Rapid-quenching of high-pressure depolymerized hydrous silicate (peridotitic) glasses

Experimental and spectroscopic investigation of glasses synthesized at high pressure provides fundamental information about the structure/physical properties relationships of these materials. However, glass synthesis in conventional large-volume high-pressure devices is limited by the achievable quenching rates. This study reports the first successful quenching, recovery, and characterization of high-pressure hydrous silicate glasses of peridotite composition, with H2O contents from 0 to 5 wt%, using a large-volume high-pressure apparatus equipped with a novel rapid-quench cell. The synthesized glasses are transparent, optically isotropic, and chemically homogeneous, but they contain nano- to micron-size metal droplets from the capsules. Except for the two glasses with the highest H2O contents, the glasses are crystal-free. Raman spectroscopy revealed the absence of long-range ordering in the atomic structure of peridotitic glasses. However, it was demonstrated that dissolution of H2O leads to an increase in melt polymerization. This study provides fertile ground for developing new studies of the structure/physical properties relationships of extremely depolymerized melts.