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1.
张贺  骆军  朱航天  刘泉林  梁敬魁  李静波  刘广耀 《中国物理 B》2012,21(10):106101-106101
Polycrystalline p-type Ag 0.9 Sb 1.1 x Mn x Te 2.05(x = 0.05,0.10,and 0.20) compounds have been prepared by a combined process of melt-quenching and spark plasma sintering.The sample composition of Ag 0.9 Sb 1.1 x Mn x Te 2.05 has been specially designed in order to achieve the doping effect by replacing part of Sb with Mn and to present the uniformly dispersed Ag 2 Te phase in the matrix by adding insufficient Te,which is beneficial for optimizing the electrical transport properties and enhancing the phonon scattering effect.All the samples have the NaCl-type structure according to our X-ray powder diffraction analysis.After the treatment of spark plasma sintering,only the sample with x = 0.20 has a small amount of MnTe 2 impurities.The thermal analysis indicates that a tiny amount of Ag 2 Te phase exists in all these samples.The presence of the MnTe 2 impurity with high resistance and high thermal conductivity leads to the deteriorative thermoelectric performance of the sample with x = 0.20 due to the decreased electrical transport properties and the increased thermal conductivity.In contrast,the sample with x = 0.10 exhibits enhanced thermoeletric properties due to the Mn-doping effect.A dimensionless thermoelectric figure of merit of 1.2 is attained for the sample with x = 0.10 at 573 K,showing promising thermoelectric properties in the medium temperature range.  相似文献   

2.
肖星星  谢文杰  唐新峰  张清杰 《中国物理 B》2011,20(8):87201-087201
With good electrical properties and an inherently complex crystal structure,Cu 2 x Se is a potential "phonon glass electron crystal" thermoelectric material that has previously not attracted much interest.In this study,Cu 2 x Se (0 ≤ x ≤ 0.25) compounds were synthesized by a melting-quenching method,and then sintered by spark plasma sintering to obtain bulk material.The effect of Cu content on the phase transition and thermoelectric properties of Cu 2 x Se were investigated in the temperature range of 300 K-750 K.The results of X-ray diffraction at room temperature show that Cu 2 x Se compounds possess a cubic structure with a space group of F m3m (#225) when 0.15 < x ≤ 0.25,whereas they adopt a composite of monoclinic and cubic phases when 0 ≤ x ≤ 0.15.The thermoelectric property measurements show that with increasing Cu content,the electrical conductivity decreases,the Seebeck coefficient increases and the thermal conductivity decreases.Due to the relatively good power factor and low thermal conductivity,the nearly stoichiometric Cu 2 Se compound achieves the highest ZT of 0.38 at 750 K.It is expected that the thermoelectric performance can be further optimized by doping appropriate elements and/or via a nanostructuring approach.  相似文献   

3.
To enhance the thermoelectric performance of Cu_2GeSe_3, a series of Te-alloyed samples Cu_2Ge(Se_(1-x)Te_x)_3 are synthesized and investigated in this work. It is found that the lattice thermal conductivity is reduced drastically for x = 0.1 sample, which may be attributed to the point defects introduced by alloying. However, for samples with x ≥ 0.2, the lattice thermal conductivity increases with increasing x, which is related to a less distorted structure. The structure evolution,together with the change in carrier concentration, also leads to a systemically change in electrical properties. Finally, a z T of 0.55@750 K is obtained for the sample with x = 0.3, about 62% higher than that for the pristine sample.  相似文献   

4.
Nb-doped SrTiO_3 thermoelectric ceramics with different niobium concentrations,sintering temperatures and Sr-site vacancies are successfully prepared by high energy ball milling combined with carbon burial sintering.For fully understanding the effect of niobium doping on SrTiO_3,thermoelectric transport properties are systematically investigated in a temperature range from 300 K to 1100 K.The carrier mobility can be significantly enhanced,and the electrical conductivity is quadrupled,when the sintering temperature rises from 1673 K to 1773 K(beyond the eutectic temperature(1713 K) of SrTiO_3–TiO_2).The lattice vibration can be suppressed by the lattice distortion introduced by the doped niobium atoms.However,Sr-site vacancies compensate for the lattice distortion and increase the lattice thermal conductivity more or less.Finally,we achieve a maximum value of figure-of-merit z T of 0.21 at 1100 K for Sr Ti_(0.9)Nb_(0.1)O_3 ceramic sintered at1773 K.  相似文献   

