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<p>This study demonstrates precise control overnon the fluorite-to-pyrochlore phase transition in (La<sub>x</sub>Gd<sub>1−x</sub>)<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> (<i>x</i> = 0-1) through tailored rare-earth (RE) site engineering. Non-equimolar compositions, particularly <i>x</i> = 0.3 and <i>x</i> = 0.6, exhibit optimized size disorder (<i>δ</i> = 0.0341 and 0.0356, respectively) and configurational entropy (Δ<i>S</i><sub>conf</sub> = 5.08 and 5.597&#xa0;J/mol·K, respectively), which results in exceptional sintering resistance and 40‐50% lower grain growth (38‐43&#xa0;nm compared with 54‐93&#xa0;nm in single-cation (<i>x</i> = 0 and <i>x</i> = 1) systems) after 50&#xa0;h at 1300&#xa0;°C. Structural analyses confirm systematic phase evolution: defective fluorite dominates at <i>x</i> = 0, ordered pyrochlore forms at <i>x</i> = 1, and stable dual-phase structures persist at intermediate compositions (<i>x</i> = 0.3, 0.6) under prolonged heating. Raman spectroscopy verifies enhanced cation ordering with increasing La content, while XRD/FESEM validate suppressed crystallite growth and phase purity. These findings establish non-equimolar RE-site engineering as a critical strategy for next-generation thermal barrier coatings, delivering 2X enhanced sintering resistance and operational stability in extreme environments.</p>

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Tailored Multi-component Rare Earth Zirconate: Precise Control of Fluorite-to-Pyrochlore Phase Transition during Calcination

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • Melika Tahmasebi,
  • Milad Bahamirian,
  • Mohammad Farvizi

摘要

This study demonstrates precise control overnon the fluorite-to-pyrochlore phase transition in (LaxGd1−x)2Zr2O7 (x = 0-1) through tailored rare-earth (RE) site engineering. Non-equimolar compositions, particularly x = 0.3 and x = 0.6, exhibit optimized size disorder (δ = 0.0341 and 0.0356, respectively) and configurational entropy (ΔSconf = 5.08 and 5.597 J/mol·K, respectively), which results in exceptional sintering resistance and 40‐50% lower grain growth (38‐43 nm compared with 54‐93 nm in single-cation (x = 0 and x = 1) systems) after 50 h at 1300 °C. Structural analyses confirm systematic phase evolution: defective fluorite dominates at x = 0, ordered pyrochlore forms at x = 1, and stable dual-phase structures persist at intermediate compositions (x = 0.3, 0.6) under prolonged heating. Raman spectroscopy verifies enhanced cation ordering with increasing La content, while XRD/FESEM validate suppressed crystallite growth and phase purity. These findings establish non-equimolar RE-site engineering as a critical strategy for next-generation thermal barrier coatings, delivering 2X enhanced sintering resistance and operational stability in extreme environments.