HREM investigations of intermediate ZnO and ZnO/Y–ZrO2 layers in Y–ZrO2 bicrystals and ZnO films grown on Y–ZrO2 bicrystal substrates

The structure of yttrium-stabilized ZrO₂ (YSZ) bicrystals with ZnO and ZnO/YSZ/ZnO/YSZ/ZnO intermediate layers, as well as ZnO films grown on YSZ bicrystal (1 1 0)/90° substrates, has been investigated by means of high-resolution electron microscopy (HREM) and microanalysis. All bicrystals were produced by the solid-phase intergrowth (SPI) method. The internal ZnO film in the bicrystal formed at the SPI temperature of 1400°C consisted of domains with two symmetrical orientations: , and , . A bicrystal with a ZnO/YSZ/ZnO/YSZ/ZnO internal film was formed at the temperature of 1200°C. There was no mixing of ZnO and YSZ films and no traces of any solid-phase reactions were observed. Grains in all internal ZnO films and ZnO films grown on the bicrystal substrates had numerous stacking faults. It was found that SPI does not influence the density and structure of these defects. Orientational relationships between YSZ and ZnO in all samples were determined. The ZnO films grown on (1 1 0)/90° bicrystal substrates inherited the grain boundary (GB) from the substrate. Its structure and geometry is determined by four variants of ZnO grain growth.