High-Performance p-Type Magnesium Silicon Thermoelectrics
High-Performance p-Type Magnesium Silicon Thermoelectrics
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DOI：
10.1007/s11664-012-2450-6
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发表时间：
2013-02
影响因子：
2.1
通讯作者：
T. Kajitani;M. Kubouchi;S. Kikuchi;K. Hayashi;T. Ueno;Y. Miyazaki;K. Yubuta
中科院分区：
文献类型：
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作者：
T. Kajitani;M. Kubouchi;S. Kikuchi;K. Hayashi;T. Ueno;Y. Miyazaki;K. Yubuta
预期的p型镁硅化合物是由混合和烧结的Mg2Si、Mg2Sr或Mg2Ba粉末生产的。通过放电等离子烧结 (SPS) 工艺在 1123 K、50 MPa 下进行 10 分钟。观察由标称成分 (Mg2Si)0.7(Mg2Sr)0.3 和 (Mg2Si)0.7(Mg2Ba)0.3 的烧结粉末制备的样品的 p 型热电性能。前一个样品的最大无量纲品质因数 ZT 在 700 K 时达到 0.24。通过粉末和单晶 X 射线衍射 (XRD) 测量、扫描电子显微镜 (SEM) 和透射电子显微镜 (TEM) 以及能量色散 X 射线光谱 (EDS)，仔细阐明了晶体结构和化学含量。 SPS 样品由两个新的未知相组成。基于单晶XRD数据，成功确定了两种不同A(Sr或Ba)-Mg-Si晶体的晶体结构。这两种结构分别是六方P63/m型A2Mg12Si7和(189号)型A2Mg4Si3。这两种结构由三维互连的 MgSi4 四面体网络和平行于 4.3-Å 轴排列的碱土离子柱组成。两个相具有相同的[(A2+, Mg2+)]2[Si4−]型化学式，被鉴定为一种Zintl相。
Prospectivep-type magnesium-silicon compounds have been produced from mixed and sintered Mg2Si, Mg2Sr or Mg2Ba powders. The synthesis was carried out through the spark plasma sintering (SPS) process at 1123 K for 10 min at 50 MPa.p-Type thermoelectric performance was observed for samples prepared from sintered powder at nominal compositions (Mg2Si)0.7(Mg2Sr)0.3and (Mg2Si)0.7(Mg2Ba)0.3. The maximum dimensionless figure of merit,ZT, of the former sample reached 0.24 at 700 K. The crystal structures and chemical contents were carefully elucidated by powder and single-crystal x-ray diffraction (XRD) measurements, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with the use of energy-dispersive x-ray spectroscopy (EDS). The SPS samples consisted of two new unknown phases. Based on the single-crystal XRD data, the crystal structures of two different A(Sr or Ba)-Mg-Si crystals are successfully determined. The two structures are hexagonalP63/m-type A2Mg12Si7and(no. 189)-type A2Mg4Si3. The two structures consist of three-dimensionally interconnecting MgSi4tetrahedron networks and alkaline-earth ion columns aligned parallel to the 4.3-Å axes. Both phases have identical [(A2+, Mg2+)]2[Si4−]-type chemical formulae, being identified as a kind of Zintl phase.