Rare-Earth-Engineered Interfacial Polarization and Dielectric Relaxation in Lead-Free Bilayer Multiferroic Laminates

Abstract The synergistic combination of different ferroic properties on a single material is provided by lead-free multiferroic laminates while keeping the intrinsic properties of the different phases intact. In this study, a 2–2 laminated heterostructure with ferroelectric Ba0.9Dy0.1Ti0.8Zr0.2O3 (DBZT) and ferrimagnetic Ni0.8Co0.2Fe1.99Yb0.01O4 (YNCF) was successfully fabricated by the cofiring technique to investigate the role of interface-controlled polarization and magnetic interactions in layered multiferroics. X-ray diffraction showed that no interfacial reaction phases formed between DBZT and YNCF, and both phases coexisted in a bilayer (NB). Cross-sectional FESEM and EDS analyses demonstrated that the interface between ferroic phases was dense and chemically distinct, with negligible elemental interdiffusion. Dielectric studies reveal that the dielectric response of the bilayer is controlled by the combined effect of defect dipole polarization in DBZT and Maxwell–Wagner interfacial polarization at the DBZT/YNCF interface. Ferroelectric measurements show that the ferrite layer affects the polarization switching mechanism by mechanically clamping and introducing electrical heterogeneity at the interfaces, resulting in a decrease in polarization and energy-storage capability while maintaining the stability of ferroelectric characteristics. Magnetic measurements verify that the bilayer has the same soft ferrimagnetic properties as those of YNCF. By employing the law of approach to saturation (LAS), the bilayer is shown to have a slower approach to saturation because of an increase in strain-induced anisotropic effects at the interface, which outweigh the magnetic dilution due to the ferroelectric layer. The studies conclude that rare-earth substitution and cofired ceramic bonding technique is an effective method of tailoring the charge-transport dynamics, polarization relaxation, and magnetic anisotropy of high-performance lead-free laminated heterostructures.