Synthesis of cubic sodium tungsten bronze NaxWO3 in air

A solid-state reaction route was used to synthesis cubic sodium tungsten bronze, NaxWO3. The NaxWO3 crystals were successfully prepared through reducing Na2WO4 with boron carbide (B4C) in air condition, followed by washing with hot-water. The solid-state reaction between Na2WO4 and B4C occurred at 600-700 degrees C, and the insertion amount of sodium ion is as high as 0.82. The obtained NaxWO3 crystals present an orange color, and the crystal size can grow to 40m in just 20minutes. The advantage of the method lies in the potential energy and cost savings over other conventional synthetic routes.