부산대학교 도서관

This study aims to investigate the strong correlation effect of spin and charge carriers for the Mg2+-substituted into Cr3+sites of CuCrO2delafossite on thermoelectric properties. The CuCr0.98Mg0.02O2sample was synthesized by a solid state reaction. The starting powder CuO, Cr2O3and MgO were ball milled with poly vinyl alcohol solution for 24 h. The ball milled powder was pressed and sintered in air atmosphere at temperature 1050 C for 6 h. The crystal structure was characterized by XRD, TGA, XPS and the thermoelectric properties were measured at high temperature. The XRD displayed peaks of the pure phase CuCrO2structure as hexagonal delafossite-type structure space group:Rm. The Seebeck coefficient of the samples displayed positive sign as p-type (hole) conductor. The XPS results displayed Mg2+, Cu1+, Cr3+and Cr4+ion states. The Mg2+induced mixed-valance Cr3+/Cr4+states resulting in enhanced Seebeck coefficient due to a strong correlation of the spin-entropy. The experimental results of Seebeck value were close to calculated results by the extended Heikes formula confirming of the strong correlation effect. In addition, the Mg-doped CuCrO2resulted in increased electrical conductivity and reduced thermal conductivity with increasing temperature. These indicate that the Mg2+-substituted for Cr3+of CuCrO2delafossite enhance the thermoelectric properties. [ABSTRACT FROM AUTHOR]