Lanthanum-doped Lead Zirconate Titanate Research Articles

Fingertip tactile sensation via piezoelectric micromachined ultrasonic transducers with an amplified interface

Tactile devices are often used in the field of robotics; however, the development of compact high-resolution tactile devices remains challenging. In this study, we developed a haptic device for force presentation using a DC motor and a tactile sensation device to simultaneously present haptic and tactile stimuli. A microelectromechanical system was selected to maintain the compactness of the tactile device. Piezoelectric micromachined ultrasonic transducers are known for high-power stimulation, and we selected lanthanum-doped lead zirconate titanate as the high-power amplified actuator. A finger mount structure that transfers force for amplifying ultrasonic waves was considered to combine acoustic pressure and aeroacoustics by attaching silicone rubber. The device was fabricated, and the performance of the tactile sensations was evaluated. The developed device uses the novel concept of combining acoustic pressure and aeroacoustics, and its compactness renders it suitable for wearable systems.

An ON-OFF Closed-Loop Control of Photoelectric Actuator Based on PLZT Ceramic

PLZT (lanthanum-doped lead zirconate titanate) ceramic with outstanding photostrictive effect has been widely used in the micro precision drive field. In this article, a new closed-loop control method with ON-OFF control strategy is proposed for the photoelectric actuator based on PLZT ceramic. The closed-loop control model under driving voltage control strategy is established, and the parameters are identified by a series of experiments. Then, the control equations of driving voltage and output displacement of the photoelectric actuator are derived on the basis of the closed-loop control model during the light on and light off phases. After that, the numerical simulation analysis is carried out when the driving voltage and output displacement are taken as control objects respectively. According to the analysis results, the output displacement of the photoelectric actuator can be successfully controlled at a specific target value, and the proposed control method has excellent control effect, the feasibility and effectiveness of the control method are verified. Relevant conclusions can lay a foundation and provide theoretical guidance for the practical application of the photoelectric actuator in the field of active control.

Effect of ferroelectric filler nanoarchitectonics on the electrical and mechanical properties of the nanocomposite thick films of polyvinylidene fluoride and lanthanum-doped lead zirconate titanate in 0–3 connectivity

Effect of ferroelectric filler nanoarchitectonics on the electrical and mechanical properties of the nanocomposite thick films of polyvinylidene fluoride and lanthanum-doped lead zirconate titanate in 0–3 connectivity

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.

Comparison of the effect of temperature variation in AVC using PLZT and PZT-5H as smart sensor and actuator

Piezoelectric material has unique electro-mechanical property, which encourages its use in the smart structure. The performance of a piezoelectric material strongly depends on the piezoelectric strain coefficient and dielectric constant. These piezoelectric properties can get affected by environmental factors like the electric field, humidity, aging, temperature, etc. In this paper variation in the piezoelectric strain coefficient and dielectric constant with temperature are considered in the finite element model of a smart dynamic structure. Time response of sensor voltage is observed for PZT-5H (Lead Zirconate Titanate) and PLZT (Lanthanum doped Lead Zirconate Titanate) piezoelectric sensors. The response of PLZT sensor is much more linear as compared to the PZT-5H sensor with the variation in temperature.

Investigation on influence factors of opto-electrostatic hybrid driving torsion actuator based on PLZT ceramic

PLZT (lanthanum-doped lead zirconate titanate) ceramic has obtained widespread applications in the engineering fields. Especially, it has broad application prospects in driving field. In this article, aiming at the proposed opto-electrostatic hybrid driving torsion actuator, the influence of different factors on driving voltage and output deformation is analyzed and verified by a new mathematical model and a variety of experiments. According to the analysis and experimental results, different PLZT ceramics with different sizes can produce different driving voltage and deformation of the actuator. And as the length of the torsion beam increases or the width of the torsion beam decreases, the deformation increases while the driving voltage remains the same. The driving performance is better when the copper foil attached to the right end of the upper electrode. Moreover, when the area of copper foil decreases or the distance between electrodes increases, the driving voltage increases while the change of deformation is determined by driving voltage, area and distance between electrodes. Therefore, the analysis of the influence factors can not only explore their influence on driving performance, but also provide a theoretical basis for the practical application of opto-electrostatic hybrid driving torsion actuator based on PLZT ceramic.

