PZN-PT Single Crystals Research Articles

PZN-PT single crystal based high-frequency intravascular ultrasound transducers

Cardiovascular disease (CVD) is a kind of high life-threatening illness for humans. Intravascular ultrasound (IVUS) technology could highly help the physicians to know the condition of human's vessel wall. In this work, the novel lead zinc niobate-lead titanate (PZN-PT) single crystals-based IVUS transducers were prepared. The electrical properties of PZN-PT single crystals were investigated with high d33 of 2531 pC/N and dielectric constant. The high piezoelectric response could improve the transmission and receive properties of IVUS transducers. Moreover, the high dielectric constant (8050) could highly help the miniaturization of IVUS transducer. The IVUS transducers have a center frequency at 43.5 MHz and a -6dB bandwidth of 62.3%. It promising the PZN-PT based IVUS transducers are suitable for the clinical diagnosis field for CVD.

Realization of high performance PZN-PT single crystal based piezoelectric flexural mode hydrophone for underwater sensor applications

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d33 > 2000 pm V−1) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.

Development of Cardiac Phased Array With Large-Size PZN-5.5 %PT Single Crystals.

In recent years, the manufacturing process of lead zinc niobate-lead titanate [Pb(Zn1/3Nb2/3)O3-PbTiO3, also called PZN-PT], has been enhanced with improvements in size, consistency, and a suitable compromise between piezoelectric properties and phase transition temperature, which means that it is possible to obtain PZN-PT single crystals in sufficient size for performance characterization studies and batch manufacturing to produce high-performance medical ultrasonic transducers. This article mainly focuses on the development of the 64-element phased array ultrasonic transducer based on novel large-size PZN-PT piezoelectric single crystals. The composition of the single crystal was chosen as PZN-5.5 %PT. The designed center frequency of the phased array is 3.0 MHz, which is suitable for cardiac ultrasound imaging. The array elements were spaced at a 0.254-mm pitch, and interconnected through a custom-designed flexible circuit. Double matching layers with a light backing structure were applied in the transducer fabrication process to improve the performance of the array. The test results of the developed phased array showed a center frequency of 3.0 MHz, and an average -6 dB fractional bandwidth of 72%. In the vicinity of the center frequency, the two-way insertion loss (IL) was about -46 dB, while a crosstalk between the adjacent elements was less than -31 dB. The wire phantom can be distinctly imaged with the phased array, and the axial and lateral resolutions were measured to be 660 and [Formula: see text], respectively. The image of a standard phantom was acquired to present the imaging performance of the transducer. The final results indicate that the transducer arrays based on novel large-size PZN-PT single crystals are quite promising for use in medical ultrasound imaging applications.

Axial compressive stress for depolarization suppression and source level enhancement of underwater projectors made of [011]-poled PZN-PT single crystals

Lead-based relaxor-PT single crystals of rhombohedral phase, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 and Pb(Mg1/3Nb2/3)O3-PbTiO3, exhibit excellent piezoelectric properties and are candidate active materials for high-performance underwater projectors. However, their low coercive field would cause depolarization under high ac drive field, making them unsuitable for high power applications. The present work investigates the effect of axial compressive stress on the depolarization and phase transition behaviors of [011]-poled 32-mode PZN-5.5%PT single crystals. Our results show that with appropriate compressive stress in the [100]-crystal direction, the magnitude of depolarization field of the crystal can be increased to close to the R-O phase transformation field, enabling the application of higher ac drive field. The result further shows that with optimal axial compressive stress, >5 dB increase in the figure-of-merit (FOM) can be achieved without dc bias. The effect of axial compressive stress on material properties of [011]-poled 32-mode PZN-5.5%PT single crystals are also presented, which are useful for underwater projector design purposes.

