Influence of tungsten substitution and oxygen deficiency on the thermoelectric properties of CaMnO3−δ

Autor:	Anke Weidenkaff, Max Döbeli, Leyre Sagarna, James Eilertsen, Philipp Thiel, Andrey Shkabko, Gesine Saucke, Lassi Karvonen, Sascha Populoh
Rok vydání:	2013
Předmět:	Thermal conductivity Materials science chemistry Condensed matter physics Impurity Thermoelectric effect General Physics and Astronomy Sintering chemistry.chemical_element Thermal stability Tungsten Polaron Stoichiometry
Zdroj:	Journal of Applied Physics. 114:243707
ISSN:	1089-7550 0021-8979
Popis:	Polycrystalline tungsten-substituted CaMn1−xWxO3−δ (0.00 ≤ x ≤ 0.05) powders were synthesized from a polymeric precursor, pressed and sintered to high density. The impact of tungsten substitution on the crystal structure, thermal stability, phase transition, electronic and thermal transport properties is assessed. Tungsten acts as an electron donator and strongly affects high-temperature oxygen stoichiometry. Oxygen vacancies form in the high figure-of-merit (ZT)-region starting from about T = 1000 K and dominate the carrier concentration and electronic transport far more than the tungsten substitution. The analysis of the transport properties yields that in the investigated regime the band filling is sufficiently high to overcome barriers of polaron transport. Therefore, the Cutler-Mott approach describes the electrical transport more accurately than the Mott approach for small polaron transport. The lattice thermal conductivity near room temperature is strongly suppressed with increasing tungsten concentration due to mass-difference impurity scattering. A ZT of 0.25 was found for x = 0.04 at 1225 K.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::c3369b2a056a0f6303b6c3be12e01b0d https://doi.org/10.1063/1.4854475 Zobrazit plný text záznamu