PT Crystals Research Articles

The performance enhancement and temperature dependence of piezoelectric properties for Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal by alternating current polarization

The comparison and analysis of piezoelectric properties for [001]-oriented PMN-0.30PT by different polarization conditions were investigated. It should be noticed that the average piezoelectric coefficients d33 of PMN-0.30PT crystals were 1860 pC/N by alternating current (AC) polarization and 1380 pC/N by direct current (DC) polarization, which indicates a promotion of 35.3%. The domain patterns in the [001] surface of PMN-0.30PT single crystals under different polarization conditions are obtained by piezo-response force microscopy. The enhancement of piezoelectric performance by AC polarization is attributed to the regular stripe domains with high domain wall density. With the temperature increased to TR-T, both the values of dielectric constant εrT and piezoelectric coefficients d33 under AC polarization condition maintain higher compared to traditional DC poled samples. In addition, both the values of e33 and ε33S under AC polarization retain higher than that of DC polarization, suggesting that the special domain structure with high domain wall density by AC polarization keeps a stable state as the temperature increased to TR-T. When the temperature increased from TR-T to TT-C, the piezoelectric properties of crystals (εrT and d33) under different polarization conditions become the same status, which indicates that the domain structure under the different conditions of polarization may tend to the similar state and the extrinsic contribution from the domain wall motion by AC polarization is disappeared.

Polarization investigation of Mn-doped 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 single crystals for infrared detecting application

This work has been carried out to investigate the poling temperature and poling field dependences of pyroelectric and dielectric properties of ⟨111⟩ oriented Mn-doped 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 single crystals. Poling treatments are implemented at 25 °C, 90 °C, and 120 °C with DC poling electric fields of 1, 2, 3, and 4 times the corresponding coercive field, respectively. The correlation between ferroelectric domain transition and pyroelectric properties is investigated. The optimized pyroelectric and dielectric performances with the highest pyroelectric coefficient p and the lowest dielectric loss tan δ, as well as the optimized figures of merit, are achieved by poling samples at 90 °C in this study, instead of those conventionally poled at nearly Curie temperature (120 °C). Moreover, excellent long-term performances of 90 °C poled Mn-PMN-0.28PT crystals are disclosed over a 30-day range.

The effect of machining on domain configuration in [001]-oriented tetragonal Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals have attracted increasing attention in electro-optic and nonlinear optical applications. In this paper, it was found that the domain configuration of PMN–PT single crystals was influenced by machining and electric process, such as cutting, grinding, polishing, and electrical field poling. The ordered herringbone/stripe domain pattern can be changed into an unexpected disordered domain state in tetragonal PMN–PT crystals which was observed in some crystal samples. Those chaotic structures can decrease transmittance and increase possibility of cracking during poling. However, the disordered domain pattern can be eliminated by a temperature cycling process. Crack-free single-domain crystals were successfully obtained by electric field poling, exhibiting complete optical extinction in an orthogonal polarized light microscope. The results suggest that the domain configuration of PMN–PT single crystals is sensitive to machining process and can be controlled by proper temperature and electric field.

Temperature and DC bias dependence of the phase transition behavior of [011]- and [001]-oriented PIN–PMN–PT single crystals with MPB composition

Abstract

Structure analysis and systematical electric properties investigation of PSN–PMN–PT single crystal

