Nanostructure in Functional Ceramics

Lead Research Organisation: University of Sheffield
Department Name: Materials Science and Engineering

Abstract

The functional properties of many ceramics are controlled principally by displacements of ions which create small electric dipoles across the unit cells of certain types of oxides. However, in order for these electric dipoles to affect the bulk properties, they must be cooperative, i.e. the displacemetns must occur in the same direction for at least several tens of unit cells. Functional properties are tailored for a specific application by modifying the direction and length over which the dipoles are cooperative as well as the temperature at which they occur (Tc). In ceramic capacitors which act as rf filters, a mesoscale heterogeneous distribution of dopants modifies the magnitude, direction and onset temperature of the dipoles, preventing the filter frequency from changing significantly with temperature. In piezoelectric ceramics, a nanoscale mixture of monoclinic, tetragonal and rhombohedral phases in which the direction/magnitude of the dipoles differs in each structure, optimises the charge/displacement produced. This programme aims to investigate the local nanostructure of ceramics using advanced analystical instrumentation and determine its relation to bulk properties (permittivity, dielectric loss, piezoelectricity). This understanding will be used to improve performance and develop new functional ceramics.

Publications

10 25 50
 
Description The grant was designed to establish a combined experimental initiative in which Raman spectroscopy was used in tandem with advanced electron microscopy on a routine basis. The key findings were:

1) A new PbZrO3 structured AFE ceramic based on Nd doped BiFeO3. This is the first AFE/AFM structured ceramic and publication of the data has resulted in many research groups pursuing studies on this topic.

2) A new methodology of using Raman spectrosocpy to help determine site occupancy in perovskite structured ceramics. In the development of functional ceramics, it essential to know where dopant ions reside in the structure. This technique adds a new dimension to dopant studies and understanding defect structure/property relations in perovskites.

3) Sheffield is now able to act as a informal centre for Raman spectroscopy studies in the UK. The Raman microscope has been improved and a 3rd laser added. In situ, He and LN2 stages have been purchased along with a Diamond anvil pressure stage and an in house constructed poling stage. The Sheffield facility is now the leading Raman facility in the UK for the study of inorganic compounds.
Exploitation Route We are currently investigating Nd doped BiFeO3 for potential piezoelectric applications but to date there have no major breakthroughs.
Sectors Aerospace, Defence and Marine,Electronics

 
Description The grant has facilitated the development of the leading Raman spectroscopy facility in the UK for the study of inorganic compounds. The Raman has 3 lasers, in situ strain and poling stages and a LHe and LN2 cooling/heating stages. The discovery of a non PbO based AFE ceramic with the PbZrO3 strcutured has driven great interest in oxide research groups. Papers published during and subsequent to the grant are highly cited. The grant has allowed MSE at Sheffield to establish the leading UK inorganic Raman facility which has been utilised by a number of external groups, e.g. Leeds (A.J. Bell and Manchester (D. Hall). New techniques have been developed on this and related grants to study perovskites using Raman spectroscopy. The use of electron diffraction in combination with Raman has facilitated a deeper understanding of the crystal structure of perovskites. Some PbO based compounds such as PbZrO3 and PbHfO3 are know to have AFE structures. The discovery of a non PbO version based on Nd doped BiFeO3 is a significant data point in terms of the crystal chemistry of perovskites and it is hoped that this will act as a base for the development of new materials. Beneficiaries: Multiferroics community and UK perovskite community (Raman facility) Contribution Method: The grant facilitated the development of the Raman facility at Sheffield which has resulted in further funding and increased quality of research output
First Year Of Impact 2011
Sector Aerospace, Defence and Marine,Electronics
Impact Types Societal

 
Description EPSRC
Amount £392,058 (GBP)
Funding ID EP/I038934/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2011 
End 12/2014
 
Description EPSRC
Amount £20,964 (GBP)
Funding ID EP/J009679/1 + EP/I038934/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 06/2012 
End 12/2012
 
Description EPSRC
Amount £23,635 (GBP)
Funding ID EP/H048049/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2010 
End 07/2010
 
Description EPSRC
Amount £30,250 (GBP)
Funding ID EP/I033319/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2010 
End 07/2010
 
Description EPSRC
Amount £23,635 (GBP)
Funding ID EP/H048049/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2010 
End 07/2010
 
Description EPSRC
Amount £280,149 (GBP)
Funding ID EP/H048049/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2009 
End 09/2012
 
Description EPSRC
Amount £280,149 (GBP)
Funding ID EP/G069069/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2009 
End 09/2012
 
Description Conference Invited talks (international) Invited Seminars (National) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The research formed the basis of multiple invited presentations at international conferences, e.g. Electronic Materials and their Applications, Electroceramics, International Symposium on Applied Ferroelectrics. The audience members varied from post graduate researchers to faculty in other universities (professional practioners). The research was also presented at Glasgow University and Liverpool University in their seminar series.
Year(s) Of Engagement Activity 2009,2011,2012,2013,2014