Synthesis of cubic sodium tungsten bronze NaxWO3 in air

Abstract A solid‐state reaction route was used to synthesis cubic sodium tungsten bronze, Na x WO 3 . The Na x WO 3 crystals were successfully prepared through reducing Na 2 WO 4 with boron carbide (B 4 C) in air condition, followed by washing with hot‐water. The solid‐state reaction between Na 2 WO 4 and B 4 C occurred at 600‐700°C, and the insertion amount of sodium ion is as high as 0.82. The obtained Na x WO 3 crystals present an orange color, and the crystal size can grow to ~40 μm in just 20 minutes. The advantage of the method lies in the potential energy and cost savings over other conventional synthetic routes.