Pb(Mg1/3Nb2/3)O3-xPbTiO3 Single Crystals Research Articles

Ferroelectric Domain Wall Engineering Enables Thermal Modulation in PMN-PT Single Crystals.

Acting like thermal resistances, ferroelectric domain walls can be manipulated to realize dynamic modulation of thermal conductivity (k), which is essential for developing novel phononic circuits. Despite the interest, little attention has been paid to achieving room-temperature thermal modulation in bulk materials due to challenges in obtaining a high thermal conductivity switching ratio (khigh /klow ), particularly in commercially viable materials. Here, room-temperature thermal modulation in 2.5mm-thick Pb(Mg1/3 Nb2/3 )O3 -xPbTiO3 (PMN-xPT) single crystals is demonstrated. With the use of advanced poling conditions, assisted by the systematic study on composition and orientation dependence of PMN-xPT, a range of thermal conductivity switching ratios with a maximum of ≈1.27 is observed. Simultaneous measurements of piezoelectric coefficient (d33 ) to characterize the poling state, domain wall density using polarized light microscopy (PLM), and birefringence change using quantitative PLMreveal that compared to the unpoled state, the domain wall density at intermediate poling states (0< d33 <d33,max ) is lower due to the enlargement in domain size. At optimized poling conditions (d33,max ), the domain sizes show increased inhomogeneity that leads to enhancement in the domain wall density. This work highlights the potential of commercially available PMN-xPT single crystals among other relaxor-ferroelectrics for achieving temperature control in solid-state devices.

A phenomenological study on temperature-concentration-electric field phase diagram of relaxor ferroelectrics PMN-PT single crystals

The theoretical temperature-concentration-electric field (T-x-E) phase diagram of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) is investigated under the electric fields applied along the [001], [011] and [111] directions in the pseudo-cubic coordinate. Using the structurally stable tenth-order Landau–Ginzburg–Devonshire potential model, different two-dimensional sections of T-x-E phase diagram such as T-x (E[001] = E[101] = 0.1, 1kV/㎝) and E-T (x = 0.26, 0.28, 0.3, 0.32, 0.34, 0.36 and 0.38) phase diagrams, and T-x-E[001] one are constructed for PMN-PT single crystals. Also, based on the phenomenological results for T-x-E phase diagram, the features of symmetry changes from high symmetry phase, cubic one, to low symmetry phases, rhombohedral, tetragonal, orthorhombic, monoclinic and triclinic ones, possible during the phase transitions occurring at different temperatures, concentrations and electric fields in PMN-PT single crystals are predicted. The anomalies in dielectric and piezoelectric coefficients accompanied with the symmetry changes are studied. The topological features of T-x-E phase diagram of PMN-PT single crystals are qualitatively in good agreement with those of different piezo/ferroelectrics (BaTiO3, KNbO3, (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT)) in which the symmetry of order parameter is characterized by the image-group ImΓ4− = m3m of the irreducible representation Γ4− of the space group Pm3‾m as in PMN-PT single crystals.

Linear optical properties and second-harmonic generation of (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 single crystals

Transmission spectrum and refractive index of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-xPT) single crystals were studied and second-harmonic generation signal of the crystal powder was measured in order to characterize the nonlinear optical properties of the crystals. The poling procedure led to increase in the optical transmittance in visible spectral region. PMN-xPT single crystals were optically negative and the refractive index increased with PT concentration. Moreover, PMN-xPT crystals proved to have high nonlinear optical properties and the second-harmonic generation signal measured in powder of PMN-0.39PT crystal was greater than that of KH2PO4, KTiOPO4, and LiNbO3.

Optical bandgap and phase transition in relaxor ferroelectric Pb(Mg1∕3Nb2∕3)O3-xPbTiO3 single crystals: An inherent relationship

We report band to band transition behaviors of relaxor ferroelectric Pb(Mg1∕3Nb2∕3)O3-xPbTiO3 (PMN-xPT) single crystals derived from temperature-dependent spectral transmittance. A typical bandgap formula with the temperature and composition (8 K≤Texp≤453 K, 0.1≤x≤0.4) has been presented. Moreover, the phase diagram of PMN-xPT crystals can be well proposed, which is based on the bandgap variations and can be explained by electronic structure evolution. It reveals an intrinsic relationship between fundamental bandgap and phase transition of PMN-xPT single crystals, which pioneers an effective methodology to explore the phase transition of ferroelectric oxides.

