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Development of Thermoelectric Materials Using Electron Localization Effects in Cluster Semiconductors

利用团簇半导体中电子局域效应开发热电材料

基本信息

批准号：
11555160
负责人：
KIMURA Kaoru
金额：
$ 8.83万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

β-Rhombohedral boron(β-boron) is one of polymorphs of pure boron which consists mainly of B_<12> icosahedral clusters. To search the condition in β-boron to enhance ZT, which is represented by ZT=σS^2T/κ, we investigated the change of the thermoelectric parameters, σ, S and κ, from 20K to 1073K when various metal atom(V, Co, Ni, Cu, Fe, Sr, Zr or W) was doped. The data for arc-melted and hot-pressed samples were used to see the effect of micro-structure. V, Co, Ni, Cu, Fe and Zr are successfully doped and the amount of second phases are very small. While there is only little difference on σ and S between hot-pressed and arc-melted samples, κ for hot-pressed sample is smaller than that for arc-melted one because of its porous structure or small grain size. Especially, for the V doped hot-pressed sample, in which V atoms mainly occupy A_1 site of β-boron, σ is increased very much, S is decreased even to negative value and κ is decreased. The maximum and n-type ZT value in this study is o … More btained for the V doped hot-pressed sample and is approaching to that of B_4C which is considered to have the largest and p-type ZT value in boron-rich icosahedral cluster solids.We investigated the composition dependence of the Seebeck coefficient and the electrical conductivity of AlPdRe icosahedral alloys. As the concentration of transition metal (either Pd or Re) increases, the Seebeck coefficient rapidly increases. The strong composition dependence is related to the pseudogap structure in the electron density of states at the Fermi energy, and to the variation in bonding nature between Al and transition metal. Glass-like transport behavior in thermal conduction is also observed. The dimensionless thermoelectric figure of merit has a maximum value of approximately 0.1 in the temperature range from 600 to 700 K and reveals strong composition dependence. Thermoelectric properties of the quaternary AlPdReRu quasicrystal that replaced Re by Ru in AlPdRe icosahedral quasicrystals have been studied. In the middle of substitution Ru for Re, the electrical conductivity increases with increasing temperature and the peak of Seebeck coefficient shifts to a higher temperature side. By Ru addition to the AlPdRe quasicrystal, value of dimensionless figure of merit, ZT, goes up 1.5 times. Less

β-菱面体硼（β-boron）是纯硼的一种多晶型，主要由B_<12>二十面体团簇组成。为了寻找β-硼提高ZT（ZT=σS^2T/κ）的条件，我们研究了不同金属（V，Co，Ni，Cu，Fe，Sr，Zr，W）的掺杂对热电参数σ，S，κ的影响。利用电弧熔炼和热压试样的数据考察了微观结构的影响。成功地掺杂了V、Co、Ni、Cu、Fe和Zr，且第二相的量很小。热压试样和电弧熔炼试样的σ和S值相差不大，而热压试样的κ值则小于电弧熔炼试样，这是由于热压试样具有多孔结构或晶粒尺寸较小所致。特别是对于V原子主要占据β-B的A_1位的热压掺杂样品，σ大大增加，S减小甚至为负值，κ减小。本研究中的最大和n型ZT值为0 ...更多信息研究了AlPdRe二十面体合金的Seebeck系数和电导率随组成的变化关系。随着过渡金属（Pd或Re）的浓度增加，塞贝克系数迅速增加。强烈的成分依赖性与费米能级处的电子态密度中的赝能隙结构有关，并且与Al和过渡金属之间的成键性质的变化有关。在热传导中也观察到了类似玻璃的输运行为。的无量纲热电优值的最大值约为0.1的温度范围从600至700 K，并揭示了强烈的成分依赖性。研究了用Ru取代AlPdRe二十面体准晶中Re的四元AlPdReRu准晶的热电性能。在Ru替代Re的过程中，电导率随温度的升高而增大，Seebeck系数的峰值向高温侧移动。在AlPdRe准晶中加入Ru后，无量纲优值ZT提高了1.5倍。少