Influence of calcined temperature and sintered technology on the properties of NBT-KBT-BT lead-free piezoelectric ceramics

The influence of calcined temperature and sintered technology on the properties of 0.85 (Na_0.5Bi_0.5) TiO₃-0.144(K_0.5Bi_0.5)TiO₃-0.006BaTiO₃(NBT-KBT-BT) lead-free piezoelectric ceramics was investigated by conventional solid state method, and the relationship between calcined temperature, sintered technology and properties of NBT-KBT-BT lead-free piezoelectric ceramics was obtained. The influence of calcined temperature on the material phase was investigated by X-ray diffraction(XRD), the influence of sintered technology on the microstructure of ceramics was investigated by scanning electron microscopy (SEM). Results show that there are impurity phase Na_0.5Bi_4.5Ti₄O₁₅ and main crystal phase (Na_0.5Bi_0.5) TiO₃ while calcined temperature is 830-870°C, the impurity phase decreases while calcined temperature increases, there is pure (Na_0.5Bi_0.5)TiO₃ phase while calcined temperature is more than 890°C. The density of ceramics first increases and then decreases, the crystal grain size first increases and then decreases while sintered temperature increases. The crystal grain size increases straight while soaking time prolonges. When calcined temperature is 890°C, sintered temperature is 1160°C and soaking time is 2 h, the comprehensive properties is good which the dielectric constant(ε_r) is 1055, the piezoelectric constant(d₃₃) is 144 pC/N, the dielectric loss(tanδ) is 4.0%.