Microstructures And Properties Of Textured Piezoelectric Ceramics Oriented With BaTiO₃ Template

As high technical function materials exchange electrical and mechanical energy, piezoelectric ceramics were widely applied in human living and manufacturing field. Though traditional Lead-based ceramics were of excellent piezoelectric and electromechanical properties, theirs application and production brought a great pollution on environment. Therefore, developing and improving new kinds of lead-free piezoelectric ceramics became the keystone in the field of piezoelectric ceramics.In the research, BaTiO3 plates of micron-thickness synthesized by a solidification method were used as templates to prepare the textured ceramics of BaTiO3(BT), Na0.5Bi0.5TiO3 (NBT) and Ko.5Nao.5NbO3(NBT) by the technique of template grain growth (TGG). The effects of BaTiO3 templates on the microstructure and properties of these ceramics were investigated. The results are as follows:(1) BaTiO3 templates of anisotropy dimension were synthesized by a solidification method. The BaTiO3 templates like plate with the diameter of about 10-20μm and thickness of about 5μm. The ratio of thickness to diameter was about 5-10:1.(2) The BaTiO3 templates were oriented by a tape casting process. Comparatively, when the thickness of tape casting film was 200μm, theBaTiO3 templates were aligned obviously.(3) NBT textured ceramics could be made by crystal grain growth along the direction that plate-like BaTiO3 templates oriented. When the dose of BaTiO3 templates was wt.15%, the relative volume density of NBT textured ceramics reached 90.2%. Sintered at 1175℃, the NBT ceramic reached a high degree of texture which the relative height of (200) peak in XRD spectrum was 76.7%.(4) NKN ceramic grains could be induced to grow attaching themselves to the surface of plate-like BaTiO3 templates. The higher the sintering temperature was, the higher the degree of texture was in NKN ceramic. Sintered at 1175℃, the NKN ceramic with the addition of wt.25% BaTiO3 templates was of a d33 being 69 pC/N.(5) Though BT ceramic could be induced to form texture morphologies by plate-like BaTiO3 templates, but its piezoelectric and dielectric properties were low and sintering process was difficult.