Year: 2014
Type: article
Abstract: We present here a study of electrical and thermoelectric properties of n ‐ and p ‐Bi 2 Te 3 microwires ( n ‐type Bi 2 Te 2 Se; p ‐type Bi 0.5 Sb 1.5 Te 3 ) with different diameters ( d =10–20 µm). Cylindrical Bi 2 Te 3 crystals with glass coating were prepared by the liquid phase casting in a glass capillary. The X‐ray studies have shown that the microwire core is in general polycrystal consisting of big disoriented single crystal blocks. Measurements of resistance and thermopower were carried out over a wide range of temperatures (4.2–300 K) and magnetic fields (0–14 T). At 300 K for samples of n ‐ and p ‐type the thermopower S and power factor P.f. = S 2 σ were (100–140) µV/K, 1.6×10 ‐3 W/(K 2 m) and (150–300) µV/K, 4.5×10 ‐3 W/(K 2 m), respectively. Magnetic field dependences of Power factor were measured at various temperatures ( T =35, 100, 270 K) and different magnetic field orientations. A broad maximum is the dominant feature of the magnetic field dependence of power factor for p‐ type samples, while power factor decreases for n‐ type samples. We have obtained maximum power factor P.f. =6.8×10 ‐3 W/(K 2 m) for p ‐type sample at longitudinal magnetic field B =3 T at T =100 K. Shubnikov de Haas oscillations with equal periods ΔB =0.038 T ‐1 both in longitudinal and transverse magnetic fields for carriers with m c = 0.15 m 0 in p ‐type Bi 2 Te 3 microwire were observed. These oscillations could arise from the topological surface states. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1960646482