Tailorable thermal expansion in leucite‐pollucite materials derived from geopolymers for environmental barrier coatings

Abstract The K[AlSi 2 O 6 ]‐Cs[AlSi 2 O 6 ] pseudo‐binary system was synthesized by geopolymer crystallization. The thermal expansion properties of these materials were studied by in situ high‐temperature X‐ray diffraction to characterize thermal expansion behavior for potential application as environmental barrier coatings. Tailorable thermal expansion through changing cation stoichiometry allowed reduced thermal expansion mismatch with SiC f /SiC composites compared to rare‐earth‐based coatings.