Lead Lanthanum Zirconate Titanate Ceramics Research Articles

Photo-induced electrostatic actuators towards micro gap regulator and micro gripper based on lead lanthanum zirconate titanate ceramics

Photo-induced actuators enable potential applications involving soft robots, biomedical engineering, and microelectromechanical system due to the contactless energy supply and high spatial and temporal controllability of light. However, obtaining a fast and reliable photo-induced actuation remains a great challenge. Herein, we report a strategy to realize rapid photo-induced actuation by utilizing a composite actuation mechanism, which combines photoelectric effect and electrostatic actuation mechanism. Novel photo-induced PLZT-based electrostatic actuators (PPEAs) are then proposed towards micro gap regulator (MGR) and micro gripper. Within the electrostatic pull-in point, we demonstrate that the gap of the PPEA regarded as an MGR can be tunable upon light irradiation through simulations. Besides, the pull-in instability enables the PPEA with rapid clamping action to be a micro gripper. Micro grippers with sandwich-like multilayer arms are fabricated using a simplified photolithography process and the fundamental operation and performance of our gripper are demonstrated through a series of experiments. More importantly, the two developed components are driven rapidly and reliably by light, providing great potential to facilitate the current research in photo-induced actuation.

Improved sensitivity of temperature sensor based on three-photons pumped upconversion in highly transparent Er3+ doped lead lanthanum zirconate titanate ceramics

Efficient two-photons and three-photons pumped upconversion emission were investigated in highly transparent Er3+ ions doped lead lanthanum zirconate titanate ceramics excited by using near infrared lasers centered at 980 nm, 1064 nm, and 1550 nm. Temperature dependent spectral changes of the multi-photons upconversion emission were explored, and highly sensitive temperature sensors were obtained based on the energy difference between 2H11/2 and 4S3/2. Using this temperature sensor, the temperature changes of the Er3+ ions doped lead lanthanum zirconate titanate ceramics was tested by irradiating the sample with a high-energy femtosecond laser at 1550 nm. This work is useful for developing a highly sensitive non-contact temperature measurement sensors, which provides the necessary theoretical basis for its practical application.

Strain Characteristics of PLZT-Based Ceramics for Actuator Applications

Lead lanthanum zirconate titanate (PLZT) ceramics exhibit excellent dielectric, ferroelectric and piezoelectric properties, and they can be used in many applications, including actuators. In this review, the processing and properties of PLZT-based ceramics will be the main focus of the first part. An introduction to PLZT ceramics is given and the methods to improve processing of PLZT-based ceramics are explained in terms of the addition of sintering aids, fabrication in the form of composites, and the application of dopants. The second part will be related to strain measurement to investigate converse piezoelectric properties (actuating effect). Strain measurement techniques by Michelson interferometry and case studies in PLZT-based ceramics (aging effect, temperature dependence and magnetic field effect) are included.

Neodymium and samarium codoped PLZT ferroelectric ceramics for potential betavoltaic nuclear batteries

In this work, neodymium (Nd) and samarium (Sm) codoped lead lanthanum zirconate titanate (PLZT) ceramics were prepared by a high-temperature solid-state method. The samples were characterized by X-ray diffraction, scanning electron microscopy and ferroelectric analysis. Rare earth-doped PLZT ceramics show good phase formation. An appropriate rare earth element doping amount increases the densities of PLZT ceramics and reduces their resistivities, which is due to the role of rare earth elements in grain refinement. However, the increase in the amount of grain boundaries caused by grain refinement also affects domain inversion. Therefore, with increasing doping concentration, the remnant polarization of PLZT gradually decreases, and the doping of rare earth elements also slightly reduces the band gap of PLZT. Under irradiation with an X-ray simulated beta source with a particle energy of 10 keV (between the average energies of the beta particles of 3H and 63Ni), the ceramic sheets in this work produce current densities of up to 1.38 nA/cm2. This indicates that Nd and Sm codoped PLZT ceramics have a certain potential for application in betavoltaic batteries.

