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Details of Grant 

EPSRC Reference: EP/R011753/1
Title: Chemical control of function beyond the unit cell for new electroceramic materials
Principal Investigator: Rosseinsky, Professor M
Other Investigators:
Claridge, Dr JB Alaria, Dr J
Researcher Co-Investigators:
Project Partners:
CeramTec UK Limited Ionix Advanced Technologies Ltd NanoSpin Group
Oak Ridge National Laboratory STFC Laboratories (Grouped) Thales Ltd
Trinity College Dublin Xaar Plc
Department: Chemistry
Organisation: University of Liverpool
Scheme: Standard Research
Starts: 01 November 2017 Ends: 31 October 2020 Value (£): 742,473
EPSRC Research Topic Classifications:
Materials Characterisation Materials Synthesis & Growth
EPSRC Industrial Sector Classifications:
Electronics Manufacturing
Related Grants:
EP/R010293/1
Panel History:
Panel DatePanel NameOutcome
13 Sep 2017 EPSRC Physical Sciences - September 2017 Announced
Summary on Grant Application Form
Discovery and development of advanced materials requires understanding and control of the relationship between composition, structure and function. In crystalline materials, there is considerable focus on a design process that is informed by a single macroscopic structure defined by the average crystallographic unit cell determined by Bragg diffraction. This is a powerful approach, but it has become increasingly apparent that local chemical and positional deviations from this long-range average view of the structure can have decisive effects even in crystalline systems. Charge stripes in the high temperature superconductors and the role of "panoscopic" order spanning meso- to nano-scopic length scales in thermoelectric performance are just two examples of the limitations of average structure considerations in explaining how an apparently small compositional change can transform functional behaviour. This in turn restricts the utility of such a view of structure in designing new materials with enhanced performance.

This is particularly critical for the many functional materials in which modulation or switching of a ferroic order parameter (i.e., polarization or magnetization) by a stimulus such as an applied field produces the property (e.g., piezoelectricity or magnetoresistance) used in devices (e.g., actuators or data storage). Their properties are optimised by formation of solid solutions e.g., in PbZrO3-PbTiO3 (PZT), responsible for >90% of piezoelectric devices, the Zr/Ti ratio is adjusted to coincide with the boundary between rhombohedral and tetragonal symmetries, at which the piezoelectric charge coefficient maximizes. There is competition between the randomising effect of the local configuration of Zr and Ti cations (which occupy the same position in the average unit cell, but locally exert quite different influences on the displacements producing the polarisation) and the effect of the long-range dipolar and elastic interactions favouring the average polarisation direction. This local structure effect and the finite size correlations it produces exerts decisive control of function that is invisible from the average structure central to traditional design. The properties of the solid solutions are thus not an average of the end members, and simple design rules do not exist.

The project team have recently shown how design based on quantitative local structure analysis can afford materials families with important properties that had not been accessed by classical average structure design approaches. Using nanoscale information from total Bragg scattering studies to control properties, they identified chemistry that would have been disregarded based on the average structure but led to a new lead-free piezoelectric family (Advanced Materials 2015) and then to the first bulk room temperature ferromagnetic ferroelectric multiferroic (Nature 2015): combination of these two long range orders in a single phase has been a longstanding scientific challenge.

This project will develop the control of function by understanding and manipulating symmetry and structure beyond the unit cell length scale. We will build a toolkit that enables this approach by combining solid state materials chemistry, materials science and condensed matter physics to integrate synthesis, crystal chemistry, crystallography, local structure analysis, scanning probe microscopy, magnetism, electroceramic measurement physics, and materials processing. The toolkit exploits the synergies between the skills of the two participating groups.

By designing then preparing new piezoelectric and multiferroic materials, we will demonstrate how this approach can guide synthesis for function, with ramifications for control of properties beyond the exemplar areas studied, for example in heterogeneous catalyst and electrode (fuel cell, battery) materials, contributing to the EPSRC Physical Sciences Grand Challenge of Nanoscale Design of Functional Materials.
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Organisation Website: http://www.liv.ac.uk