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| 1 | Achieving High Thermoelectric Performance in Rare-Earth Element-Free CaMg_(2)Bi_(2) with High Carrier Mobility and Ultralow Lattice Thermal Conductivity显示文摘CaMg_(2)Bi_(2)-based compounds,a kind of the representative compounds of Zintl phases,have uniquely inherent layered structure and hence are considered to be potential thermoelectric materials.Generally,alloying is a traditional and effective way to reduce the lattice thermal conductivity through the mass and strain field fluctuation between host and guest atoms.The cation sites have very few contributions to the band structure around the fermi level;thus,cation substitution may have negligible influence on the electric transport properties.What is more,widespread application of thermoelectric materials not only desires high ZT value but also calls for low-cost and environmentally benign constituent elements.Here,Ba substitution on cation site achieves a sharp reduction in lattice thermal conductivity through enhanced point defects scattering without the obvious sacrifice of high carrier mobility,and thus improves thermoelectric properties.Then,by combining further enhanced phonon scattering caused by isoelectronic substitution of Zn on the Mg site,an extraordinarily low lattice thermal conductivity of 0.51Wm^(-1) K^(-1) at 873 K is achieved in(Ca_(0.75)Ba_(0.25))_(0.995)Na_(0.005)Mg_(1.95)Zn_(0.05)Bi_(1.98) alloy,approaching the amorphous limit.Such maintenance of high mobility and realization of ultralow lattice thermal conductivity synergistically result in broadly improvement of the quality factorβ.Finally,a maximum ZT of 1.25 at 873K and the corresponding ZTave up to 0.85 from 300 K to 873K have been obtained for the same composition,meanwhile possessing temperature independent compatibility factor.To our knowledge,the current ZTave exceeds all the reported values in AMg_(2)Bi_(2)-based compounds so far.Furthermore,the low-cost and environmentfriendly characteristic plus excellent thermoelectric performance also make the present Zintl phase CaMg_(2)Bi_(2) more competitive in practical application. | Muchun Guo Fengkai Guo Jianbo Zhu Li Yin Qian Zhang Wei Cai Jiehe Sui | 2020 | Research2020,,1: | 2 |
| 2 | Enhanced thermoelectric properties of Zintl phase YbMg_(2)Bi1.98 through Bi site substitution with Sb显示文摘Benefiting from the unique'Phonon-Glass,Electron-Crystal'(PGEC)characteristic,Zintl phases have been considered as a kind of promising thermoelectric materials.For the typical AM2X2 compounds with the CaAl2Si2-type structure,YbMg_(2)Bi2 has shown competitive thermoelectric performance recently.Nevertheless,the optimization of YbMg_(2)Bi2 compounds is primarily focused on the substitution on Yb or Mg site.Herein,the Bi site is substituted by isoelectric Sb and the effect on the thermoelectric transport behavior is investigated.The partial substitution reduces the carrier concentration and induces the lattice deformation caused by the different atomic radius and mass between Bi and Sb,further leading to the decreased power factor and thermal conductivity.Fortunately,the reduction extent of the thermal conductivity outperforms that of power factor.Finally,the Sb substitution successfully results in a better thermoelectric performance compared with that of the pristine YbMg_(2)Bi1.98.Especially,the calculated energy conversion efficiency(a)of YbMg_(2)Bi1.88Sb0.1 which also possesses a relatively high output power density reaches the maximum value of 9.8% when Th=873 K,and Tc=300 K,respectively.This work demonstrates that the idea of substitution on anionic site should be a new strategy to achieve better ZT values for AM2X2 compounds. | Jing Wang Muchun Guo Jianbo Zhu Dandan Qin Fengkai Guo Qian Zhang Wei Cai Jiehe Sui | 2020 | Journal of Materials Science & Technology2020,59,24: | 1 |
| 3 | Promoted application potential of p-type Mg_(3)Sb_(1.5)Bi_(0.5)for thematched thermal expansion with its n-type counterpart显示文摘Recently,n-type Mg3Sb1.5Bi0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric performance.Ideally,thermoelectric generators should be made of the same material system to avoid thermal mismatch in the practical application.In this work,p-type Mg3Sb1.5Bi0.5 which has almost the same composition as the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01 was synthesized by ball milling and spark plasma sintering,and then Na was chosen as an acceptor dopant to optimize the carrier concentration and further improve the thermoelectric performance.Na0.0075Mg2.9925Sb1.5Bi0.5 sample gets the highest ZT of~0.5 at 773 K.While Na0.005Mg2.995Sb1.5Bi0.5 sample shows the highest average ZT of~0.29 in the temperature range of 300 e773 K and matched thermal expansion behavior with the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01,which is of great significance for practical applications.Taking the Joule and Thompson heat into account,a high theoretical conversion efficiency(η)of~9.5%was calculated for the thermoelectric module consists of the present p-type Na0.005Mg2.995Sb1.5Bi0.5 and the state-of-the-art n-type Mg3.2Sb1.5Bi0.49Te0.01Mn0.01 with the leg length of 2 mm,and cold and hot side temperature of 300 K and 773 K,respectively,which shows a good potential for the use of this class of materials in the midtemperature power generation applications. | Jinsuo Hu Fengkai Guo Muchun Guo Jianbo Zhu Chen Chen Qian Zhang Wei Cai Jiehe Sui | 2020 | Journal of Materiomics2020,6,4: | 1 |
| 4 | The bioleaching feasibility for Pb/Zn smelting slag and community characteristics of indigenous moderate-thermophilic bacteria显示文摘 | Yi Cheng Zhaohui Guo Xueduan Liu Huaqun Yin Guanzhou Qiu Fengkai Pan Hongwei Liu | 2008 | Bioresource Technology2008,,10: | 1 |
| 5 | Electronic Orbital Alignment and Hierarchical Phonon Scattering Enabling High Thermoelectric Performance p-Type Mg_(3)Sb_(2) Zintl Compounds显示文摘Environmentally friendly Mg_(3)Sb_(2)-based materials have drawn intensive attention owing to their promising thermoelectric performance.In this work,the electrical properties of p-type Mg_(3)Sb_(2) are dramatically optimized by the regulation of Mg deficiency.Then,we,for the first time,found that Zn substitution at the Mg2 site leads to the alignment of px,y and pz orbital,resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient,demonstrated by the DFT calculations and electronic properties measurement.Moreover,Zn alloying decreases Mg1(Zn)vacancies formation energy and in turn increases Mg(Zn)vacancies and optimizes the carrier concentration.Simultaneously,the Mg/Zn substitutions,Mg vacancies,and porosity structure suppress the phonon transport in a broader frequency range,leading to a low lattice thermal conductivity of~0.47 W m^(-1) K^(-1) at 773 K.Finally,a high ZT of~0.87 at 773 K was obtained for Mg_(1.95)Na_(0.01)Zn_(1)Sb_(2),exceeding most of the previously reported p-type Mg_(3)Sb_(2) compounds.Our results further demonstrate the promising prospects of p-type Mg_(3)Sb_(2)-based material in the field of mid-temperature heat recovery. | Jinsuo Hu Jianbo Zhu Fengkai Guo Haixu Qin Yijie Liu Qian Zhang Zihang Liu Wei Cai Jiehe Sui | 2022 | Research2022,,4: | 0 |