A novel Pb(Sc1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PSN–PMN–PT) single crystal with large size ϕ25 mm × 40 mm was grown by the Bridgman technique. The crystal was cut along [100] orientation with composition of 6PSN–63PMN–31PT, and then its structure and electric properties were investigated systematically. Raman test demonstrates that the crystal is typical relaxor ferroelectrics with perovskite structure. At room temperature, [100]-oriented 6PSN–63PMN–31PT crystal shows the excellent electric properties, such as the dielectric constant er = 4793, the piezoelectric constant d33 = 1237 pC/N, and the remanent polarization Pr = 34.41 µC/cm2, respectively. It is more important that the large coercive field Ec = 8.17 kV/cm in [100]-oriented 6PSN–63PMN–31PT crystal is almost four times than that of PMN–PT, even higher than that of Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT) and Pb(Lu1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PLN–PMN–PT), indicating its potential application for high-power transducers. With elevating temperature, the [100]-oriented 6PSN–63PMN–31PT crystal shows the large pyroelectric coefficient p = 3.49 × 10−2 C/m2/K at phase transition temperature, and the related figures of merit (FOMs) for current responsivity Fi, for voltage responsivity Fv and for detectivity FD increase from 1.968 × 10−10 m/V, 0.00485 m2/C and 0.59 × 10−5 Pa−1/2 to 1.396 × 10−8 m/V, 0.054 m2/C, and 52.94 × 10−5 Pa−1/2, respectively. Furthermore, the thermal strain at heating process was analyzed for unpoled and poled crystal.

Field induced O-MC phase transition and domain structure evolution in Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 single crystals under radial poling

Radial electric (E)-field induced periodic polarization rotation from orthorhombic (O) to MC-type monoclinic (MC) phase in Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PMN-0.34 PT) single crystals has been studied by in situ polarized light microscope. The piezoelectric coefficient (d33∗) and dielectric permittivity (ε33T/ε0) were 1800 pm/V and 5100, respectively, for [100]-oriented MC samples, almost three times of those in [011]-oriented O phase crystals. The domain structure evolution from 1O to 4MC was confirmed based on the optical extinction rules and permissible domain configurations. Moreover, the phase transition sequences of [100]- and [011]-poled PMN-0.34 PT crystals were MC—Tetragonal (T)—Cubic (C) and O—T—C upon heating, respectively. Our findings suggest that the phase stability of this crystals is associated with the orientation of applied field and radial E-field can serve as a general strategy to get fundamental insights into large piezoelectric activity and anisotropic phase stability in ferroelectric single crystals.

Piezoelectric performance enhancement of Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 crystals by alternating current polarization for ultrasonic transducer

The [001]-oriented Pb(Mg1/3Nb2/3)O3-0.25PbTiO3(PMN-0.25PT) single crystal has been poled by alternating current polarization (ACP). The piezoelectric, dielectric, and electromechanical properties of PMN-0.25PT crystals were investigated with the variations of the electric field, polarization frequency, and cycles. For the piezoelectric performance of the PMN-0.25PT crystal, the optimum ACP condition was obtained under the electric field of 12–18 kV/cm in the frequency range of 20–40 Hz and after 20 cycles. It gives the crystals an increase by 40% from 1220 pC/N to 1730 pC/N in the piezoelectric coefficient compared with traditional direct current polarization. The patterns of the periodic stripe nanodomains under different polarization conditions were revealed by piezoresponse force microscopy. The enhancement of the piezoelectric performance is attributed to the high density of these domain walls. This work indicates that ACP is an effective way to modify the piezoelectric performance of PMN-0.25PT crystals and make it a promising candidate for sensors and transducers.

Comprehensive analysis of Mn:PIN-PMN-PT single crystals for Class IV flextensional transducer

As a crucial part of flextensional transducer (FT), the piezoelectric stack has an essential influence on the transducer. However, up to date, there are no literatures on considering the loss characteristics of the piezoelectric materials in the design of FT. Manganese-modified PIN-PMN-PT (Mn:PIN-PMN-PT) single crystals have greatly improved Qm values compared with the binary and ternary single crystals. In this paper, Class IV FTs based on Mn:PIN-42%PMN-32%PT and Mn:PIN-47%PMN-29%PT crystals were analyzed comprehensively on the heat losses, as well as transmitting voltage response (TVR), source level (SL), acoustic pressure (AP) and admittance. Compared with PIN-47%PMN-29%PT, PMN-28%PT and PZT4, the Mn:PIN-42%PMN-32%PT FT has a decrease of heat loss by 47.9%, 79.5% and 93.6%, respectively, under the same strain of 5 × 10−5. The results indicated that the Mn:PIN-PMN-PT FT possesses simultaneously the less heat loss and lower resonant frequency, the higher AP, TVR, SL and effective electromechanical coupling coefficient. This research provides a guide for the design of FT and illuminates the immense potential of Mn:PIN-PMN-PT single crystals in making low heat generation, low frequency and high power FT.

