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Titanium oxide ceramics doped with niobium is synthesized in reduced atmosphere at 1200 ℃ by conventional solid-state reaction technique. From their crystal structures determined by the powder X-ray diffraction(XRD), the samples have multiple-phase with low Nb concentration, but they have single tetragonal rutile phase when Nb content is larger than 0.02. The electrical conductivities, the Seebeck coefficients and the thermal conductivities of the samples with single phase are measured at a temperature range between room temperature and 900 K. The electrical conductivity and the Seebeck coefficient show non-metallic behaviors. According to the fitting, it is found that the samples show thermal-activation mechanism at low temperatures and small-polaron hopping conduction mechanism at high temperatures. Moreover, the analyses of XRD, electrical conductivity and Seebeck coefficient show that the concentration of oxygen vacancy decreases with Nb content increasing. Thermal conductivity decreases with temperature increasing, dominating by lattice thermal conductivity. In the measurement region, the figure of merit (ZT) reaches a highest value of 0.19 at 873 K in the Ti0.98Nb0.02O2- sample.
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Keywords:
- titanium oxide ceramics /
- thermoelectric properties /
- oxygen vacancy
[1] Shi Y W, Qiao G J, Jin Z H 2005 Rare Metal Mater. Eng. 34 12
[2] Chen X Y, Xu X F, Hu R X, Ren Z, Xu Z A, Cao G H 2007 Acta Phys. Sin. 56 1627 (in Chinese) [陈晓阳、徐象繁、胡荣星、任 之、许祝安、曹光旱 2007 56 1627]
[3] [4] Ohta H, Sugiura K, Koumoto K 2008 Inorg. Chem. 47 8429
[5] [6] Wang Y, Sui Y, Su W H 2008 J. Appl. Phys. 104 093703
[7] [8] [9] Park K, Seong J K 2008 J. Alloys Compd. 464 1
[10] [11] Wang H C, Wang C L, Su W B, Liu J, Zhao Y, Peng H, Zhang J L, Zhao M L, Li J C, Yin N, Mei L M 2010 Acta Phys. Sin. 59 529 (in Chinese)[王洪超、王春雷、苏文斌、刘 剑、 赵 越、彭 华、张家良、赵明磊、李吉超、尹 娜、梅良模 2010 59 529]
[12] [13] Li H, Tang X F, Cao W Q, Zhang Q J 2009 Chin. Phys. B 18 287
[14] [15] Deng S K, Tang X F, Tang R S 2009 Chin. Phys. B 18 1674
[16] [17] Lu Y, Hirohashi M, Sato K 2006 Mater. Trans. 47 1449
[18] [19] He Q Y, Hao Q, Chen G, Poudel B, Wang X W, Wang D Z, Ren Z F 2007 Appl. Phys. Lett. 91 052505
[20] Yamada H, Miller G R 1973 J. Solid State Chem. 6 169
[21] [22] Mott N F, Davis E A 1979 Electronic Processes in Non-crystalline Materials (Oxford: Clarendon) p52
[23] -
[1] Shi Y W, Qiao G J, Jin Z H 2005 Rare Metal Mater. Eng. 34 12
[2] Chen X Y, Xu X F, Hu R X, Ren Z, Xu Z A, Cao G H 2007 Acta Phys. Sin. 56 1627 (in Chinese) [陈晓阳、徐象繁、胡荣星、任 之、许祝安、曹光旱 2007 56 1627]
[3] [4] Ohta H, Sugiura K, Koumoto K 2008 Inorg. Chem. 47 8429
[5] [6] Wang Y, Sui Y, Su W H 2008 J. Appl. Phys. 104 093703
[7] [8] [9] Park K, Seong J K 2008 J. Alloys Compd. 464 1
[10] [11] Wang H C, Wang C L, Su W B, Liu J, Zhao Y, Peng H, Zhang J L, Zhao M L, Li J C, Yin N, Mei L M 2010 Acta Phys. Sin. 59 529 (in Chinese)[王洪超、王春雷、苏文斌、刘 剑、 赵 越、彭 华、张家良、赵明磊、李吉超、尹 娜、梅良模 2010 59 529]
[12] [13] Li H, Tang X F, Cao W Q, Zhang Q J 2009 Chin. Phys. B 18 287
[14] [15] Deng S K, Tang X F, Tang R S 2009 Chin. Phys. B 18 1674
[16] [17] Lu Y, Hirohashi M, Sato K 2006 Mater. Trans. 47 1449
[18] [19] He Q Y, Hao Q, Chen G, Poudel B, Wang X W, Wang D Z, Ren Z F 2007 Appl. Phys. Lett. 91 052505
[20] Yamada H, Miller G R 1973 J. Solid State Chem. 6 169
[21] [22] Mott N F, Davis E A 1979 Electronic Processes in Non-crystalline Materials (Oxford: Clarendon) p52
[23]
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