Enhanced piezoelectricity and nature of electric-field induced structural phase transformation in textured lead-free piezoelectric Na0.5Bi0.5TiO3-BaTiO3 ceramics

Abstract

This letter provides a comparative description of the properties of textured and randomly oriented poly-crystalline lead-free piezoelectric 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 (NBT-BT) ceramics. A high longitudinal piezoelectric constant of (d33) ∼ 322 pC/N was obtained in (001)PC textured NBT-7BT ceramics, which is almost ∼2× times the d33 coefficient reported for randomly oriented ceramics of the same composition. In situ neutron diffraction experiments revealed that characteristically different structural responses are induced in textured and randomly oriented NBT-BT ceramics upon application of electric fields (E), which are likely related to the varying coherence lengths of polar nanoregions and internal stresses induced by domain switching.

Polarization Rotation and Monoclinic Distortion in Ferroelectric (Bi0.5Na0.5)TiO3–BaTiO3 Single Crystals under Electric Fields

“…Although there have been detailed studies on the crystal structures of BNT and BNT-BT [39][40][41][42][43], their underlying mechanism of ferroelectricity and piezoelectricity is not well understood, e.g., how the local structures near Bi and Na are developed, how the constituent ions are displaced, and how the vector of spontaneous polarization (P s ) responds to the application of E. The study on the responses of the unit-cell parameters and atomistic polarization with respect to E are essential to clarifying the origin of the ferroelectric polarization and piezoelectric properties in the BNT system.…”

Anomalous change in leakage and displacement currents after electrical poling on lead-free ferroelectric ceramics

“…The bulk density of S1, S2, S3, and S4 sintered ceramics were found around 91.6%, 90.5%, and 92.4%, and 93.8%, respectively, within the limit of experimental errors (62%). 7,23 Phase purity and crystal structure were examined on sintered electroceramics by an XRD (Bruker AXS D8 Advance X-ray diffractometer) using the Cu-ka (ka ¼ 1.54059 Å ) monochromatic radiation, in the 2h range between 20 and 80 . To measure the ferroelectric and leakage properties, samples were carefully polished by mechanical pressure technique to make thin slabs of 0.5 mm and painted with silver paste on both surfaces.…”

“…In general, researchers avoid long time E-poling in the samples for piezoelectric sensors and actuators applications. [20][21][22][23][24] However, it is also true that built-in hysteresis loops are widely used to decrease hysteresis and self heating in hard piezoelectrics. 25 Takenaka group has carried out extensive studies on polarization, phase transition, dielectric and electrical properties of (1 À x)NBT-xBiAlO 3 solid solution with pre intended Al substitution at B-site.…”

A new insight into structural complexity in ferroelectric ceramics

“…Recently, Refs. [34][35][36] demonstrated that the observed electric field induced phase transformation behavior in BNT-BT is a consequence of the changes in the coherence lengths of the PNRs. Therefore, the widely accepted theory of field-induced phase transition may be a transition from adaptive diffraction of the nanodomains to conventional diffraction of the coarse domains.…”