using a mortar and pestle before grinding in a planetary ballmill using a zirconia set for 1 h at 600 rpm. Ground powders were fired for 24 h at 900 °C in air. Then, the samples were ground, using a mortar and pestle, and fired at 900−1000 °C, with the exception of Li 3 RuO 4 which suffers from reduction upon prolonged heating. This step was repeated