A new room-temperature equation of state of Bi up to 260 GPa

Abstract

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.