Search for: All records

Developing novel lead‐free ferroelectric materials is crucial for next‐generation microelectronic technologies that are energy efficient and environment friendly. However, materials discovery and property optimization are typically time‐consuming due to the limited throughput of traditional synthesis methods. In this work, we use a high‐throughput combinatorial synthesis approach to fabricate lead‐free ferroelectric superlattices and solid solutions of (Ba_0.7Ca_0.3)TiO₃(BCT) and Ba(Zr_0.2Ti_0.8)O₃(BZT) phases with continuous variation of composition and layer thickness. High‐resolution x‐ray diffraction (XRD) and analytical scanning transmission electron microscopy (STEM) demonstrate high film quality and well‐controlled compositional gradients. Ferroelectric and dielectric property measurements identify the “optimal property point” achieved at the composition of 48BZT–52BCT. Displacement vector maps reveal that ferroelectric domain sizes are tunable by varying {BCT–BZT}_Nsuperlattice geometry. This high‐throughput synthesis approach can be applied to many other material systems to expedite new materials discovery and properties optimization, allowing for the exploration of a large area of phase space within a single growth.

image

As the energy demand is expected to double over the next 30 years, there has been a major initiative towards advancing the technology of both energy harvesting and storage for renewable energy. In this work, we explore a subset class of dielectrics for energy storage since ferroelectrics offer a unique combination of characteristics needed for energy storage devices. We investigate ferroelectric lead-free 0.5[Ba(Ti0.8Zr0.2)O3]-0.5(Ba0.7Ca0.3)TiO3 epitaxial thin films with different crystallographic orientations grown by pulsed laser deposition. We focus our attention on the influence of the crystallographic orientation on the microstructure, ferroelectric, and dielectric properties. Our results indicate an enhancement of the polarization and strong anisotropy in the dielectric response for the (001)-oriented film. The enhanced ferroelectric, energy storage, and dielectric properties of the (001)-oriented film is explained by the coexistence of orthorhombic-tetragonal phase, where the disordered local structure is in its free energy minimum.

Phase separation in manganites leads to unique magnetic and electronic properties. 50% Ca‐doped LaMnO₃(LCMO), at the boundary of ferromagnetic (FM) and antiferromagnetic (AFM) states in La_1‐xCa_xMnO₃(0 ≤ x ≤ 1), is an ideal system to study phase separation behavior. The investigation reveals the effect of a 5d‐metal perovskite SrIrO₃(SIO) on the phase separation, magnetic, and magnetoresistance (MR) properties of LCMO. Single‐layer and bilayer LCMO films, both appear purely ferromagnetic along the in‐plane (IP) magnetic field direction, but show the tendency of temperature‐dependent ferromagnetic and antiferromagnetic or charge‐ordered (CO) phase separation with the out‐of‐plane (OOP) applied field. The MR, and colossal magnetoresistance (CMR), observed in LCMO/SIO bilayers are two orders and an order of magnitude (in %) larger, respectively than that in the single‐layer film. The coexistence of FM and AFM/CO phases is responsible for the CMR and MR enhancement in the LCMO/SIO bilayer, pointing toward the importance of the phase separation and competition of both the individual materials in enhancing their magnetic and electronic properties.