Electron-doped SrTiO3 is a well-known n-type thermoelectric material, although the figure of merit of SrTiO3 is still inferior compared with p-type metal oxide-based thermoelectric materials due to its high lattice thermal conductivity. In this study, we have used a different amount of the non-ionic surfactant F127 during sample preparation to introduce nanoscale porosities into bulk samples of La-doped SrTiO3. It has been observed that the porosities introduced into the bulk sample significantly improve the Seebeck coefficient and reduce the thermal conductivity by the charge carrier and phonon scattering respectively. Therefore, there is an overall enhancement in the power factor (PF) followed by a dimensionless figure of merit (zT) over a wide scale of temperature. The sample 20 at% La-doped SrTiO3 with 600 mg of F127 surfactant (SLTO 600F127) shows the maximum PF of 1.14 mW m−1 K−2 at 647 K which is 35% higher than the sample without porosity (SLTO 0F127), and the same sample (SLTO 600F127) shows the maximum value of zT is 0.32 at 968 K with an average enhancement of 62% in zT in comparison with the sample without porosity (SLTO 0F127).

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SrTiO3 is a well-studied n-type metal oxide based thermoelectric (TE) material. In this work, the first-principles calculation of La-doped SrTiO3 has been performed using the density functional theory. In addition, high TE properties of bulk SrTiO3 material have been achieved by introducing nanoscale porosity and optimizing carrier concentration by La doping. The X-ray diffraction, atomic resolution scanning transmission electron microscopy imaging, and energy-dispersive X-ray spectrometry results show that La has been doped successfully into the lattice. The scanning electron microscopy images confirm that all the samples have nearly similar nanoscale porosities. The significant enhancement of electrical conductivity over the broad temperature range has been observed through optimization of La doping. Additionally, the samples possess very low thermal conductivity, which is speculated because of the nanoscale porosity of the samples. Because of this dual mechanism of doping optimization and nanoscale porosity, there is a remarkable improvement in power factor, 1 mW/m2K from 650 to 800 K, and figure of merit, zT of 0.26 at 850 K, of the sample, 22 at. % La-doped SrTiO3.

High‐performance thermoelectric materials require simultaneous reduction of thermal conductivity and electrical resistivity, among other criteria. Here it is shown that the introduction of Na2CO3 into the melt‐route fabrication process for the well‐known thermoelectric Cu2Se has a beneficial and surprisingly strong effect. There is a significant enhancement in electrical conductivity which density functional theory calculations suggest may be due to the effect of Na and O doping in the Cu2Se matrix. There is also a 34% reduction in thermal conductivity which is likely due to a high density of defects causing scattering of phonons. Overall, however, there is only relatively a small change in Seebeck coefficient. A higher power factor of 12.6 µW cm−1 K−2 is achieved versus 8.8 µW cm−1 K−2 for standard Cu2Se. A very high value of zT of 2.3 is obtained at 804 K versus 1.1 for standard Cu2Se.

The effects of carbon fiber additions on the electrical, thermoelectric, and magnetotransport performance in p-type CoSb3-based skutterudite are reported. A three-fold enhancement in electrical conductivity and a large increase in magnetoresistance are found. Two different explanations for the increased electrical conductivity are considered; either that carbon atoms form cause defects that makes the CoSb3 more conductive, or that the increase in conductivity is due to electrical percolation of the carbon fibers in the composite. X-ray diffraction data show that the lattice parameter of the CoSb3 is not affected by the presence of the carbon fiber, however adding carbon causes precipitation of 20 wt. % elemental Sb. DFT calculations show that the enthalpy of formation of a solid-solution of carbon (both interstitial and as a substitution for Sb) is favorable. These results support an explanation based on an improved electrical conductivity of a dilute solid solution of C in CoSb3. The average thermoelectric parameters of the composite material, including heat conductivity, average composite Seebeck coefficient, Hall effect, carrier mobility and carrier concentration were influenced by the carbon addition. Unfortunately, the effects largely cancel each other so that the overall zT of the composite was not improved. Finally, large room temperature magnetoresistance (up to 90% at 13T) is observed, which increases with content of carbon fiber.