Room-temperature superconductivity has been attracting increasing attention in recent years. Recent studies have proved the potential of compressed H-rich materials for achieving room-temperature superconductivity. In this paper, we study the phononic thermal transport in the rare earth yttrium hydrides allotropes under 0, 50, and 300 GPa by using Boltzmann transport equation. We find that the lattice thermal conductivity of yttrium hydrides increases with the pressure among different allotropes, which is attributed to the increase of bond strength and the decrease of phonon-phonon scattering due to structural compression. Yttrium hydrides structure at high pressure of 300 GPa is the superconducting phase, and has high thermal conductivity around 1,360 Wm⁻¹K⁻¹ at room temperature. Comparison of phonon properties with existing high thermal conductivity materials further uncovers the origin for the observed high thermal conductivity. For the zero pressure allotrope, a large number of optical flat bands mix with the low-frequency acoustic phonons, which significantly increases the phonon scattering channel and effectively suppresses the phonon lifetime. As for yttrium hydrides allotropes under 50 and 300 GPa, there are two obvious band gaps in the phonon dispersion relation, and the band gap of the structure at 300 GPa is significantly wider. The occurrence of the band gap effectively inhibits the absorption and emission process of the three-phonon interactions, leading to the decrease of phonon scattering and thus the increase of the phonon lifetime and thermal conductivity at high pressure. Our work reveals the physical mechanism of the thermal transport behaviors in yttrium hydrides structures under different pressures.

近年来，室温超导已引起越来越多的关注。最近的研究证明，压缩的富氢材料具有实现室温超导性的潜力。本文利用玻尔兹曼输运方程研究了0、50和300 GPa下稀土氢化钇同素异形体中的声子热输运。我们发现，氢化钇的晶格热导率随同素异形体之间的压力而增加，这归因于键合强度的增加和由于结构压缩而引起的声子-声子散射的减少。在300 GPa高压下的氢化钇结构是超导相，在1,360 Wm ^-1 K ^-1附近具有较高的热导率在室温下。将声子特性与现有的高导热率材料进行比较，进一步揭示了观察到的高导热率的起源。对于零压力同素异形体，大量光学平坦带与低频声子混合，这显着增加了声子散射通道并有效地抑制了声子寿命。对于50 GPa和300 GPa以下的氢化钇同素异形体，在声子色散关系中存在两个明显的带隙，并且在300 GPa下结构的带隙明显更宽。带隙的出现有效地抑制了三声子相互作用的吸收和发射过程，导致声子散射的减少，从而增加了高压下的声子寿命和导热系数。