Strain-induced nanostructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 on SrTiO3 epitaxial thin films with low PbTiO3 concentration

Takanori Kiguchi, Cangyu Fan, Takahisa Shiraishi, Toyohiko J. Konno

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6 Citations (Scopus)


The singularity of the structure in (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) (x = 0-50 mol-) epitaxial thin films of 100 nm thickness was investigated from the viewpoint of the localized residual strain in the nanoscale. The films were deposited on SrTiO3 (STO) (001) single-crystal substrates by chemical solution deposition (CSD) using metallo-organic decomposition (MOD) solutions. X-ray and electron diffraction patterns revealed that PMN-xPT thin films included a single phase of the perovskite-type structure with the cube-on-cube orientation relationship between PMN-xPT and STO: (001)Film k (001)Sub, [100]Film k [100]Sub. X-ray reciprocal space maps showed an in-plane tensile strain in all the compositional ranges considered. Unit cells in the films were strained from the rhombohedral (pseudocubic) R phase to a lower symmetry crystal system, the monoclinic (MB) phase. The morphotropic phase boundary (MPB) that split the R and tetragonal (T) phases was observed at x = 30-35 for bulk crystals of PMN-xPT, whereas the strain suppressed the transformation from the R phase to the T phase in the films up to x = 50. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) analysis and its related local strain analysis revealed that all of the films have a bilayer morphology. The nanoscale strained layer formed only above the film/substrate semi-coherent interface. The misfit dislocations generated the localized and periodic strain fields deformed the unit cells between the dislocation cores from the R to an another type of the monoclinic (MA) phase. Thus, the singular and localized residual strains in the PMN-xPT/STO (001) epitaxial thin films affect the phase stability around the MPB composition and result in the MPB shift phenomena.

Original languageEnglish
Article number10PB12
JournalJapanese Journal of Applied Physics
Issue number10
Publication statusPublished - 2017 Oct


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