Investigation of structural and enhanced piezoelectric properties in low lead content Na0.5Bi0.5TiO3-BaTiO3-PbTiO3 system

Through this work the authors report the structural, ferroelectric, and piezoelectric properties of PbTiO3 modified ceramics: (1-2x)Na0.5Bi0.5TiO3-xBaTiO(3)-xPbTiO(3): (1-2x)NBT-xBT-xPT with x = 0.01, 0.03, 0.05, 0.07 and 0.09. The X-ray diffraction analysis of (1-2x)NBT-xBT-xPT revealed the existence of monoclinic (M) phase for x = 0.01 and 0.03 with the presence of 1/2(311) superlattice reflection, which acts as a structural bridge between the Rhombohedral (R) and Tetragonal (T) phases. Phase transition from M to T phase was observed at x = 0.03 which is supported by the presence of (002)/(200) splitting in the diffraction pattern. The measured mean grain size and density for x = 0.03 was 5.7 mu m and 5.834 g/cm(3) respectively, which was the maximum compared to other compositions. The chemical state of elements in the ternary system is found out using the X-ray photoelectron spectroscopy. A diffuse phase transition is perceived from the temperature dependent dielectric studies for x <= 0.03, while this diffusiveness decreases for x > 0.03 with the increase in concentration of substituents. Besides, the ferroelectric (FE) to relaxor (RE) transition, T-FR is also diminished in higher concentration of BT and PT. A well saturated ferroelectric hysteresis loop with saturation polarization (P-s) and remnant polarisation (P-r) values of 35 and 32 mu C/cm(2) respectively is achieved for x = 0.03. Under an applied field of 48 kV/cm, a unipolar strain value of 0.26% is achieved for the same composition with a piezoelectric charge co-efficient (d(33)*) of 541 pm/V. The superior piezoelectric performance shown by (1-2x)NBT-xBT-xPT with a very low lead content of 3 mol%, which is at the proximity of M-T phase transition is explained using the polarisation rotation mechanism, that occurs in conjunction between polar-polar phases. The flat free energy profile that exists at the phase boundaries, eases the rotation of the polarisation vector and hence the piezoelectric constant. Also, a larger grain size will also relieve the polarisation rotation. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The authors reported the structural, ferroelectric, and piezoelectric properties of PbTiO3 modified ceramics with specific compositions, showing superior piezoelectric performance under certain conditions.