Influence of the PbO-excess on the structural, microstructural and ferroelectric properties of PLZT ceramics

The physical properties of lead lanthanum zirconate titanate (PLZT) ceramics have been investigated as a function of a PbO excess from 0 to 20 mol% in samples of Pb0.94La0.06(Zr0.6895Ti0.2955)O3 (composition that reveals the best performance for piezoelectric applications for materials with rhombohedral symmetry). Results are presented in a compressive way in the frame of an overview on PLZT. Structural, microstructural and ferroelectric properties were investigated as a function of the PbO content. The X-ray diffraction results confirmed the formation of the perovskite structure for all the cases. However, the presence of the Pb2O3 secondary phase has been observed for the sample containing 15 mol% PbO excess. Raman spectroscopy studies revealed a strong influence of the PbO content on the active modes shifts. The ferroelectric properties have shown a decrease of both remnant (PR) and saturation (PS) polarizations for compositions up to 10 mol% PbO, whereas an increase of PR and PS was observed for the higher PbO content samples. Results reveal the effect of the PbO excess on the long-range order interactions for the studied system.

Visible or Near-Infrared Light Self-Powered Photodetectors Based on Transparent Ferroelectric Ceramics.

Transparent ferroelectrics, with promising prospects in transparent optoelectronic devices, have unique advantages in self-powered photodetection. The self-powered photodetectors based on the photovoltaic effect have quicker responses and higher stability compared with those based on the pyroelectric effect. However, the ferroelectric ceramics previously applied are always opaque and have no infrared light-stimulated photovoltaic effect. Thus, it would be very meaningful to design photodetectors based on infrared light-stimulated photovoltaic effect and/or transparent ferroelectric ceramics. In this work, highly optical transparent pristine lead lanthanum zirconate titanate (PLZT) and band gap-engineered Ni-doped PLZT ceramics with excellent piezoelectric/ferroelectric properties were prepared by hot-pressing sintering. Stable and excellent photovoltaic performance was obtained for pristine PLZT and band gap-engineered PLZT. The value of short-circuit current density is at least 2 orders of magnitude larger than those in PLZT reported in previous works. The transparent PLZT and Ni-doped PLZT ferroelectric ceramics are applied as self-powered photodetectors for the first time for 405 nm and near-infrared light, respectively. The devices based on PLZT under 405 nm light exhibit high detectivity (7.15 × 107 Jones) and quick response (9.5 ms for rise and 11.5 ms for decay), and those devices based on Ni-doped PLZT, under near-infrared light filtered from AM 1.5 G simulated sunlight, also exhibit high detectivity (6.86 × 107 Jones) and short response time (8.5 ms), both presenting great potential for future transparent photodetectors.

Temperature dependent fluorescence properties and mid-infrared random lasing emission in Ho3+ and Tm3+ co-doped lead lanthanum zirconate titanate ceramics

In this study, obvious up-conversion emission peaks centred at 553 nm and 696 nm were investigated in transparent Ho3+ and Tm3+ co-doped lead lanthanum zirconate titanate (PLZT) ceramics. Temperature dependent visible up-conversion emission and mid-infrared photoluminescence at approximately 2.0 μm were studied, and obvious luminous color modulation from yellow-green to red was observed. Energy transfer between Ho3+ and Tm3+ ions was studied by analyzing the suppression and enhancement of the emission peaks. Moreover, random lasing emission peaks at 1.95 μm were achieved with a full width at half maximum of 5 nm, which was desirable for developing mid-infrared lasers in ceramics materials.

Broadband photochromic effect and photoluminescence modulation in rare-earth-doped (Pb,La)(Zr,Ti)O3 ceramics

The broadband photochromic effect on undoped and rare-earth-doped lead lanthanum zirconate titanate (PLZT) ceramics was studied under the illumination of ultraviolet light at 360 nm. The photocarriers’ trapping and detrapping processes of thermal disconnected traps played the vital role in both darkening and bleaching processes. The interaction between photocarrier traps and rare-earth ion energy levels was demonstrated, which influenced the photochromatic darkening performance greatly. The transformation of photoluminescence spectra in Er3+-doped PLZT ceramics also improved the physical picture of the trap’s distribution of the materials. This work could be used to modulate the photoluminescence and lasing behavior.

