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Author: search.filters.author.Chotsawat, ManeeratHas files: No

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    First-principles study of Bi and Al in orthorhombic PbZrO3
    (2016-04-01)
    Chotsawat, Maneerat
    ;
    Sarasamak, Kanoknan
    ;
    Thanomngam, Pitiporn
    ;
    Limpijumnong, Sukit
    ;
    T-Thienprasert, Jiraroj
    Lead zirconate PbZrO<inf>3</inf> (PZO) is one of the most important ceramic materials due to its antiferroelectric property, which can be used in many technological applications. Due to the toxicity of Pb, there is an attempt to replace Pb with other non-toxic elements. It has been reported that doping orthorhombic-PZO with Bi and Al atoms could stabilize the antiferroelectric property in a wide temperature range and reduce the lead content in the material. In this work, we used first-principles calculations based on density functional theory to investigate the microscopic and electronic structures of Bi and Al defects in orthorhombic-PZO. Our calculated defect formation energies revealed that Bi atom can substitute on either Pb site (A-site) or Zr site (B-site); depending on the Fermi-level as well as the crystal growth condition. On the other hand, Al atom is likely to substitute only on the Zr site. In addition, our calculations revealed that there is only a small binding between Bi<inf>Pb</inf> and adjacent Al<inf>Zr</inf> or Bi<inf>Zr</inf> with the binding energies of ∼0.2 eV. This indicates that Bi<inf>Pb</inf> and Al<inf>Zr</inf> (or Bi<inf>Zr</inf>) are unlikely to form complexes.
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    First-principles study of antisite defects in orthorhombic PbZrO 3
    (2014-09-02)
    Chotsawat, Maneerat
    ;
    Sarasamak, Kanoknan
    ;
    Thanomngam, Pitiporn
    ;
    T-Thienprasert, Jiraroj
    First-principles calculations based on density functional theory (DFT) within local density approximation were employed to investigate the antisite defects, including Pb<inf>Zr</inf> and Zr<inf>Pb</inf>, in orthorhombic PbZrO<inf>3</inf> by determining their defect formation energies. The formation energies of antisite defects were then compared with those of other dominant defects, i.e., lead Pb, zirconium Zr, and oxygen O vacancies to examine the likelihood of their existence. Our results revealed that Pb<inf>Zr</inf> defect in neutral charge state is the most dominant defect under O-rich or oxidizing condition in agreement with the previous work. In addition, there is a little structural relaxation when the Zr atom is replaced by Pb atom to form Pb <inf>Zr</inf> defect in neutral charge state. In opposite, under O-poor or reducing condition, the formation energies of antisite defects are quite high and higher than those of vacancy defects. This suggests that antisite defects are unlikely to form under reducing condition. © 2014 Taylor & Francis Group, LLC.