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements.

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric elements in transmitting and receiving modes is rather different. Therefore, for transmission and reception of ultrasonic signals, separate piezoelectric elements with different dimensions must be used. The objective of this research was development of novel air-coupled ultrasonic receivers with PMN-32%PT strip-like piezoelectric elements vibrating in a transverse-extension mode with electromechanically controlled operation and suitable for applications in ultrasonic arrays. Performance of piezoelectric receivers made of the PMN-32%PT strip-like elements vibrating in this mode may be efficiently controlled by selecting geometry of the electrodes covering side surfaces of the piezoelectric element. It is equivalent to introduction of electromechanical damping which does not require any additional backing element. For this purpose; we have proposed the continuous electrodes to divide into two pairs of electrodes. The one pair is used to pick up the electric signal; another one is exploited for electromechanical damping. Two types of electrodes may be used—rectangular or non-rectangular—with a gap between them directed at some angle, usually 45°. The frequency bandwidth is wider (up to 9 kHz) in the case of non-rectangular electrodes. The strip-like acoustic matching element bonded to the tip of the PMN-32%PT crystal may significantly enhance the performance of the ultrasonic receiver. It was proposed to use for this purpose AIREX T10.110 rigid polymer foam, the acoustic impedance of which is close to the optimal value necessary for matching with air. It was found that in order to get a wide bandwidth the length of the matching strip should be selected not a quarter wavelength λ/4 at the antiresonance frequency but at lower frequency. It allowed achieving the frequency bandwidth (14–18)% with respect to the central frequency at −3 dB level.

Origin of Peridotites and Chromitites in the Pozanti‐kar Santi Ophiolite, Turkey

The Pozanti‐Karsanti ophiolite (PKO) in Turkey's eastern Tauride belt comprises mantle peridotites, ultramafic to mafic cumulates, isotropic gabbros, sheeted dikes and pillow lavas. The mantle peridotites are dominated by spinel harzburgites with minor dunites. The harzburgites and dunites have quite depleted mineral and whole‐rock chemical composition, suggesting high degrees of partial melting. Their PGEs vary from Pd‐depleted to distinct Pd‐enriched patterns, implying the crystallization of interstitial sulphides from sulphur‐saturated melts (e.g. MORB‐like forearc basalt). U‐shaped or spoon‐shaped REE patterns indicate that the PKO peridotites may have also been metasomatized by the LREE‐enriched fluids released from a subducting slab in a suprasubduction zone. Based on the mineral and whole‐rock chemical compositions, the PKO peridotites show affinities to forearc peridotites. Chromitites occur both in the mantle peridotites and the mantle‐crust transition zone horizon (MTZ). Chromitites from the two different horizons have different textures but similar mineral compositions, consistent with typical high‐Cr chromitites. Chromitites hosted by mantle harzburgites generally have higher total platinum‐group element (PGE) contents than those of the MTZ chromitites. However, both chromitites show similar chondrite‐normalized PGE patterns characterized by clear IPGEs, Rh‐enrichments relative to Pt and Pd. Such PGE patterns indicate no or only minor crystallization of Pt‐ and Pd enriched sulphides during formation of chromitites from a sulphur‐undersaturated melt (e.g. boninitic or island arc tholeiitic melt). Dunite enveloping chromitite lenses in the hosting harzburgite resulted from melt‐rock reaction.We have performed mineral separation work on samples of podiform chromitite hosted by harzburgites. So far, more than 200 grains of microdiamond and more than 100 grains of moissanite (SiC) have been separated from podiform chromitites. These minerals have been identified by EDX and Laser Raman analyses. The diamonds and moissanite are accompanied by large amounts of rutile. Additionally, zircon, monazite and sulphides are also common phases within the heavy mineral separates. Both diamond and moissanite have been analyzed for carbon and nitrogen isotopic composition using the CARMECA 1280‐HR large geometry Secondary Ion Mass Spectrometer at the Helmholtz Zentrum Potsdam. In total, 61 δ13CPDB results for diamond were acquired, exhibiting a range from −28.4 ‰ to −18.8 ‰. 31 δ13CPDB results for Moissanite vary between −30.5 ‰ to −27.2 ‰, with a mean value of −29.0 ‰. Diamond has relatively large variation in nitrogen isotopic composition with 40 δ15NAIR results ranging from −19.1 ‰to 16.6 ‰.The discovery of diamond, moissanite and the other unusual minerals from podiform chromitite of the Pozanti‐Karsanti ophiolite provides new support for the genesis of ophiolitic peridotites and chromitites under high‐pressure and ultra‐high reducing conditions. Considering the unusual minerals, the high Mg# silicate inclusions, and the needle‐shaped exsolutions in the PKO chromitites, the parental melts of these chromitites may have been mixed with deep asthenospheric basaltic melts that had assimilated materials of the descending slab when passing through the slab in a subduction zone environment. We suggest melt‐rock reactions, magma mixing and assimilation may have triggered the oversaturation of chromites and the formation of PKO chromitites.

