Lead-free piezoelectrics are becoming increasingly important in view of environmental problems of currently used lead-based perovskites such as lead zirconate titanate (PZT). One of the recent candidates for PZT replacement, solid solutions of BaZr 0.2 Ti 0.8 O 3 and Ba 0.7 Ca 0.3 TiO 3 , are investigated in this work by piezoresponse force microscopy. Coexistence of the tetragonal and rhombohedral phases in this material is observed, which probably gives rise to easy polarization switching due to multiple domain states. The period of observed domain lamella scales with the grain size obeying well-known square root dependence characteristic of BaTiO 3 ceramics. Domain switching and relaxation are investigated at the nanoscale as a function of the applied voltage and duration of the applied voltage pulses. The observed distortion of piezoresponse hysteresis loops near grain boundaries is attested to the increased concentration of defects. Nanoscale piezoelectric properties of these materials are discussed. V C 2015 AIP Publishing LLC.

International audienceIn this paper, we present the material characterization that has been made to explain the poor nonlinear performance observed in certain channel waveguides produced by soft proton exchange in periodically poled congruent lithium niobate (PPLN) crystals. The study was performed using complementary methods of domain visualization: piezoelectric force microscopy and confocal Raman microscopy. It has been shown that the waveguide fabrication process can induce the formation of the structure of needle like nanodomains, which can be responsible for the degradation of the nonlinear response of the waveguides created in PPLN crystals

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