Molybdenum trioxide (MoO₃) in-plane anisotropy has increasingly attracted the attention of the scientific community in the last few years. Many of the observed in-plane anisotropic properties stem from the anisotropic refractive index and elastic constants of the material but a comprehensive analysis of these fundamental properties is still lacking. Here we employ Raman and micro-reflectance measurements, using polarized light, to determine the angular dependence of the refractive index of thin MoO₃ flakes and we study the directional dependence of the MoO₃ Young’s modulus using the buckling metrology method. We found that MoO₃ displays one of the largest in-plane anisotropic mechanical properties reported for 2D materials so far.

在过去的几年中，三氧化钼（MoO ₃）的面内各向异性越来越引起科学界的关注。观察到的许多面内各向异性特性是由材料的各向异性折射率和弹性常数引起的，但是仍然缺乏对这些基本特性的全面分析。在这里，我们使用拉曼光谱和微反射率测量方法（使用偏振光）确定薄MoO ₃薄片的折射率的角度依赖性，并使用屈曲计量方法研究MoO ₃杨氏模量的方向依赖性。我们发现，到目前为止，MoO ₃显示了2D材料中最大的面内各向异性机械性能之一。