Observation of Surface Deformation of Ferroelectric and Ferroelastic Crystals by Atomic Force Microscopy

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AFM(Atomic Force Microscopy) is one of the useful methods for visualizing the surface morphology due to the ferroelectric and ferroelastic domain configurations, since the measurement is possible without any modification or damage of the sample surface in contrast to other methods such as surface etching, scanning electron microscopy, etc.In this project, we made AFM observations about surface structure of the following five crystals, BaTiO_3(BT), PbTiO_3(LT), Gd_2(MoO_4)_3(GMO), NdP_<5p>O_<14>(NDPP) and W0_3, all of which show phase transitions with alteration of the crystal system. Namely, 90 degree domain structure due to the cubic to tetragonal phase transition in BT and LT, the tetragonal to orthorhoinbic domain structure in GMO, and the orthorhombic to monoclinic domain structure in NDPP and W0_3, were visualized at room temperature, respectively. In particular, further experiments such as observation of the 90 degree domain image under application of electric field in BT, temperature-dependent triclinic-domain images in W0_3 were also made.