Trapp, Maximilian ; Keil, Peter ; Frömling, Till ; Rödel, Jürgen ; Kleebe, Hans-Joachim (2020)
Segregation and properties at curved vs straight (0001) inversion boundaries in piezotronic ZnO bicrystals.
In: Journal of the American Ceramic Society, 103 (4)
doi: 10.1111/jace.16912
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

TEM and SEM investigations of ZnO bicrystal interfaces were undertaken with an aim to study the correlation of local grain-boundary structure, segregation, and electrical transport perpendicular to the interface. To this end, varistor-like ZnO bicrystals with piezotronic characteristics were chosen with (0001)║(0001) tail-to-tail orientation with respect to the c-axis. In order to contrast different local grain-boundary structures with different coherency and segregation of bismuth, but identical macroscopic polarization state, two complementary processing techniques were applied. A diffusion-bonded bicrystal with an intermediate thin film containing Zn–Bi–Co–O provided a straight interface as reference. In contrast, a ZnO bicrystal prepared by epitaxial solid-state transformation was manufactured by bonding two ZnO single crystals with a 100 μm thick polycrystalline ZnO varistor material with a typical dopant composition including bismuth and cobalt. This structure was annealed to the point that a bicrystal was formed with the varistor concentration at the boundary,which was strongly curved due to the polycrystalline microstructure still providing a shadow image at the interface. The results highlight a distinct correlation between local interfacial morphology, degree of segregation of bismuth, and degree of nonlinearity of the electrical transport across the interface.

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