Synergistic effects of Eu and Nb dual substitution on improving the thermoelectric performance of the natural perovskite CaTiO3

Controlling Precipitation and Dopant Effects To Achieve Promising Thermoelectric Performance in CaTiO3

“…For more detailed results, please refer to Figure S1. However, no Nb-derived impurity energy levels were detected in the mid-gap region according to DFT calculations, which does not agree with the prediction in the reported work . In order to investigate the electronic properties of Nb-doped CaTiO 3 in the absence of oxygen vacancies, the electronic structure calculations were conducted.…”

“…Xiao et al found that the substituting Eu and Ca in CaTiO 3 significantly improves electron concentration, reduces thermal conductivity, and leads to a zT value of 0.137 at 1031 K for Eu 0.2 Ca 0.8 TiO 3 samples . Expanding on this foundation, the introduction of the Nb donor atom, which can be attributed to the d – f electron exchange resulting from the strong hybridization of Eu 4 f , Nb 4 d , and Ti 3 d orbitals, combined with mass fluctuation arising from the significant mass contrast between Eu and Ca, leads to an enhancement in the zT value to 0.257 at 1038 K . Nb substitution in CaTiO 3 facilitates hybridization between the Nb 4 d and Ti 3 d states, improving the electronic properties of CaTiO 3 .…”

“…Consequently, these effects enhance the Seebeck coefficient, and thus, thermoelectric properties of CaTiO 3 are enhanced. However, Nb as the primary dopant in CaTiO 3 does not demonstrate exceptional electronic properties when compared with A-site doping. , This can be primarily attributed to the failure to acknowledge the substantial influence of oxygen vacancies on the electrical transport properties. As previously reported, ,− oxygen vacancies can be effectively generated under a low-pressure, high-temperature, and high-vacuum sintering environment.…”

“…In this work, we selected Nb as a dopant to enhance electrical transport by manipulating the Fermi level and hybridizing the Ti 3 d and Nb 4 d states . Moreover, the excess Nb can be precipitated as Nb inclusions to strengthen phonon scattering and significantly reduce κ L .…”

Emerging homogeneous superlattices in CaTiO3 bulk thermoelectric materials

“…Additionally, Ce doping is more effective than La doping for CaTiO 3 materials because the σ values of Ce10 and Ce25 are much higher than those of La10 and La25, respectively. All these compounds exhibit the typical transport behaviors of highly degenerated semiconductors, 62 and high σ values are frequently obtained through doping under a strong reducing atmosphere. However, if these samples were prepared by sintering in air, they tend to be insulators.…”