The crossover of (Ba_(1−x)Ca_x)(Ti_(0.9)Sn_(0.1))O_3 piezoelectric ceramics from single-phase to composite with studying the structural and dielectric properties

摘要

Lead-free (Ba_(1−x)Ca_x)(Ti_(0.9)Sn_(0.1))O_3 perovskite ceramics (x = 0.02-0.5) (BCTS) were synthesized using the solid-state reaction technique. X-ray diffraction was used to identify the formed phases of the prepared compositions. The morphology of ceramics has been studied using a scanning electron microscope equipped with an energy dispersive spectrometer. Field emission scanning electron microscope was used to examine the morphology of sensing film calcined powder. The crossover from BCTS single-phase (x = 0.02) to BCTS composite(x = 0.5) was obtained via coexistence of both (x = 0.3) of Ca addition. The composite powder was sintered at higher temperature rather than the single-phase powder. The calcined powder sensing film was prepared by the screen-printing technique as humidity sensors. Thereafter, DC resistance measurements were performed in the presence of relative humidity RH at room temperature. All the compositions exhibited a poor sensitivity toward the humidity sensing in the range of 0-98% RH. The compositions 0.02 and 0.06 have shown orthorhombic-tetragonal phase transition (T_(O−T)) below the room temperature, while the other compositions have shown a pure tetragonal phase. The highest value of permittivity at Curie temperature (ε = 29241 at 100 Hz) and piezoelectric coefficient (d_(33) = 495 pC/N) at room temperature were obtained at Ca = 0.06 due to present polymorphic phase transition. The effect of frequency on the dielectric constant and dielectric loss at room temperature were investigated. All the prepared compositions exhibited small values of dielectric loss from 50 Hz up to 100 KHz, which indicates a good reliability for electronic applications such as capacitors or memory devices.