scholarly journals Negative and positive thermal expansion-like volume changes due to intermetallic charge transfer based on an ionic crystal model of transition-metal oxides

APL Materials ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 086106 ◽  
Author(s):  
Yuichi Shimakawa ◽  
Michael W. Lufaso ◽  
Patrick M. Woodward
Keyword(s):  
Thermal Expansion ◽  
Charge Transfer ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Ionic Crystal ◽  
Volume Changes ◽  
Crystal Model

Surface Band Gaps and Superexchange Interaction in Transition Metal Oxides

1995 ◽  
Vol 401 ◽  
Author(s):  
J. J. M. Pothuizen ◽  
O. Cohen ◽  
G. A. Sawatzky
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Metal Oxides ◽  
Band Gap ◽  
Transition Metal Oxides ◽  
Band Gaps ◽  
Superexchange Interaction ◽  
Surface Band ◽  
Madelung Potential

AbstractIn this paper, we discuss the change in the band gap of charge transfer insulators for different surface terminations. We have calculated the Madelung potential of the unreconstructed (100) surfaces of the rocksalt structured TM-O compounds (TM = Mn, Fe, Co and Ni). We also considered possible step defects on a (100) surface. The presented results are calculated in both the purely ionic case (TM2+O2−) and in the strong ligand p - cation 4s, phybridization (TM1+O1−) case. In both cases the charge transfer gap, Δ, for the surface is reduced compared to the bulk value. As a consequence of this reduction there is a large increase of the surface superexchange interaction, Jsur, and a decrease of the band gap.

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