Review of the thermoelectric properties of layered oxides and chalcogenides

2021 ◽  
Author(s):  
Anatoly Romanenko ◽  
Galina Chebanova ◽  
Tingting Chen ◽  
Wenbin Su ◽  
Hongchao Wang
Keyword(s):  
Thermal Conductivity ◽  
Phase Transitions ◽  
Electron Transport ◽  
Transition Metal ◽  
Thermoelectric Properties ◽  
Layered Structure ◽  
Thermoelectric Materials ◽  
Magnetic Phase Transitions ◽  
Maximum Efficiency ◽  
Layered Chalcogenides

Abstract The current state of investigation on thermoelectric properties of layered chalcogenides and oxides is considered. The relationship between the quasi-two-dimensionality of electronic transport properties and thermoelectric properties is confirmed. A decrease in the dimension of electron transport from three-dimensional to quasi-two-dimensional in materials with a layered structure increases the thermopower with a slight change in electrical conductivity. The bismuth tellurides, bismuth selenides and its alloys are currently one of the outstanding state of the art bulk thermoelectric materials with layered structure. Layered transition metal dichalcogenides MX$_2$ (M is a transition metal, X is a chalcogen) are efficient thermoelectric materials at higher temperatures (500-800 K). In these materials, an increase in thermoelectric properties associated with the two-dimensionalization of electron transport is also observed. Layered monochalcogenides MX (M = Sn, Pb, Ge; X = S, Se, Te) are also a promising class of thermoelectric materials. In SnSe single crystals, $ZT\sim$ 2.6 is obtained at 923 K due to the very low thermal conductivity along the $b$ axis (0.23 W/(m$\cdot$K) at 973 K). Layered chalcogenides CuCrX$_2$ (X - S, Se, Te) containing magnetic Cr atoms are effective thermoelectrics at higher temperatures (up to 800 K) due to the presence of phonon glass – electron crystal state led to a significant decrease in thermal conductivity at high temperatures. Magnetic atoms in CuCrX$_2$ compounds lead to the presence of magnetic phase transitions affecting their thermoelectric properties. Interest in oxide-based thermoelectric materials has significantly increased due to their stability in air and higher temperatures for maximum efficiency. The most promising thermoelectric oxide materials are Ca$_3$Co$_4$O$_9$, Na$_x$CoO$_2$, Bi$_2$Ca$_2$Co$_2$O$_x$, and CaCo$_2$O$_4$ have a layered structure and contain magnetic Co atoms leading to magnetic ordering and influence on thermoelectric properties. The presence of phase transitions affects the thermoelectric parameters of thermoelectrics and the thermoelectric figure of merit $ZT$.

scholarly journals The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Đorđe Dangić ◽  
Olle Hellman ◽  
Stephen Fahy ◽  
Ivana Savić
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Phase Transitions ◽  
Thermoelectric Materials ◽  
Ferroelectric Phase Transition ◽  
Lattice Thermal Conductivity ◽  
Ferroelectric Phase ◽  
Structural Phase ◽  
High Symmetry ◽  
Structural Phase Transitions

AbstractThe proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.

Thermoelectric properties and thermal stability of layered chalcogenides, TlScQ2, Q = Se, Te

2017 ◽  
Vol 46 (48) ◽  
pp. 17053-17060 ◽  
Author(s):  
Vijayakumar Sajitha Aswathy ◽  
Cheriyedath Raj Sankar ◽  
Manoj Raama Varma ◽  
Abdeljalil Assoud ◽  
Mario Bieringer ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Band Structure ◽  
Thermoelectric Properties ◽  
Layered Chalcogenides ◽  
Low Thermal Conductivity ◽  
Structure Characteristics ◽  
Thermal Stability Of

The layered chalcogenides, TlScQ2 (Q = Se, Te), possess intriguing band structure characteristics and very low thermal conductivity.

Effect of FAPAS Process on the Thermoelectric Properties of β-FeSi2

2010 ◽  
Vol 650 ◽  
pp. 137-141
Author(s):  
Qing Sen Meng ◽  
Wen Hao Fan ◽  
L.Q. Wang ◽  
L.Z. Ding
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Phase Transformation ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Annealing Time ◽  
Figure Of Merit ◽  
Iron Disilicide ◽  
Temperature Range ◽  
Average Grain Size

Iron disilicide (-FeSi2, and -FeSi2+Cu0.1wt%) were prepared by a field-activated pressure assisted synthesis(FAPAS) method from elemental powders and the thermoelectric properties were investigated. The average grain size of these products is about 0.3m. The thermal conductivity of these materials is 3-4wm-1K-1in the temperature range 300-725K. These products’ figure of merit is 28.50×10-4 in the temperature range 330-450K. The additions of Cu promote the phase transformation of -Fe2Si5 + -FeSi → β-FeSi2 and shorten the annealing time. It is proved that FAPAS is a benign and rapid process for sintering of -FeSi2 thermoelectric materials.

