Pressure-induced color change in the lutetium dihydride LuH2

TL;DR

This study investigates how the color of lutetium dihydride LuH2 changes under pressure, revealing reversible color transitions from blue to pink to red up to 4 GPa, but no superconductivity was observed.

Contribution

It reports the pressure-induced color changes in LuH2 and compares them to N-doped lutetium hydride, providing new insights into its physical properties under compression.

Findings

Color changes from dark blue to pink at ~2.2 GPa

Color changes from pink to bright red at ~4 GPa

No superconductivity observed up to 7.7 GPa down to 1.5 K

Abstract

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