A method of improving the sensitivity of infrared to visible light conversion of temperature sensor based on Er3+ doped PLZT transparent ceramics

A high sensitivity temperature sensor based on the fluorescence intensity ratios, absorption cross section and the reflectivity of light has been investigated in Er3+ doped lead lanthanum zirconate titanate ceramics. The fluorescence intensity ratios (FIR) of two green upconversion emission peaks from different levels (2H11/2 and 4S3/2) to the ground state level were investigated for temperature performance from 313 K to 573 K when the sample was excited by a 980 nm diode laser with different incident light power, in which the sensitivity of the temperature sensor was also described as a function of temperature. Transmission spectra and absorption coefficient were measured in the same temperature range, which presented a good linear relationship with temperature and could be used as a temperature sensor. With the help of the helium-neon laser and power meter, the reflectivity and transmittance of the sample for a 632.8 nm light were measured, which showed a linear relationship with temperature in 3% Er3+: PLZT, and could also be used in temperature sensing applications. This work provided a tool to determine the temperature using different ways (such as FIR, absorption coefficient, reflectivity, transmittance), it can greatly improve the sensitivity and credibility of temperature sensors.

Cr-doped lead lanthanum zirconate titanate (PLZT) ceramics for pyroelectric and energy harvesting device applications

Abstract Cr-doped PLZT ceramic compositions (Pb0.94La0.06)(Zr0.57Ti0.43)O3 + X mol% of Cr2O3, (X = 0.00, 0.05, 0.11 and 0.16) prepared by solid state reaction have been characterized for their structural and pyroelectric properties. Rietveld refinement of X-ray diffraction (XRD) data reveals tetragonal structure with space group P4mm, and the tetragonality ratio c/a increases with increasing Cr content. Raman spectroscopy reveals the coexistence of both rhombohedral and tetragonal phases in the system suggesting a polymorphic character providing easy rotation of polarization and improved pyroelectric response. Figures of merit (FOM) useful for device design have been estimated using the measured material properties such as pyroelectric current, density, specific heat, polarization, dielectric constant and loss. A specific Cr2O3 content of X = 0.11 in PLZT is found to exhibit optimum performance characteristics for pyroelectric and thermal energy harvesting applications.

Enhancement of the electrocaloric effect over a wide temperature range in PLZT ceramics by doping with Gd3+ and Sn4+ ions

The electrocaloric effect (ECE) in gadolinium and tin ions doped lead lanthanum zirconate titanate ceramics was investigated. Five samples with different compositions and hence different relaxor behaviors and polarization properties were prepared via a conventional solid-state reaction process. The ECE was measured directly by a high resolution thermometer from 293 K to 423 K. The results show that the ECE is mainly determined by the number of polarization states and polar-correlation strength. Furthermore, the results reveal that the temperature variation of ECE around Curie temperature is associated with the generation rate, activation energy, size and freezing temperature of polar nanoregions. As a result, Sn doped PLZT composition exhibits the best ECE, i.e., a peak ΔT > 2 K obtained at 5 MV/m, and ΔT > 1.78 K achieved in the whole temperature range measured at the same field, which are very attractive for high performance ECE devices.

Evolution of depolarization temperature of PLZT from normal to relaxor ferroelectrics

Lead lanthanum zirconate titanate (PLZT x/59/41) ceramics with x from 0 to 6.5 mol. % are synthesized by the traditional solid-state reaction method. The temperature dependences of dielectric and resonant responses are used to characterize the depolarization processes of poled samples. It is found that the temperature of anti-resonance frequency minima (Tmin-a) accords completely with dielectric loss peak temperature (Tloss). The Tloss instead of anomalous dielectric peak temperature (Td*) can be regarded as depolarization temperature (Td). The Td* deviated from the Tloss suggests that the depolarization process in all the samples includes two stages: domain decoupling and polarization disorientation. With La content increasing, the Tloss decreases and the temperature difference ΔT between Tloss and dielectric peak temperature (Tm) increases nearly linearly. Since all studied samples have similar depolarization and freezing processes and the 0 mol. % La sample behaves like a normal ferroelectric, here we suggest that there may be no essential difference in depolarization process between relaxor and normal ferroelectrics.Lead lanthanum zirconate titanate (PLZT x/59/41) ceramics with x from 0 to 6.5 mol. % are synthesized by the traditional solid-state reaction method. The temperature dependences of dielectric and resonant responses are used to characterize the depolarization processes of poled samples. It is found that the temperature of anti-resonance frequency minima (Tmin-a) accords completely with dielectric loss peak temperature (Tloss). The Tloss instead of anomalous dielectric peak temperature (Td*) can be regarded as depolarization temperature (Td). The Td* deviated from the Tloss suggests that the depolarization process in all the samples includes two stages: domain decoupling and polarization disorientation. With La content increasing, the Tloss decreases and the temperature difference ΔT between Tloss and dielectric peak temperature (Tm) increases nearly linearly. Since all studied samples have similar depolarization and freezing processes and the 0 mol. % La sample behaves like a normal ferroelectric, here we ...

