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In this paper, the plasmonic system composed of a Metal-Insulator-Metal (MIM) waveguide and dual asymmetric side-coupled U-shaped cavities is reported. It demonstrates that the strong coupling effect can lead to the opening of new transmission window. One of new peaks originates from the interference between the dual U-shaped cavities and bus waveguide, and the other is induced by the asymmetry of the structure, and each peak can be well tuned independently by changing the structural parameters of the U-shaped cavity. The effects of dielectric parameters on the transmission characteristics of the coupled system are also analysis, we find that the sensor sensitivity can reach 496 nm/RIU and a new sharp peak will exist in the short-wave region when dielectric parameter n = 1.2. By combining the magnetic field distributions, the internal physical mechanism is discussed. The proposed compact and simple plasmonic structure may have potential applications in nano-scale filter and other high density plasmonic integration circuits.

Large-sized multiferroics Pb(Fe1/2Nb1/2)O3 (PFN) single crystal was grown by Bridgeman method in order to understand the giant dielectric response by investigating the electrical conductivity and dielectric properties. The synchrotron radiation soft x-ray absorption spectrum revealed the valence states of Fe in PFN crystal. PFN exhibits semiconductor behaviors in the thermal active electrical conductivity investigation. Besides, the frequency-dependent dielectric constants were measured in the frequency range from 100 Hz to 1 MHz to study the dielectric relaxation behaviors. Two relaxation processes were found and described by Havriliak-Negami equation. The origin of dielectric relaxation in PFN with semiconductor characters was discussed based on the universal relaxation law for a dipolar system.

Poling method is very important for ferroelectric and piezoelectric materials and their applications. We propose an interdigitated (ID) electrodes geometry and screen-print the ID electrodes on cut 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 plates. However, it is very hard to pole the piezoelectric phase without cracks, resulting in high dielectric loss and high dielectric noise in corresponding sensors, which should be avoided in ME magnetic sensor devices. Because there appears a malformed region between longitudinal beams and tips of transverse electrodes. In this paper, we propose and adopt high temperature poling technique to reduce the strain and internal stress to reduce cracks. Strain-temperature curve of PMN-PT has a peak at 100 °C and strain at 140 °C (0.32%) is less than ½ of that at 100 °C (0.66%) under the same tested voltage (1000 V/mm). The noise equivalent magnetic induction (NEB) numerical simulation indicates that ME composite with high temperature poled PMN-PT (140 °C) has the lowest NEB, demonstrating that high temperature poling technique can lower dielectric loss and enhance ME effect by improving piezoelectric effects gently.

Mn:0.15Pb(In1/2Nb1/2)O3-0.55Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (Mn:PIMNT) pyroelectric chips were prepared by a two-step annealing method. For the two steps, annealing temperatures dependence of microstructure, defects, surface stress, surface roughness, dielectric properties and pyroelectric properties were studied comprehensively. The controlling factors influencing the pyroelectric properties of the Mn:PIMNT crystals were analyzed and the optimum annealing temperature ranges for the two steps were determined: 600&ndash, 700 &deg, C for the first step and 500&ndash, 600 &deg, C for the second step. The pyroelectric properties of the thin Mn:PIMNT chips were significantly enhanced by the two-step annealing method via tuning oxygen vacancies and eliminating surface stress. Based on Mn:PIMNT pyroelectric chips annealed at the most favorable conditions (annealed at 600 &deg, C for the first step and 500 &deg, C for the second step), infrared detectors were prepared with specific detectivity D* = 1.63 &times, 109 cmHz1/2W&minus, 1, nearly three times higher than in commercial LiTaO3 detectors.

Ferroelectric, dielectric and pyroelectric properties of Mn-doped Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PMN-0.28 PT) single crystals has been investigated with surfaces of different roughness, and thickness in the range of 487–16 μm. The crystals were grown by modified Bridgman method and treated by mechanical lapping and chemical mechanical polishing (CMP) for different thickness and surface. The experimental results indicate that the lapping process deteriorates the ferroelectric, dielectric, and pyroelectric performances by introducing domain reorientation and damage into the surface, which can be substantially reduced by polishing process. The surface state exhibits greater impact on the ferroelectric, dielectric and pyroelectric performances when the sample thickness becomes smaller. By lapping, the 109° and 71° domain reorientation occurs along with the generation of non-ferroelectric damage layer, the surface stress and defects.

