Enhancement of the thermopower in in the large-x regime ()

Autor:	L. Viciu, Minhyea Lee, Robert J. Cava, Robert A. Pascal, N. P. Ong, Yayu Wang, Lu Li, M. L. Foo, Satoshi Watauchi
Rok vydání:	2008
Předmět:	Superconductivity Materials science Magnetoresistance Condensed matter physics Hall effect Seebeck coefficient Phase (matter) Thermoelectric effect Doping Electrical and Electronic Engineering Conductivity Condensed Matter Physics Electronic Optical and Magnetic Materials
Zdroj:	Physica B: Condensed Matter. 403:1564-1568
ISSN:	0921-4526
DOI:	10.1016/j.physb.2007.10.320
Popis:	We observe two distinct phases of Na x CoO 2 in the large Na-doping region ( x ⩾ 0.75 ), a pure phase H 2 , and a mixed phase H 2 + H 3 . The H 2 phase is characterized by a steep increase of the Peltier conductivity α defined as J = α ( - ∇ T ) , where J the thermoelectric current driven by the temperature gradient - ∇ T . The mixed-phase state H 2 + H 3 exhibits an unusual layered phase separation with conducting layers existing in parallel with insulating ones. At the critical doping x p ∼ 0.85 , the figure-of-merit Z at 80 K is 40 times larger than that of the as-grown sample ( x ∼ 0.7 ). The Hall coefficient and magnetoresistance are also reported.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::1d8d6d37666acafa629da20c21b24541 https://doi.org/10.1016/j.physb.2007.10.320 Zobrazit plný text záznamu Full Text from ScienceDirect