5.
《中国物理 B》2021,30(6):67101-067101
It is reported that SnSe_2 consisting of the same elements as SnSe, is a new promising thermoelectric material with advantageous layered structure. In this work, the thermoelectric performance of polycrystalline SnSe_2 is improved through introducing SnSe phase and electron doping(Cl doped in Se sites). The anisotropic transport properties of SnSe_2 are investigated. A great reduction of the thermal conductivity is achieved in SnSe_2 through introducing SnSe phase, which mainly results from the strong SnSe_2–SnSe inter-phase scattering. Then the carrier concentration is optimized via Cl doping, leading to a great enhancement of the electrical transport properties, thus an extraordinary power factor of ~5.12 μW·cm~(-1)·K~(-2) is achieved along the direction parallel to the spark plasma sintering(SPS) pressure direction( P). Through the comprehensive consideration on the anisotropic thermoelectric transport properties, an enhanced figure of merit ZT is attained and reaches to ~ 0.6 at 773 K in SnSe_2-2% SnSe after 5% Cl doping along the P direction, which is much higher than ~ 0.13 and ~ 0.09 obtained in SnSe_2-2% SnSe and pristine SnSe_2 samples, respectively.  相似文献   

6.
The tuning of electron and phonon by ion doping is an effective method of improving the performances of thermoelectric materials. A series of lower concentration K-doped Ca_(3-x)K_xCo_4O_9(x = 0, 0.05, 0.10, 0.15) polycrystalline ceramic samples are prepared by combining citrate acid sol-gel method with cold-pressing sintering method. The single-phase compositions and plate-like grain morphologies of all samples are confirmed by x-ray diffraction and field emission scanning electron microscope. The effects of lower concentration K doping on the thermoelectric properties of the material are evaluated systematically at high temperatures(300–1026 K). Low concentration K doping causes electrical conductivity to increase up to 23% with little effect on the Seebeck coefficient. Simultaneously, the thermal conductivity of K-doped sample is lower than that of the undoped sample, and the total thermal conductivity reaches a minimum value of approximately1.30 W·m~(-1)·K~(-1), which may be suppressed mainly by the phonon thermal conduction confinement. The dimensionless figure-of-merit ZT of Ca_(2.95)K_(0.05)Co_4O_9 is close to 0.22 at 1026 K, representing an improvement of about 36% compared with that of Ca_3Co_4O_9, suggesting that lower concentration K-doped Ca_3Co_4O_9 series materials are promising thermoelectric oxides for high-temperature applications.  相似文献   

7.
We study the effect of pressure on electronic and thermoelectric properties of Mg_2Si using the density functional theory and Boltzmann transport equations. The variation of lattice constant, band gap, bulk modulus with pressure is also analyzed. Further, the thermoelectric properties(Seebeck coefficient, electrical conductivity, electronic thermal conductivity) have been studied as a function of temperature and pressure up to 1200 K. The results show that Mg_2Si is an n-type semiconductor with a band gap of 0.21 eV. The negative value of the Seebeck coefficient at all pressures indicates that the conduction is due to electrons. With the increase in pressure, the Seebeck coefficient decreases and electrical conductivity increases. It is also seen that, there is practically no effect of pressure on the electronic contribution of thermal conductivity.The paper describes the calculation of the lattice thermal conductivity and figure of merit of Mg_2Si at zero pressure. The maximum value of figure of merit is attained 1.83 × 10~(-3) at 1000 K. The obtained results are in good agreement with the available experimental and theoretical results.  相似文献   

8.
The composition-dependent thermoelectric properties of lead telluride (PbTe) doped with bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3) and (BiSb)2Te3 have been studied at room temperature. All the sampies exhibit small thermal conductivity. The figures of merit, 7.63, 1.03 and 8.97 x 10-4, have been obtained in PbTe with these dopants, respectively. These values are several times higher than those of PbTe containing other dopants with small grain sizes. The high thermoelectric performance is explained by electronic topological transition induced by alloying. The results indicate that these dopants are effective to enhance the thermoelectric performance of PbTe.  相似文献   

9.
The optimization of ion beam sputtering deposition process for Sb2 Te3 thin films deposited on BK7 glass substrates is reported. The influence of composition ratio on the thermoelectric properties is investigated. X-ray diffraction shows that the major diffraction peaks of the films match with those of Sb2 Te3. Hall effect and Seebeck coefficient measurement reveal that all the samples are of p-type. The Sb2 Te3 thin films exhibit the Seebeck coefficient of 190μVk^-1 and the electrical conductivity of 1.1 × 10^3 Scm^-1 when the atomic ratio of Sb to Te is 0.65. Carrier concentration and motility of the films increase with the increasing atomic ratio of Sb to Te. The Sb2 Tea film with a maximum power factor of 2.26×10^-3 Win^-1K^-2 is achieved when annealed at 400℃. Raman measurement shows that the main peaks are at about 120 cm^-1, 252 cm^-1 and 450 cm^-1, in agreement with those of V-VI compound semiconductors.  相似文献   

