Compressibility of pyrochlore-type MgZrSi_2O_7 determined by in situ X-ray diffraction in a large-volume high pressure apparatus

摘要

The pyrochlore-type MgZrSi_2O_7 has been investigated by in situ synchrotron energy-dispersive X-ray diffraction measurements up 24.3 GPa at room temperature in a multianvil high pressure apparatus. The pressure has been calculated using an internal gold metal pressure calibrant. No phase transformation was observed in this study. A third-order Birch-Murnaghan equation of state was used to fit the pressure-volume data. The fitting gives a volume of V_0 = 802.8±0.2 A~3, an isothermal bulk modulus of K_T = 249±12 GPa, and first pressure derivative of K'_T = 3.2±1.3. If K'_T is fixed as 4, K_T is obtained as 241.8±2.6 GPa. Compared with zirconate or titanate pyrochlores, MgZrSi_2O_7 shows a smaller compressibility due to a larger cation radii ratio (r_(Mg), Zr/r_(Si)).