Effect of donor dopants on the properties of flux grown PZN-PT single crystals

Rare-earth Nd-doped lead zinc niobate-lead titanate (Nd:PZN-PT) and W-doped lead zinc niobate-lead titanate (W:PZN-PT) single crystals have been grown by self-flux technique and their dielectric, ferroelectric and piezoelectric properties have been investigated. Pure perovskite phases were observed, and lattice parameters were obtained by Rietveld refinement. Diffuse phase transition and frequency dispersive phenomena was observed in the dielectric peaks confirming the enhancement of relaxor behaviour for doped crystals. Variation of dielectric constant (e), AC conductivity and piezoelectric charge coefficient (d33) as a result of doping is investigated in detail. From the hysteresis behaviour, it was evident that a simple domain switching mechanism was observed for doped crystals.

Electric and photoluminescence properties of Eu3+-doped PZN-9PT single crystal

Eu3+-doped 0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3 (PZN-9PT: Eu) single crystals were grown by the flux technique. The phase structure, ferroelectric, dielectric, and photoluminescence properties of the crystal were investigated. The PZN-9PT: Eu crystal has a pure perovskite structure. The residual polarization Pr, coercive field Ec, total bipolar strain, and unipolar stain are 36.7664 μC/cm2, 11.0597 kV/cm, 0.35%, and 0.12%, respectively. The coercive field Ec of PZN-9PT: Eu crystal is three times higher than that of PZN-9PT crystal. The Curie temperature Tc of the PZN-9PT: Eu crystal is about 172 °C which is slightly higher than that of PZN-PT single crystal. Under the excitation of 464 nm laser, four broadband peaks appear around 593 nm, 613 nm, 657 nm, and 716 nm, corresponding to the 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transition emission, respectively. The luminescence intensity of all the emission peaks decreases with increasing temperatures range from 298 to 393 K. Our results can provide a new way for the design of multifunctional materials used in optical-electrical devices.

Complete Sets of Elastic, Dielectric, and Piezoelectric Properties of [001]-Poled Rhombohedral Pb(Zn1/3Nb2/3)O3-(4.5-7)%PbTiO3 Single Crystals.

Complete sets of elastic, dielectric, and piezoelectric properties of flux grown rhombohedral Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT; x = 0.0475 , 0.055, and 0.065) single crystals poled along [001] crystal direction have been determined in the present work. Their phase transformation temperatures, coercive fields, and mechanical quality factors are also provided. The results show that [001]-poled rhombohedral PZN-PT single crystals exhibit superior longitudinal piezoelectric properties ( k33 ≥ 0.90 , d33 ≈ 1580 -2500 pC/N). While the piezoelectric properties increase with PT content, the T RT and hence temperature stability of the crystal degrade accordingly. These unique properties, together with the property matrices provided in this work, can be used advantageously to design high-performance piezoelectric devices of longitudinal activation/sensing mode to suit various application needs.

Property matrices of [011]-poled rhombohedral Pb(Zn1/3Nb2/3)O3–(4.5-7)%PbTiO3 single crystals

This paper reports the elastic, piezoelectric and dielectric properties of [011]-poled flux grown Pb(Zn1/3Nb2/3)O3-xPbTiO3 (x = 0.0475, 0.055 and 0.065) single crystals of rhombohedral phase measured using the resonance technique at room temperature. The [011]-poled PZN-PT single crystals exhibit excellent transverse and shear properties with reasonable phase transformation properties (k32 ≥ 0.90, k15 ≈ 0.92, d32 ≈ –(2400-3200) pC/N, d15 ≈ 4800 pC/N, TRO ≈ 90-104 °C for PZN-6.5%PT and k32 ≥ 0.90, k15 ≈ 0.89, d32 ≈ –(1850-2400) pC/N, d15 ≈ 4200 pC/N, TRO ≈ 105-115 °C for PZN-5.5%PT). These unique piezoelectric properties of [011]-poled PZN-PT crystals, together with the property matrices provided in this work, can be used advantageously to design high-performance single crystal transducers of transverse or shear activation/sensing modes to suit various application needs.