10.
The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range,and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at hightemperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be ~0.19 at 1073 K in the heaviest oxygen reduced sample.  相似文献   

11.
In this work,we report that the thermoelectric properties of Bi_(0.52)Sb_(1.48)Te_3alloy can be enhanced by being composited with Mn Te nano particles(NPs)through a combined ball milling and spark plasma sintering(SPS)process.The addition of Mn Te into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phononscattering between Bi_(0.52)Sb_(1.48)Te_3 and MnTe NPs,and enhance the electrical transport properties by optimizing the hole concentration through partial Mn~(2+)acceptor doping on the Bi~(3+)sites of the host lattice.It is observed that the lattice thermal conductivity decreases with increasing the percentage of Mn Te and milling time in a temperature range from 300 Kto 500 K,which is consistent with the increasing of interfaces.Meanwhile,the bipolar effect is constrained to high temperatures,which results in the figure of merit z T peak shifting toward higher temperature and broadening the z T curves.The engineering z T is obtained to be 20%higher than that of the pristine sample for the 2-mol%Mn Te-added composite at a temperature gradient of 200 K when the cold end temperature is set to be 300 K.This result indicates that the thermoelectric performance of Bi_(0.52)Sb_(1.48)Te_3 can be considerably enhanced by being composited with Mn Te NPs.  相似文献   

12.
用高温熔融结合放电等离子烧结(SPS)方法合成了Sb掺杂的单相n型Ba8Ga16-xSbxGe30化合物,探索了Sb对Ga的取代对其热电性能的影响规律.研究结果表明:随着Sb取代分数x的增加,Seebeck系数逐渐降低,Seebeck系数峰值对应的温度向低温方向偏移.电导率随着x的增加先增大后减小,当x=2时达到最大值.Sb取代Ga后对化合物的热性能有较大影响,其热导率和晶格热导率都有不同程度的降低.在所有n型Ba8Ga16-xSbxGe30化合物中,Ba8Ga14Sb2Ge30化合物的ZT值最大,在950K左右其最大ZY值达1.1.  相似文献   

13.
熊聪  唐新峰  祁琼  邓书康  张清杰 《物理学报》2006,55(12):6630-6636
用高温熔融结合放电等离子烧结(SPS)方法合成了Sb掺杂的单相n型Ba8Ga16-xSbxGe30化合物,探索了Sb对Ga的取代对其热电性能的影响规律.研究结果表明随着Sb取代分数x的增加,Seebeck系数逐渐降低,Seebeck系数峰值对应的温度向低温方向偏移.电导率随着x的增加先增大后减小,当x=2时达到最大值.Sb取代Ga后对化合物的热性能有较大影响,其热导率和晶格热导率都有不同程度的降低.在所有n型Ba8Ga16-xSbxGe30化合物中,Ba8Ga14Sb2Ge30化合物的ZT值最大,在950 K左右其最大ZT值达1.1.  相似文献   

14.
张贺  骆军  朱航天  刘泉林  梁敬魁  饶光辉 《物理学报》2012,61(8):86101-086101
利用熔融快淬结合放电等离子烧结(SPS), 制备了CuxAg1-xSbTe2(x= 0---0.3)样品. 粉末X射线衍射(XRD)分析结果显示, SPS处理以前, 含Cu样品形成NaCl型结构的固溶体, 而未加入Cu的样品析出Ag2Te第二相. 根据热分析和XRD测量结果, Cu的加入能够有效抑制Ag2Te的析出, 但同时会在快淬样品中产生少量非晶相. 在温度升高到540 K左右时, 非晶相发生晶化, 形成Sb7Te亚稳相, 并最终转变成Sb2Te3稳定相. 对快淬样品进行低温SPS快速处理后, x =0.1样品为面心立方结构的单相化合物, 但是x =0.2, 0.3的样品分别析出第二相Sb7Te和Sb2Te3. 由于析出第二相, x=0.2, 0.3样品的电导率增大, Seebeck系数减小, 热导率相应升高, 综合热电性能降低. x=0.1单相样品的功率因子与文献报道的AgSbTe2化合物相当. 元素替代的合金化效应 增强了Cu0.1Ag0.9SbTe2化合物的声子散射, 有效降低了样品的热导率. 因此, 单相样品Cu0.1Ag0.9SbTe2表现出较佳的热电性能, 在620 K时热电优值达到1.  相似文献   

