The Influence of Ag2Te Addition on Thermoelectric Properties of Bismuth Telluride

• Published in: Archives of metallurgy and materials 2022-01, Vol.67 (1), p.5-15
• Main Authors: Drzewowska, S, Lan, Tian-Wey, Onderka, B
• Format: Article
• Language: English
• Subjects: bi2te3-ag2te system; Bismuth tellurides; Cathodic protection; Electricity distribution; Evaluation; Figure of merit; Heat conductivity; N-type semiconductors; Phase transitions; Power factor; resistivity; seebeck coefficient; Seebeck effect; Silver compounds; Temperature; Temperature dependence; Ternary systems; Thermal conductivity; Thermal diffusivity; thermoelectric materials
• ISSN: 1733-3490; 2300-1909
• DOI: 10.24425/amm.2022.137466

The resistivity, Seebeck coefficient and thermal diffusivity were determined for Bi2Te3 + Ag2Te composite mixtures. Subsequent measurements were carried out in the temperature range from 20 to 270°C, and for compositions from pure Bi2Te3 to xAg2Te = 0.65 selected along the pseudo-binary section of Ag-Bi-Te ternary system. It was found that conductivity vs. temperature dependence shows visible jump between 140 and 150°C in samples with highest Ag2Te content, which is due to monoclinic => cubic Ag2Te phase transformation. Measured Seebeck coefficient is negative for all samples indicating they are n-type semiconductors. Evaluated power factor is of the order 1.52·10–3 and it decreases with increasing Ag2Te content (at. %). Recalculated thermal conductivity is of the order of unity in W/(m K), and is decreasing with Ag2Te addition. Finally, evaluated Figure of Merit is 0.43 at 100°C and decreases with temperature rise.