Refined room-temperature equation of state of Bi up to 260 GPa
Daniel Campbell, Daniel T. Sneed, Earl F. O’Bannon, Per Söderlind, Zsolt Jenei
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, makes 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, a higher point density, and a decreased uniaxial stress component, we are able to provide more reliable equation of state parameters. We also conduct density functional theory electronic-structure calculations that confirm that the bcc phase is energetically favored at high pressure.