Design development of (Ba1-xCax)(Ti1-ySny)O3 lead-free piezo ceramic by two manufacturing methods of CSS and SPS, promising for delamination damage detection

Abstract

Delamination in laminated composite structures plays a major role in decreasing structural strength and stiffness, consequently downgrading system integrity and reliability. Therefore, the delamination detection by the method of sending and receiving propagated wave with piezoelectric sensors is very important. In order to detect the structural damage using piezo ceramics sensors with a high piezoelectric coefficient (d33), a lead-free piezo ceramic (B1-xCxT1-ySy)O3 or (Ba1-xCax)(Ti1-ySny)O3 was designed and manufactured by two methods of conventional solid-state reaction sintering (CSS) and spark plasma sintering (SPS). The electrical and electromechanical properties, X-ray diffraction analysis, thermal analysis (DSC) and scanning electron microscopy (SEM) were investigated on the samples and the samples properties were compared with different contents of Ca and Sn dopants. (Ba1-xCax)(Ti1-ySny)O3 (x = 0.05, 0.1 mole% and y = 0.02–0.12 mole %) ceramics with a high relative density over 97.02 (±0.2)% were prepared by CSS method at 1480 °C. A polymorphic phase transition from orthorhombic phase to tetragonal phase was confirmed in the composition range of x = 0.05, 0.1 and 0.02 ≤ y ≤ 0.12 by XRD analysis that was measured at room temperature. In CSS method a high piezoelectric coefficient (d33) up to 605 pC/N was obtained for x = 0.05 mole% and y = 0.09 mole%, which was higher than the other previously reported components of B1-xCxT1-ySy system. The corresponding planar electromechanical coupling factor (kp) and inversed piezoelectric coefficient (dS/dE) reached to 42.8% and 1203 pm/V, respectively. For the prepared SPS samples at 1330 °C and under the pressure of 55 MPa, the corresponding d33, kp, tanδ and dS/dE were 752 pC/N, 54.2%, 2.7% and 1248 pm/V, respectively. The average relative density of SPSed samples of the same composition reached to 99.50 (±0.2)%. It seems that designing and forming a suitable phase boundary starting from a tricritical triple point in the MPB zone that along with SPS manufacturing method could enhance and develop high-performance Pb-free piezoelectrics.