1 wt% Li-doped 0.75BaTiO3–0.15CaTiO3–0.1BaZrO3 (BCZT) ceramics were prepared by the citrate method. XRD measurement showed that pure perovskite BCZT precursor powders are obtained calcined at 600–700 °C, which exhibit rather homogeneous microstructure morphology with nm-scale grain size. The sintered BCZT ceramics exhibit pure perovskite structure with composition locating at rhombohedral side around the morphotropic phase boundary (MPB). Oxide doping and citrate method exert great influences on microstructure and electrical properties of the Li-doped BCZT ceramics. All the synthesized ceramics exhibit excellent dielectric and ferroelectric properties. The Li-doped BCZT ceramics calcined at 700 °C and sintered at 1500 °C exhibit the best dielectric, ferroelectric and piezoelectric properties. The high piezoelectric response of the synthesized Li-doped BCZT ceramics is considered as relating to the MPB effect, Li-doping and wet chemical synthesis method.

1 wt% Li2CO3- or La2O3-doped 0.75BaTiO3–0.15CaTiO3–0.1BaZrO3 (BCZT) lead-free ceramics were prepared by the solid-state reaction method sintered at 1480–1520 °C for 2 h. Sintering temperature, oxide doping and poling electric field influence crystal structure and electrical properties of the sintered BCZT ceramics. Due to oxide doping the BCZT ceramics exhibit pure perovskite structure sintered in a rather wide sintering temperatures with composition locating at the rhombohedral side around the morphotropic phase boundary. The oxide-doped BCZT ceramics exhibit rather homogeneous microstructure morphology, in which grain size of the Li2CO3-doped BCZT ceramics and La2O3-doped BCZT ceramics is around nm-scale and in μm-scale, respectively. Li2CO3 doping increases the value of dielectric constant maximum (em), sharpens the dielectric response peaks and suppresses the dielectric frequency dispersion of the BCZT ceramics, whereas the temperature of em (TC/Tm) changes negligibly. As comparison, La2O3 doping decreases the Tm temperature and enhances dielectric frequency dispersion greatly. The Li2CO3-doped BCZT ceramics exhibit similar P–E hysteresis loop to that of the undoped BCZT ceramics, whereas La2O3 doping deteriorates ferroelectric property apparently. Li2CO3 doping improves piezoelectric property whereas La2O3 doping deteriorates piezoelectric property of the BCZT ceramics, which can be interpreted by the formation of different point-charge defects induced by oxide doping.

0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 (0.69PMN-0.31PT) ceramics were prepared by the solid-state reaction method via the columbite precursor route, which exhibit phase-pure perovskite structure with the morphotropic phase boundary (MPB) composition and excellent electrical properties, and are appropriate for further research. Dielectric aging behavior of the 0.69PMN-0.31PT ceramics exhibits a linear decrease dependence on the logarithm of time, proving partly its relaxor ferroelectric characteristic and correlates with microcompositional inhomogeneity. The electrical properties of the 0.69PMN-0.31PT ceramics decrease greatly above the depolarization temperature, being 120°C, whereas they exhibit excellent time stabilization. Mechanical properties of the 0.69PMN-0.31PT ceramics are improved apparently after coating Ag electrode and poling, which relate to the contributions of electrode status and domain switching. The major failure mechanism is transgranular fracture in the compression fracture samples and inter...

Compositional segregation usually has negative effects on the growth of solid solution ferroelectric single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (abbr. PIN-PMN-PT or PIMNT). A modified Bridgman method was adopted in this work to control the segregation and improve the compositional homogeneity significantly. The characteristic of this work is to use multiround growths and gradient composition raw materials in order to keep the PbTiO3 concentration constant during the crystal growth. As an example, the two-round growth of ternary PIN-PMN-PT single crystal is conducted in the same Pt crucible with gradient raw materials, where the first-round boule was used as the seed crystal for the second-round growth. Our results show that the as-grown (Ф80 mm × 270 mm) PIN-PMN-PT crystals exhibit higher phase transition temperatures (Tc∼180 °C, Tr/t∼110 °C) and larger coercive field (Ec∼5–5.5 kV/cm), which are much better than the performances of Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals, and similar dielectric and piezoelectric performances (e∼5000, tanδ∼1.25%, d33∼1500 pC/N, kt∼60%). And about 85 percent of the crystal boule grown by the two-round growth technique could maintain its compositions around the morphotropic phase boundary.

