Structural, humidity sensing and dielectric properties of Ca-modified Ba(Ti_(0.9)Sn_(0.1))O_3 lead free ceramics

摘要

Developing a new lead-free ceramics with similar piezoelectric properties of lead-based ceramics has rapidly grown for various applications such as transducers, sensors, capacitors and memories. (Ba_(1-x)Ca_x)(Ti_(0.9)Sn_(0.1))-O_3 (BCTS; 0 ≤ x ≤ 0.1) lead-free ceramics were prepared by a conventional solid state reaction technique at 1400 ℃ for 4 h. Effect of Ca content on the phase structure and on electrical properties has been investigated. For x ≥ 0.04 the particle size was reduced and the density was observed in the ceramics. Pure BaTiO_3 shows a better humidity sensing response at room temperature compared to the Ca doped samples. Temperature dependent dielectric constant has been investigated at two different frequencies. The results shows that by increasing Ca content, the crystal structure changed from orthorhombic to tetragonal (T_(o-T)) phase and shifted toward lower temperature. The highest piezoelectric coefficient (d_(33)) and electromechanical coupling factor (K_p) were obtained at Ca content 0.02. These results can be considered as a promising for piezoelectric applications.