Ab-initio studies of pressure induced phase transitions in BaO

Uludogan M., Cagin T., Strachan A., Goddard W.

JOURNAL OF COMPUTER-AIDED MATERIALS DESIGN, vol.8, pp.193-202, 2002 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 8
  • Publication Date: 2002
  • Journal Name: JOURNAL OF COMPUTER-AIDED MATERIALS DESIGN
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED)
  • Page Numbers: pp.193-202
  • Middle East Technical University Affiliated: No

Abstract

We use ab-initio Quantum Mechanics to study the zero temperature phase diagram of BaO. We calculate zero temperature Equations of State of different crystalline phases [B1 (NaCl), B8(NiAs), B2(CsCl), and distorted B2] using Density Functional Theory (DFT) with the generalized gradient approximation (GGA). We find the B1 structure to be the thermodynamically stable one at zero pressure; followed by three pressure induced phase transitions. We find that at P=11.3 GPa BaO transforms from B1 to B8; at P=21.5 GPa from B8 to distorted B2. The distorted B2 phase continuously approaches the B2 structure, the phase transformation occurs at P=62 GPa. We also study the band structure of BaO in its high pressure (B2) phase. For P=60.5 GPa, we find a band gap of 3.5 eV in agreement with experimetal value. We find metallization at P=230.6 GPa.