High-pressure study ofα-quartzGeO2using extended x-ray-absorption fine structure

The effect of pressure on silicates and germanates is of importance to the geological sciences. Germanates generally act as models for the corresponding silicates at higher pressures in the sense that the same pressure-induced transitions occur at lower pressures in germanates. Using x-ray-absorption spectra obtained at the Stanford Synchrotron Radiation Laboratory (SSRL), we have determined the variation with pressure of the structural parameters of α-quartz ${\mathrm{GeO}}_2$ up to 58 kbar at room temperature. Our data appear consistent with the time-of-flight powder-neutron-diffraction studies done by Jorgensen. We see no evidence of a transition from the metastable α-quartz structure to the rutile structure as is seen in ${\mathrm{SiO}}_2$.