Paragenesis of multiple platinum-group mineral populations in Shetland ophiolite chromitite: 3D X-ray tomography and in situ Os isotopes

Chromitite from the Harold’s Grave locality in the mantle section of the Shetland ophiolite complex is extremely enriched in Ru, Os and Ir, at µg/g concentrations. High-resolution X-ray computed tomography on micro-cores from these chromitites was used to determine the location, size, distribution and morphology of the platinum-group minerals (PGM). There are five generations of PGM in these chromitites. Small (average 5µm in equivalent sphere diameter, ESD) euhedral laurites, often with Os-Ir alloys, are totally enclosed in the chromite and are likely to have formed first by direct crystallisation from the magma as the chromite crystallised. Also within the chromitite there are clusters of larger (50µm ESD) aligned elongate crystals of Pt-, Rh-, Ir-, Os- and Ru-bearing PGM that have different orientations in different chromite crystals. These may have formed either by exsolution, or by preferential nucleation of PGMs in boundary layers around particular growing chromite grains. Thirdly there is a generation of large (100µm ESD) composite Os-Ir-Ru-rich PGM that are all interstitial to the chromite grains and sometimes form in clusters. It is proposed that Os, Ir and Ru in this generation were concentrated in base metal sulfide droplets that were then re-dissolved into a later sulfide-undersaturated magma, leaving PGM interstitial to the chromite grains. Fourthly there is a group of almost spherical large (80µm ESD) laurites, hosting minor Os-Ir-Ru-rich PGM that form on the edge or enclosed in chromite grains occurring in a sheet crosscutting a chromitite layer. These may be hosted in an annealed late syn- or post magmatic fracture. Finally a few of the PGM have been deformed in localised shear zones through the chromitites.The vast majority of the PGM – including small PGM enclosed within chromite, larger interstitial PGM and elongate aligned PGM – have Os isotope compositions that give Re-depletion model ages approximately equal to the age of the ophiolite at ∼492Ma. A number of other PGM – not confined to a single textural group – fall to more or less radiogenic values, with four PGM giving anomalously unradiogenic Os corresponding to an older age of ∼1050Ma. The 187Os/188Os isotopic ratios for PGM from Cliff and Quoys, from the same ophiolite section, are somewhat more radiogenic than those at Harold’s Grave. This may be due to a distinct mantle source history or possibly the assimilation of radiogenic crustal Os.

Air-Coupled Low Frequency Ultrasonic Transducers and Arrays with PMN-32%PT Piezoelectric Crystals.

