Engineering zero thermal expansion over a wide temperature range in PbTiO3-based ferroelectrics.

Abstract

Thermal expansion mismatches in precision optics, aerospace, and electronics can lead to delamination and fatigue, driving urgent demand for zero thermal expansion (ZTE) materials. At present, the majority of single-phase ZTE materials only function effectively below 500 K, limiting potential applications in many critical fields. Herein, we employ high-pressure and high-temperature synthesis to develop (1 - x)PbTiO₃-xBi(Cu_3/4W_1/4)O₃ perovskite ferroelectrics, utilizing spontaneous volume ferroelectrostriction to achieve an ultrawide ZTE regime from 300 to 725 K. In situ synchrotron X-ray diffraction tracks the lattice contraction and phase stability, while transmission electron microscopy provides insights into atomic-scale A/B-site cation displacements and tetragonal distortions. First-principles calculations reveal that polar ferroelectric-active Bi³⁺, Cu²⁺, and W⁶⁺ ions synergistically reorganize electron density to reinforce ferroelectric distortion, while Cu-derived van Hove singularities near the Fermi level dominate the density of states and govern the elastic anomalies linked to the ultrawide ZTE behaviors. This study extends the scope of high-temperature ZTE materials and establishes a ferroelectric-active ion-doping strategy to engineer thermal expansion.