Yttria-stabilized zirconia (YSZ) is the most common material used as a thermal barrier in several engineering applications. The majority of films produced by physical vapor deposition (PVD) techniques use normal incidence and lead to the columnar growth normal to the substrate. The typical columnar structure of sputter-deposited films is largely influenced, among other parameters, by pressure, temperature, thickness, and the ion-to-atom ratio incident at the substrate or substrate bias voltage. Another important experimental parameter used to modify the film properties is the direction of the incident flux of the depositing species with respect to the substrate surface. In this chapter an oblique angle deposition (OAD) approach was used to grow YSZ with tilted columnar structures, to study the impact of this deposition technique on the microstructure, morphology, and, correspondingly, the thermal conductivity of YSZ films, in order to improve the insulator potential of these thin films. Additionally, in the chapter, we present a detailed description of the oblique angle deposition (OAD) technique and double-layer model used for determination of the effective thermal conductivity of YSZ samples grown over thick substrates.
Part of the book: Coatings and Thin-Film Technologies