Enhanced effective mass in doped SrTiO3 and related perovskites

By W. Wunderlich, H. Ohta, Kunihito Koumoto. 2005

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Abstract The effective mass is one of the main factors determining the Seebeck coefficient and electrical conductivity of thermo-electrics. In this ab-initio LDA-GGA study the effective mass is estimated from the curvature of electronic bands by one-band-approximation and is in excellent agreement with experimental data of Nb- and La-doped SrTiO 3 . It is clarified that the deformation of SrTiO 3 crystals has a significant influence on the bandgap, effective electronic DOS-mass and band-mass, but the electronic effect due to the e g -band flattening near the Γ -point due to Nb-doping up to 0.2 at% is the main factor for the effective mass increase. Doping of La shows a linear decrease of the effective mass; this can be explained by the different surroundings of A- and B-sites in perovskite. Substitution with other elements such as Ba on the A-site and V on the B-site in SrTiO 3 increases the effective mass as well.

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Materials Chemistry

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