Decrease of Ca3Co4O9+? thermal conductivity by Yb-doping
Küçük Resim Yok
Tarih
2015
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Sci Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In this study, the effect of Yb-substitution on the structural, electrical and thermal transport properties of the Ca3Co4O9+delta system has been investigated in the low temperature region (between 10 and 300 K). The resistivity of samples increases with raising the Yb-concentration in the system. All the samples show a metal-semiconductor transition below 85 K. In the analysis based on Strongly Correlated Fermi Liquid Model, an increased bandwidth and a reduced electronic correlation are found. It has also been found that the energy gap, E-0, value also decreases with Yb-substitution. The samples show positive thermoelectric power, indicating that dominant charge carriers are holes in all the samples. The thermoelectric power value decreases with Yb-substitution. From Mott equation, it is determined that the Fermi energy and hole concentration decrease in the Yb-susbtituted samples, compared to the undoped ones. Thermal conductivity, kappa, is decreased in about 50% of the measured in undoped samples for the 0.01 and 0.03 Yb-doped samples at 300 K. Highest figure of merit, ZT, value is found to be 5.4 10(-3) at 300 K for the unsubstituted sample and the ZT value decreases by the substitution. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Açıklama
Anahtar Kelimeler
Thermal conductivity, Ceramics, Doping, Electrical transport
Kaynak
Ceramics International
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
41
Sayı
10
