Ab-initio studies of pressure induced phase transitions in BaO

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

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

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 8
  • Basım Tarihi: 2002
  • Dergi Adı: JOURNAL OF COMPUTER-AIDED MATERIALS DESIGN
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED)
  • Sayfa Sayıları: ss.193-202
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

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.