We propose the split coaxial nanotube resonator pair and investigate its plasmon resonance properties theoretically. It is found that the resonance peak splits and forms more dips with the increase of the number of slits in the structure. We present that the splitting behaviors result from the phaselike resonance of adjacent tubes. In addition, it shows the optical transmission peaks can shift and attenuate by tuning the split width, the thickness and dielectric constant of the medium layer between two coaxial nanotubes. The instantaneous electric field distributions show that symmetry and antisymmetry quadrupole modes exist in these structures.

0.695Pb(Mg1/3Nb2/3)O3–0.305PbTiO3 (PMN–0.305PT) single crystals were grown by a modified Bridgman method. X-ray powder diffraction (XRPD) and X-ray single crystal diffraction (XRSCD) measurements showed that the crystal structure of PMN–0.305PT can be identified as distorted rhombohedral structure or triclinic structure, with both close to pseudo-cubic structure. Polarization exerts significant influences on electrical properties, domain configuration, and infrared spectra of the PMN–0.305PT crystal plates with different orientations. An additional dielectric peak or dielectric shoulder is induced at lower temperature in the dielectric response behavior, in which the shape and temperature of the dielectric anomaly exhibit great dependency on the crystal orientation. The PMN–0.305PT single crystals exhibit complex domain configuration with statistical 4 mm symmetry after poling. The “stretching” normal vibration of [Mg1/3Nb2/3]/TiO3 group is observed in the fourier transform infrared spectroscopy (FT-IR) spectra with infrared-absorption band occurring around 609 cm−1. The PMN–0.305PT single crystals exhibit excellent pyroelectric property, which will lead to promising advance in pyroelectric applications.

The effects of the dielectric core and the dielectric embedding medium separately on transmission spectra and plasmon resonance properties of gold nanoshell arrays were investigated by using the finite-difference time-domain (FDTD) theory. It is found that when the hollow nanoshell arrays are placed in air, the wide photonic band gap becomes narrower as the core dielectric constant increases. On the contrary, when the nanoshell arrays with dielectric core are placed in the dielectric medium, the photonic band gap becomes wider. Furthermore, increasing core or medium dielectric constant leads to a redshift of the transmission spectra due to the polarization of the dielectric. Based on the electric field distributions, we also clearly show that the plasmon properties of the nanoshell arrays are strongly influenced by the presence of the dielectric.

We propose a square-core metallic nanotube array and investigate its optical transmission property theoretically. We find that the transmission spectra can be tuned by the width of square-core edge, the intertube spacing and the dielectric constants of the core and the embedding medium between the nanotubes. We show that there is a band gap over a wide optical wavelength, and its width, number and position are sensitive to the tunable parameters. We also discuss the situation of the rectangular-core nanotube arrays and present that modification of the size of internal holes leads to redshift of the transmission spectra. Based on the localized nature of the field distributions, we show that there are local plasmonic resonant modes that originate from multipolar plasmon polaritons and a large number of opposing surface charges build up in the gap between adjacent nanotubes.

We propose the coaxial gold nanotubes for their transmission and plasmon resonances theoretically. We find that the transmission spectra are highly adjustable by tuning the thickness of the nanotubes, the separation and the dielectric constant between the inner and outer nanotubes. The resonance peaks close to the left forbidden band gap edge are strongly correlated with the dielectric constant, the inner and outer tube thickness, and the separation between the two tubes. Based on the localized nature of the electric field distributions, we show that local plasmon resonance modes result from hybridized resonances of multifold multipolar plasmon polaritons in the cross section of the coaxial nanotubes.

