Ionic conductivity of Li4SiO4 solid solutions in the system Li2O-Al2O3-SiO2

In the system Li2O-Al2O3-SiO2, Li4SiO4 forms two limited ranges of solid solutions: Li4+xSi1−xAlxO4: 0 < x ≲ 0.4, containing interstitial Li+ ions and Li4−3yAlySiO4: 0⩽y≲ 0.06, containing Li+ vacancies. The a.c. conductivity of polycrystalline samples of several compositions was measured over a range of frequency (2×102 to 5×104 Hz) and temperature (25 to 500°C). Both solid solutions, especially the Li+ interstitial ones, have markedly higher conductivity than has stoichiometric Li4SiO4. This is due to an increase in the number of mobile ions and a decrease in the activation energy for conduction in the solid solutions.

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