Dependence of crystal symmetry, electrical conduction property and electronic structure of LnFeO(3) (Ln: La, Pr, Nd, Sm) on kinds of Ln(3+)

作者：Niwa Eiki^*; Sato Tsubasa; Watanabe Yuki; Toyota Yuichiro; Hatakeyama Yoshikiyo; Judai Ken; Shozugawa Katsumi; Matsuo Motoyuki; Hashimoto Takuya

来源：Journal of the Ceramic Society of Japan, 2015, 123(1438): 501-506.

DOI：10.2109/jcersj2.123.501

• Perobskite-type oxide
• X-ray diffraction
• Electrical conductivity
• Mossbauer spectroscopy
• Diffuse reflecrance spectroscopy
• Crystallite symmetry
• Electrical conduction property
• Electronic structure

Dependence of crystal symmetry, electrical conductivity, chemical state of Fe and optical property of LnFeO(3) (Ln: La, Pr, Nd, Sm) on kinds of Ln(3+) was investigated. All the LnFeO(3) showed orthorhombic structure, with which order of high crystal symmetry was LaFeO3 > PrFeO3 > NdFeO3 > SmFeO3. Using tolerance factor, the order was successfully explained. The electrical conductivity of all the specimens could be explained by using small polaron hopping model. With increasing crystallite symmetry, electrical conductivity increased and activation energy for hopping conduction decreased. This can be ascribed to larger overlapping of Fe3d orbital and O2p orbital on nearly linear Fe-O-Fe bond in LnFeO(3) with higher crystal symmetry. The larger overlapping of Fe3d orbital and O2p orbital in LnFeO(3) with higher crystal symmetry can also be an origin of larger spin-spin interaction detected by Mossbauer spectroscopy and larger optical band gap observed by diffuse reflectance spectroscopy. Since chemical state of Fe, evaluated by Mossbauer spectroscopy, in LnFeO(3) is fundamentally constant at +3 regardless of kinds of Ln(3+), carrier concentration of LnFeO(3) was revealed to be constant. It is concluded that the predominant factor which determine the electrical property of LnFeO(3) is mobility affected by crystal symmetry.

• 出版日期2015-6