Thermoelectric properties of Nb-doped SrTiO₃ films prepared by co-sputtering

Abstract

SrTiO 3 (STO), a member of perovskite structure materials, exhibits a large thermoelectric figure of merit at high temperatures. Theoretically, its property can be significantly improved by niobium (Nb) dopant. So far, the synthesis method of Nb-doped STO and the evaluation of their thermoelectric properties at low temperatures have not been explored fully. Here, our development of highly Nb-doped STO films using the co-sputtering with STO and Nb targets at room temperature (298 K) is introduced. A rapid annealing process (30 min, at 1073 K) is applied to further crystallize these films. Through measurements at 300 ~ 600 K, a significant improvement of the thermoelectric performance of STO films upon 2% Nb-doping is observed. Particularly, the working temperature of Nb-doped STO begins at 350 K instead of 475 K of STO. The figure of merit of Nb-doped STO can reach 0.53 at 600 K. Through TEM-EDS and TOF-SIMS characterizations, the mechanism of Nb-doping effect on the STO properties is revealed and discussed in detail. Our doping method at room temperature is potential, as compared to other synthesis methods, regarding the uniform incorporation of Nb dopants in STO films. Overall, our work showed another way for further improvement of perovskite-based thermoelectric materials.

Effect of Crystal Orientation on Seebeck Coefficient and Electrical Conductivity of SrTiO3 Single Crystals

“…The PF of sample Sto-C [270] is 2.3 mW m –1 K –2 at 323 K, close to that of sample Sto:La 2 mol %-C [160]. Sample Sto:La 2 mol %-C [270] has the highest PF value of 2.5 mW m –1 K –2 at 323 K. Its PF is higher than that of many SrTiO 3 ceramics. , The SrTiO 3 films are normally produced along the [100] or [110] direction. − Based on our experimental results of the single crystals, higher TE properties should be achieved along the [270] direction of the films. The optimization of the crystal orientation provides an efficient way to improve the TE properties.…”

“…Although the perovskite SrTiO 3 crystal is isotropic in a , b , and c directions, the difference in the atomic arrangement in other directions will make the SrTiO 3 crystal anisotropic in TE properties, which has not been well investigated until now. Research work on the TE properties of SrTiO 3 single crystals or films is mainly in two common directions, i.e., the [100] and [110]. − The investigation of anisotropy of TE properties in other crystal orientations should be essential to obtain high TE properties and provides practical guidance for the design and preparation of anisotropic SrTiO 3 materials, especially the SrTiO 3 films and textured ceramics. Thus, optimization of the TE properties of SrTiO 3 by anisotropic design has potential application in TE devices, such as TE power generators.…”

Stabilizing High-Voltage Performance of Nickel-Rich Cathodes via Facile Solvothermally Synthesized Niobium-Doped Strontium Titanate

“…When the Nb doping level increased to 3% and 5%, their resistance increased approximately 400 and 3000 times under RT. This result is consistent with the previous reports that when Nb dopants are over a threshold value (1 wt %), their conductivity at RT will decrease because their thermoelectric performances are prominently influenced by the relatively large amount of Nb substitution. , …”

Development of La and Mo Co-Doped SrTiO3 as Novel Anode Material for Solid Oxide Fuel Cell Applications

“…The DTA curve steadily grows with temperature up to the peak value of 560 °C due to the dissolution of metal nitrates and citric acid then begins to decrease in a parabolic manner with abrupt dips [7,8]. The TGA curve depicts the sample disintegration in three stages, which is caused by the thermal change of water evaporation, organic species and metal nitrates [9,10]. Single-phase perovskite-type LSMT crystallises with a weight loss of 2% after a rapid start and offsets breakdown between temperatures of 800-880 °C.…”