Enhanced thermoelectric performance of n-type Bi2O2Se ceramics induced by Ge doping

0484654 - ÚMCH 2019 RIV US eng J - Článek v odborném periodiku
Ruleová, P. - Plecháček, T. - Kašparová, J. - Vlček, Milan - Beneš, L. - Lostak, P. - Drašar, Č.
Enhanced thermoelectric performance of n-type Bi2O2Se ceramics induced by Ge doping.
Journal of Electronic Materials. Roč. 47, č. 2 (2018), s. 1459-1466. ISSN 0361-5235. E-ISSN 1543-186X
Grant CEP: GA ČR(CZ) GA16-07711S
Institucionální podpora: RVO:61389013
Klíčová slova: semiconductors * chalcogenides * x-ray diffraction
Obor OECD: Inorganic and nuclear chemistry
Impakt faktor: 1.676, rok: 2018

Ceramic samples with the composition Bi2−x Ge x O2Se1.01 (x = 0, 0.05, 0.075, and 0.1) were synthesized by solid-state reaction and compacted using a hot-pressing technique. The prepared materials were characterized by x-ray diffraction analysis, electron microscopy, and measurements of electrical conductivity σ, Seebeck coefficient S, and thermal conductivity in the temperature range 300–780 K. Ge in the Bi2O2Se host structure led to an increase of the free electron concentration compared to pristine Bi2O2Se1.01. The donor effect is attributed to point substitutional defects in the Bi sublattice—Ge+Bi, and oxygen vacancies V+2O producing free electrons. As a result, we observe an increase in the electrical conductivity and decrease in Seebeck coefficient while thermal conductivity κ changes slightly. The highest value of the dimensionless figure of merit ZT = σS 2 T/κ reaches 0.25 for the composition Bi1.95Ge0.05O2Se1.01 at T = 723 K, which is, to date, the highest ZT value reported for Bi2O2Se ceramics. Our results suggest that Bi2O2Se is still worth exploring.
Trvalý link: http://hdl.handle.net/11104/0282590