Affiliations: [a] Key Laboratory for Electromagnetic Processing of
Materials (EPM), Northeastern University, Shenyang, Liaoning, China | Doshisha University, Kyoto, Japan | Department of Human and Information Systems, Faculty
of Engineering, Gifu University, Gifu, Japan
Abstract: La_{1-x}(Ca,
RE)_xVO_3 (0⩽ x ⩽ 1)
composition-spread films were fabricated successfully by Combinatorial Pulsed
Laser Deposition (CPLD). The structures and thermoelectric (TE) properties of
the films were evaluated paralelly by Concurrent X-ray Diffraction (CXRD) and
Multi-channel Thermoelectric Measurement systems respectively. The CXRD (200)
peaks of the composition-spread films changed linearly, which indicated that
the composition-spread films formed solid solution in the whole composition
range (0 ⩽ x ⩽ 1). The effects of oxygen content and the substitutions
of Ca and rare earth (RE: Ce, Nd, Eu) ions on TE properties of
LaVO_3 were also analysed respectively. There was little
change in the Seebeck coefficients of LaVO_3 films grown at
different growth temperatures, while the resistivity decreased with the enhance
of the growth temperatures. The largest power factor (0.7 μW/cm
K^2) of LaVO_3 film was obtained at
800°C, while the valence of vanadium ion changed from 3+ to 2+ because of
the lack of oxygen. With the increase of the content of
Ca^{2+} ions, the valence of vanadium ion changed from 3+ to
4+, which was responsible for the decrease of TE properties in
La1-xCaxVO_3 system. The substitution of RE (Ce, Nd, Eu)
ions for La ions changed not only Seebeck coefficient but also resistivity, but
power factor (α) was not increased obviously. In
La1-xCexVO_3 system, La ion took 3+, and Ce ion took 3+
although Ce^{4+} was stable in theory, which caused the
valence of V ion not changed as expected from 3+ to 2+. The reason may be that
the size of Ce^{3+} ion is similar to that of
La^{3+} ion, so Ce takes the valence of 3+ easily in
LaVO_3.
