J. Korean Ceram. Soc. > Volume 46(6); 2009 > Article
 Journal of the Korean Ceramic Society 2009;46(6): 689. doi: https://doi.org/10.4191/kcers.2009.46.6.689
 NaxCo2O4의 열전특성에 미치는 Na 함량변화와 첨가제의 효과 최순목, 정성민, 서원선 한국세라믹기술원 Determination of the Thermolelectric Properties of NaxCo2O4 by Controlling the Concentration of Na and Additive Soon-Mok Choi, Seong-Min Jeong, Won-Seon Seo Korea Institute of Ceramic Engineering and Technology(KICET) ABSTRACT Layer-structured $Na_xCo_2O_4$ was synthesized from $Na_2CO_3;and;Co_3O_4$ powders. The chemical concentrations of Na and additive were controlled to enhance the thermoelectric properties over the temperature range from 400 K to 1,150 K. As a result, we obtained the maximum thermoelectric properties at a single phase region with Na content of x=1.5. When Na content was smaller than x=1.5, the thermoelectric properties was low due to formation of second phases of CoO and other oxides. Additionally, Mn was doped to improve thermoelectric properties by means of decreasing thermal conductivity. The results showed that the concentrations of both Na and Mn are all governing factors to determine the thermoelectric properties of $Na_xCo_2O_4$ system. Key words: Thermoelectrics, $Na_xCo_2O_4$, Nonstoichiometry, Mn, p-type semiconductor
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