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Rietveld refinement for GGG crystal at 8.5 GPa pressure. Below the fitted pattern, vertical bars representing the peak positions and a difference pattern are shown.
Variation of relative unit-cell volume of gadolinium gallium garnet with pressure: experimental points (squares), BM fits of the experimental and theoretical data, for pressures ranging to (curves). The third order BM fit of the experimental data for the hydrostatic range (up to ) and fourth order of theoretical data (up to ) are given in the main figure. The inset illustrates the consequences of the nonhydrostatic conditions (i) for experimental data (squares above ) and (ii) for the resulting fit leading to EOS with unphysically large (dotted line). Moreover, the improvement of the fit of theoretical data (in a large range up to ) obtained by selection of the fourth order BM is shown in the inset (dashed and dash-dotted lines).
Variation of experimental (solid lines) and theoretical (dashed lines) bulk modulus (a) and its first pressure derivative (b) for GGG with pressure in the hydrostatic pressure range. The insets show the dependencies extended to 106 GPa. The dotted vertical lines at 80 GPa refer to experimental crystalline-to-amorphous state transition see Ref. 11.
The values of bulk modulus and its pressure derivatives (for the third order BM, is implied by and values) determined theoretically and experimentally. The BM equation was fitted to the data in the pressure range from ambient pressure to a selected limit, . Accepted (given in bold) and discarded (given in italics) results of the present work are included.
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