High-Performance Thermoelectric Oxides Based on Spinel Structure

Abstract

High-performance thermoelectric oxides could offer a great energy solution for integrated and embedded applications in sensing and electronics industries. Oxides, however, often suffer from low Seebeck coefficient when compared with other classes of thermoelectric materials. In search of highperformance thermoelectric oxides, we present a comprehensive density functional investigation, based on GGA+U formalism, surveying the 3d and 4d transition-metal-containing ferrites of the spinel structure. Consequently, we predict MnFe 2 O 4 and RhFe 2 O 4 have Seebeck coefficients of ∼ ±600 µV K −1 at near room temperature, achieved by light hole and electron doping. Furthermore, CrFe 2 O 4 and MoFe 2 O 4 have even higher ambient Seebeck coefficients at ∼ ±700 µV K −1 . In the latter compounds, the Seebeck coefficient is approximately a flat function of temperature up to ∼ 700 K, offering a tremendous operational convenience. Additionally, MoFe 2 O 4 doped with 10 19 holes /cm 3 has a calculated thermoelectric power factor of 689.81 µW K −2 m −1 at 300 K, and 455.67 µW K −2 m −1 at 600 K. The thermoelectric properties predicted here can bring these thermoelectric oxides to applications at lower temperatures traditionally fulfilled by more toxic and otherwise burdensome materials.

Co and Mo Co-doped Fe2O3 for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation

“…The cutoff energy of 340 eV and Monkhorst–Pack k point mesh of 3 × 3 × 1 were chosen for surface calculations. The GGA + U method was adapted to describe the strong electron correlations of transition metals, and the U values used for Fe, Co, and Mo cations were 3.3, 3.3, and 2.0 eV, respectively. , Spinel-structured cells of CoFe 2 O 4 , MoFe 2 O 4 , and Co 1/4 Mo 3/4 Fe 2 O 4 with the antiferromagnetic spin arrangement were constructed and optimized, as shown in Figures S5–S7 in the Supporting Information, respectively. , Nine-layer slab models for the spinel cells (with a Miller index of (100)) were then established, where the top five layers were relaxed and the bottom four layers were fixed . The vacuum space was 15 Å, and the convergence criterion for the total energy, maximum interatomic force, and displacement were 2.0 × 10 –5 eV/atom, 0.05 eV/Å, and 0.002 Å, respectively.…”

Thermoelectric properties of a vertically aligned carbon nanotube array with embedded bismuth telluride

“…The power factor is most often used for the properties of the thermoelectric, which is given by S 2 r term in the numerator of ZT [4]. Among various categories of thermoelectric bulk materials including metals [5], oxides [6], and polymers [7] for any working temperatures. In addition, Bi 2 Te 3 -based alloys doped with Sb, Sn, Zn, and Pb have been widely considered to make thermoelectric devices, because of the high atomic weights which affect the phonon transport in the material and hence decreasing the thermal conductivity [8].…”

Selective Enhancement in Phonon Scattering Leads to a High Thermoelectric Figure-of-Merit in Graphene Oxide-Encapsulated ZnO Nanocomposites

“…which shows zT of more than one and the next generation materials having zT of even about two 3,8 . These are even used in commercial devices however the mere fact that they contain elements like Bi, Te, Sb, Pb etc which are toxic and less earth abundant, demands the scientific community to search for new earth abundant and high TE efficiency materials 9,10 . In order to overcome the severe problem of environmental hazards of these materials and low abundance, drove a strong push for exploring earth abundant elements and particularly benign oxides.…”

“…In order to overcome the severe problem of environmental hazards of these materials and low abundance, drove a strong push for exploring earth abundant elements and particularly benign oxides. Because oxides are thermally as well as chemically stable, and are easier to synthesize compared to alloys 10 . Among the oxides, ZnO, SrTiO3, complex cobaltates with layered structure have been extensively investigated, both experimentally and theoretically 11,12 .…”

“…Therefore, enhancement in the PF and reduction in thermal conductivity are the key to achieve a high value for the TE efficiency of a material . A large number of chemical compositions have been explored for a high zT from alloys to oxides and even polymers. , There are a few highly efficient TE materials such as Bi 2 Te 3 , PbTe, and so forth, which shows zT of more than one and the next-generation materials having zT of even about two. ,, These are even used in commercial devices; however, the mere fact that they contain elements such as Bi, Te, Sb, Pb, and so forth, which are toxic and less earth-abundant, demands the scientific community to search for new earth-abundant and high-TE efficiency materials. , To overcome the severe problem of environmental hazards of these materials and low abundance, there is a strong​ need for exploring earth-abundant elements. Particularly benign oxides, because oxides are thermally as well as chemically stable and are easier to synthesize compared to alloys …”