Proceedings - Viện Vật lý

Advances _________________________________________________________________________________in Optics, Photonics, Spectroscopy and Applications. Aug. 2006, Cantho, Vietnam7. H. Kaibe, M. Sakata, I. J. Ohsuji, and I. Nishida, J. Phys. Chem. Solids, 50 (1989)945.THERMOELECTRIC AND OPTICAL PROPERTIESOF SINGLE CRYSTAL Bi 1.8 Sb 0.2 Te 3.0Ngo Thu HuongFaculty of Physics, Hanoi University of Science, VNU,Abstract: Single crystal Bi 1.8 Sb 0.2 Te 3.0 has been grown by a Gradient Freezemethod. The thermoelectric properties such as Seebeck coefficient, resistivityand thermal conductivity of single crystal Bi 1.8 Sb 0.2 Te 3.0 were investigated in thetemperature range from 4.2 K to 300 K along a and c axes. Raman spectra weremeasured in the z ( xx)z and in the z ( xy)z geometries. We have found that thethermopower and figure of merit ZT along the a-axis are larger than along the c-axis. Raman spectra in the geometry z ( xx)z have three peaks but only one peakappears in the z ( xy)z geometry.Keywords: Thermoelectric materials, Bi 2 Te 3 , Raman scattering175