Researchers propose strategy to design high-entropy environmental barrier coating material

In aviation technology, environmental barrier coatings (EBCs) are designed to protect the turbine components made of SiC_f/SiC ceramic matrix composites (CMCs) from environmental degradations in the combustion environment. Multicomponent/high-entropy rare-earth disilicates ((nRE_xi)₂SI₂O₇) are promising in EBCs applications.

However, the design of (nRE_xi)₂Si₂O₇ materials remains a crucial challenge, due to the versatile combinations of multiple RE elements, as well as the complex polymorphic phase competitions during materials fabrication.

In a study recently published in Nature Communications, researchers from the Institute of Metal Research, Chinese Academy of Sciences, have uncovered the mechanisms of phase formation capability for multicomponent/high-entropy rare-earth disilicate materials and proposed a compositional design strategy.

The researchers synthesized 21 multicomponent (RE^I_0.25RE^II_0.25RE^III_0.25RE^IV_0.25)Si₂O₇ (RE = Y, La, Ce, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). They found that the phase formation and stabilization of these materials was dependent on the average RE³⁺ radius as well as the deviations (σ_r) of different RE³⁺ combinations.

Based on high-throughput density-functional-theory simulations, the researchers constructed ensembles containing several hundreds of representative configurations for model compositions, and calculated the configurational entropy mixing.

They proposed an entropy descriptor, which captures whether the configurational randomness brought by multiple RE³⁺ cations can be sufficiently accommodated in the crystal lattice, and thus can be used to predict the phase formation capability of (nRE_xi)₂SI₂O₇ materials.

Based on these findings, the researchers proposed a strategy to design (nRE_xi)₂SI₂O₇ materials with controlled phase formation capability and high-temperature stability, which leads to efficient design and synthesis of many new (nRE_xi)₂SI₂O₇ (n = 2, 5, 6; equal and non-equal molar fraction of RE) materials.