We propose the coupled gold bowtie nanoantennas array and investigate its plasmonic properties theoretically. The bowtie antenna consists of a pair of opposing truncated cones. We calculate the transmission spectra and the electric field distributions. The evolution of the transmission spectrum with the gap width of the bowtie, the diameter of the tip of the cone and the distance between adjacent bowties is directly visualized. Furthermore, the sensitivity of the antennas array to dielectric constant changes of the environment is also investigated in detail. We show the electric field distribution of this nanostructure and find that E x is mainly located at the corners of the cross section, especially at the extremity of the cone. As for the E y , the electric field enhancement localizes at the external edges and the gap of the bowtie. Our work elucidates further the plasmonic interactions can be useful in the design of optimized, sensitive optical sensors, and the enhancement of the fluorescence of molecules.

We have theoretically investigated the effect of the dielectric core and the dielectric embedding medium separately on the transmission spectra and plasmonic properties of coupled metallic nanotube arrays. It is found that the plasmonic properties of the nanotube arrays are strongly influenced by the presence of the dielectric which induces additional screening charges. We show that instead of one single photonic bandgap for the hollow nanotube arrays placed in air, an additional photonic bandgap arises from the presence of dielectric media in the transmission spectra. Based on the localized nature of the electric field distributions, we also clearly show the presence of the local plasmonic resonant modes that originate from multipolar plasmon polaritons in the cross section of these nanotube arrays, and that a large amount of opposing surface charges are built up in the gap between adjacent nanotubes.

In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (Tm, em) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718), (305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were obtained by investigating the piezoelectric constants d33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied during the poling process. The as-grown 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10−11 Ω−1⋅m−1 and 3.95×10−9 Ω−1⋅m−1 at 25°C and 150°C for the 〈001〉 oriented crystal sample.

In this paper, polycrystalline material of 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 (abbreviated as NBBT94/6) was synthesized by solid-state reaction techniques. DTA and TG analysis indicate the proper temperature for solid-state reaction is 1200 °C. A single crystal with dimensions of 25 mm × 10 mm was successfully grown by using the top-seeded solution growth (TSSG) method. X-ray fluorescence analysis revealed that the composition of the as-grown crystal is NBBT98/2. X-ray powder diffraction results show that the as-grown NBBT98/2 crystal possesses the perovskite structure and belongs to the rhombohedral system. The unit-cell constants of the as-grown NBBT98/2 crystal are a = b = c = 3.8862 A and α = β = γ = 89.2°. At room temperature, the dielectric constant of oriented NBBT98/2 crystal is 770 at 10 kHz and it decreases to 430 after poling under the E-field of 7 kV/mm. Maximum d33 values of 60, 65 and 30 pC/N were obtained for , and oriented NBBT98/2 crystal, respectively.

Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZNT91/9) single crystals were grown by a modified Bridgman method directly from melt using an allomeric Pb[(Mg 1/3 Nb 2/3 ) 0.69 Ti 0.31 ]O 3 (PMNT69/31) single crystal as a seed. X-ray diffraction (XRD) measurement confirmed that the as-grown PZNT91/9 single crystals are of pure perovskite structure. Electrical properties and thermal stabilization of PZNT91/9 crystals grown directly from melt exhibit different characters from those of PZNT91/9 crystals grown from flux, although segregation and the variation of chemical composition are not seriously confirmed by X-ray fluorescence analysis (XPS). The [0 0 1]-oriented PZNT91/9 crystals cut from the middle part of the as-grown crystal boules exhibit broad dielectric-response peaks at around 105 °C, accompanied by apparent frequency dispersion. The values of piezoelectric constant d 33 , remnant polarization P r , and induced strain are about 1800–2200 pC/N, 38.8 μC/cm 2 , and 0.3%, respectively, indicating that the quality of PZNT crystals grown directly from melt can be comparable to those of PZNT91/9 single crystals grown from flux. However, further work deserves attention to improve the dielectric properties of PZNT crystals grown directly from melt. Such unusual characterizations of dielectric properties of PZNT crystals grown directly from melt are considered as correlating with defects, microinhomogeneities, and polar regions.

Graduate School of Chinese Academy of Sciences, Beijing 10039, P.R. China Received 31 May 2005, revised 26 August 2005, accepted 6 September 2005 Published online 4 November 2005 PACS 77.22.Ch, 77.65.Bn, 77.65.Fs, 77.84.Dy, 77.84.Lf PMN-31% PT/expoxy 1–3 piezoelectric composites with a different volume fraction of PMN-31% PT single crystals from 0.4 to 0.7 have been studied as regards fabrication and electric properties. The 〈001〉 oriented piezoelectric composites exhibit functional properties of low dielectric constant, high electrome-chanical coupling coefficient (0.80), and low acoustic impendence compared to the 〈110〉 oriented ones. The vibration characteristics of the piezoelectric composites strongly depend on the rod geometry and the volume fraction. The results obtained indicate that these piezoelectric composites with better global pro-perties are promising candidates for biomedical imaging and underwater transducer applications.

