Elastic constants of amorphous thin films in the systems SiO 2Al 2O 3 and AlPO 4Al 2O 3

Abstract

The Young modulus and the Poisson ratio of RF-sputtered amorphous SiO 2Al 2O 3 and AlPO 4Al 2O 3 films were obtained by using the vibration reed method and their bulk modulus was calculated from the values of both Young's modulus and Poisson's ratio. The compositional dependence of Young's modulus for the amorphous SiO 2Al 2O 3 films was different from that for the amorphous AlPO 4Al 2O 3 films; that is, no drastic increase in Young's modulus appeared in the SiO 2Al 2O 3 system, while a sharp increase in Young's modulus appeared above 70 mol% Al 2O 3 in the AlPO 4Al 2O 3 system. The compositional dependence of Poisson's ratio showed a tendency similar to that of Young's modulus. The dependence of the elastic moduli of amorphous SiO 2Al 2O 3 and AlPO 4Al 2O 3 films on the coordination state of aluminum ions was in good agreement with the previous results of the coordination state of aluminum ions in the same systems determined by the chemical shifts of Al K α and the data of the other physical properties.