Structure-composition-property relationships in complex ACu3B4O12 perovskites
Lead Research Organisation:
University of Sheffield
Department Name: Materials Science and Engineering
Abstract
Preliminary results in our laboratory have shown two members (CaCu3Ti4O12, CCTO, and Na1/2Bi1/2Cu3Ti4O12) from a large family of perovskite-related compounds based on the general formula ACu3B4O12 have high intrinsic permittivity (> 100) at low temperatures and that appropriate doping (with Mn) can produce ceramics with encouraging microwave dielectric resonance properties at room temperature. The large values of intrinsic permittivity suggests some (as yet unknown) form of additional polarisation, other than ionic polarisation plays an important role in these compounds and that ACu3Ti4O12-type materials possess fundamentally interesting dielectric behaviour and potentially useful bulk dielectric properties after appropriate chemical doping. The aim of this study is therefore to prepare and characterise a wide variety of undoped and Mn-doped ACu3B4O12-type compounds to establish their structure-composition-property relationships. Particular emphasis will be given to optimising the bulk dielectric properties to assess their potential as commercially-useful high permittivity and/or temperature-stable dielectrics.
Organisations
Publications
Costa S
(2013)
Modulus spectroscopy of CaCu3Ti4O12 ceramics: clues to the internal barrier layer capacitance mechanism
in RSC Advances
Ferrarelli M
(2010)
Soft-mode behavior and incipient ferroelectricity in Na 1 / 2 Bi 1 / 2 Cu 3 Ti 4 O 12
in Physical Review B
Ferrarelli M
(2009)
Comment on the origin(s) of the giant permittivity effect in CaCu3Ti4O12 single crystals and ceramics
in Journal of Materials Chemistry
Ferrarelli M
(2011)
Microwave dielectric properties of Na 1/2 Bi 1/2 Cu 2.82 Mn 0.18 Ti 4 O 12 ceramics
in IOP Conference Series: Materials Science and Engineering
Ferrarelli M
(2009)
Possible incipient ferroelectricity in Mn-doped Na1/2Bi1/2Cu3Ti4O12
in Applied Physics Letters
Fiorenza P
(2010)
Detection of heterogeneities in single-crystal CaCu 3 Ti 4 O 12 using conductive atomic force microscopy
in IOP Conference Series: Materials Science and Engineering
Li M
(2007)
Incipient ferroelectricity and microwave dielectric resonance properties of CaCu2.85Mn0.15Ti4O12 ceramics
in Applied Physics Letters
Li M
(2013)
Transformation from insulating p-type to semiconducting n-type conduction in CaCu3Ti4O12-related Na(Cu5/2Ti1/2)Ti4O12 ceramics
in Journal of Applied Physics
Li M
(2011)
Extrinsic origins of the apparent relaxorlike behavior in CaCu3Ti4O12 ceramics at high temperatures: A cautionary tale
in Journal of Applied Physics
| Description | Discovered that CaCu3Ti4O12 (CCTO) is a barrier layer capacitor material and that the giant permittivity effect is associated with a Maxwell Wagner effect. This occurs when the grains are semiconducting and the grain boundaries are insulating. Related materials, eg (Na,Bi)Cu3Ti4O12 also show similar effects. We developed doping mechanisms to suppress the leakage conductivity (i.e. Mn for Cu) and to reveal the intrinsic dielectric properties. These materials are incipent ferroelectrics with high permittivity, in the range of 80 -120, however they have quite strong temperature dependence and this means they cant be used as microwave dielectric materials for resonators or filters. |
| Exploitation Route | Other groups are investigating this CCTO class of perovskites. for other potential functional applications, such as thermoelectrics. |
| Sectors | Digital/Communication/Information Technologies (including Software) Electronics |
| Description | New and Improved Electroceramics |
| Amount | £3,658,771 (GBP) |
| Funding ID | EP/G005001/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 08/2008 |
| End | 03/2013 |