Microstructure and ionic conductivity of Li1 + xAlxTi2 − x(PO4)3 NASICON glass-ceramics

Fully crystallized glass-ceramics of the Li1 + xAlxTi2 − x(PO4)3 system were obtained by crystallization of a precursor glass, which shows a tendency for homogeneous nucleation. Different microstructures were obtained by single and double stage heat treatments. It is shown that, in the case of a single heat treatment, the ionic conductivity increases by three orders of magnitude when the temperature treatment increases from 700 to 1000 °C, reaching a maximum of 1.3 × 10− 3 S⋅cm− 1 at room temperature. As deduced from X-ray diffraction, this enhancement in ionic conductivity is related to an increase of the sampleʹs crystallinity. For samples obtained by double stage heat treatments, i.e., a heat treatment to induce nucleation followed by a second one for crystal growth, the ionic conductivity tends to increase when the duration of the nucleation treatment is reduced which leads to an increase in the average grain size of the glass-ceramics.