All preparation was performed inside an argon atmosphere. Powders were mixed at a stoichiometric ratio with a 10% excess of InCl 3 to account for its preferential adhesion to the agate mortar and pestle. The powders were hand-ground for 15 minutes with breaks to scrape off the adhered powder. The mixture was then loaded into a zirconia jar with fifteen 10 mm Y-stabilized zirconia spherical grinding media and sealed using parafilm. The mixture was ball-milled at 500 rpm in cycles of 15 minutes milling followed by 1 minute rest for a total of 3 hours using a high-energy planetary ball mill (Retsch PM 200).