Lithium−Sodium Metazirconate Solid Solutions, Li_2-xNa_xZrO₃ (0 ≤ x ≤ 2): A Hierarchical Architecture

Solid solutions of lithium and sodium metazirconates, Li 2 - x Na x ZrO 3 (0 ≤ x ≤ 2), were prepared by coprecipitation. Then, samples were characterized by powder X-ray diffraction, small-angle X-ray scattering, transmission electron microscopy, solid-state nuclear magnetic resonance, and N 2 adsorption (BET). Results show that the solubility limits of sodium into Li 2 ZrO 3 and lithium into Na 2 ZrO 3 are definitely different. While the maximum amount of sodium that can be inserted into Li 2 - x Na x ZrO 3 is 0.2, the amount of soluble lithium into Na 2 - x Li x ZrO 3 is 0.6. Furthermore, the analyses strongly suggest that Li 2 - x Na x ZrO 3 encloses Na 2 - x Li x ZrO 3, as in a cherry model, and the internal phase is lithium enriched, as shown by the fractal dimension values. The core size is close to 10−20 nm, and the full particle is about 1 μm. The outer shell presents some microporosity. Such a model is supported by kinetic and thermodynamic data.