P. Pankaj | Searcharxiv

arXiv2026

Unified Phase-Field Framework for Antiferroelectric, Ferroelectric and Dielectric Phases: Application to HZO Thin Films

Polycrystalline hafnia-based thin films exhibit mixed ferroelectric (FE), antiferroelectric (AFE), and dielectric (DE) behavior, with switching characteristics strongly influenced by microstructure and phase distribution. Here, we develop a unified grain-resolved three-dimensional phase-field framework for metal-insulator-metal capacitors that simultaneously captures ferroic phase characteristics in realistic polycrystalline microstructures by explicitly incorporating grain topology and crystallographic orientation. Antipolar sublattice kinetics are represented via the coupled evolution of macroscopic and staggered polarization order parameters. All thermodynamic and kinetic parameters are calibrated to experimental P-E hysteresis loops and held fixed across all simulations. The results show that phase fractions primarily determine hysteresis character, while vertical segregation of AFE- and FE-rich regions systematically reduces the effective coercive field (Ec) under identical electrical loading. Grain-resolved analysis reveals that this reduction arises from microstructure-assisted switching pathways and electrostatic coupling between layers. These findings demonstrate that vertical phase arrangement provides a viable strategy to engineer switching behavior in hafnia-based ferroic capacitors and highlight the importance of explicit microstructural resolution for quantitative phase-field modeling.

cond-mat.mtrl-sci↗

arXiv2022

Surface-directed and bulk spinodal decomposition compete to decide the morphology of bimetallic nanoparticles

An embedded-domain phase-field formalism is used for studying phase transformation pathways in bimetallic nanoparticles (BNPs). Competition of bulk and surface-directed spinodal decomposition processes and their interplay with capillarity are identified as the main determinants of BNP morphology. The former is characterized by an effective bulk driving force $\Delta\tilde{f}$ which increases with decreasing temperature, while the latter manifests itself through a balance of interfacial energies captured by the contact angle $\theta$. The simulated morphologies, namely, core-shell, Janus and inverse core-shell, cluster into distinct regions of the $\Delta\tilde{f}$-$\theta$ space. Variation of $\theta$ with $\Delta\tilde{f}$ in the Ag-Cu alloy system is computed as a function of temperature using a CALPHAD approach in which surface energies are estimated from a modified Butler equation. This $\theta-\Delta\tilde{f}$ trajectory for Ag-Cu, when superimposed on the morphology map, enables the prediction of different morphological transitions as a function of temperature. Therefore, the study establishes a unique thermodynamic framework coupled with phase-field simulations for predicting and tailoring nanoparticle morphology through a variation of processing temperature.

cond-mat.mtrl-sci↗