Enhancing Seebeck coefficient through magnetic and non-magnetic dual doping in CuCrO2 crystallites: A study on cationic influence

The manipulation of thermoelectric properties through doping strategies offers a promising route to optimize material performance. Here we explore the effects of magnetic and non-magnetic dual cation doping (Zn and Ni) on the Seebeck coefficient of CuCrO${}_2$ crystallites. Examining how lattice structure changes with increasing dopant concentrations provides deeper insights, aiding in optimizing superior thermoelectric materials. XPS investigation explores and substantiates the alterations in lattice sites resulting from the variation of two dopants Zn and Ni. The lattice distortion favors the superexchange interaction mediated by the ferromagnetic phase and the upsurge in carriers, the plateau in the MR graph, and the moderated reduction after the steep decline of Seebeck coefficients after 450 K serve as indicators of the magnetic phase transition and structural modulation. Our findings reveal that magnetic dopants introduce spin-related effects, which modify carrier concentration and scattering processes, while non-magnetic dopants mainly affect the electronic band structure. It is intriguing that the sample exhibiting higher magnetic remanence ($M_r$) demonstrates the lowest electrical conductivity during the ferromagnetic phase, yet displays higher conductivity during the paramagnetic phase. In this context, achieving the right concentration is pivotal, and the sample doped with 0.4 wt% showcases enhanced conductivity of 2823 S/m and Seebeck coefficient of 421 $\mu \mathrm{V/K}$, culminating in an impressive power factor of 456 $\mu {\mathrm{W/mK}}^2$ and ZT of 0.135 at 973 K.