Synthesis of High-Entropy Gradient Crystals via the Soret Effect during Bridgman Growth

Functionally gradient materials exhibit compositional or structural gradient changes, creating new functional materials for diverse application domains. High-entropy crystals containing multiple elements hold the promise of continuous elemental regulation, facilitating the realization of functionally gradient materials. However, intrinsic property studies of high-entropy gradient crystals remain limited, and the synthesis of high-entropy gradient crystals is challenging due to the strong inherent disorder. Herein, we propose a general approach to synthesize high-entropy gradient crystals via the Soret effect in Bridgman growth. Based on the polycrystalline AgSbPbSnGeTe₅, we integrate the concepts of gradient crystals and high-entropy crystals, culminating in the first successful synthesis of high-entropy gradient crystals via the Soret effect during crystal growth. The macroscopic temperature gradient in the Bridgman method drives the growth of dense, intact millimeter-sized single crystals, while the microscopic temperature gradient induces the Soret effect, leading to a compositional gradient in the high-entropy ingot. As a demonstration of its thermoelectric utility, an intrinsically high ZT ∼1.44 at 673 K was achieved in high-entropy gradient crystals. This work establishes a general paradigm for designing high-entropy gradient crystals via the Soret effect in the Bridgman method, providing a new man-made material for emerging functional needs and shedding useful light on the synthesis of large-sized high-entropy single crystal.