A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings
Xenotime rare-earth (RE) phosphates are emerging as promising materials for environmental barrier coatings (EBCs) for SiC-based ceramic–matrix composites (CMCs) because of their close coefficients of thermal expansion (CTEs) and resistance to calcium–magnesium–alumina-silicate (CMAS) corrosion. In t...
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Tsinghua University Press
2025-03-01
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| Series: | Journal of Advanced Ceramics |
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| Online Access: | https://www.sciopen.com/article/10.26599/JAC.2025.9221041 |
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| author | Bishnu Pada Majee Keith Bryce Liping Huang Jie Lian |
| author_facet | Bishnu Pada Majee Keith Bryce Liping Huang Jie Lian |
| author_sort | Bishnu Pada Majee |
| collection | DOAJ |
| description | Xenotime rare-earth (RE) phosphates are emerging as promising materials for environmental barrier coatings (EBCs) for SiC-based ceramic–matrix composites (CMCs) because of their close coefficients of thermal expansion (CTEs) and resistance to calcium–magnesium–alumina-silicate (CMAS) corrosion. In this work, high-entropy (HE) (Sc0.2Lu0.2Yb0.2Er0.2Y0.2)PO4 and five single-component REPO4 (RE = Sc, Lu, Yb, Er, and Y) compounds were synthesized, and their stability, thermal properties, and CMAS corrosion resistance were investigated. The CTE values of four REPO4 compounds (RE = Lu, Yb, Er, and Y; ~(5.6–6)×10−6 °C−1) are close to those of SiC–CMC ((4.5–5.5)×10−6 °C−1), whereas ScPO4 (6.98×10−6 °C−1) and HE (5RE0.2)PO4 (6.39×10−6 °C−1) have slightly higher values in the temperature range of 200–1300 °C. HE phosphate has the lowest thermal conductivity due to its size and mass disorder. Systematic CMAS corrosion tests at 1300 °C for 5, 45, and 96 h revealed that all RE phosphates formed a continuous and dense reaction layer predominantly composed of Ca8MgRE(PO4)7, effectively impeding CMAS penetration. Additionally, REPO4 with smaller RE³− cations displays a slower reaction rate and reduced corrosion kinetics, as evidenced by the smaller thickness of the reaction layer. A larger negative difference in the optical basicity (OB) value between REPO4 and CMAS signifies greater corrosion resistance. A mechanistic understanding of CMAS corrosion and elucidation of the effects of critical parameters such as the ionic mass and ionic radius of RE elements on their thermal properties and CMAS corrosion kinetics are useful for the development of novel xenotime-type phosphates as EBCs for SiC–CMCs. |
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| issn | 2226-4108 2227-8508 |
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| publishDate | 2025-03-01 |
| publisher | Tsinghua University Press |
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| series | Journal of Advanced Ceramics |
| spelling | doaj-art-6a5f7ab8cbbc4a70b1e64cb2e9d9de1e2025-08-20T01:47:55ZengTsinghua University PressJournal of Advanced Ceramics2226-41082227-85082025-03-01143922104110.26599/JAC.2025.9221041A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatingsBishnu Pada Majee0Keith Bryce1Liping Huang2Jie Lian3Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, NY 12180, USADepartment of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, NY 12180, USADepartment of Materials Science and Engineering, Rensselaer Polytechnic Institute, NY 12180, USADepartment of Materials Science and Engineering, Rensselaer Polytechnic Institute, NY 12180, USAXenotime rare-earth (RE) phosphates are emerging as promising materials for environmental barrier coatings (EBCs) for SiC-based ceramic–matrix composites (CMCs) because of their close coefficients of thermal expansion (CTEs) and resistance to calcium–magnesium–alumina-silicate (CMAS) corrosion. In this work, high-entropy (HE) (Sc0.2Lu0.2Yb0.2Er0.2Y0.2)PO4 and five single-component REPO4 (RE = Sc, Lu, Yb, Er, and Y) compounds were synthesized, and their stability, thermal properties, and CMAS corrosion resistance were investigated. The CTE values of four REPO4 compounds (RE = Lu, Yb, Er, and Y; ~(5.6–6)×10−6 °C−1) are close to those of SiC–CMC ((4.5–5.5)×10−6 °C−1), whereas ScPO4 (6.98×10−6 °C−1) and HE (5RE0.2)PO4 (6.39×10−6 °C−1) have slightly higher values in the temperature range of 200–1300 °C. HE phosphate has the lowest thermal conductivity due to its size and mass disorder. Systematic CMAS corrosion tests at 1300 °C for 5, 45, and 96 h revealed that all RE phosphates formed a continuous and dense reaction layer predominantly composed of Ca8MgRE(PO4)7, effectively impeding CMAS penetration. Additionally, REPO4 with smaller RE³− cations displays a slower reaction rate and reduced corrosion kinetics, as evidenced by the smaller thickness of the reaction layer. A larger negative difference in the optical basicity (OB) value between REPO4 and CMAS signifies greater corrosion resistance. A mechanistic understanding of CMAS corrosion and elucidation of the effects of critical parameters such as the ionic mass and ionic radius of RE elements on their thermal properties and CMAS corrosion kinetics are useful for the development of novel xenotime-type phosphates as EBCs for SiC–CMCs.https://www.sciopen.com/article/10.26599/JAC.2025.9221041environmental barrier coatings (ebcs)rare-earth (re) phosphatecoefficients of thermal expansion (ctes)thermal conductivitycalcium–magnesium–alumina–silicate (cmas) corrosion |
| spellingShingle | Bishnu Pada Majee Keith Bryce Liping Huang Jie Lian A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings Journal of Advanced Ceramics environmental barrier coatings (ebcs) rare-earth (re) phosphate coefficients of thermal expansion (ctes) thermal conductivity calcium–magnesium–alumina–silicate (cmas) corrosion |
| title | A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings |
| title_full | A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings |
| title_fullStr | A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings |
| title_full_unstemmed | A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings |
| title_short | A high-entropy rare-earth phosphate and its principle single component REPO4 for environmental barrier coatings |
| title_sort | high entropy rare earth phosphate and its principle single component repo4 for environmental barrier coatings |
| topic | environmental barrier coatings (ebcs) rare-earth (re) phosphate coefficients of thermal expansion (ctes) thermal conductivity calcium–magnesium–alumina–silicate (cmas) corrosion |
| url | https://www.sciopen.com/article/10.26599/JAC.2025.9221041 |
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