Orientation and Surface Properties of Sol-Gel Derived Y2O3 Films

Abstract

The orientation, surface and optical properties of sol-gel derived Y2O3 films have been investigated. Transparent Y2O3 films were prepared on quartz glass substrates by sol-gel processes using YCl3·6H2O as a starting material. The water droplet contact angles of the films reached constant values between 79° and 90° after the films were left for 8 to 10 days in air at ambient temperature, indicating that the film surface exhibited hydrophobicity. When 2-(2-methoxyethoxy)ethanol (MEE) was added to the sol, yttria in the films crystallized to a strongly oriented cubic phase at firing temperatures between 400°C and 500°C. The intensity of the XRD peaks increased as the firing temperature was increased to 900°C. However, yttria crystallized to a non-oriented cubic phase when MEE was not used. The refractive index and packing density of the Y2O3 films increased from 1.55 to 1.68 and from 0.67 to 0.79, respectively, as the firing temperature was raised from 400°C to 900°C, indicating that sol-gel derived Y2O3 films are lower in density than evaporated ones.