Effect of composition and grain size on dielectric, ferroelectric and induced strain behavior of PLZT/ZrO2 composites

Lead lanthanum zirconate titanate ceramics (PLZT) are well known for their excellent dielectric, piezoelectric and ferroelectric properties. In this study, PLZT 9/70/30, 9/65/35 and 9/60/40 ceramics were prepared by vibro-milling mixed-oxide method. All compositions of powders were uniaxial pressed in pellets and sintered at the temperatures of 1200–1275°C with various soaking times of 2, 4 and 6h. The X-ray diffraction (XRD) patterns confirmed that all the PLZT samples had perovskite structure with ZrO2 as a second phase and PLZT/ZrO2 composite structure was formed. Dielectric behavior at the frequency of 1kHz showed broad peak indicating relaxor ferroelectric behavior and the difference of the temperature at maximum dielectric at different frequencies increased when Zr:Ti ratio increased. Polarization with electric field (P-E loop) at room temperature showed that when Zr:Ti ratio increased, the coercive field decreased resulting from crystal structure change from tetragonal to rhombohedral. Induced strain with electric field depended on microstructure where the value of Smax/Emax tended to decrease with increasing grain size. It can be concluded that dielectric and ferroelectric behavior predominantly depended on composition of PLZT ceramics and induced strain behavior predominantly depended on grain size of PLZT ceramics.

Enhanced photoluminescence intensity by modifying the surface nanostructure of Nd3+-doped (Pb, La)(Zr, Ti)O3 ceramics.

Quasi-period cylindrical nanostructures with both diameters and intervals of about 100nm are manufactured on the surfaces of Nd3+-doped lanthanum lead zirconate titanate ceramics by femtosecond laser irradiation under SF6 atmosphere. A light-emission enhancement of more than 20 times is investigated, accompanied by an extremely long trailing-off time of light emission and lower threshold. A specific polarization state of the light emission is achieved and tuned by changing the incident regions of the pumping source. The increased absorption coefficient of the specimen is discussed based on multiple scattering and weak localization of light. In addition, both the scatterers provided by the laser-machined nanostructure and the recurrent photoinduced trapping and re-excitation process participated in the enhancement of the light emission. This Letter offers new insight to improve the luminescence property of laser materials, as well as to broaden the range of exploring the weak localization of light and random lasers.

Multiple scattering and random walk based spectra modulation in Ho^3+/Tm^3+ codoped (Pb,La)(Ti,Zr)O_3 ceramics under plasma atmosphere

Remarkable enhancement of light emission in Ho3+/Tm3+codoped lanthanum lead zirconate titanate ceramics was investigated upon exposure to the plasma atmosphere. Photoinduced scatterers and weak localization of light played primary roles in these experimental results. Various long fading-off times were obtained and used to tune the light emission. An extreme sharp spike at 590 nm was detected, which originated from the variation and random lasing action of Ti4+ cations. These findings offer opportunities in designing new lasers, which might take advantages of rare earth elements and transitional metal activators in the same host materials.

Effect of Sintering Condition on Electrical Properties of PLZT Ceramics

Feroelectric lead lanthanum zirconate titanate (PLZT) ceramics 9/70/30 were synthesized by conventional mixed-oxide method via a vibro-milling technique. The effect of sintering temperature and two-stage sintering method on electrical properties of PLZT ceramics was investigated. The ceramic powder was uniaxially pressed in pellets and sintered at the temperatures ranging from 1200 to 1275 °C for 4hrs and two-stage sintering temperature at 1200 °C for 4 hrs. Dielectric, ferroelectric and strain properties of ceramics were characterized by LCR meter, modified Sawyer–Tower Circuit and modified Michelson interferometric technique respectively.

