Affiliation:
1. Faculty of Materials Science and Engineering Kunming University of Science and Technology Kunming 650093 China
2. Ernst Ruska‐Centre for Microscopy and Spectroscopy with Electrons Forschungszentrum Jülich GmbH 52425 Jülich Germany
3. Electron Microscopy Center South China University of Technology Guangzhou 511442 China
4. Key Laboratory for Macromolecular Science of Shaanxi Province Shaanxi Key Laboratory for Advanced Energy Devices School of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 China
Abstract
AbstractPolymorphism (and its extended form – pseudopolymorphism) in solids is ubiquitous in mineralogy, crystallography, chemistry/biochemistry, materials science, and the pharmaceutical industries. Despite the difficulty of controlling (pseudo‐)polymorphism, the realization of specific (pseudo‐)polymorphic phases and associated boundary structures is an efficient route to enhance material performance for energy conversion and electromechanical applications. Here, this work applies the pseudopolymorphic phase (PP) concept to a thermoelectric copper sulfide, Cu2‐xS (x ≤ 0.25), via CuBr2 doping. A peak ZT value of 1.25 is obtained at 773 K in Cu1.8S + 3 wt% CuBr2, which is 2.3 times higher than that of a pristine Cu1.8S sample. Atomic‐resolution scanning transmission electron microscopy confirms the transformation of pristine Cu1.8S low digenite into PP‐engineered high digenite, as well as the formation of (semi‐)coherent interfaces between different PPs, which is expected to enhance phonon scattering. The results demonstrate that PP engineering is an effective approach for achieving improved thermoelectric performance in Cu‐S compounds. It is also expected to be useful in other materials.
Funder
National Natural Science Foundation of China
National Key Research and Development Program of China
Alexander von Humboldt-Stiftung
Subject
Mechanical Engineering,Mechanics of Materials,General Materials Science