15.
Sm和Ce复合掺杂Skutterudite化合物的制备及热电性能   总被引:1,自引:0,他引:1       下载免费PDF全文
用熔融法结合放电等离子快速烧结(SPS)制备出了单相的Sm和Ce复合掺杂的Skutterudite化合物SmmCenFe1.5Co2.5Sb12,研究了Sm和Ce复合掺杂总量对其热电性能的影响规律.结果表明:随着Sm和Ce复合掺杂总量的增加,p型SmmCenFe1.5Co2.5Sb12化合物的Seebeck系数增加、电导率和热导率降低.当掺杂总量相近时,和Sm、Ce单原子掺杂相比,Sm和Ce复合掺杂使Skutterudite化合物的热导率低10%—40%.Sm0.22Ce0.20Fe1.54Co2.46Sb11.89化合物的最大热电性能指数ZTmax值在775K时为0.84. 关键词: 复合掺杂 方钴矿 热电性能  相似文献   

16.
杜保立  徐静静  鄢永高  唐新峰 《物理学报》2011,60(1):18403-018403
采用高纯元素直接熔融、淬火并结合放电等离子烧结方法制备了非化学计量比AgSbTe2+x(x=0—0.05)系列样品,研究了不同Te含量在300—600 K范围内对样品热电性能的影响规律.结果表明:随着Te含量的增加,Ag+离子空位浓度增加,空穴浓度和电导率大幅度提高,Seebeck系数减小.热导率随Te过量程度的增加略有增加,但所有Te过量样品的晶格热导率均介于0.32—0.49 W/mK之间,低于化学计量比样品的值,接近理论最低晶格热导率.AgS 关键词: 2')" href="#">AgSbTe2 非化学计量比 热电性能 热导率  相似文献   

17.
邹平  吕丹  徐桂英 《物理学报》2020,(5):182-189
采用高压烧结技术制备了稀土元素Tb掺杂的n型Bi2Te2.7Se0.3基纳米晶块体热电材料.将高压烧结成型的样品于633 K真空退火36 h.研究了Tb掺杂量对样品的晶体结构和热电性能的影响.结果表明,高压烧结制备的样品为纳米结构, Tb掺杂使样品的晶胞体积变大,功率因子增大,热导率降低,从而使ZT值提高.Tb掺杂量为x=0.004是最优的掺杂量,该掺杂量的高压烧结样品经退火处理后,于373 K时ZT值达到最大为0.99,并且在323-473 K范围内, ZT值均大于0.8,这对用于温差发电领域具有重要意义.  相似文献   

18.
霍凤萍  吴荣归  徐桂英  牛四通 《物理学报》2012,61(8):87202-087202
以Pb粉、Te粉、Ag粉、Ge粉为原材料,在真空气氛下合成(AgSbTe2)100-x-(GeTe)x (x=80---90) (TAGS)合金热电材料, X射线衍射(XRD)分析表明,热压烧结后合金具有低温菱形结构. 通过热压烧结法将TAGS粉末制备成块体材料,运用XRD和扫描电子显微镜对材料的物相成分、 晶体结构和形貌进行了表征.采用直流四探针法测定样品的电导率,当样品两端的温差为1---4℃ 的情况下测量Seebeck系数.通过材料热电性能测试,研究了30---500℃温度范围内不同组分 样品性能参数的变化.结果表明,所制备的TAGS热电材料具有纳米结构, 其性能随着组分的变化而变化, TAGS-80具有较好的热电性能,在530℃时具有最高热电优值(ZT=1.80).  相似文献   

19.
In order to study the thermoelectric properties of TiO2-based hybrid materials, TiO2/polyparaphenylene(PPP)nanocomposites are fabricated by spark plasma sintering(SPS). The results show that the electrical conductivity follow percolation theory is enhanced due to the electron transfer highway provided by the conducting PPP phase. Furthermore,the thermal conductivity is reduced due to the drastic difference of vibrational spectra between organic and inorganic components. As a result, the greatest ZT= 0.24 is obtained for Ti O2/0.75 wt% PPP sample, which is 15-fold higher than pure Ti O2(ZT= 0.016).  相似文献   

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