Pb(Mg1/3Nb2/3)O3–PbTiO3(PMN-PT) Material for Actuator Applications

Due to its large piezoelectric and electrostrictive responses to an applied electric field the (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3(PMN-PT) solid solution has been widely investigated as a promising material for different actuator applications. This paper discusses some of the recent achievements in the field of PMN-PT piezoelectric and electrostrictive actuators manufactured from PMN-PT single crystals, bulk ceramics, or thick films. The functional properties of PMN-PT materials and some representative examples of the investigated PMN-PT actuator structures and their applications are reported.

The Growth and Properties of Relaxor‐Based Ferroelectric Single Crystals

Much attention is drawn to the fundamental research and the applications of the relaxor‐based ferroelectrics for the next generation of piezoelectric devices. Mass production of Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMNT) and ternary xPb(In1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–zPbTiO3 (PIMNT) single crystals with a Bridgman method was reported. The piezoelectric, pyroelectric, and electric–optical performances of PMNT single crystals are much more excellent than traditional ceramics with the composition near morphotropic phase boundaries. Compared with PMNT crystal, PIMNT crystals can be used in a more broad range of device applications due to their high Curie temperature Tc and large coercive fields Ec. A relaxor‐based Na0.5Bi0.5TiO3–xBaTiO3 (NBBT) crystal grown by the top seeded solution growth method was also investigated to find a lead‐free material with better piezoelectric performance. The properties of these relaxor‐based single crystals were summarized. The mechanism of the enhanced piezoelectric response is discussed, based on the phase transitions induced by the variations of the temperature, pressure, composition, and electric field.

Large signal electromechanical properties of low loss (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 single crystals

The use of single crystals based on the solid solution (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMNT) has been demonstrated in many piezoelectric devices, but the low mechanical quality factor has limited its use in high power projector applications. In this work, 33-mode properties of PMNT single crystals with various modifications were evaluated to see if self-heating may be reduced by decreasing the mechanical and electrical losses within the active material. Three modifications were evaluated: incorporating ternary components, adding acceptor dopants, or orienting the crystal along different crystallographic directions. The electromechanical properties of these modified crystals were evaluated under increasing levels of dynamic strain. The results suggest that modified single crystal PMNT may improve the source level from a projector while reducing thermal effects from self-heating, making them appropriate for high power applications.

High electric-field-induced strain of Pb(Mg1/3Nb2/3)O 3 -PbTiO 3 crystals and their application in multilayer actuators

Electric-field-induced strain behavior of differently oriented and componential (1-x)Pb(Mg1/3Nb2/3)O3xPbTiO3 (PMNT) crystals was investigated. An optimum composition range (29%≤x≤31%) of 〈001〉-oriented PMNT crystals was ascertained for multilayer actuator applications, which exhibited high-strain and low-hysteresis behavior. The rhombohedral (monoclinic)–tetragonal phase-transition behavior in PMNT single crystals is dependent on their thermal and electric history, which markedly impacts on the strain performance of the crystals. In contrast to PZT-SF (doped PZT ceramics) multilayer actuators, the strain values for 20-layer PMNT actuators with individual element sizes of 6×6×0.3 mm3 are larger by more than five times at 20 kV/cm (0.373% compared to 0.072%), and 23-μm displacements can been achieved. Against 40-N load, the displacements are decreased to 20.2 μm.

Cooling-Rate-Dependent Domain Structures of Pb(Mg1/3Nb2/3)O3-PbTiO3 Single Crystals Observed by Contact Resonance Piezoresponse Force Microscopy

The domain structures of (001) plates of (1–x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystals were observed at room temperature after 240°C thermal treatment at various cooling rates. The starting composition of the PMN-PT single crystals was x=0.32; the dielectric constant of the single crystals exhibited a maximum at 153°C. Contact resonance piezoresponse force microscopy (CR-PFM) was utilized for domain imaging, because microdomain images could be obtained without domain structure degeneration. The average size of domains strongly depended on the cooling rate. The obtained domain images were approximately fingerprint patterned on a micron scale, but were fragmented by circular domains on a submicron scale. These finer circular domain structures were probably microdomains that existed in the relaxor phase and were subsequently quenched during the relaxor-to-ferroelectric phase transition.