Transmission electron microscopy characterization of a Yttria-stabilized zirconia coating fabricated by electron beam-physical vapor deposition

Yttria-stabilized zirconia (YSZ) film was deposited on to a metal substrate by electron beam-physical vapor deposition (EB-PVD) at 850 °C. The film was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The YSZ film predominantly consisted of the tetragonal phase with a small amount of monoclinic phase. In addition, the film was composed of inverted triangular-based pyramidal grains (T-grains) and inverted diamond-based pyramidal grains (D-grains). The T-grains were aligned in the <111> direction and D-grains in <110>. Furthermore, striated lines of nanopores, which were strongly related to the thermal conductivity of the film, were observed in each YSZ grain. The pores are aligned in the <110> direction in the (111) plane and distributed across {114̄} planes in T-grains, and aligned in the [1̄10] and the [001] directions in the (110) plane, and distributed across the (001) and (1̄10) planes in D-grains.