Magnetic, electrochemical and thermoelectric properties of $P2-N{a}_x(C{o}_{7/8}S{b}_{1/8})O_2$

Abstract

We theoretically investigated the electronic, electrochemical and magnetic properties of Sb doped $N{a}_{x}Co{O}_2$ ($x=1,0.75$ and $0.50$). $S{b}_{Co}$ dopants adopt +5 oxidation state in $N{a}_{x}Co{O}_2$ host lattice for all Na concentrations ($x$). Due to high oxidation states, $S{b}^{5+}$ strongly repels Na ions and therefore it decreases the electrochemical potential (vs. Na/Na${}^{+}$). The electrons introduced by $S{b}^{5+}$ localize on nearby Co ions creating $C{o}^{2+}$ species which are absent in undoped $N{a}_{x}Co{O}_2$. $C{o}^{2+}$ ions reduce the spin entropy flow decreasing the Seebeck coefficient in the Sb doped compounds. The results can be generalized to other dopants with high oxidation state.

6 pages, 3 figures, 2 tables

References in corpus (6)

• Phase Diagram of Na${}_x$CoO${}_2$ Studied by Gutzwiller Density Functional Theory
• Na order and Co charge disproportionation in Na${}_x$CoO${}_2$
• Restoration of long range order of Na ions in $N{a}_{x}Co{O}_2$ at high temperatures by sodium site doping
• Evolution of Co charge disproportionation with Na order in Na${}_x$CoO${}_2$
• Dopant incorporation site in sodium cobaltate's host lattice: A critical factor for thermoelectric performance
• Interplay between magnetism and sodium vacancy ordering in NaxCoO2

Cited by in corpus (1)

• High-Performance Thermoelectric Oxides Based on Spinel Structure