Theoretical Study of Defect induced Electronic and Structural Properties in Perovskite-type Oxides

3 February 2011 (Thu), 16:00 - 17:00

4F seminar room (#431-2), MANA Bldg., Namiki site (並木地区MANA棟4Fセミナー室)

Mr. Yoshiki IWAZAKI (岩崎誉志紀氏)

Taiyo Yuden Co., Ltd. (太陽誘電株式会社)

Theoretical Study of Defect induced Electronic and Structural Properties in Perovskite-type Oxides

ペロブスカイト型酸化物中における欠陥が電子構造や結晶構造に及ぼす影響の理論計算

Physical properties in perovskite-type ABO3 oxides are well known to be affected by defects and impurities, and the deep understandings of the defect are indispensable for the further improvement of this material. We will discuss the electronic structure of donor-type defects (oxygen vacancy) and impurities (hydrogen, substitutional dopants) in ATiO3 (A=Ba, Sr, Ca) based on the DFT calculations. One of the biggest problems in the defect calculations are insufficient treatment of exchange-correlation energy of local density approximation (LDA) to handle with the localized nature of defect states, and improved methods such as LDA+U and hybrid functional are required to eliminate self-interaction effects in LDA. We present some interesting results of our DFT calculations related with defects in perovskite-type oxides, such as stabilization of hydride ion (H–) at oxygen-vacancy site in ATiO3, and carrier induced phase transition of ferroelectric BaTiO3.

Dr. Yoshitaka Tateyama(館山佳尚)