Figure 1

(Color online) The pressure-temperature phase diagram of ${\mathrm{H}}_2\mathrm{S}$. The solid curves are phase boundaries determined by a Raman experiment.[11] The dotted lines between ${\mathrm{I}}^{\prime }$ and II are determined by a neutron experiment.[12] The triangles (run 1), the inverse triangles (run 2) the circles (run 3), the diamonds (run 4), and the squares (run 5) show the measured points from five independent samples. Three dashed lines are determined in this report.Reuse & Permissions

Figure 2

(Color online) (a) The powder pattern of ${\mathrm{H}}_2\mathrm{S}$ obtained at $42\text{GPa}$. (b) The powder pattern of recovered sample after unloading from $48\text{GPa}$ to ambient. The negative slopes of the backgrounds below 9 degrees are due to air scattering of the direct beams.Reuse & Permissions

Figure 3

(Color online) Rietveld fits and their derived structures of (a) ${\mathrm{H}}_2\mathrm{S}$ phase ${\text{III}}^{\prime }$ at $1.1\text{GPa}$ and $38\mathrm{K}$, and (b) ${\mathrm{H}}_2\mathrm{S}$ phase ${\text{IV}}^{\prime }$ at $3.8\text{GPa}$ and $27\mathrm{K}$. Broad peaks labeled W represent diffraction from the plastic film of the cryostat window. The solid circles beneath the patterns show the differences between phases ${\text{III}}^{\prime }$ and ${\text{IV}}^{\prime }$.Reuse & Permissions

Figure 4

(Color online) Interatomic sulfur-sulfur distances of ${\mathrm{H}}_2\mathrm{S}$ under pressure. The data drawn with the triangles, the inverse triangles, the circles, the diamonds, and the squares correspond to the phases I, ${\mathrm{I}}^{\prime }$, ${\text{III}}^{\prime }$, ${\text{IV}}^{\prime }$, and IV, respectively. Our previous data for phases I, ${\mathrm{I}}^{\prime }$, and IV at room temperature (Ref. 5) are included in this plot. The open circles at $0\text{GPa}$ show the phase III data at $1.5\mathrm{K}$ (Ref. 1). The horizontal arrows represent twice the sulfur van der Waals radius $\left(vdW\right)$ and twice the sulfur constant energy radius $\left(2r^{*}\right)$. The vertical dashed line represents the ${\text{IV}}^{\prime }\text{−}\text{IV}$ boundary at $12.0\text{GPa}$.Reuse & Permissions