Research on the response improvement of optical actuation based on lead lanthanum zirconate titanate ceramics

Lead lanthanum zirconate titanate actuators taken as one type of photo-deformable actuators have been widely applied for micro-driven systems and active vibration control of photostrictive laminated flexible structures. However, the slow response of photodeformation of single patch lead lanthanum zirconate titanate actuator greatly affects its application. In this article, the main factors for the slow response of the lead lanthanum zirconate titanate actuator are investigated using experimental method. The increasing temperature during light on state and the residual photovoltage and photodeformation during light off state are considered as dominant factors causing the slow response of the lead lanthanum zirconate titanate actuator. To gain a better driving capability of lead lanthanum zirconate titanate actuator, some effective solutions through weakening the effect of increasing temperature and eliminating residual photovoltage and photodeformation are proposed and experimentally validated in this article. Considering the effective solutions proposed in this article, a novel optical driving mechanism based on multi-patches combination is proposed.

Effect of Dy substitution on ferroelectric, optical and electro-optic properties of transparent Pb0.90La0.10(Zr0.65Ti0.35)O3 ceramics

Highly transparent Dy-codoped lead lanthanum zirconate titanate (PLZT) ceramics were sintered from oxide powders by the hot pressing method. The ceramics exhibited a transparency as high as 67% at 632.8nm (close to the theoretical value). The effects of substituting Lanthanum by Dysprosium on the phase structure, microstructure, dielectric, ferroelectric, optical and electro-optic properties of PLZT were examined. The results showed that Dy substitution decreased the coercive field, improved the optical transmittance and electro-optic properties of PLZT ceramics. Moreover, the high half-wave voltage (affecting the working voltage of devices) of PLZT was reduced from 850V to 510V by Dy substitution. Modified PLDZT transparent ceramics are competitive candidate materials for modern optical communication, and the variable optical attenuator (VOA) based on PLDZT exhibited excellent performances.

Electroinduced structural change- and random walks-based impact on the light emission in Er3+/Yb3+ doped (Pb,La)(Zr,Ti)O3 ceramics

Remarkable enhancement/reduction of light emission and competition among different wavebands with rare earth doped lanthanum lead zirconate titanate ceramics were observed in a corona atmosphere caused by an externally applied electric field. Quantum-mechanical analyses, based on variation of structural symmetry of the unit cell and hence the crystal field due to electrostriction, were given to elucidate the effect. Apart from the symmetry of crystal field, the obvious contribution from the optoenergy storage and weak localization of light involved were discussed. These results are promising in designing and implementation of lasers and sensors.

Pyroelectric energy conversion using PLZT ceramics and the ferroelectric–ergodic relaxor phase transition

This paper is concerned with direct conversion of waste heat into electricity by executing the Olsen cycle on lead lanthanum zirconate titanate (PLZT) ceramics undergoing a relaxor–ferroelectric phase transition. The Olsen cycle consists of two isothermal and two isoelectric field processes. First, the temperature-dependent dielectric properties were measured for x/65/35 PLZT. The polarization transition temperature of x/65/35 PLZT was found to decrease from 240 to 10 °C as x increased from 5 to 10 mol%. This suggests that the different compositions should be operated over different temperature ranges for maximum thermal to electrical energy conversion. The energy and power densities generated by the Olsen cycle using x/65/35 PLZT samples were measured by successively dipping the samples in isothermal dielectric oil baths. Large energy and power densities were obtained when the samples underwent the ergodic relaxor–ferroelectric phase transition. A maximum energy density of 1014 J l−1 per cycle was obtained with a 190 μm thick 7/65/35 PLZT sample cycled at 0.026 Hz between 30 and 200 °C and between 0.2 and 7.0 MV m−1. To the best of our knowledge, this is the largest pyroelectric energy density ever demonstrated experimentally with ceramics, single crystals, or polymers. A maximum power density of 48 W l−1 was achieved using a 200 μm thick 6/65/35 PLZT sample for temperatures between 40 and 210 °C and electric fields between 0 and 8.5 MV m−1 at a frequency of 0.060 Hz. The maximum applied electric field and temperature swings of these materials were physically limited by dielectric breakdown and thermomechanical stress.