Abstract:
Na0.5Bi0.5TiO3–BaTiO3 (NBT–BT) ceramics are promising lead-free candidates for energy storage and electrocaloric applications, but their performance is limited by dielectric breakdown strength and thermal stability. In this work, NBT–BT/AlN composites were designed to investigate how electrically insulating, thermally conductive nitride inclusions influence interfacial structure and functional response without altering the intrinsic ferroelectric framework. Structural and spectroscopic analyses reveal that AlN incorporation induces lattice strain, enhanced octahedral tilting, and increased local structural heterogeneity, while remaining outside the perovskite lattice. Microstructural observations indicate a relatively homogeneous distribution of Al-containing phases at low loadings and progressive grain-boundary accumulation at higher concentrations. These interfacial effects modify polarization dynamics, leading to reduced polarization and enhanced dielectric diffuseness. However, an optimal AlN content (2–4 wt%) significantly improves dielectric breakdown strength from 117 to 144 kV/cm. Finite-element simulations indicate that this enhancement originates from redistribution and partial homogenization of the local electric field at AlN/NBT–BT interfaces. The increased breakdown tolerance enables operation at higher electric fields, resulting in improved functional performance, including a recoverable energy density of 1.2 J/cm³ and an electrocaloric temperature change of 1.8 K with an entropy change of 3.16 kg-1 K-1. In addition, the incorporation of AlN is expected to influence heat dissipation through enhanced thermal transport, contributing to a more uniform electrothermal response. These results demonstrate that interfacial engineering via oxide–nitride composites provide an alternative pathway to tune high-field performance in NBT–BT ceramics without relying on compositional modification.
Title: Interfacial effects on breakdown strength and electrocaloric response in Na0.5Bi0.5TiO3–BaTiO3/AlN ceramic composites
Authors: J.P. Pramod, Munendra Pal, Saket Asthana, Mohammad Gousuddin, D. Kavitha, I. Bdikin, D.M. Tobaldi, M.A. Valente, E. Venkata Ramana
Reference: Materials Research Bulletin, 204, 114321, 2026
