Top-seeded solution growth and investigation of electrical and energy storage performance of pure and doped (1−x)Na0.5Bi0.5TiO3–xBaTiO3 ferroelectric single crystals

Abstract

Urgent requirement exists to develop the lead-free piezoelectric energy storage devices, sensors and actuators for the reduction of toxicity in the environment. This paper deals with the lead-free ferroelectric single crystals with excellent piezoelectric behaviour. A series of pure and doped (Mn and Nb) (1−x)Na0.5Bi0.5TiO3–xBaTiO3 (NBBT) bulk size single crystals was successfully grown by the top-seeded solution growth (TSSG) method. The crystal growth, phase confirmation, compositional analysis, electric properties and energy storage density were investigated. The NBBT crystal belongs to perovskite structure and is confirmed using X-ray Powder diffraction pattern (PXRD). The elemental composition of the NBBT crystals grown by TSSG was investigated by the Inductively coupled plasma-Atomic Emission spectroscopy (ICP-AES). The electrical properties like dielectric constant (er = 674, 700, 837, 694, 2872 and 378) and dielectric loss (tanδ = 0.2, 0.6, 0.5, 0.7, 0.47 and 0.27) were measured and it was found to be relaxor-type behaviour due to diffuseness of NBBT crystals by the dielectric permittivity. The piezoelectric coefficients (d33 = 374, 290, 167, 110, 410 and 103) and piezoelectric voltage coefficients (g33 = 6.26, 4.6, 2.2, 1.79, 1.6 and 3.0) were obtained. Greater value of remnant polarization (Pr = 87, 46, 30, 0.30, 117 and 0.11), maximum polarization (Pm = 104, 55, 49, 1.08, 136 and 0.34) and lower value of coercive electric field (Ec = 16.5, 13.8, 26, 0.64, 20 and 233) were obtained from the P–E hysteresis loop of NBBT crystals studied to identify good performance of the compositions. The NBBT 90/10 crystal was found to be of 94/06 composition as obtained from ICP-AES. Moreover, NBBT 90/10 was doped by Mn and Nb and its electrical properties were measured. The Mn-doped NBBT 90/10 crystal attained a large energy storage density (W) of 0.27 Jcm−3 at ~ 20 kV cm−1 compared to the undoped and Nb-doped NBBT 90/10 crystal.