  At room temperature, bismuth undergoes several structural transitions with
increasing pressure before taking on a body-centered cubic (bcc) phase at
approximately 8 GPa. The bcc structure is stable to the highest measured
pressure and its simplicity, along with its high compressibility and atomic
number, make it an enticing choice as a pressure calibrant. We present three
data sets on the compression of bismuth in a diamond anvil cell in a neon
pressure medium, up to a maximum pressure of about 260 GPa. The use of a soft
pressure medium reduces deviatoric stress when compared to previous work. With
an expanded pressure range, higher point density, and a decreased uniaxial
stress component, we are able to provide more reliable equation of state (EOS)
parameters. We also conduct density functional theory (DFT)
electronic-structure calculations that confirm the stability of the bcc phase
at high pressure.
