little about the magnetic behaviour at low temperatures. Such a magnetic system is a clear target as it offers a rare opportunity for us experimentalists to tell theoreticians how the world really is.

This is just one of many types of magnetic materials which are considered as "hot topics" in the field of magnetochemistry today.
Our research is directed at the formation of just such magnetically interesting materials, where we control the nature of the microscopic magnetic moment (the spins) and the structure of the extended magnetically coupled network. We use a variety of techniques to grow colourful crystals with transition metal network structures, where bridging ligands mediate a particular type of interaction. Our studies include significant initial magnetic and other characterisation of any new materials. The group makes use of a wide range of techniques including: UV, Visible, NIR, IR, spectroscopy, TGA with EGA, PXRD and single crystal XRD, powder and single crystal SQUID magnetometry
(RSO/dc/ac- as a function of temperature, field, offset field, drive frequency), heat capacity, neutron diffraction, MuSR, single crystal paramagnetic NMR, NQR, Mössbauer, High field experiments, EPR, SEM, EDAX.
Hydrothemally grown crystals: GaNa2Ba3Fe3(ox)9

Recent Highlights:

Pseudo 1-D atiferromagnets

 

Ba4Fe4(OH)4(ox)5Cl2:

Consists of chains of hydroxide bridged iron(II) ions, that are then connected into 3-D array by bridging oxalate ions. Magnetically there is a strong intra-chain interaction, thus as the sample is cooled a significant 1-D correlation between spin moments develops. The system behaves with XY anisotropy, and the experiences a crossover to conventional 3-D ordering below 32 K.

Single crystal magnetometry, muon spin rotation, and powder neutron diffraction, are consistent with the behaviour, and allow us to extract the thermal evolution of the 1-D spin correlation length, as well as the sub-lattice magnetisation order parameter.

  • "Hydrothermal synthesis, X-ray structure and complex magnetic behaviour of Ba4(C2O4)Cl2[{Fe(OH)(C2O4)}4]", D.J. Price, S. Tripp, A.K. Powell and P.T. Wood, Chem. Euro. J., 2001, 7, (1) 200 - 208.

 

Change in asymmetry of polarized implanted muons across the magnetic phase transition.

Network structure formed by Iron hydroxyl oxalate components (Fe - Yellow).

Ni(ox)(pip): is comprised of antiferromagnetically coupled nickel(II) oxalate chains that are magnetically well isolated by the piperazine spacer. Ni(II) has a d8 (S = 1) electronic configuration, and this material appears to show a Haldane phase (i.e. the unusual magnetic order described above) at low temperatures. The crystal symmetry make this material a particularly interesting candidate for further study as the position of inversion centres simplifies/constrains the magnetic behaviour.
Left: structure of Ni(pip)(ox).

Below left: Thermal dependence of magnetic susceptibility.

Below right: Derived nearest neighbour pair correlation function as a function of thermal energy.

K2M(ox)2 M=Fe, Co: The structure consists of zigzag chains of oxalate bridged M(II) ions. The materials are isostructural and the M(II) ion experiences a very rare trigonal prismatic coordination geometry. The coupling in the chains is strong and antiferromagnetic, however a weak inter-chain coupling is responsible for a magnetic phase transition to and ordered antiferromagnet at temperatures below ~ 10 K. This is most clearly seen in the magnetic neutron diffraction (D20, ILL Grenoble) which develop new Bragg peaks below the critical temperature.

 

The structure of K2Co(ox)2, showing the chain of oxalate bridged Co(II) ions with trigonal prismatic coordination.

Neutron powder diffraction of K2Co(ox)2 as the sample is cooled through a magnetic phase transition, showing the evolution of new purely magnetic Bragg peaks.

Vacancies:

Please contact Dr Price directly for more information.

Publications

2005

2004

2003

2002

2001

2000

Pre 2000

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