Magnetoelectric coupling and thermoelectric behaviors in Ni-doped CuCrO[formula omitted] crystallites

Abstract

A novel and effective approach to improve thermoelectric conversion efficiency is of utmost importance for its commercial viability. The increased ferromagnetism caused by the Ni-doping alters the antiferromagnetic interactions between Cr3+ ions in CuCrO2 and likely produces the conical-like spin component. The magnetostrictive ferromagnetic Ni2+ doped CuCrO2 generates stress through the elastic property at the grain interface and piezoelectricity which couples and generates an electric field. The built-in electric field and magnetic scattering produced by magnetic doping reduce carrier concentration and mobility and raise the Seebeck coefficient. The engendered multiferroic nature and the alteration of electron transport properties with magnetic phase transition from ferromagnetic to paramagnetic of Ni2+ doped CuCrO2 are evidenced by magnetoresistance and vibrating-sample magnetometry (VSM) investigations. The magnetic inclusion of Ni2+ generates carrier magnon drag which steers the highest Seebeck coefficient of 625 μV/K at 100 °C. The conductivity of 4203 S/m and the Seebeck coefficient of 386 μV/K leads excellent power factor (S2σ) of 0.62 mW/mK2 and ZT of 0.163 at 700 °C. The Ni2+ dopants, on the other hand, cause broad frequency phonon scattering, which significantly lowers the lattice thermal conductivity of CuCrO2. This study demonstrates how magnetic particle-induced thermoelectromagnetic coupling effects can significantly boost the efficiency of electro-thermal conversion.