Charging capacitors using single crystal PMN-PT and PZN-PT energy harvesters coupled with the SSHI circuit

Piezoelectric energy harvesting technology is regarded as a remedy to the short-life battery issue in low-power electronic devices, and has been extensively studied in the past two decades. Although a variety of new structures and mechanisms have been proposed for piezoelectric energy harvesters (PEHs), there is not much progress made on the piezoelectric materials that play a determinant role in PEHs performance. Most energy harvesters are still constructed with lead zirconate titanate (PZT). Recently, the new-generation piezoelectric materials PMN-PT and PZN-PT single crystals are proposed and start to be used in transducers. Their electromechanical coupling factor (k33) is over 90%, and the piezoelectric coefficient (d33) can reach three times of that of PZT. This study characterizes the PMN-PT and PZN-PT single crystals used in energy harvesters, compared with the polycrystalline PZT, in terms of charging capacitors. Systematic discussions are presented on the voltage, power and energy responses, as well as the reverse coupling effect on the mechanical response and the self-discharge effect of capacitors. Furthermore, a self-powered synchronized switch harvesting on inductor (SSHI) circuit is constructed and tested with the new single-crystal based energy harvesters. Experiments indicate that PMN-PT and PZN-PT can significantly boost the charging capability of energy harvesters, and that performance can be further enhanced by the SSHI circuit.

PZN-PT based smart probe for high temperature fluid viscosity measurements

Abstract A smart sensing system is proposed for high-temperature (up to 90 °C) viscosity measurement of viscous fluids. The proposed sensing system is based on a smart cantilever probe on which a new generation of piezoelectric materials, relaxor ferroelectric Pb(Zn(1/3)Nb(2/3))O(3−x)PbTiO(3) (PZN-PT), is bonded. The proposed system utilizes a PZN-PT single crystal for actuation and a laser displacement sensor for vibration detection. By analyzing the vibrational properties of the cantilever probe, the viscosity of measured fluids at different temperatures (up to 90 °C) were extracted. Lab tests were carried out to verify and evaluate the effect of this system on high-temperature measurements. Results show a consistent agreement with theoretical analysis. In comparison to the existing high-performance piezoelectric material, lead magnesium niobate-lead titanate solid solution (1−x)[Pb(Mg1/3Nb2/3)O3]−x[PbTiO3] (PMN-PT), PZN-PT has a steady performance at high temperatures and shows more reliability. The proposed sensing system can be applied to real-time monitoring of viscous fluids in high-temperature environments, such as vehicle cooling systems, power plant cooling tower fluid monitoring, and other heat transfer systems.

Domain structure, local surface potential distribution and relaxation of Pb(Zn1/3Nb2/3)O3–9%PbTiO3 (PZN–9%PT) single crystals

The local domain structure and surface potential of Pb(Zn1/3Nb2/3)O3–9%PbTiO3 (PZN–9%PT) single crystals were investigated by Kelvin probe force microscopy (KPFM) and piezoresponse force microscopy (PFM), respectively. The results confirm the existence of the screening layer on the surface of the material. The relaxation of the surface potential and its relation to polarization switching within the poled regions in air and argon gas were analyzed. It is found that the surface potential increases with the poling voltage to a limited range. Comparing the relaxation behavior in ambient air with that in argon gas, we find that the relaxation time in argon is much shorter than that in air, and the relaxation in air is dominated by the space charge transport phenomena. In addition, the results show that the injected charges have significant effects on the pinning of the polarization in PZN–PT single crystals.

