Fig. 3: X-ray diffraction (XRD) patterns collected at 38 GPa and 3100 K, and at 50 GPa and 3300 K.

The experimental XRD patterns are shown with dots and the Rietveld refinements and the residuals with solid lines. Three rows of vertical ticks show the calculated positions for orthorhombic Pnma-Nb, body-centered cubic bcc-Nb, and B2-NaCl, respectively.