Anomalous density, sound velocity, and structure of pressure-induced amorphous quartz

The study of quartz and other silica systems under pressure is one the most prolific domains research over past 50 years because their applications in material science fundamental relevance to planetary interiors. characterization amorphous state essential for comprehension pressure-induced amorphization minerals, metamorphism observed shocked materials, melt structures pressure. Here, we measured situ, static compression density, sound velocities, electronic structure as it passes through its transition. transition could be derived from abrupt increase density velocity at 24 GPa, strong changes silicon ${L}_{2,3}$ edge oxygen $K$ between 22 27 GPa x-ray Raman scattering data, confirming previous results diffraction. Above this pressure, our data show an anomalous behavior velocity, fine compared cold compressed glass polymorphs. has a lower relative that glass, consistent with average coordination inferred different signature Si O absorption edges by spectroscopy. This sheds light on limit tetrahedral units ${\mathrm{SiO}}_{2}$ components existence polyamorphism network-forming highlights possibility discriminate states