Thallium-Free Thermoelectric Materials with Extremely Low Thermal Conductivity

2007 ◽  
Vol 1044 ◽  
Author(s):  
Shinsuke Yamanaka ◽  
Ken Kurosaki ◽  
Anek Charoenphakdee ◽  
Hideaki Mastumoto ◽  
Hiroaki Muta
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
High Performance ◽  
Next Generation ◽  
Practical Application ◽  
Low Thermal Conductivity ◽  
New Class ◽  
Thallium Compounds ◽  
Thallium Tellurides

AbstractWith the goal of developing high-performance bulk thermoelectric materials, we have characterized ternary silver thallium tellurides. The ternary silver thallium tellurides exhibit extremely low thermal conductivity (<0.5 Wm−1K−1) and consequently their thermoelectric performance is excellent. Although the extremely low thermal conductivity materials, as typified by the ternary silver thallium tellurides, would be a new class of next-generation thermoelectric materials, thallium compounds are unsuitable for practical application because of their toxicity. Against such a background, we are currently exploring thallium-free thermoelectric materials with extremely low thermal conductivity. In this paper, we will briefly summarize the thermoelectric properties of ternary thallium tellurides obtained in our group. Further experiments aimed at improving the ZT of these materials will be presented. Finally, we will propose two candidates: Ag8GeTe6 and Ga2Te3 as thallium-free low thermal conductivity materials.

scholarly journals Transport properties in nanostructured thermoelectric materials and single crystal perovskites

2021 ◽  
Author(s):  
◽  
Michael Ng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Ligand Exchange ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Surface Degradation

<p>Energy consumption worldwide is constantly increasing, bringing with it the demand for low cost, environmentally friendly and efficient energy technologies. One of these promising technologies is thermoelectrics in which electric power is harvested from waste heat energy. The efficiency of a thermoelectric device is determined by the dimensionless figure of merit ZT = σS²T/k where σ is the electrical conductivity, S is the thermopower, k is the thermal conductivity, and T is the average temperature. In this thesis we investigate the use of nanostructuring, which has been known to lead to significant reduction in the lattice thermal conductivity to maximise the figure of merit.  One of the most successful bulk thermoelectric materials is Bi₂Te₃, with a ZT of unity at room temperature. Here we investigate the effects of nanostructuring on the thermoelectric properties of Bi₂Te₃. Sub-100 nm ₂Te₃ nanoparticles were successfully synthesized and the figure of merit was found to be ZT ~ 5X10⁻⁵ at room temperature. The effect of a ligand exchange treatment to replace the long chain organic ligand on the as-synthesized nanoparticles with a short chain alkyl ligand was explored. After ligand exchange treatment with hydrazine the figure of merit of sub-100 nm Bi₂Te₃ was found to increase by two fold to ZT ~ 1X10⁻⁴ at room temperature. Overall the figure of merit is low compared to other nanostructured Bi₂Te₃, this was attributed to the extremely low electrical conductivity. The thermopower and thermal conductivity were found to be ~96 μVK⁻¹ and ~0.38 Wm⁻¹ K⁻¹ at 300 K respectively, which show improvements over other nanostructured Bi₂Te₃.  Further optimisation of the figure of merit was also investigated by incorporating Cu, Ni and Co dopants. The most successful of these attempts was Co in which 14.5% Co relative to Bi was successfully incorporated into sub-100 nm Bi₂Te₃. The figure of merit of nanostructured Bi₁.₇₁Co₀.₂₉Te₁.₇₁ alloy was found to increase by 40% to a ZT ~ 1.4X10⁻⁴ at room temperature. Although overall the figure of merit is low, the effect of Co alloying and hydrazine treatment shows potential as a route to optimise the figure of merit.  A potential novel material for thermoelectrics applications is inorganicorganic perovskite single crystals. Here we report a synthetic strategy to successfully grow large millimetre scale single crystals of MAPbBr₃₋xClx, FAPbBr₃₋xClx, and MAPb₁-xSnxBr₃ (MA = methylammonium and FA = formamidinium) using inverse temperature crystallisation (ITC) in a matter of days. This is the first reported case of mixed Br/Cl single crystals with a FA cation and mixed Pb/Sn based perovskites grown using ITC. The bandgap of these single crystals was successfully tuned by altering the halide and metal site composition. It was found that single crystals of FAPbBr₃₋xClx were prone to surface degradation with increased synthesis time. This surface degradation was observed to be reversible by placing the single crystals in an antisolvent such as chloroform.  A tentative model was proposed to analyse the IV characteristics of the single crystal perovskites in order to extract mobilities and diffusion lengths. The MAPbBr₃ and MAPbBr₂.₅Cl₀.₅ single crystal mobilities were found to be between 30-390 cm² V⁻¹ s⁻¹ and 10-100 cm² V⁻¹ s⁻¹ respectively, the diffusion lengths were found to be between 2-8 μm and 1-4 μm respectively. This is an improvement over polycrystalline thin film perovskites and comparable to other single crystal perovskites. The conductance of MAPb₁-xSnxBr₃ based perovskites was found to increase by 2 orders of magnitude even with just 1% of Sn incorporated. The thermal conductivity of MAPbBr₃ single crystals was found to be ~1.12 Wm⁻¹ K⁻¹ at room temperature which is reasonable low for single crystals, however no other thermoelectric properties could be measured due to the self cleaving nature of the single crystals with decreasing temperature and the high resistivity of the material.</p>