In this letter, we present our investigation of elastic, piezoelectric, and dielectric performances in 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 (0.70PMN–0.30PT) single crystals using a resonance technique. The complete set of constants was determined for this [001]-poled domain-engineered system by the effective tetragonal 4-mm symmetry. The electromechanical coupling coefficient k33, k31, k31 , kt and k15 are 92%, 89.5%, 76%, 62%, and 55%, respectively. The 0.70PMN–0.30PT crystal, which is slightly away from the morphotropic phase boundary (MPB), has remarkable and stable piezoelectric properties and becomes one of the premier considering materials for present applications in making high-sensitivity medical ultrasonic transducers and large displacement actuators.

Single crystals of Pb((Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 )O 3 (PZNT 91/9), 28 mm in diameter and 30 mm in length, have been successfully grown using a modified Bridgman technique with an allomeric seed crystal. X-ray fluorescence analysis (XRFA) measurement confirms that the effect of segregation is not serious. The segregation coefficient k for PbTiO 3 content during crystal growth is 0.99, which causes some fluctuation in the composition along the growth direction. The fluctuation of composition and the complicated domain structure cause a variation of electric properties. Dielectric measurement indicates that PZNT 91/9 crystals exhibit an almost normal ferroelectric phase transition at ∼183°C from the tetragonal phase to the cubic phase. In addition, a weak frequency-dependent ferroelectric-ferroelectric phase transition is observed at ∼85°C, which is attributed to partial conversion of the rhombohedral phase to a tetragonal phase. The dielectric thermal hysteresis behavior and the existence of polarization above the Curie temperature verify that the phase transitions at ∼85° and 183°C are first order with a slight diffuse character and first order, respectively. It is demonstrated that the effects of segregation can be decreased and the homogeneity of the obtained PZNT 91/9 single crystals can be improved by optimizing growth parameters.

Relaxor-based piezoelectric Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZNT 91/9) single crystals 28 mm in diameter and 30 mm in length were grown by a modified Bridgman technique with PbO flux using an allomeric seed crystal. The crystals were grown in sealed platinum crucibles at about 1250°C. The obtained crystals are of pure perovskite structure within the sensitivity of X-ray diffraction measurement and the as-grown crystals have three appearing faces with slight deviation in angle from the pseudocubic (0 0 1) cub face. The growth mechanism of the PZNT crystals could be explained from the viewpoint of the formation of growth units and the incorporation of growth units into different interfaces of the crystal lattice. The growth rate of various crystal faces is related to the assembling modes of the growth units into different interfaces. Assembling of [BO 6 ] octahedral growth unit into (1 1 1) cub interface has the strongest bonding force, and this crystal direction has the fastest growth rate; therefore, (1 1 1) cub crystal face disappears, assembling of [BO 6 ] into (0 0 1) cub interface has the smallest bonding force, and this crystal face has the smallest growth rate; therefore, (0 0 1) cub crystal face appears. The growth steps aligning approximately along the 〈0 0 1〉 cub direction reveal that (0 0 1) cub face proceeds by a layer growth mechanism controlled by two-dimensional nucleation starting at crystal corners or edges. Dielectric measurement proves that the quality of the obtained PZNT crystals is good. Domain observation shows that both the rhombohedral and tetragonal orientation state domain coexist in the morphotropic PZNT 91/9 single crystals.

