Tetragonal superstructure and thermal history of Li0.3La 0.567TiO3 (LLTO) solid electrolyte by neutron diffraction

Michele Catti, Marco Sommariva, Richard M. Ibberson

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

High-resolution time-of-flight neutron powder diffraction data (ISIS facility, Rutherford Appleton Laboratory, U. K.) were collected on sample I, prepared by slow cooling from 1300 °C, of the Li0.3La 0.567TiO3 (LLTO) lithium ion conductor, and on sample II quenched in liquid N2. Patterns were obtained at room temperature (RT), 400 and 700 °C on sample I, and at 550 °C on sample II, studied at RT in previous work. The structure was resolved and Rietveld refined in the tetragonal P4/nbm space group with √2ap × √2a p × 2ap unit-cell [a = 5.48162(1), c = 7.74646(1) Å at RT, Z = 4; ap is the cell edge of cubic perovskite] in all cases except 700 °C, where a P4/mmm (ap × ap × 2ap) structure was determined and refined [a = 3.89827(2), c = 7.8002(1) Å, Z = 2]. In both space groups lanthanum ordering over two La1 and La2 sites is present, but only in P4/nbm can an additional anti-phase octahedral tilting of type a0a0c- be observed, similar to what occurs in the I4/mcm RT metastable phase of the quenched sample. The two distortions are associated to hkl superlattice reflections with h + k even, l odd, and h + k odd, l odd, respectively. Lithium atoms were located in highly disordered sites within the less populated La1 hollows, with short Li-Li′ distances accounting for the high ionic mobility. Possible ordering schemes indicate a mainly (001) two-dimensional mechanism of ion hopping among Li sites.

Original languageEnglish
Pages (from-to)1300-1307
Number of pages8
JournalJournal of Materials Chemistry
Volume17
Issue number13
DOIs
StatePublished - 2007
Externally publishedYes

Fingerprint

Dive into the research topics of 'Tetragonal superstructure and thermal history of Li0.3La 0.567TiO3 (LLTO) solid electrolyte by neutron diffraction'. Together they form a unique fingerprint.

Cite this