Thermoelectric Properties of Wires Bi2Te3 in the Glass Coating p and n Type

Abstract

The aim of our research was to prepare micro- and nanowires of n- and p-type Bi2Te3 in glass insulation and to study their thermoelectric properties as a function of heat treatment, i.e., annealing, recrystallization, and wire diameter. The n- and p-type Bi2Te3 wires in glass insulation were prepared via liquid-phase casting through heating a glass tube containing the Bi2Te3 material of the appropriate composition using an outer furnace. For the first time, by re-drawing wires vitrified Bi2Te3 were obtained with the wires diameter up to 1 mkm. Due to the fact that the resistivity of the thin wires (d = 2 mkm) is almost an order of magnitude smaller than in the wires of p-type Bi2Te3 (d> 50 mkm), Power factor= α2σ at 300 K = 3,5*10-5 W/cm*K2 exceeds the maximum P.f= 1,2*10-5 W/cm*K2, obtained in wires with d> 50 mkm, even after additional annealing for 24 hours. It has been shown that the isothermal annealing increases both thermopower α and resistivity ρ in the samples of hole conductivity; unlike p-type, the parameters α and ρ vary only slightly after annealing. The parameters of the annealed samples hardly changed during the entire test period. Therefore, it is recommended to subject Bi2Te3 wires in glass insulation to an additional long-term annealing at appropriate temperatures in the case of their use in thermoelectric energy converters.