Li 3 InCl 6 and Li 3 PO 4 powders were each pressed into 175 mg pellets using a 6 mm stainless steel die set under 9.1 kN of force in a hydraulic press. Pellets were each sealed inside a fused quartz tube under vacuum and subsequently heat treated at 300 °C for 12 hours in a tube furnace (Thermo-Scientific Lindberg Blue M) ending with an air quench. The quartz tubes were previously dried in a vacuum oven at approximately 225°C for 12 hours. Both pellets were then briefly crushed into a powder using an agate mortar and pestle.