Preparation of Amorphous Thin Films with High Elasticity

在固体材料的各种性质中，弹性性质，如杨氏模数、体积模数、剪切模数和泊松比等，在科学和技术方面都很受关注。已知，含有高结合强度和/或网络形成阳离子配位状态的组分的玻璃可以获得高的弹性模数。然而，由于普通的熔融急冷法很难制备出高配位阳离子状态的玻璃，因此必须探索其他玻璃制备方法，如溅射法、CVD法和溶胶凝胶法。本课题采用射频溅射方法在Al_203-AlN和Al_2O_3-TiO_2系统中制备了非晶态薄膜。而在Al_2O_3-AlN体系中，随着AlN的加入，非晶态Al_2O_3的弹性模量降低。这一结果可以用较高配位的铝离子的减少来解释。另一方面，在Al_2O_3-TiO_2体系中，射频溅射非晶薄膜可以获得阳离子的高配位状态，并测量了它们的弹性模数。在该系统中，16Al_2O_3.84TiO_2非晶薄膜的杨氏模量值达到最大，为175 GPa.这是目前已知的最高的非晶态玻璃。

Among various properties of solid materials, elastic properties such as Young's modulus, bulk modulus, shear modulus and Poisson's ratio are of considerable interest from both scientific and technical aspects. It is known that the glasses containing the constituents with high bond strength and/or having high coordinated state of network forming cations could achieve high elastic moduli. However, since it is not easy to make the glasses with high coordinated state of cations by ordinary melting-quenching procedure, other glass making processes such as sputtering, CVD and sol-gel methods have to be explored. In this project, radio-frequency sputtering method was applied to make amorphous thin films in the systems Al_203-AlN and Al_2O_3-TiO_2. The elastic moduli commonly increase as nitrogen is introduced into a glass. However, in the Al_2O_3-AlN system, the elastic moduli decreased as AlN was added to amorphous Al_2O_3. This result can be successful to be explained by decrease of the higher coordinated aluminum ions. On the other hand, the high coordinated state of cations could be achieved in rf-sputtered amorphous films in the system Al_2O_3-TiO_2, and their elastic moduli were measured. The amorphous film of 16Al_2O_3.84TiO_2 showed the maximum value of Young's modulus, 175GPa, in this system, which is higher than any other glass ever known.