engKiirat, G.Aksan, M.A.Rasekh, Sh.Madre, M.A.Diez, J.C.Sotelo, A.Decrease of Ca3Co4O9+δthermal conductivity by Yb-dopingART-2015-146853In this study, the effect of Yb-substitution on the structural, electrical and thermal transport properties of the Ca 3Co 4O 9 þ δ 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, E0, 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, κ, 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.2015http://zaguan.unizar.es/record/168086http://zaguan.unizar.es/record/168086oai:zaguan.unizar.es:168086info:eu-repo/grantAgreement/ES/DGA/T12info:eu-repo/grantAgreement/ES/DGA/T87info:eu-repo/grantAgreement/ES/MINECO-FEDER/MAT2013-46505-C3-1-RCeramics International 41, 10 (2015), 12515-12528by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess