Optimization Of The Properties On Bi_0.5Na_0.5TiO₃-BaTiO₃ Lead-free Piezoelectric Ceramics

As a kind of extremely important functional materials, the piezoelectric ceramic has been found its application throughout human lives and manufacturing. Traditional PZT-based piezoelectric ceramics have been widely used for the sake of mature manufacturing process and excellent piezoelectric properties. However, the research and development of new lead-free piezoelectric ceramics has become an emergent issue of great significance in order to protect environment.As it exhibits good ferroelectric and piezoelectric properties, (Bio.5Nao.5)Ti03-BaTi03(abbreviated as BNBT) has been considered to be an excellent candidate of lead-free piezoelectric ceramics to replace the widely used lead-based piezoelectric materials.In this paper, the current situation on lead-free piezoelectric ceramics and the process of BNBT are systematically discussed. The process conditions of BNBT are established with analyzing technologies such as DSC/TGA, XRD, SEM and so on. The effects of the main processing parameters such as BaTiO₃ content, calcining temperature, sintering temperature and soaking time on the dielectric and piezoelectric properties of BNBT ceramics are investigated by using orthogonal design. The results indicate that the BaTiO₃ content has the most significant impact. The optimal processes conditions to produce BNBT ceramics are as follows: BT mol content 0.06, calcining temperature 850℃, sintering temperature 1 130℃ and soaking time 2h. BNBT ceramics produced with the conditions possess outstanding dielectric andpiezoelectric properties (tgδ = 1.78 %, d₃₃=138pC·N^-1,ε₃₃^T/ε₀=587).The influence of BaTiO₃ content on the properties and crystal structure of BNBT is investigated. The crystal structures of BNBT-100x(x=0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) are investigated using XRD, which confirm that the rhombohedral-tetragonal morphotropic phase boundary of BNBT is at around x=0.06～0.08. The lattice parameters and lattice distortion with different BaTiO₃ content are calculated according to the XRD data. BNBT ceramics samples are...