Comparison of PZN-PT, PMN-PT single crystals and PZT ceramic for vibration energy harvesting

Vibration energy harvesting has a great potential to achieve self-powered operations for wireless sensors, wearable devices and medical electronics, and thus has attracted much attention in academia and industry. The majority of research into this subject has focused on the piezoelectric effect of synthetic materials, especially the perovskite PZT ceramics. Recently the new-generation piezoelectric materials PMN-PT and PZN-PT single crystals have gained significant interest because of their outstanding piezoelectric properties. They can be used to replace the widely-adopted PZT ceramics for improving energy harvesters’ performance substantially. However, there is little research on comparing PMN-PT and PZN-PT energy harvesters against PZT harvesters. In this paper, we present a systematic comparison between vibration energy harvesters using the PMN-PT, PZN-PT single crystals and those using the PZT ceramics. Key properties of the three materials are summarized and compared. The performance of the PMN-PT and PZN-PT energy harvesters is characterized under different conditions (beam length, resistance, frequency, excitation strength, and backward coupling effect), and is quantitatively compared with the PZT counterpart. Furthermore, the effect of the synchronized switch harvesting on inductor (SSHI) circuit on the three harvesters is discussed. The experimental results indicate that energy harvesters using the PMN-PT and PZN-PT single crystals can significantly outperform those using the PZT ceramics. This study provides a strong base for future research on high-performance energy harvesters using the new PMN-PT and PZN-PT single crystals.

High‐Performance Ferroelectric Solid Solution Crystals: Pb(In1/2Nb1/2)O3–Pb(Zn1/3Nb2/3)O3–PbTiO3

A series of regular shaped Pb(Zn1/3Nb2/3)O3‐based ternary ferroelectric single crystals (1 − x)Pb(In1/2Nb1/2)O3–0.33Pb(Zn1/3Nb2/3)O3–xPbTiO3 (PIN–PZN–PT) have been grown by means of the top‐seeded solution growth method that prevented pyrochlore phase and promoted [001] or [111] growth. The nucleation and crystallization behavior of the Pb(Zn1/3Nb2/3)O3‐based ferroelectric single crystals differed from other relaxor‐based ferroelectric single crystals was discovered. Di‐/piezo‐/ferro‐/pyroelectric properties were characterized systematically. The PIN–PZN–PT single crystals showed large coercive fields Ec, high Curie temperature TC and high pyroelectric coefficient P, presenting similar performance but better thermal stability compared with the PZN–PT single crystals, and making it a promising material for transducers and IR detectors in a wider temperature range.

Pb(Zn1/3Nb2/3)O3–PbTiO3single crystal and device development

This paper describes recent device developments with relaxor ferroelectric Pb ( Zn1/3Nb2/3) O3– PbTiO3(PZN–PT) single crystals carried out at Microfine Materials Technologies Pte. Ltd, Singapore. Promising [011]-poled transverse cuts of PZN–PT single crystals and the results on the effect of electric field and axial compressive stress on the rhombohedral-to-orthorhombic ( R – O ) phase transformation behavior of such cuts are presented and discussed. The single crystal devices described include a compact low-frequency broadband power-efficient underwater tonpilz projector, high sensitivity shear accelerometers and acoustic vector sensors (AVS). The unique characteristics offered by these PZN–PT single crystal devices are highlighted, which serve as examples of new-generation piezoelectric devices and systems for a wide range of demanding applications.

Polarization rotation and phase transition in [100]-oriented PZN-PT single crystals determined by the electro-crystalline anisotropy

We have investigated the polarization rotation and phase transition in [100]-oriented PZN-4.5%PT and PZN-8%PT single crystals on the basis of the single domain polarization rotation model. The dependence of both the polarization and the electrostrictive responses in ferroelectric crystals on the field at various temperatures has been numerically obtained. The numerical results have shown that both the polarization rotation and the phase transition are in nature determined by the electro-crystalline anisotropy constants. These constants are dependent on the composition of PZN-PT solution and ferroelectric properties of its components. Without considering the piezoelectric effect, the numerical results are in agreement with the experimental data. This paper is useful for better understanding of the polarization switching and the phase transition in ferroelectric crystals.