The crystallographic orientation dependence of the P–E behavior and dielectric and piezoelectric properties in tetragonal Pb(Mg1/3Nb2/3)O3–38%PbTiO3 (PMNT62/38) single crystals were investigated. When the electric field was applied to 15 kV/cm the coercive electric fields Ec varied from E c [0 0 1] ∼8.25 to E c [1 1 0] ∼6.80 to E c [1 1 1] ∼4.11 kV/cm and the remnant polarizations were P r [0 0 1] ∼34.25 , P r [1 1 0] ∼22.64 , and P r [1 1 1] ∼18.87 μC/cm2. In [1 1 0] and [1 1 1] poled crystals, the formation of the engineered domain configuration caused more enhanced dielectric and piezoelectric activities: d 33[1 1 0] ∼1350 pC/N and e r [1 1 0] ∼6972 ; d 33[1 1 1] ∼980 pC/N and e r [1 1 1] ∼9784 , compared with d 33[0 0 1] ∼350 pC/N and e r [0 0 1] ∼760 at room temperature.

(Ba[Formula: see text]Ca[Formula: see text])(Zr[Formula: see text]Ti[Formula: see text])O3 (BCZT) lead-free ferroelectric ceramics were prepared at low sintering temperature via a hydrothermal route. The hydrothermal-synthesized BCZT precursor powder presents phase-pure perovskite structure and rather homogenous particles with dozens nanometers, which provides high sintering activity. Pure perovskite BCZT ceramics are synthesized at rather low sintering temperature accompanied by rather uniform microstructure morphology and high relative density. Dielectric peaks of the BCZT ceramics are rather broad, and their dielectric response behavior combines the characteristics of both the normal and relaxor ferroelectrics. The BCZT ceramics exhibit excellent ferroelectricity and promising electric energy density, which can be enhanced further with increasing electric field.

Single crystals of 0.05Pb(Sc 1.2 Nb 1.2 )O 3 -0.63Pb(Mg 1.3 Nb 2.3 )O 3 -0.32PbTiO 3 have been grown directly from melt by a modified Bridgman technique. The crystals with perovskite structure were 15 mm in diameter and 20 mm in length. The segregation during the growth of the single crystals was studied by means of X-ray diffraction analysis. The results show that PbTiO 3 content increases throughout the crystal growth. The electrical properties of the single crystals oriented along the [001] axis have been characterized. The plates cut from the seed end of a boule exhibited a permittivity (e 33 /e 0 ) of about 3500, dielectric loss tangent (tgδ)

Relaxor ferroelectric single crystals PMNT with the size of ϕ40 mm × 80 mm have been grown by a modified Bridgman method and their ferroelectric and piezoelectric properties have been characterized. The properties varied with the compositions and cut types. On the (001) cut, PMNT76/24 single crystals exhibited a dielectric constant ∈ of about 3 400, a dielectric loss of tanδ

Partial oxalate route is an efficient method to synthesize complex perovskite ferroelectric ceramics, in which the synthesized (1 - x) Pb ( Mg 1/3 Nb 2/3) O 3–x PbTiO 3 (PMN–PT) ceramics exhibit rather pure perovskite structure, densified microstructure morphology, and excellent dielectric and piezoelectric properties. The PMN–PT ceramics synthesized by the partial oxalate route exhibit rather symmetric strain–electric (S–E) field hysteresis loops, where the strain is large and far less than saturated at 2 kV/mm. The PMN–PT ceramics exhibit excellent pyroelectric properties, in which the values of the pyroelectric coefficient and the calculated pyroelectric figures of merit maintain almost stable over the frequency range of 100 Hz–2000 Hz, and vary differently depending on composition with the increase of temperature. Such investigations reveal that high-performance piezoelectric and pyroelectric devices can be prepared by the partial oxalate route in low production cost.

x Pb(Yb 1/2 Nb 1/2 )O3-(1 − x )Pb(Zr 0.36 Ti 0.64 )O 3 ( x PYN-(1 − x )PZT) piezoelectric ceramics were prepared by the conventional ceramic processing via a B-site oxide mixing route. The synthesized x PYN-(1 − x )PZT ceramics exhibit majority of perovskite structure with slight content of impurity, which exhibit typical tetragonal structure with slight orthorhombic distortion depending on compositions. All the x PYN-(1 − x )PZT ceramics exhibit high Curie temperature ( T C / T m ), higher than 380 °C, and their dielectric behavior above T C / T m can be fitted well by the Curie-Weiss law. The x PYN-(1 − x )PZT ceramics exhibit large resistivity, and excellent ferroelectric and piezoelectric properties, which provide promising for the high-power and high-temperature piezoelectric applications. However, electric energy density of the x PYN-(1 − x )PZT ceramics is small due to their nearly rectangular shape of polarization-electric field ( P-E ) hysteresis loop and early electric displacement saturation, which is not suitable for high energy and power storage applications.

