Low-temperature growth of idiomorphic cubic-phase Li7La3Zr2O12 crystals using LiOH flux†
Abstract
Micrometer-sized Li7La3Zr2O12 crystals with well-developed facets were grown from a LiOH flux at 700 °C. Supersaturation-controlled crystallization driven by the cooling of a homogeneous hot solution with a Li/Zr ratio of 70 achieved one-step formation of cubic-phase Li7La3Zr2O12 that potentially exhibits high lithium-ion conductivity. Excess LiOH flux decreased the reaction temperature dramatically to 700 °C, lower than that of solid-state-reaction processes. The flux growth of the Li7La3Zr2O12 crystals in response to varying reaction conditions was studied systematically and indicated that the initial Li/Zr ratio and the holding temperature significantly affected the crystal phase, shape, and size. We further demonstrated Li7La3Zr2O12 crystal growth at 500 °C, beginning with La2Zr2O7 powders that dissolve readily in hot LiOH. This will be examined in greater depth in the near future.