BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Novel complex fast ion conductors: challenges for crystallographer
 s and spectroscopists! - Professor Stephen Skinner\, ICL
DTSTART:20120119T160000Z
DTEND:20120119T170000Z
UID:TALK34849@talks.cam.ac.uk
CONTACT:Sian Bunnage
DESCRIPTION:Fast ion conductors are by convention three dimensional materi
 als that offer isotropic conduction\, and in the case of oxide ion conduct
 ors\, the conduction mechanism is typically via lattice oxygen vacancies. 
 Much research over the last 25-30 years has been devoted to the optimisati
 on and identification of new materials that will be of use in high tempera
 ture ion conducting devices such as solid oxide fuel cells\, sensors and b
 atteries\, with the focus on oxide ion conductors being the perovskite (AB
 O3) and fluorite (AO2) structure types. Despite extensive research activit
 y it is apparent that step changes in ion conduction are unlikely to be fo
 und in these materials\, and that new approaches to materials engineering 
 and development are required to improve on the performance of existing dev
 ices. One such approach is to consider interstitial ion conduction in anis
 otropic materials.\n In recent years fast oxide ion conduction has been de
 monstrated in layered perovskites such as the A2BO4+d and AA’B2O5+d syst
 ems1-3\, both of which display performance competitive with La1-xSrxCoO3-d
 \, the material acknowledged to have the highest level of oxide ion conduc
 tion at elevated temperatures\, and have introduced the concept of fast io
 n conducting anisotropic materials. Using these concepts\, we have investi
 gated structurally complex materials with nominally excess oxygen contents
  and have demonstrated competitive oxide ion conductivity. In CeNbO4+d\, f
 or example\, conduction in a superstructured\, monoclinic\, oxygen excess\
 , modulated phase has been demonstrated which leads to questions regarding
  the conduction mechanism in these phases4\, 5. Given the structural compl
 exity of the materials this provides an intriguing challenge for crystal c
 hemists\, materials modellers and spectroscopists.\nHere we will discuss r
 ecent progress in characterising the structure of the CeNbO4 and CeNbO4.25
  materials\, linking these observations with redox chemistry and will disc
 uss a suggestion as to the oxide ion conduction pathway which is proposed 
 to be via helical CeO polyhedral chains.       \n\n\nReferences\n1.	Taranc
 on\, A.\; Morata\, A.\; Dezanneau\, G.\; Skinner\, S. J.\; Kilner\, J. A.\
 ; Estrade\, S.\; 	Hernandez-Ramirez\, F.\; Peiro\, F.\; Morante\, J. R.\,.
  J. Power Sources 2007\, 174\, 255.\n2.	Tarancon\, A.\; Burriel\, M.\; San
 tiso\, J.\; Skinner\, S. J.\; Kilner\, J. A.\, J. Mater. Chem. 2010\, 20\,
  	3799.\n3.	Sayers\, R.\; De Souza\, R. A.\; Kilner\, J. A.\; Skinner\, S.
  J.\, Solid State Ionics 2010\, 181\, (8-10)\, 	386\n4.	Packer\, R. J.\; T
 sipis\, E. V.\; Munnings\, C. N.\; Kharton\, V. V.\; Skinner\, S. J.\; Fra
 de\, J. R.\, Solid 	State Ionics 2006\, 177\, 2059.\n5.	Packer\, R. J.\; S
 kinner\, S. J.\, Adv. Mater. 2010\, 22\, 1613.\n\n
LOCATION:Wolfson Lecture Theatre\, Department of Chemistry
END:VEVENT
END:VCALENDAR