Air-coupled ultrasonic techniques are being increasingly used for material characterization, non-destructive evaluation of composite materials using guided waves as well as for distance measurements. Application of those techniques is mainly limited by the big losses of ultrasonic signals due to attenuation and mismatch of the acoustic impedances of ultrasonic transducers and air. One of the ways to solve this problem is by application of novel more efficient piezoelectric materials like lead magnesium niobate-lead titanate (PMN-PT) type crystals. The objective of this research was the development and investigation of low frequency (<50 kHz) wide band air-coupled ultrasonic transducers and arrays with an improved performance using PMN-32%PT crystals. Results of finite element modelling and experimental investigations of the developed transducers and arrays are presented. For improvement of the performance strip-like matching elements made of low acoustic impedance, materials such as polystyrene foams were applied. It allowed to achieve transduction losses for one single element transducer −11.4 dB, what is better than of commercially available air-coupled ultrasonic transducers. Theoretical and experimental investigations of the acoustic fields radiated by the eight element ultrasonic array demonstrated not only a good performance of the array in a pulse mode, but also very good possibilities to electronically focus and steer the ultrasonic beam in space.

Voltage-tunable pass band in cylindrical multilayered structure containing PMMA and 0.67PMN–0.33PT single crystal as a defect layer

In present paper, an inline optical demultiplexer through cylindrical multilayered structure having a cavity of Poly-methyl methacrylate surrounded with single crystal 0.67PMN–0.33PT is presented. The required transmission of the proposed structure is obtained by transfer matrix method using cylindrical coordinate system. It is observed that the multilayer cylindrical structure is able to provide the photonic band gap, where groups of wavelengths are stopped from propagation through the waveguide. The insertion of cavity in considered structure also provides a pass band in the photonic band gap region. The 0.67PMN–0.33PT crystal in the present structure is used to control the thickness of cavity by applying an external DC voltage. Hence, the obtained shift of pass band is approximately 6 nm/V in the proposed structure.

Domain Reengineering of the [011]‐Poled PMN–0.35PT Single Crystals for Dielectric Bolometer Arrays

The domain configuration was reengineered with a modified poling procedure for the [011]‐poled single‐domain PMN–0.35PT crystals located at the morphotropic phase boundary. As a consequence, the dielectric constant εr at room temperature was significantly enhanced by more than 10 times to about 18 000, extremely higher than the reported (1 − x)Pb(Mg1/3Nb2/3)O3‐xPbTiO3 ferroelectric crystals. Besides, the decreasing rate of the dielectric constant (dεr/dT) was about 300/K with a temperature coefficient (α) of 1.7%/K, comparable to the BST materials for dielectric bolometer applications. The ferroelectric phase transition behavior was investigated to establish the poling procedure and a thermal hysteresis of about 25°C was indicated across the room temperature for the orthorhombic–tetragonal phase transition, which contributed to the revolution of the domain pattern.

Scandium modified lead magnesium niobate-lead titanate single crystals for high temperature and high power applications

Within the morphotropic phase boundary region, 0.39PSN-0.13PMN-0.48PT crystals exhibit excellent properties. The dielectric response of poled 〈001〉-oriented 0.39PSN-0.13PMN-0.48PT crystal plates displays non-relaxor behavior with Curie and depolarization temperatures of about 230°C and 199°C, respectively, exhibiting high temperature stability of the ferroelectric phase. The saturated polarization-electric field loop of the same plate manifests the switching of domains, with the coercive field of approximately 5.6kV/cm, indicating stable piezoelectric properties. The out of plane and in plane domain configurations exhibit obvious domain walls. The typical butterfly strain-electric field curve presents a large peak to peak strain value of about 0.59%. The piezoelectric constant is calculated to be about 1670pC/N from the unipolar stain-electric field curve.

