Effect of lattice distortion in high-entropy RE₂Si₂O₇ and RE₂SiO₅ (RE=Ho, Er, Y, Yb, and Sc) on their thermal conductivity: Experimental and molecular dynamic simulation study

XY Liu and P Zhang and MZ Huang and Y Han and N Xu and Y Li and ZJ Zhang and W Pan and CL Wan, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 43, 6407-6415 (2023).

DOI: 10.1016/j.jeurceramsoc.2023.06.052

High-entropy materials are considered to be born with lattice distortion, which is still lack of comprehensive investigation in rare earth silicates to date. In this paper, we confirmed the existence of lattice distortions in highentropy rare-earth silicates via experiments and molecular dynamic simulations. The effects of the lattice distortion on the thermophysical properties are elucidated. Simulation results indicate the lattice distortion is present in both cation and anion sublattice, leading to the compressing and stretching of atomic bond as well as fluctuation of atomic bond strength. Accordingly, lattice distortion in the Si and O sublattice is also verified by the Raman spectra. Furthermore, the thermal conductivity of high-entropy rare earth silicates remarkably reduces and exhibits glass-like behavior, which is confirmed by experiments in cooperation with molecular dynamic simulations. Simulation also reveals that the lifetimes and group velocities of vibrational modes are significantly reduced by lattice distortion, which result in the reduction of overall thermal conductivity of highentropy rare-earth silicates.

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