The experimental analysis on the driving characteristics of photo response torsion actuator

The lanthanum-doped lead zirconate titanate ceramic is a well-known photostrictive material and has been studied extensively as wireless photo-controlled microactuators for its characteristic of photostrictive effect. However, the hysteresis phenomenon between photovoltage and photo-induced deformation has seriously hindered the application of the high-frequency dynamic field. The primary purpose of this article is to propose a photo response torsion actuator driven by opto-electrostatic hybrid driving method based on lanthanum-doped lead zirconate titanate ceramic to achieve the goal of rapid response regardless of the hysteresis phenomenon. To this end, this study observed the driving voltage, the relationship between the photovoltaic voltage of lanthanum-doped lead zirconate titanate ceramic and the deflection of the actuator, and the influence of different loads on driving characteristics through a series of experiments. From these experiments, the results indicate that when lanthanum-doped lead zirconate titanate ceramic is irradiated by ultraviolet light, the photovoltaic voltage with load is lower than that without load. The trend of deformation curves is in agreement with the trend of the driving voltage curves under different loads conditions. And the deformation of torsion actuator increases with the increase in light intensity. Therefore, the photo response torsion actuator driven by the opto-electrostatic hybrid driving method can control the deformation with rapid response speed effectively; meanwhile, the hysteresis phenomenon can be ignored.

Enhancement in energy storage and piezoelectric performance of three phase (PZT/MWCNT/PVDF) composite

The conversion of mechanical energy (vibration) to electrical signal (voltage/power) is one of the versatile phenomena in energy harvesting process. In the effort to develop self-powered devices that will convert readily available vibrations into electrical power and no external source of energy will be required for operation, a three phase hybrid piezoelectric nanogenerator comprising of Lanthanum doped Lead Zirconate Titanate (PLZT), Polyvinyldene fluoride (PVDF) and Multi-walled Carbon Nanotubes (MWCNT) as supplement filler was fabricated. Piezoelectric composite films were prepared using tape casting technique, followed by hotpress. The addition of PLZT to PVDF and further MWCNT in PLZT-PVDF composite resulted in the enhancement of dielectric, ferroelectric, piezoelectric and energy storage properties. A maximum open circuit AC peak-to-peak voltage of 20 V was obtained from the nanogenerator after applying repeated human figure tapping and releasing motion on the sample. After rectification of the output AC voltage by bridge rectifier, the DC voltage was able to charge a 40 μF commercial capacitor up to 8 V (2 mW power) and during discharging of the capacitor, around 50 LEDs were glowed. A 40 μF capacitor was also charged by using the same method after applying foot pressure on the nanogenerator which delivered 1.5 mW power with 6 V DC voltage and 250 μA short circuit current. Thus the amount of power delivered by the fabricated nanogenerator can drive several LEDs and charge capacitor which can be used for powering small electronic devices.

Electrocaloric properties of Bi and Cu doped PLZT 9/65/35 ceramics at low electric field

In this work, bismuth (Bi) and copper (Cu) doped lead lanthanum zirconate titanate (PLZT) 9/65/35 ceramics were fabricated by solid state sintering. Measurement of dielectric and ferroelectric properties at various temperatures was performed to determine electrocaloric effect in the ceramics. It was found that both undoped and doped PLZT ceramics exhibited relaxor behavior and phase transition from ferroelectric to relaxor. Indirect measurement of electrocaloric effect revealed that pure PLZT had broad peak of temperature change around the temperature at maximum dielectric constant and doped PLZT had narrower peak. Temperature change resulting from electrocaloric effect due to phase transition at low electric field could be observed in co-doped PLZT. It can be concluded that compositional effect played an important role to the change of dielectric, ferroelectric and electrocaloric properties because doping caused the change of electronic structure from A- and B-site substitution in perovskite structure of PLZT and the change of dynamic polar nanoregions.

Hydrothermal synthesis and characteristics of lanthanumdoped Pb(Zr₀.₆₅Ti ₀.₃₅)O₃ ceramics

Lanthanum-doped lead zirconate titanate (PLZT) powders were synthesized using thehydrothermal method. The influence of pH, reaction temperature and time, lanthanum concentration on the formation and characteristics of PLZT were investigated. Obtained powders were investigated using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) techniques and a dielectric analyzer. The results showed that Pb1-xLax(Zr0.65Ti0.35)O3 with x= 0.0 – 0.1 were well formed under conditions: pH≥13, reaction time of 12hrs, reaction temperature of 180oC. Dielectric constant of PLZT is higher than PZT. The grain size of the PLZT is found to be 1–3.5 µm.

