Preparation and Thermoelectric Properties of a Chimney-Ladder (Mn1-xFex)Siγ (γ∼1.7) Solid Solution
Preparation and Thermoelectric Properties of a Chimney-Ladder (Mn1-xFex)Siγ (γ∼1.7) Solid Solution
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DOI：
10.1143/jjap.50.035804
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发表时间：
2011-03
影响因子：
1.5
通讯作者：
Y. Miyazaki;Y. Saito;K. Hayashi;K. Yubuta;T. Kajitani
中科院分区：
文献类型：
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作者：
Y. Miyazaki;Y. Saito;K. Hayashi;K. Yubuta;T. Kajitani
采用电弧熔炼和退火工艺制备了部分Fe取代的高硅化锰固溶体（Mn_（1-x）Fe_x）Si_γ。根据x与晶格参数之间的线性关系，可以制备x = 0.35的固溶体。这些化合物由[Mn 1-xFex]和[Si]两个四元体系组成，其无理c轴比γ= cMn/cSi <$1.7。随着x从0增加到0.35，相当于电子载流子的增加，a轴和cMn轴的长度逐渐减小，而cSi轴的长度线性增加。根据价电子计数规则，我们预计在x = 0.23 ±0.05处将发生从p型到n型的转变。这种转变在x ≤ 0.28时得到实验证实; n型样品在0.28 ≤x ≤0.35时制备。在室温下的电导率表现出对称曲线与x的p型和n型样品。然而，Fe的溶解度极限似乎抑制载流子浓度的任何进一步增加，导致n型样品的导电性差。因此，对于x = 0.30的样品，在644 K下获得最大无量纲优值ZT = 0.071。
A partially Fe-substituted solid solution of a higher manganese silicide, (Mn1-xFex)Siγ, has been prepared by means of arc-melting and a subsequent annealing process. According to the linear relationship between x and lattice parameters, the solid solution can be prepared up to x = 0.35. The compounds consist of two tetragonal subsystems of [Mn1-xFex] and [Si], with an irrational c-axis ratio γ= cMn/cSi ∼1.7. With increasing x from 0 to 0.35, equivalent to increase electron carriers, the a-axis and cMn-axis lengths gradually decrease, while the cSi-axis length linearly increases. On the basis of a valence electron counting rule, we expected that a transition from p-type to n-type would occur at x = 0.23 ±0.05. This transition is experimentally confirmed at x ∼0.28; the n-type samples are prepared at 0.28 ≤x ≤0.35. The electrical conductivity at room temperature exhibits symmetrical curves versus x for both p- and n-type samples. However, the solubility limit of Fe appears to suppress any further increase in carrier concentration, resulting in poor electrical conductivity for n-type samples. As a consequence, the maximum dimensionless figure-of-merit ZT = 0.071 at 644 K is obtained for a sample with x = 0.30.