Rapid synthesis and thermoelectric properties of clathrate Ba8Cu6Ge15Si25 by high temperature and high pressure

2016 ◽  
Vol 30 (07) ◽  
pp. 1650087 ◽  
Author(s):  
Bing Sun ◽  
Xiaopeng Jia ◽  
Dexuan Huo ◽  
Hairui Sun ◽  
Yuewen Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
High Temperature ◽  
Thermoelectric Properties ◽  
Layered Structure ◽  
Bulk Material ◽  
Rapid Synthesis ◽  
Synthesis Time ◽  
Fine Layered Structure ◽  
Pressure Synthesis

Ba8Cu6Ge[Formula: see text]Si[Formula: see text] were successfully synthesized by a simple high pressure and high temperature (HPHT) method to investigate the microstructures and thermoelectric (TE) properties. After high pressure synthesis, a highly dense bulk material with lots of fine-layered structure, lattice defects and disorders has been obtained. As expected, the thermal conductivity decreased greatly and the ZT value has been improved significantly, which reaches up to 0.43 at around 773 K. Comparing with other methods, HPHT could shorten the synthesis time from several days to half an hour. It reveals that the HPHT method will become an effective approach for optimizing the TE performance of these materials.

BaCu2Se2 based compounds as promising thermoelectric materials

2015 ◽  
Vol 44 (5) ◽  
pp. 2285-2293 ◽  
Author(s):  
Jing Li ◽  
Li-Dong Zhao ◽  
Jiehe Sui ◽  
David Berardan ◽  
Wei Cai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Low Thermal Conductivity ◽  
Na Doping

The thermoelectric properties of Na doped BaCu2Se2 were studied. The electrical conductivity of BaCu2Se2 was increased by 2 orders of magnitude through Na doping at the Ba sites, combined with a surprisingly low thermal conductivity; a ZT of 1.0 has been obtained for Ba0.925Na0.075Cu2Se2 at 773 K.

scholarly journals YCuTe2: a member of a new class of thermoelectric materials with CuTe4-based layered structure

2016 ◽  
Vol 4 (7) ◽  
pp. 2461-2472 ◽  
Author(s):  
Umut Aydemir ◽  
Jan-Hendrik Pöhls ◽  
Hong Zhu ◽  
Geoffroy Hautier ◽  
Saurabh Bajaj ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Layered Structure ◽  
Thermoelectric Materials ◽  
Low Thermal Conductivity ◽  
New Class

Intrinsically doped YCuxTe2 samples exhibit very low thermal conductivity (∼0.5 W m−1 K−1) with high zT ∼0.75 at 780 K.

THERMOELECTRICITY OF Ca2.9Ce0.1Co4O9+δ BASED NANOCOMPOSITES WITH Cu2O NANOINCLUSION

2013 ◽  
Vol 27 (22) ◽  
pp. 1350108
Author(s):  
FANG JU LI
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Energy Harvesting ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Temperature Dependent ◽  
Resistivity Measurements ◽  
Carrier Scattering ◽  
Scattering Centers

Ca 2.9 Ce 0.1 Co 4 O 9+δ/x wt% Cu 2 O nanocomposites have been studied as the thermoelectric materials for energy harvesting purpose. We evaluate the thermoelectric properties of the composites through temperature dependent thermopower, thermal conductivity and resistivity measurements. It is found that the introduction of Cu 2 O nanoparticles serves as phonon scattering centers, which reduces the thermal conductivity. The nanoinclusions contribute to a remarkable increase in electrical resistivity due to enhanced carrier scattering. As a result, Cu 2 O nanoinclusions do not succeed in improving ZT of Ca 2.9 Ce 0.1 Co 4 O 9+δ material.

Measurement of the Thermoelectric Properties of Quasicrystalline AlPdRe and AlCuFe Alloys.

1997 ◽  
Vol 478 ◽  
Author(s):  
M.L. Wilson ◽  
S. Legault ◽  
R.M. Stroud ◽  
T.M. Tritt
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
General Class ◽  
Careful Investigation

AbstractWe report the measurement of the thermal conductivity, electrical resistivity, and thermoelectric power on two quasicrystalline compounds, A170Pd20Re10 and A162.5Cu25Fe12.5. These materials are found to posses a thermal conductivity of order 1 W/m K, while retaining their semimetallic conductivity. These features coupled with moderately large thermopowers, up to 55 μV/K, imply that the general class of quasicrystalline compounds warrants careful investigation for their potential as new thermoelectric materials.

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