In-doped multifilled n-type skutterudites with ZT = 1.8
In-doped multifilled n-type skutterudites with ZT = 1.8
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DOI：
10.1016/j.actamat.2015.05.024
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发表时间：
2015-08
期刊：
影响因子：
9.4
通讯作者：
G. Rogl;A. Grytsiv;K. Yubuta;S. Puchegger;E. Bauer;C. Raju;R. Mallik;P. Rogl
中科院分区：
文献类型：
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作者：
G. Rogl;A. Grytsiv;K. Yubuta;S. Puchegger;E. Bauer;C. Raju;R. Mallik;P. Rogl
在本文中，我们最大化热电（TE）的优值，ZT，n型方钴矿，（In，Sr，Ba，Yb）yCo 4Sb 12，通过三种不同的路线：（i）找到最佳分数的In作为第四填料（ii）检查粉末颗粒，晶粒和微晶尺寸对TE性能的影响和（iii）检查热稳定性。将填充的n型（Sr，Ba，Yb）yCo 4Sb 12以三种不同的比例与In0.4Co4Sb12混合，球磨（常规或高能（HB）球磨）并热压。热压样品破碎表面的粒度分析和SEM照片证明，只有HB产生平均晶粒尺寸<100 nm的均匀颗粒/晶粒，这一点通过透射电子显微镜得到证实。X-射线Rietveld精修结合EDX表明，在所有情况下，铟进入二十面体空隙的方钴矿。所有三个定期球磨样品的温度依赖性的物理性能表明，增加In含量推断增加电阻率，增加塞贝克系数，但降低总热导率。虽然ZT（823 K）与不含In的样品在相同的范围内，但在整个温度范围内的ZT值较高，因此TE转换效率η至少高10%。将样品在600 °C下退火三天显示出结构和热电性质的微小变化，表明TE稳定性。HB样品，由于均匀的小颗粒，等尺寸的晶粒和微晶，表现出高功率因数（4.4 mW/m K− 2在730 K）和非常低的热导率，导致一个突出的高ZT = 1.8在823 K（ηmax= 17.5%）。
In this paper we maximize the thermoelectric (TE) figure of merit,ZT, of n-type skutterudites, (In, Sr, Ba, Yb)yCo4Sb12, via three different routes: (i) find the optimum fraction of In as fourth filler (ii) check the influence of powder particle, grain, and crystallite size on the TE properties and (iii) check thermal stability. Filled n-type (Sr, Ba, Yb)yCo4Sb12was mixed in three different proportions with In0.4Co4Sb12, ball milled (regular or high-energy (HB) ball milling) and hot-pressed. Particle size analyses and SEM pictures of the broken surfaces of the hot pressed samples document that only HB produces uniform particles/grains with average crystallite sizes ∼100 nm, proven by transmission electron microscopy. X-ray Rietveld refinements combined with EDX indicate that in all cases indium entered the icosahedral voids of the skutterudite. Temperature dependent physical properties of all three regularly ball-milled samples show that increasing In-content infers an increasing electrical resistivity, increasing Seebeck coefficient but a decreasing total thermal conductivity. AlthoughZT(823 K) is in the same range as for the sample without In, theZTvalues in the whole temperature range are higher and consequently the TE-conversion efficiency,ηis at least 10% higher. Annealing the samples at 600 °C for three days shows minor changes in structure and thermoelectric properties, indicating TE stability. The HB sample, due to uniformly small particles, equally sized grains and crystallites, exhibits a high power factor (4.4 mW/m K−2at 730 K) and a very low thermal conductivity leading to an outstanding highZT= 1.8 at 823 K (ηmax= 17.5%).