4.7 Article

Thermoelectric properties and phase transition of doped single crystals and polycrystals of Bi2Te3

期刊

JOURNAL OF THE AMERICAN CERAMIC SOCIETY
卷 104, 期 12, 页码 6242-6253

出版社

WILEY
DOI: 10.1111/jace.17988

关键词

low temperature; phase transition; polycrystalline materials; single crystals; thermoelectric properties

资金

  1. Russian Foundation for Basic Research [21-53-53008]
  2. Natural Science Fund of China [51871134]
  3. [2017YFE0195200]

向作者/读者索取更多资源

The study investigates the temperature dependences of electrical properties of Bi2Te3 and doped samples, revealing a phase transition at 120-200K. Both single crystals and polycrystalline samples exhibit quasi-two-dimensional electron transport, with changes in Fermi energy and thermoelectric performance observed.
The temperature dependences of the electrical conductivity sigma(T), Seebeck coefficient sigma(T), and heat capacity C-p(T) of polycrystalline samples of Bi2Te3, Bi2Te3+1%CuI, and Bi2Te3+1%(CuI+1/2Pb) are investigated in the temperature range below room temperature. Based on the temperature dependences of all investigated physical properties, it is discovered that phase transition occurs at 120-200 K. Investigation of single crystals shows that anomalies in the electrical resistivity (rho(T)=1/sigma(T)) occur only across the crystal growth axis (across the well-conducting Bi-Te plane). Investigation of the low-temperature dependence of electrical conductivity shows that all polycrystalline samples exhibit quasi-two-dimensional electron transport. Additionally, quasi-two-dimensional transport is detected in single crystals based on anisotropy analysis rho perpendicular to(T)/rho||(T):10 (where rho||(T) is the resistivity along the crystal growth axis, and rho perpendicular to(T) is resistivity across the crystal growth axis) and temperature dependence rho(T):T2 below 50 K. The Fermi energy EF is estimated using the temperature dependence of S(T). It is discovered that an increase in EF at T > 200 K is associated with the phase transition. For single-crystal samples, the maximum thermoelectric figure of merit ZT, as observed along the crystal growth axis, increases with doping. A maximum ZT value of similar to 1.1 is observed for the Bi2Te3+1%(CuI+1/2Pb) sample at room temperature (T=300K).

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