Enhancement of energy storage and thermal stability of relaxor Pb0.92La0.08Zr0.52Ti0.48O3-Bi(Zn0.66Nb0.33)O3 thick films through aerosol deposition

Relaxor ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT 8/52/48) has been studied widely for applications to high energy storage capacitors because of its polarization-electric (P-E) field hysteresis. On the other hand, its energy storage characteristics are unsatisfactory because the dielectric properties deteriorate with temperature. In the present study, a dense nano-composite thick film (∼5 μm) was fabricated by the aerosol deposition (AD) of mixed powders of BZN [Bi(Zn0.66Nb0.33)O3] corresponding to 0, 5, and 10 at.% with lanthanum-doped lead zirconate titanate ceramics (PLZT) at room temperature, followed by post-annealing for crystallization recovery. The composition of 0.95(Pb0.92La0.08Zr0.52Ti0.48O3)-0.05Bi(Zn0.66Nb0.33O3) PLZT-BZN5 was made artificially, which accommodates the coexistence of two different phases, demonstrating superior energy storage performance. The 550°C-annealed PLZT-BZN5 film showed a superior energy density of 14.7 J/cm3 under an electric field of 1400 kV/cm and an efficiency of 81%. The PLZT-BZN5 film also exhibited low dielectric loss and improved temperature stability.

Influence of Zr/Sn ratio on the Transverse Piezoelectric Coefficient in Lanthanum-Doped Lead Zirconate Titanate Stannate Thin Films

In this study, we report the effect of Zr/Sn ratio on the Antiferroelectric (AFE) → Ferroelectric (FE) phase transition and transverse piezoelectric characteristics on AFE thin films of compositions having the general formula Pb0.97La0.02(Zr1-x+ySnxTiy)O3, where y = 0.10 and 0.10 ≤ x ≤ 0.15 along the phase boundary in the ternary system Pb(Zr0.50Ti0.50)O3-Pb(Zr0.50Sn0.50)O3-PbZrO3. Thin films having a thickness of 2.0 µm were fabricated on platinised silicon substrates by sol–gel method. Data obtained from dielectric, ferroelectric and structural studies have been combined to explain the mechanism of AFE → FE switching.

Reconstruction of IrO2/(Pb, La)(Zr, Ti)O3 (PLZT) interface by optimization of postdeposition annealing and sputtering conditions

We reconstruct the interface between ferroelectric (FE) lanthanum-doped lead zirconate titanate (PLZT) and an iridium oxide (IrOx) top electrode (TE), taking advantage of the interdiffusion of Ir and Pb during postdeposition annealing. The tetragonal perovskite phase with a low c/a axis ratio at the IrOx/PLZT interface is observed by X-ray diffraction. It is suggested that the low c/a axis ratio in the interfacial layer is due to the effect of diffusion of Ir from the TE-IrOx. It is also considered that the low c/a axis ratio interfacial layer functions as a nucleation layer for reversal of polarization, thereby achieving a low coercive electric field. The formation of the interfacial layer is very sensitive to the O2 content of the Ar/O2 atmosphere during TE-IrOx deposition. Although an optimized Ar/O2 ratio achieves excellent polarization characteristics (high polarization value and low coercive field), the optimum Ar/O2 region is very narrow at around 36% O2. In other Ar/O2 regions, a pyrochlore phase is formed at the interface owing to interdiffusion of the TE and FE films, and polarization characteristics deteriorate.

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.

Raman study of pyroelectric and injected charge induced fields in PLZT 8/65/35 ceramics

Electric fields of different nature induced in lanthanum doped lead zirconate-titanate (PLZT) ceramics were studied by confocal Raman microscopy. Temperature dependence of the pyroelectric field was determined and the value of pyroelectric coefficient was estimated. An appearance of additional line in Raman spectrum of PLZT after e-beam irradiation was revealed and its spatial distribution was studied. The origin of this spectral line was discussed in terms of defects formation and phase transitions.

