A single crystal X-ray and powder neutron diffraction study on NASICON-type Li1+xAlxTi2−x(PO4)3 (0 ≤ x ≤ 0.5) crystals: Implications on ionic conductivity

• First single crystal X-ray diffraction study of LATP.
• Exact crystal chemical description of structural parameters depending on substitution level.
• Discussion of the structure-conductivity relationship.

Single crystals of NASICON-type material Li1+xTi2−xAlx(PO4)3 (LATP) with 0 ≤ x ≤ 0.5 were successfully grown using long-term sintering techniques. Sample material was studied by chemical analysis, single crystal X-ray and neutron diffraction. The Ti4+ replacement scales very well with the Al3+ and Li+ incorporation. The additional Li+ thereby enters the M3 cavity of the NASICON framework at x, y, z ∼ (0.07, 0.34, 0.09) and is regarded to be responsible for the enhanced Li+ conduction of LATP as compared to Al-free LTP. Variations in structural parameters, associated with the Ti4+ substitution with Al3+ + Li+ will be discussed in detail in this paper.

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