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Towards elucidating microscopic structural changes in Li-ion conductors Li1+yTi2–yAly[PO4 ]3 and Li1+yTi2–yAly[PO4 ]3–x [MO4 ]x(M=V and Nb) : X-ray and27Al and31P NMR studies

journal contribution
posted on 01.01.1998, 00:00 authored by S Wong, P Newman, A Best, K Nairn, D MacFarlane, Maria ForsythMaria Forsyth
A combination of X-ray powder diffraction (XRD) and nuclear magnetic resonance (NMR) studies has demonstrated that attempted substitutions of Al, V and Nb into the framework of LiTi2(PO4)3 yield several impurity phases in addition to direct substitutions of Al into Ti and V, Nb into P sites. Direct substitutions were confirmed by changes in the unit cell dimensions as indicated by the peak shifts observed in the X-ray diffractographs and by analyses of the 27Al and 31P magic angle spinning (MAS) spectra. A major impurity phase was identified as AlPO4 (found in at least two polymorphs) and the amount present increases with increasing Al additions. The formation of AlPO4 appeared to be enhanced by further V but suppressed by Nb substitution. These results suggest that the presence of AlPO4 , together with the non-stoichiometric modified LTP, may be the cause for the observed densification of this material upon sintering and the increased ionic conductivity.

History

Journal

Journal of materials chemistry

Volume

8

Issue

10

Pagination

2199 - 2203

Publisher

Royal Society of Chemistry

Location

Cambridge, England

ISSN

0959-9428

eISSN

1364-5501

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1998, Royal Society of Chemistry