(color online) Pressure versus volume data for niobium at 300 K. The solid circles are the experimental data measured under nonhydrostatic conditions in this work and the solid line is the 3rd order Birch–Murnaughan fit. The open up-triangles and right-triangles are the experimental data determined by Takemura et al.^[36] in helium (Takemura–He,) and methanol–ethanol–water (Takemura–MEW) pressure media, respectively. No distinct discontinuity in pressure–volume was observed.