Dielectric and piezoelectric properties of high curie temperature 0.63Bi(Mg1/2Ti1/2)O3–0.37PbTiO3 single crystals with morphotropic phase boundary composition

Abstract Novel perovskite ferroelectric 0.63Bi(Mg 1/2 Ti 1/2 )O 3 –0.37PbTiO 3 (0.63BMT–0.37PT) single crystals with a composition around the morphotropic phase boundary (MPB) were successfully grown by a self-flux method. They presented Curie temperature ( T c ) about 460 °C and a rhombohedral to tetragonal phase transition temperature (Tr-t) 249 °C. The piezoelectric constant d 33 for (001) oriented 0.63BMT–0.37PT single crystals reached 320pC/N, which was higher than that (208pC/N) in the tetragonal phase 0.38BMT–0.62PT crystals. The large piezoelectric constant d 33 and high T c make BMT–PT single crystals promising candidates used for the next generation of high performance and high temperature actuators and transducers.

Investigation of High Frequency Mechanical Vibrations in PMN-32%PT Crystals by Laser Interferometry

Lead magnesium niobate-lead titanate (PMN-PT) single crystal has first been successfully grown in 1990 by the Bridgman method using PbO as a flux. These single crystals have excellent piezoelectric properties. The PMN-PT crystals with different vibration modes may be used for development of novel high efficiency ultrasonic transducers due to high piezoelectric properties.

Intrinsic orientation effect on the piezoelectric response of multi-domain 0.26Pb(In1/2Nb1/2)O3–0.46Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 crystals

The crystal intrinsic orientation effect on the piezoelectric response of multi-domain 0.26Pb(In1/2Nb1/2)O3–0.46Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PIN-PMN-0.28PT) crystals was investigated by coordinate transformation method. The results indicate that crystal intrinsic orientation effect plays a crucial role in determining the piezoelectric properties of multi-domain crystals. Almost 58% and 69% of the transverse piezoelectric coefficients d31 and d32, respectively, and 67% longitudinal piezoelectric coefficient d33 of multi-domain PIN-PMN-0.28PT crystals poled along [011]c originate from crystal intrinsic orientation effect. For [001]c poled multi-domain PIN-PMN-0.28PT crystals, intrinsic orientation effect contributes to the transverse and longitudinal piezoelectric coefficient at least 79% and 74%, respectively.

Domain Structure Evolutions During the Poling Process for [011]‐Oriented PMN–xPT Crystals Across the MPB Region

The poling effect on the [011]‐oriented (1−x)Pb(Mg1/3Nb2/3)O3‐xPbTiO3 (PMN–xPT) single crystals across the morphotropic phase boundary (MPB) was studied. The dielectric and piezoelectric properties were investigated as a function of the poling field. Domain structure evolutions during the poling process were recorded. In the unpoled PMN–xPT phase diagram, an apparent rhombohedral (R)‐tetragonal (T) phase boundary exists. With room‐temperature poling, the structure transformation sequence strongly depends on the composition. The crystal experiences a direct transition to the 2R/2T domain state in the rhombohedral or tetragonal phase field beyond the MPB region, whereas within the MPB zone it is hard to achieve the 2R/2T engineered configuration although the initial state is either rhombohedral or tetragonal as well. The piezoelectric responses of the MPB·PMN–xPTs are extraordinary weak (d33 ~ 250 pC/N), in contrast to the [011]‐oriented multidomain PMN–xPTs with ultrahigh‐piezoelectric coefficient (d33 &gt; 1000 pC/N). We demonstrate that a slight composition variation near the MPB will significantly influence the domain evolution route and piezoelectricity for the [011]‐oriented PMN–xPT crystals. We also confirm the feasibility to realize the 2R/2T engineered domain configuration for the [011]‐oriented MPB crystals, which will extend the desired portion of the Bridgeman‐grown boules with optimal piezoelectric properties.

Mutual interaction of redox pairs in silicate melts: Equilibria involving metallic phases

Mutual interaction of redox pairs resulting in the origin or decomposition of a metal phase is analyzed based on the concept of intrinsic oxygen fugacity. Reactions are suggested that may be responsible for the synthesis (or decomposition) of submicrometer-sized metal nuggets when experimental melts are quenched and can explain the possible crystallization of Pt—Fe alloys when basaltic melts cool and elucidate the nature of color of Au-bearing ruby glass. Possible disproportionation reactions of certain lower oxides into a higher oxide and respective metal in cooled silicate melts are discussed.