High-entropy pyrosilicate element selection is relatively blind, and the thermal expansion coefficient of traditional β-type pyrosilicate is not adjustable, making it difficult to meet the requirements of various types of ceramic matrix composites. The following study aimed to develop a universal rule for high-entropy pyrosilicate element selection and to achieve directional control of the thermal expansion coefficient of high-entropy pyrosilicate. The current study investigates a high-entropy design method for obtaining pyrosilicates with stable β-phase and γ-phase by introducing various rare earth (RE) cations. The solid-phase method was used to create twelve different types of high-entropy pyrosilicates with 4–6 components. The high-entropy pyrosilicates gradually transformed from β-phase to γ-phase with an increase in the average radius of RE3+ ions. The nine pyrosilicates with a small average radius of RE3+ ions preserve β-phase or γ-phase stability at room temperature to the maximum of 1400 °C. The intrinsic relationship between the thermal expansion coefficient, phase structure, and RE-O bond length has also been found. This study provides the theoretical background for designing high-entropy pyrosilicates from the perspective of the average radius of RE3+ ions. The theoretical guidance makes it easier to synthesize high-entropy pyrosilicates with stable β-phase or γ-phase for use in environmental barrier coatings. The thermal expansion coefficient of γ-type high-entropy pyrosilicate can be altered through component design to match various types of ceramic matrix composites.
© The Author(s) 2023.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.