Pressure-Induced Successive Phase Transitions and Optical Properties in Lu2SiO5

Herein, lutecium silicate is used as a rock example to investigate its two high-pressure phases (7.4 GPa: HP-II and 25.3 GPa: HP-III) and lattice dynamics by in situ high-pressure Raman scattering up to 35.1 GPa. The evidence for a highly symmetrical insulator HP-III phase is obtained. Importantly, the high-pressure structure (metastable phases) after pressure quenching is also intercepted, indicating pressure-induced permanent densification. These findings provide Raman evidence for pressure-induced successive phase transitions of highly symmetric insulators intercepted in prototype Lu₂SiO₅ and physical insights to explain the self-regulation of rare earth-rich regions in facilitating highly effective global carbon cycling.