Enhanced electronic and thermoelectric properties of p-type doped filled skutterudites RFe4Sb12 (R = Pr, Nd)

Abstract

A semimetallic type of electronic profile has been predicted for RFe4Sb12 (R = Pr, Nd) from a first-principles investigation, where the presence of a small energy bandgap above the Fermi energy level (EF) is a key feature. The EF lies at the top of the valence band and it is crossed by a single band more than twice, which improves the band concentration and electronic specific heat as reflected by the high Seebeck coefficient. The doping of a heavy lanthanide atom at the center of the cage formed by pnictogen atoms has a significant effect on the electronic structure that enhances the Seebeck coefficient and the thermoelectric power factor. The heavy atom at the center also dampens the lattice vibration and lowers the lattice thermal conductivity. The Nd-doped system shows an enhanced Seebeck coefficient with the highest power factor among the sample alloys. Moreover, due to significant reduction in the lattice thermal conductivity from 2.46 W/m K to 0.54 W/m K, a maximum ZT value of ∼1.11 at 800 K has been observed for an Nd-doped system. The covalent nature of PrFe4Sb12, Pr-doped NdFe4Sb12, and Nd-doped PrFe4Sb12 and the ionic nature of NdFe4Sb12 have been confirmed, where Pr-doped NdFe4Sb12 is the stiffest and a highly rigid material with strong bonding forces among the constituent atoms. The results presented in this manuscript open the possibilities for further exploration of center atom-doped filled skutterudites with improved Seebeck coefficient and reduced lattice thermal conductivity, which are promising materials for thermoelectric applications

Thermoelectric Performance of n-type Filled Skutterudites RECo4Sb12 Using Rare Earths as Filler Atoms (RE=Nd,Sm,Eu,Yb)

“…One can see that the value of τ is of the order of 10 −15 s, which is consistent with previous estimations of τ in other filled skutterudites, such as RFe 4 Sb 12 (R=P,Nd). 45 In Fig. 7, the temperature dependence of the computed Seebeck coefficient is presented.…”

“…[39][40][41] In all cases, a ZT value around unity was reported. First-principles methods have been used successfully to study the transport properties of many skutterudite systems, including SmRu 45 To our knowledge, there have not been any previous theoretical calculations of the transport properties in Co-Sb based rare Earth full-filled skutterudites. In this paper, we carried out first-principles calculations to systematically study the electronic and transport properties of REfilled skutterudites RECo 4 Sb 12 (RE=Nd,Sm,Eu,Yb).…”

Electronic and thermoelectric properties of Nd-doped Ce-filled skutterudites

“…A similar approach of enhanced ZT was also observed in our previous study, where Nd was doped in the central cage of PrFe 4 Sb 12 . 68…”

Thermal and Electrcial Transport Properities of Ge Doped MnTe Thermoelectrics

“…石能源在使用过程中有 60%的能量都以废热形式散 失，如何高效回收和利用这部分能量就显得尤为重 要。热电材料能够将热能和电能相互转换，其温差 发电技术可以实现工业生产中余热、废热的有效回 收利用。衡量热电材料性能优劣的标准是无量纲热 电优值 ZT，其定义为 ZT=S 2 T/，式中 S 为塞贝克 系数， 为电导率，T 为绝对温度， 为热导率 [1][2] 。 如何提高材料的 ZT 成为热电材料领域的核心工作。 工业生产过程中废热大多处于中温区域，这也 对高性能中温热电材料的研究提出了迫切需求。近 些年来， 研究人员接连报道了高性能中温热电材料， 例如 PbTe [3] 、 Skutterudites [4] 、 Half-Heusler [5] 、 In4Se3 [6] 等。高性能 p 型中温热电材料目前主要集中于 PbTe 基热电材料，但由于铅元素参与构成晶格，使得该 体系对环境及生物带来巨大的安全隐患。因此寻找 环境友好、原料来源丰富的高性能无铅 p 型中温热 电材料具有重要意义。MnTe 正是一种符合要求的 过渡金属化合物热电材料，它具有 NiAs 型六方结 构，空间群为 P63/mmc(194)。其高结构对称性可以 提供较大的塞贝克系数，但由于室温载流子浓度较 低(~10 18 cm -3 )和直接带隙相对较大(~1.27 eV)，导致 电导率很低、电输运性能较差、功率因子和 ZT 仍处 于较低的水平 [7] 。 MnTe 作为一种新型的无铅热电材 料，目前对其热电性能的研究还相对较少。She 等 [8] 通过加入过量的 Mn 发现多余的 Mn 可以有效减少 MnTe2 相，提高塞贝克系数并降低热导率，从而提 高热电性能， Mn1.06Te 在 850 K 时取得最高 ZT=0.57。…”