Growth and characterization of relaxor ferroelectric PMNT single crystals

Advances in the Growth and Characterization of Relaxor-PT-Based Ferroelectric Single Crystals

“…Since PMN-PT crystal exhibits the highest piezoelectric response along the <001> orientation, <001>-cut wafers have become highly demanded [16]. Owing to the inevitable axial composition segregation of this solid-solution in the Bridgman process [22,27], highly uniform (001) wafers can only be produced by successful and repeatable <001>-oriented crystal growth. However, since PMN-PT presents the slowest growth rate along the low-index <001> orientation (R <001> < R <110> < R <111> ), the Bridgman growth of bulk PMN-PT crystal along <001> becomes the most challenging.…”

“…Although the Bridgman method is a very promising technique, the composition segregation issue has to be addressed. Since PMN-PT is a complete solid-solution system, as shown by its high temperature phase diagram, it inevitably exhibits an inhomogeneous composition distribution along crystal boules grown by the Bridgman method [22,27], resulting in the variation of dielectric and piezoelectric properties along the growth direction. Even though the composition variation along the growth direction can be restrained to some degree by applying a higher growth rate and a lower axial temperature gradient across the solid-liquid interface, it can never be eliminated due to the thermodynamic nature of the solid solution system [27].…”

“…It was indicated that the formation of inclusions/voids, spontaneous nucleation, crystallization orientation control and reduction of the composition variation are the major challenges in the growth of large-sized and high quality PMN-PT crystals by the Bridgman process [15,16,22,23]. Owing to the large difference in melting point and density between each oxide, especially between PbO (T m = 886 °C, ρ = 9.53 g/cm 3 ) and MgO (T m = 2852 °C, ρ = 3.58 g/cm 3 ), it is usually difficult to get a homogeneousperovskite phase by directly mixing the oxides without the presence of a minor amount of the pyrochlore phase [16].…”

“…These studies also showed that PMN-PT has a more stable perovskite phase and exhibits less of a tendency to form the parasitic pyrochlore phase compared to PZN-PT. By pre-synthesizing PMN-PT and using sealed Pt crucibles to prevent the volatilization of PbO at high temperature, PMN-PT single crystals have been grown directly from the melt using the Bridgman method [22,23]. Compared to flux growth, the Bridgman technique can grow large-sized single crystal boules along specific crystallographic orientations with a higher growth rate, which can potentially reduce the cost of PMN-PT crystals, to be competitive with the high quality piezoelectric ceramics used in high-end applications.…”

Temperature-Dependent Phase Transition in Orthorhombic [011]c Pb(Mg1/3Nb2/3) O3-0.35PbTiO3 Single Crystal

“…Relaxor-PbTiO 3 (PT) based single crystals have generated much interest in the past two decades owing to their excellent dielectric and piezoelectric performances [1,2] compared to lead zirconate titanate (PZT) ceramics [3,4]. [001] c Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PMN-xPT) single crystals with compositions close to morphotropic phase boundary (MPB) are well known as typical relaxor ferroelectrics with ultrahigh piezoelectric coefficient (d 33 > 2000 pC/N) and electromechanical coupling factor (k 33 > 0.9) [5], with various high-tech applications, such as sonar transducers, medical ultrasonic detectors, actuators, to name a few [6][7][8].…”