In situ XRD analyses for asymmetric responses of poled PLZT ceramics during electric fatigue

Electric fatigue behaviors of the poled lanthanum-doped lead zirconate titanate (PLZT) ceramics were investigated using a home-made electric loading apparatus in conjunction with a conventional X-ray diffractometer. The XRD data were measured under actions of the applied direct current electric fields on the as-received poled PLZT specimens being experienced various cycles (10N) of alternating current (AC) electric fields. Experimental data showed that in addition to apparent degradation in remnant polarization, asymmetries in hysteresis loops and fraction of 90° domain switching curves were observed. It was found that an offset electrical field (\(\Delta {{\text{E}}_N}\)) was induced in the poled specimen by polarization with its direction against the direction of the polarization. Furthermore, the magnitude of \(\Delta {{\text{E}}_N}\) and the degree of asymmetry (δN) decreased as the number of AC electric fatigue cycles (10N) varied from 100 to 106. In situ XRD data suggested that the poled specimen exhibited different abilities to reorient a-domains into c-domains when the applied electric fields were opposite. The δN not only depended linearly on \(\Delta {{\text{E}}_N}\), but also on abilities of the poled specimen to reorient a-domains into c-domains.

Flexible ceramic film capacitors for high-temperature power electronics

Flexible ceramic film capacitors with high dielectric constant and high breakdown strength hold special promise for applications in power electronics. We deposited lanthanum-doped lead zirconate titanate (PLZT) films on aluminum-metallized polyimide films at room temperature by an aerosol deposition (AD) process and examined the electrical and dielectric properties of the PLZT films over a wide temperature range between −55 and 175 °C. The PLZT film capacitors fabricated by high deposition rate AD process not only satisfy X8R temperature rating but also exhibit superior volumetric and gravimetric specific capacitance. At room temperature, we measured a dielectric constant of ≈85, dielectric loss of ≈0.012, energy density of ≈13.2 J/cm3 with an applied voltage of ≈1000 V. A mean dielectric breakdown field strength (EB) of ≈1.25 MV/cm was determined by Weibull analysis for the ≈8-μm-thick PLZT film capacitors fabricated on flexible aluminum-metallized polyimide substrates. These results revealed that the PLZT-based ceramic film capacitors meet the requirements for advanced high-temperature power inverters. Our results demonstrated that AD process offers the greatest potential for producing low-cost, robust, compact and light-weight ceramic film capacitors with enhanced reliability for power inverters of electrical drive vehicles and various power electronic devices that are critical for high-efficiency energy conversion and renewable energy systems.

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.

A simulation model for PLZT based ferroelectric photovoltaic devices, II. Influence on charge transport and photovoltaic parameters with ITO top and Pt bottom electrodes

This work is an extension of our previously developed photovoltaic (PV) model with ferroelectric PLZT as photoactive layer, metal Pt as top and bottom electrodes. Pt electrodes result in good ferroelectric properties but lower PV output, as seen from our model. We developed a new PLZT PV model with ITO as top electrode and Pt as bottom electrode using a semiconducting thin-film optics simulation (SETFOS) software. Dependence of PV characteristics such as open circuit voltage ( and short circuit current density ) and charge transport properties such as carriers’ concentration, current density and recombination on the model parameters were investigated. The parameters including thickness of interface layer (between PLZT and ITO top electrode), thickness and work function of ITO top electrode were optimized, which were used to obtain and of the simulated model. and of the simulated and the experimental device matched closely. Charge carriers’ concentration and current density of the PLZT layer with ITO and Pt as top electrodes were compared. These properties show that ITO top electrode enhances the charge transport in PLZT, which results in higher and of the PV device.Abbreviations. PV: Photovoltaic; FE: ferroelectric; PLZT: lanthanum doped lead zirconate titanate; SETFOS: semiconducting thin-film optics simulation software; ITO: Indium tin oxide; Pt: Platinum; Ec: conduction band; Ev: valence band, : short circuit current density, : open circuit voltage; PCE: power conversion efficiency, : recombination current; IL: interface layer; ITOet: ITO top electrode; Ptet: Pt top electrode, : total current, : electron current density, : hole current density, electron concentration, hole concentration

A simulation model for understanding the charge transport and recombination behavior in PLZT based ferroelectric photovoltaic devices

ABSTRACTWe present a simulation model for ferroelectric lanthanum doped lead zirconate titanate thin film based photovoltaic devices using a semiconducting thin-film optics simulation (SETFOS) software. The model was designed by analyzing the dependence of photovoltaic characteristics (Jsc and Voc), charge carrier (electron and hole) concentration, current density, and recombination distribution on parameters such as the thickness of the interface layer and the top electrode, and the work function of the top electrode. The optimized parameters were used to obtain current-voltage curves of the simulated device. These simulated results fit with the current-voltage curves of the experimentally fabricated device, validating our model. The model is helpful in understanding the physical processes such as transport and recombination of charge carriers in PV devices that are essential for improving the photovoltaic performance.