Large-size and high-quality 0.95Pb(Zn 1/3 Nb 2/3 )O 3 –0.05PbTiO 3 (0.95PZN–0.05PT) single crystals were grown by a modified Bridgman method using an allomeric 0.69Pb(Mg 1/3 Nb 2/3 )O 3 –0.31PbTiO 3 single crystal as a seed. The as-grown 0.95PZN–0.05PT single crystals exhibit rhombohedral perovskite structure, which changes wholly into cubic structure at 165 °C confirmed by high-temperature X-ray diffraction measurement. 0.95PZN–0.05PT exhibits broad and diffused dielectric response peaks accompanied by apparent dielectric frequency dispersion. Polarization induces an additional dielectric anomaly around 109 °C accompanied by the increase of the temperature of dielectric maximum ( T m ), decrease of the value of dielectric maximum ( e m ) and the enhancement of frequency dispersion which can be assigned to the orientation of ferroelectric domain or a macro–micro domain transition upon heating. The [001]-oriented 0.95PZN–0.05PT crystals exhibit excellent electrical properties, where remanent polarization P...

Large-size and high-quality 0.85Pb(Zn1/3Nb2/3)O3–0.15PbTiO3 (0.85PZN-0.15PT) single crystals were grown by a modified Bridgman method using an allomeric 0.69Pb(Mg1/3Nb2/3)O3–0.31PbTiO3 single crystal as a seed. The as-grown 0.85PZN-0.15PT single crystals exhibit a tetragonal perovskite structure, which changes wholly into a cubic structure between 190 and 215 °C confirmed by high-temperature x-ray diffraction measurement. 0.85PZN-0.15PT exhibits sharp dielectric-response peaks with slight dielectric frequency dispersion where the ferroelectric-paraelectric phase transition is nearly first order. Polarization induces an additional dielectric anomaly around 147 °C accompanied by the increase in Curie temperature (TC), the decrease in the value of dielectric maximum (em), and the enhancement of frequency dispersion, which can be assigned to the orientation of a ferroelectric domain or a macro-micro domain transition upon heating. The [001]-oriented 0.85PZN-0.15PT crystal planes exhibit excellent electrical p...

Large-size and high-quality (1−x)Pb(Zn1∕3Nb2∕3)O3–xPbTiO3 [PZNT(1−x)∕x] single crystals (PZNT95/5, PZNT91/9, and PZNT85/15) were grown by a modified Bridgman method using an allomeric 0.69Pb(Mg1∕3Nb2∕3)O3–0.31PbTiO3 (PMNT69/31) single crystal as a seed. At room temperature, dielectric constant and loss tangent are about 1890 and 0.0692, 4710 and 0.0191, and 673 and 0.0320 for PZNT95/5, PZNT91/9, and PZNT85/15 crystals measured at 100Hz, respectively. These crystals exhibit high pyroelectric coefficients of 458, 1713, and 460μC∕Km2 for PZNT95/5, PZNT91/9, and PZNT85/15 crystals, respectively. The calculated detectivity and voltage responsivity figures of merit Fd and Fv exceed 5.27, 23.63, and 13.14μPa−1∕2, and 0.0106, 0.0162, and 0.0302m2∕C for PZNT95/5, PZNT91/9, and PZNT85/15 crystals, respectively, over the frequency range of 40–2000Hz. However, Fd and Fv increase greatly over the temperature range measured. It is needed to improve temperature stability and voltage responsivity to meet the requirements...

The dielectric and piezoelectric properties of the Mn-doped 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 (PMNT) crystals oriented along ⟨001⟩ and ⟨110⟩ directions, respectively, have been investigated. The investigations have shown that 3at.% Mn substitution results in (i) a large increment of coercive field at the cost of piezoelectric response, (ii) an increased Curie temperature and an enhanced stability of the ferroelectric rhombohedral phase, which enable a wider operation temperature range, and (iii) enhanced linearity in electric field induced strain with lower hysteresis. The hardened PMNT crystals favor their applications in high power transducers.

