Pressure-Induced Color Change in the Lutetium Dihydride LuH₂

The lutetium dihydride LuH2 is stable at ambient conditions. Here we show that its color undergoes sequential changes from dark blue pressure to pink ~2.2 GPa and then bright red ~4 upon compression in a diamond anvil cell. Such pressure-induced change reversible it very similar recently reported the N-doped hydride. However, our preliminary resistance measurements on under pressures up 7.7 evidenced no superconductivity down 1.5 K.