RT Journal Article
T1 Study of the La₁/₂+₁/₂ₓLi₁/₂-₁/₂ₓTi₁-ₓAlₓO₃ (0 ≤ x ≤ 1) solid solution. A new example of percolative system in fast ion conductors
A1 Sotomayor Lozano, María Eugenia
A1 Levenfeld Laredo, Belén
A1 Varez, Alejandro
A1 Sanz, Jesús
AB The synthesis by solid state reaction of new fast ion conductors with perovskite structure was carried out. The crystal structure and electric properties of the La1/2+1/2xLi1/2-1/2xTi1-xAlxO3 (0 ≤ x ≤ 1) solid solution were investigated by powder X-ray diffraction and impedance spectroscopy. All compositions of the La1/2Li1/2TiO3-LaAlO3 system, exhibited a single cubic perovskite structure (ac approximate to 3.87-3.79 angstrom; SG Pm-3m). The progressive decrease in the unit cell parameters agrees with the lower ionic radii of Al3+ in relation to Ti4+, which are allocated in the same octahedra. An upward deviation from the lineal ideal solid solution behavior described by Vegard's law was observed and it was tentatively associated with a volume excess created by solid dilution of non-isovalent cations. Structural features were deduced from Rietveld analysis of XRD patterns. Ti(Al)O6 octahedra are regular and La/vacancies are randomly distributed in A-site of the perovskite. The conductivity decreased almost four orders of magnitude with the Li content. This important decrease on the conductivity was attributed to the charge carrier (Li+) decrease and the blockade of the perovskite conduction pathways by La ions, according to a three dimensional percolative process. In consequence we present here a new example of percolative system of ionic conductors and the results confirm the important role played by effective vacant A-sites, neff = [Li] + nA, on Li conductivity of this fast ion conductors family with perovskite structure.
PB Elsevier B.V.
SN 0925-8388
SN 1873-4669 (online)
YR 2017
FD 2017-10-05
LK https://hdl.handle.net/10016/31262
UL https://hdl.handle.net/10016/31262
LA eng
NO Authors thank financial support received from MINECO (MAT2013-46452-C4-3-R and MAT2016-78362-C4-3-R projects), regional CAM government (MATERYENER 3CM, P2013/MIT-2753 program) and the European Commission (Program-IRSES FP7-PEOPLE Project ID: 247579 (NANOLICOM).
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RD 1 sept. 2024