IJSTR

International Journal of Scientific & Technology Research

IJSTR@Facebook IJSTR@Twitter IJSTR@Linkedin
Home About Us Scope Editorial Board Blog/Latest News Contact Us
CALL FOR PAPERS
AUTHORS
DOWNLOADS
CONTACT
QR CODE
IJSTR-QR Code

IJSTR >> Volume 4 - Issue 4, April 2015 Edition



International Journal of Scientific & Technology Research  
International Journal of Scientific & Technology Research

Website: http://www.ijstr.org

ISSN 2277-8616



High Thermoelectric Performance Of Unsintered NaCo2O4 Nanocrystal

[Full Text]

 

AUTHOR(S)

Mehmet OkanErdal, Mustafa Koyuncu, İbrahim Uslu

 

KEYWORDS

Index Terms: Thermoelectric properties, Sodium Cobal OxideNanocrystalline, Electrospinning

 

ABSTRACT

Abstract: Sodium cobaltite (NaCo2O4) nano crystalline thermoelectric materials were obtained using electrospinning technique. Electrospunnanofibers was calcined at 800 oC and sintered at 850 oC in open air atmopshere. We have investigated the microstructure and thermoelectric properties of the sintered and unsintered samples for analysis sintering effect. The calcined sodium cobaltite crystal structures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Products molded by cold pressing method, and one of the pellets were sintered at 850 oC by conventional sintering, the other not subjected to the sintering process. Thermoelectric properties of the both materials were measured by PPMS system in the temperature range 10-300 K. The dimensionless figure of merit (ZT) values at 300 K is 4×〖10〗^(-5)and 9×〖10〗^(-5) for sintered and unsintered samples respectively. Although conventional sintered technique increase thermoelectric power and thermal conductivity approximately % 50 but it 4-fold decreased electrical conductivity.

 

REFERENCES

G. D.Mahan, “Good thermoelectrics,”Solid State Phys., 51, pp. 81-157,1998.

T.Kawata, Y.Iguchi, T. Itoh, K. Takahata, I. Terasaki, “Na-site substitution effects on the thermoelectric properties of NaCo2O4,”Physical Review B, 60, 15, pp. 10584-10587, 1999.

T. M. Tritt, M. A. Subramanian, “Thermoelectric Materials, Phenomena, and Applications: A Bird’s Eye View,”Mrs Bulletin, 31, pp. 188-198, 2006.

H. Gleiter, “Nanocrystalline materials,”Prog. Mater.Sci.,pp. 223, 1989.

P. Pichanusakorn, P. Bandaru, “Nanostructured thermoelectrics,”Mater.Sci. Eng. R, 67, pp. 19-63, 2010.

D. L.Medlin,G. J.Snyder, “Interfaces in bulk thermoelectric materials: A review for Current Opinion in Colloid and Interface Science,”Curr. Opin.Colloid & In., 14, pp. 226-235, 2009.

H. Kishan, V. P. S. Awana, M. A. Ansari, A. Gupta, R. B. Saxena, V. Ganesan, A. V. Narlikar, C. A. Cardoso, R. Nirmala, D. Buddhikot, S.K. Malik, “Resistivity and thermoelectric power of Na_x Co_2 O_4(x=1.0, 0.7, and 0.6) system,”Journal of Applied Physics, 97, pp. 10A904, 2006.

G. Peleckis, T. Motohashi, M. Karppinen, H. Yamauchi, “Enhanced thermoelectric properties of NaxCoO2 whisker crystals,”Applied Physics Letters, 83(26), pp. 5416-5418, 2003.

H. Yakabe, K. Kikuchi, I. Terasaki, Y.Sasago, K. Uchinokura, “Thermoelectric Properties of Transition Metal Oxide NaCo_2 O_4 System,”16th International conference on Thermoelectrics,1997.

I. Matsubara, Y. Zhou, T. Takeuchi, R. Funahashi, M. Shikano, N. Murayama, W. Shin, N. Izu, “Thermoelectric Properties of Spark-Plazma-Sintered Na_(1+x) Co_2 O_4Ceramics,”Journal of the Ceramic Society of Japan, 111(4), pp. 238-241, 2003.

C. Feng, K.C. Khulbe, T. Matsuura, “Recent Progress in the Preparation, Characterization, and Applications of Nanofibers and Nanofiber Membranes via Electrospinning/Interfacial Polymerization,”Journal of Applied Polymer Science , 115, pp. 756–776, 2010.

D. Li, Y. Xia, “Electrospinning of nanofibers:Reinventing the wheel?”Adv. Mater., 16, 14, pp. 1151-1170, 2004.

H. Zhao, M. Pokharel, G. Zhu et al. “Dramatic thermal conductivity reduction by nanostructures for large increase in thermoelectric figure-of-merit of FeSb2,” Applied Physics Letters,99, pp. 163101–163103, 2012.

I. Terasaki, Y. Sasago, and K. Uchinokura, Large thermoelectric power in NaCo2O4 single crystals, Phys. Rev. B 56, R12685(R) 1997

I.Terasaki, Transport properties and electronic states of the thermoelectric oxide NaCo2O4. Physica B 328, 63-67, 2003.

S. Maensiri, W. Nuansing, “Thermoelectric oxide NaCo_2 O_4nanofibers fabricated by electrospinning,”Materials Chemistry and Physics, 99, pp. 104-108, 2006.

A. Satake, H. Tanaka, T.Ohkawa, T.Fujii, I.Terasaki, “Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method,”J. Appl. Phys., 96, pp. 931-933, 2004.

M. Shikano, and R. Funahashi,“Electrical and thermal properties of single-crystalline (Ca2CoO3)0.7CoO2 with a Ca3Co4O9 structure,”Appl. Phys. Lett., 82, 12, pp. 1851-1853, 2003.

J. Cheng, Y. Sui, H. Fu, Z. Lu, B. Wei, Z. Qian, J. Miao,

Z. Liu, X. Huang, R. Zhu, X. Wang, W. Su, “Fabrication and thermoelectric properties of highly textured NaCo_2 O_4 ceramic,”Journal of Alloys and Compounds, 407, pp. 299–303, 2006.

K. Park, J. H. Lee, “Enhanced thermoelectric properties of NaCo_2 O_4 by adding ZnO,”Materials Letters, 62, pp. 2366-2368, 2008.

T.Seetawan, V. Amornkitbamrung, T.Burinprakhon, S. Maensiri, P. Tongbi, K. Kurosaki, H. Muta, M. Uno, S. Yamanaka, “Effect of sintering temperature on the thermoelectric properties of NaxCo2O4.”Journal of Alloys and Compounds, 416(1-2), pp. 291-295, 2006.

F. Ma, Y.Ou, Y. Yang, Y. Liu, S. Xie, J. F. Li, G. Cao, R. Proksch, J. Li, “Nanocrysytalline structure and thermoelectric properties of electrospunNaCo_2 O_4 nanofibers,”J. Phys. Chem. C, 114, pp. 22038-22043, 2010.