The elastic, piezoelectric, and dielectric properties of tetragonal 0.65Pb(Mg1∕3Nb2∕3)O3–0.35PbTiO3 (PMN-35%PT) single crystals were determined. The piezoelectric constant d33 is ∼1250pC∕N; the electromechanical coefficients k15, k31, k33, and kt are 0.70, 0.48, 0.91, and 0.61, respectively. The dielectric properties were measured as a function of temperature for (001)-oriented crystals. Compared with the crystals with compositions in the morphotropic phase boundary, PMN-35%PT crystals have much more stable phase structure from room temperature to Curie temperature, which makes them promising materials for high power applications in fabricating transducers, actuators, and generators.

Piezoelectric Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZNT 91/9) single crystals were grown directly from melt by a modified Bridgman method. X-ray diffraction confirms that the crystals are of pure perovskite structure. The obtained crystals have piezoelectric constant d 33 in the range of 1800–2000 pC/N, which is comparable to that of the PZNT crystals grown from flux. However, compared with the flux-grown PZNT 91/9 crystals, there is a broad diffused peak on the curve of temperature dependence of the dielectric constant, and a lower dielectric peak at 105°C. Domain observation shows that both the rhombohedral and tetragonal orientation states coexist in the morphotrpic PZNT 91/9 crystals.

Large ferroelectric single crystals of 0.48 Pb(Fe1/2Nb1/2)O3–0.52 PbTiO3 solid solution system were first successfully grown using a modified Bridgman technique and their properties were investigated. The obtained crystals were about 25 mm in diameter, 100 mm in length and black in color. The crystal exhibited abnormal dielectric properties that the dielectric constant was as high as 30000 and the dielectric loss factor was about 0.5 at room temperature. The mechanism of this phenomenon was discussed.

Relaxor ferroelectric single crystals Pb((Mg1/3Nb2/3)1-x Ti x )O3 (PMNT 100(1-x)/100x) were grown directly from melt by a modified Bridgman technique. The segregation during the growth of PMNT single crystals was studied by means of differential thermal analysis (TGA), thermogravimetric analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence analyzer (XRFA). The results show that PbTiO3 content increases throughout the crystal growth. The segregation coefficient is about 0.95 during the growth of PMNT 76/24 directly from melt. Therefore, the electric properties of PMNT single crystals vary even in the same boule. It was demonstrated that the homogeneity of PMNT single crystals can be improved by optimizing growth parameters, but it cannot be eliminated because of the effect of segregation during the crystal growth. We have recently improved the growth process of the modified Bridgman technique to increase the homogeneity of the crystals. Good-quality single crystals with a boule size of more than φ40×80 mm or 30×30×1 mm plates have been achieved. For PMNT 67/33 crystals, their coupling factors are k 33≈94% for the longitudinal mode, k 33 ′≈86% for the beam mode, and k t≈62% for the thickness mode, and they have the piezoelectric constant d 33=1500–3000 pC/N, and dielectric constant ε 33/ε 0=3500–5500.

0.14 at% Mn-doped 0.95(Na1/2Bi1/2)TiO3-0.05BaTiO3 (0.95NBT-0.05BT) lead-free single crystals were grown by a top-seeded solution growth method (TSSG). X-ray powder diffraction measurement showed that the as-grown single crystals exhibit rhombohedral perovskite structure with apparent distortion. With the increase of temperature, successive structural phase transitions occur in the Mn-doped 0.95NBT-0.05BT single crystals. After poling, apparent dielectric anomaly is induced accompanied by the increase of the character of diffuse phase transition and the decrease of the value of dielectric constant. The Mn-doped 0.95NBT-0.05BT single crystals exhibit complex domain structure, in which micro and macro domains coexist with statistically 4 mm symmetry. The Mn-doped 0.95NBT-0.05BT lead-free single crystals exhibit excellent piezoelectric and pyroelectric properties, which will lead to promising advance in piezoelectric and pyroelectric applications. The infrared-absorption band occurred around 630.6 cm−1 can be assigned to the “stretching” normal vibration of [Na1/2Bi1/2]/Ti-O group. The three diffused Raman bands centered around 300, 560 and 800 cm−1 can be attributed to F2g [TiO6] bending vibration, A1g [TiO6] stretching vibration and “soft mode” mixed by bending and stretching vibrations.