Sub-20-nm magnetite-based core-shell nanoparticles with strong magnetic, magnetoelectric, and nanocatalytic properties

Magnetoelectric (ME) nanoparticles (NPs) have garnered much attention of researchers in the field of biomedicine owing to multiferroic properties. Here, novel sub-20-nm ME core–shell NPs—based on biocompatible magnetic Fe3O4 (FO) as a magnetostrictive core and ferroelectric perovskite Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) as a ferroelectric shell—were designed for the first time via in situ microwave-assisted hydrothermal synthesis. Comprehensive characterization confirmed epitaxial growth of the very thin (down to 5 nm) ferroelectric perovskite BCZT shell on the spinel FO core, with an average size of 14.5 ± 4.6 nm (mean ± standard deviation). These sub-20-nm ME FO@BCZT core–shell NPs showed high saturation magnetization (24.8 ± 0.7 emu/g). Furthermore, FO@BCZT NPs manifested robust piezoelectricity (13 ± 3 p.m./V) and a superior ME coefficient (11.9 × 105 mV/[cm•Oe]), which is comparable to that of potentially toxic Co-based analogs and significantly higher than values reported for larger magnetite-based ME NPs. Notably, ME performance of FO@BCZT NPs was tested and showed 85 % efficiency of degradation of model pollutant Rhodamine 6G after 3 h of treatment with a safe low-intensity alternating magnetic field (150 mT, 100 Hz). Thus, the newly developed ME core–shell FO@BCZT NPs are a promising candidate for diverse applications: from nanocatalysis to targeted drug delivery and cancer therapy.