Synergistic effect of high-energy ball milling and Nb doping on the multiferroicity of BaTiO3

Abstract

This study demonstrates that high-energy ball milling induces a transition from diamagnetic to weak ferromagnetism order in BaTiO₃. In addition, combining mechanical milling with niobium doping enhances its dielectric and ferroelectric properties, yielding a room-temperature multiferroic material. To achieve this, niobium-doped BaTiO₃ powders with dopant concentrations of 0.0–0.1 wt.% were prepared by high-energy ball milling for 5 h. The effect of Nb⁵⁺ incorporation on the crystal structure and electrical properties was analyzed. X-ray diffraction with Rietveld refinements confirmed that all samples retained a tetragonal phase. Electrical analyses revealed that low Nb concentrations (0.025 and 0.050 wt.%) improved the ferroelectric and dielectric behavior of the samples, achieving a maximum polarization of 7.6 µC/cm² and a relative permittivity of 1700, outperforming undoped BaTiO₃. Finally, magnetic hysteresis loops confirmed weak ferromagnetism in all samples. This process converted Ti⁴⁺ into Ti³⁺ with unpaired spins, generating a nonzero magnetic moment, as corroborated by X-ray photoelectron spectroscopy analysis.