Thermoelectric Properties of NaCo2-xCuxO4 Improved by the Substitution of Cu for Co
Thermoelectric Properties of NaCo2-xCuxO4 Improved by the Substitution of Cu for Co
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Cu替代Co提高NaCo2-xCuxO4热电性能
DOI：
10.1143/jjap.40.l65
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Y. Iguchi
中科院分区：
文献类型：
--
作者：
I. Terasaki;Y. Ishii;D. Tanaka;K. Takahata;Y. Iguchi
我们制备了一系列热电氧化物Na1.2Co2-xCuxO4(x=0，0.1，0.2和0.3)的多晶样品，并研究了铜替代对其热电性能的影响。在4~300K温度范围内，取代铜显著提高了材料的热电势，但对材料的电阻率和热导率影响不大。结果表明，当温度为100K时，热电优值系数从x=0增加到0.3，提高了5倍。这里观察到的铜替代效应与通常的杂质效应是高度不相容的，通常的杂质效应会增加电阻，保持热电势不变。掺入的铜使反射边向低能量方向移动，导致载流子浓度降低和有效质量增加。
We prepared a set of polycrystalline samples of the thermoelectric oxide Na1.2Co2-xCuxO4 (x=0, 0.1, 0.2 and 0.3), and investigated the Cu substitution effects on their thermoelectric properties. The substituted Cu significantly enhances the thermopower over the temperature range from 4 to 300 K, whereas it does not appreciably change the resistivity and the thermal conductivity. As a result, the thermoelectric figure of merit increases by five times at 100 K from x=0 to 0.3. The Cu substitution effects observed here are highly incompatible with usual impurity effects that increase the resisitivity leaving the thermopower unchanged. The doped Cu shifts the reflectivity edge to lower energies, implying that it causes a decrease of the carrier concentration and/or an increase of the effective mass.