Achieving Giant Piezoelectricity and High Property Uniformity Simultaneously in a Relaxor Ferroelectric Crystal through Rare-Earth Element Doping.

The low uniformity in properties of relaxor ferroelectric crystals is a long-standing issue in the ferroelectric community, which limits the available volume of the entire crystal boule. The aim of this study is to develop a relaxor ferroelectric crystal with improved property uniformity and excellent piezoelectricity. To this end, Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 is doped with Nd 2 O 3 (Nd-PIN-PMN-PT) to improve the crystal performance. Along the crystal boule, the piezoelectric coefficient d 33 varies from 2800 to 3500 pC N -1 , and the dielectric constant ranges from 8400 to 9800, with variations of 25% and 16%, respectively. Such high property uniformity results in over 75% available volume of the crystal boule, compared to 30-50% for undoped crystals grown by Bridgman method. At the electric field of 1 kV cm -1 , the converse piezoelectric response is up to 4780 pm V -1 . In addition, its Curie temperature (T C ) and coercive field (E C ) are above 150 °C and 3 kV cm -1 , respectively. Compared with Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 crystal (d 33 : 1500 pC N -1 , T C : 135 °C, E C : 2.3 kV cm -1 ), the larger piezoelectricity, the higher T C and E C , and improved uniformity make Nd-PIN-PMN-PT crystals promising candidates for advanced piezoelectric applications.