Domain structures on (001) and (111) planes in PZN-PT single crystal

To investigate the effect of dc-bias field on the domain structures, the authors observed polarization–electric field (P-E) hysteresis loop with corresponding multidomain structures on (001)cub and monodomain structures on (111)cub surfaces. The coercive field was found to increase from 4 kV/cm for the (001) to 9 kV/cm for the (111) orientations. Corresponding changes in the area of the hysteresis loops were observed. Piezoelectric coefficient (d33) was found to increase to (a) 860 pC/N for tetragonal, (b) 1255 pC/N for the rhombohedral and (c) 2100 pC/N for the monoclinic phases on (001)cub surface.

Highly stable piezoelectrically tunable optical cavities

We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

Comparative characterization of rhombohedral and tetragonal PZN-PT single crystals

Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN–PT) are promising full materials for nonresonant or large bandwidth transducers due to the large values of their piezoelectric properties (dij, kij) and their mechanical quality factor (Qij). However the properties of these materials depend greatly on the content of titanium which influences very significantly the symmetry of the crystal. In this paper we try to understand the influence of the percentage of Titanium in these crystals by studying the two compositions that are in very different phases at room temperature (rhombohedral and tetragonal symmetries). Crystals of pure PZN–4.5PT and PZN-12PT were grown by a Flux technique. The typical single crystals obtained are brown yellow. The room temperature dielectric permittivity along the <001> direction is about 900 for the PZN-12PT, which is smaller than that of the PZN–4.5PT (5840). The Curie point Tc of the tetragonal crystal is about 220 °C (which is higher than that of the rhombohedral one (166 °C)), while the ferroelectric phase transition temperature is 130 °C for the PZN-4.5PT single crystal. The remnant polarization and coercive field of <001> oriented crystals measured at 1 kHz are around 40 μC/cm2 and 3.30 kV/cm, respectively for the PZN-4.5PT, 27μC/cm2 and 11.1 kV/cm for the PZN-12PT single crystal. The d33 versus uniaxial stress shows that this coefficient is more stable for the single crystal with low Ti than for that with high rate of Ti. The study of temperature stability on these crystals shows a possible presence of an unidentified phase in the low and negative range temperature for the PZN-4.5PT.

Stress and electric field induced phase transformation phenomena in [0 1 1]-poled PZN–PT single crystals of [1 0 0]-length cut

For rhombohedral PZN–(4.5–7)%PT single crystals of [ 1 0 0 ] L ( A ) × [ 0 1 ¯ 1 ] W × [ 0 1 1 ] T ( P ) cut, A and P denoting Active and Poled direction respectively, the applied axial compressive stress in the [1 0 0]-length direction and electric field in the [0 1 1] poling direction aid one another to bring about the rhombohedral-to-orthorhombic (R-O) phase transformation in the crystal. On stress and/or field removal, PZN–(4.5–6)%PT single crystals revert back to the rhombohedral state and the original good properties are retained but not for PZN–7%PT single crystal which remains in the overpoled orthorhombic state with degraded properties. The stress and electric field for the R-O phase transformation, i.e. the E RO– σ RO curves, for PZN–4.5%PT, PZN–5.5%PT and PZN–6%PT of said crystal cut are provided which are useful for device design purposes.

Fabrication and Electrical Properties of Grain-Oriented 0.91Pb(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>– 0.09PbTiO<sub>3</sub> Ceramics

(200) grain-oriented 0.91Pb(Zn1/3Nb2/3)O3–0.09PbTiO3 (PMN–0.09PT) piezoelectric ceramics with a degree of orientation of 0.5052 have been produced from melt by a directional solidification method. The dielectric, ferroelectric, and piezoelectric properties were investigated, e.g., ε~4200, tanδ~0.8%, d33~2100pC/N, kt~58%, and k33~90%, some of these values are comparable to those of ~PZN–PT single crystals. The strain–electric-field curve with a maximum strain of 0.49% at a field of 7kV/cm and well-saturated hysteresis loops with a Pr~32 mC/cm2 were recorded. The results demonstrate that the directional solidification method is a promising technique to fabricate high performance grain-oriented PZN–PT ceramics.