PLZT Ceramics Research Articles

Experimental investigation on photo-deformation effect of PLZT ceramic with bias electric field

The lanthanum-doped lead zirconate titannate (PLZT) ceramic has been widely used in light-controlled wireless actuators activated by ultraviolet light for their characteristic of converting light energy directly into the mechanical energy. The photovoltaic effect of PLZT is the result of multi-phys ics fields coupling, and the primary purpose of this article is to provide a comprehensive experimental analysis on the influence of photo-induced deformation of PLZT ceramics under the action of bias electric field. To this end, the amount and the speed of arriving at the electrodes of photo-generated carriers are analyzed. Furthermore, whether the bias electric field promotes the photovoltaic effect is investigated by a series of experiments. The experimental results indicate that the deformation of PLZT ceramic with combined action of ultraviolet light and bias electric field is larger than that with only irradiation action. However, the increment is only contributed by bias electric field based on the converse piezoelectric effect, and the bias electric field has no effect on the photo-generated carriers. Therefore, adding a bias electric field cannot promote the photo-induced deformation of PLZT.

Microstructure and Properties of the Ferroelectric-Ferromagnetic PLZT-Ferrite Composites

The paper presents the technology of ferroelectric-ferromagnetic ceramic composites obtained from PLZT powder (the chemical formula Pb0.98La0.02(Zr0.90Ti0.10)0.995O3) and ferrite powder (Ni0.64Zn0.36Fe2O4), as well as the results of X-ray powder-diffraction data (XRD) measurement, microstructure, dielectric, ferroelectric, and magnetic properties of the composite samples. The ferroelectric-ferromagnetic composite (P-F) was obtained by mixing and the synthesis of 90% of PLZT and 10% of ferrite powders. The XRD test of the P-F composite shows a two-phase structure derived from the PLZT component (strong peaks) and the ferrite component (weak peaks). The symmetry of PLZT was identified as a rhombohedral ferroelectric phase, while the ferrite was identified as a spinel structure. Scanning electron microscope (SEM) microstructure analysis of the P-F ceramic composites showed that fine grains of the PLZT component surrounded large ferrite grains. At room temperature P-F composites exhibit both ferroelectric and ferromagnetic properties. The P-F composite samples have lower values of the maximum dielectric permittivity at the Curie temperature and a higher dielectric loss compared to the PLZT ceramics, however, the exhibit overall good multiferroic properties.

Dielectric and piezoelectric properties of Cr2O3-doped PLZT (7/65/35) hot pressed ceramics

Single phase PLZT (7/65/35) ceramics doped with Cr2O3 [0,0.05, 0.08, 0.18, 0.30 0.50, 0.75 and 1.0 wt%] were synthesized by high temperature solid-state reaction technique accompanied by hot pressing. XRD studies revealed that the chromium doping reduces the lattice parameter of PLZT (7/65/35) without changing its crystal structure. A relaxor like behavior with decrease in temperature of dielectric constant maxima (Tm) was observed with increase in chromium content. A sharp rise in the conductive losses were observed for higher chromium (≥0.08 wt%) contents. The room temperature dielectric constant (ε′RT) and electromechanical coupling coefficient (k31) showed maxima value for 0.08 wt% Cr2O3 doped PLZT (7/65/35) ceramic. The results were interpreted on the basis of multiple valence nature of chromium.

Micro-mirror with hybrid photoelectric-electrostatic driving of PLZT ceramic

A novel micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed based on the anomalous photovoltaic effect of PLZT ceramic. On the basis of analysis of coupling relationships of multi-physics fields of PLZT ceramic, the photovoltage of PLZT ceramic is established during illumination and light off phases. Furthermore, the relationship between the driving displacement and the photovoltage of PLZT ceramics is present. In addition, the feasibility of micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photovoltage of PLZT ceramic. The experimental results show that the photovoltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

Effects of Lanthanum Substitution on Dielectric, Ferroelectric and Electro-Optic Properties of Slim-Loop PLZT Ceramics

Highly transparent lead lanthanum zirconate titanate (Pb1−xLax)(Zr0.65Ti0.35)1-x/4O3(x=0.096-0.1) electro-optic ceramics were prepared by the hot pressing method. The ceramics exhibited transparency as high as 67% at 632.8nm (close to the theoretical value). The effects of lanthanum substitution on the phase structure, microstructure, dielectric, ferroelectric, optical and electro-optic properties of PLZT were examined systematically. The XRD results indicated that all the compositions were single perovskite phases, and La substitution decreased the lattice constant and unit-cell volume. The dielectric results showed that the Tmaxand εmaxdecreased with La content increasing. The hysteresis loops showed that the La content reduced saturate polarization (Ps), remnant polarization (Pr) and coercive field (Ec). Moreover, the half-wave voltage and EO coefficient R was enhanced and reduced respectively with increasing La.

Temperature and induced electric field dependence on the phase transition of 9/70/30, 9/65/35 and 9/60/40 PLZT ceramics

ABSTRACTIn this work, Pb0.91La0.09(Zr1–xTix)0.9775O3 ceramics where x = 0.3, 0.35 and 0.4 (the composition near MPB) were prepared by solid solution method. After fabrication process, electrical property was measured by LCR meter. Polarization and induced strain behavior of the samples were investigated by using interferometry technique modified with Sawyer–Tower circuit at various temperatures. The results of dielectric, polarization and induced strain properties were due to the Zr/Ti ratios, which changed their behavior when temperature was varied (30–70 °C). The normal to macro-micro domains to relaxor and paraelectric phase transition was demonstrated which is related to linear or nonlinear increase of polarization and induced strain as a function of applied subswitching electric field.

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.

PLZT Ceramic Driving Rotary Micro-mirror Based on Photoelectric-electrostatic Mechanism

Based on the anomalous photovoltaic effect of PLZT, a rotary micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed. Firstly, the mathematical modelling of coupled multi-physics fields of PLZT ceramic is established during illumination and light off phases. Then, the relationship between the rotation angle and the photovoltage of PLZT ceramics is established. In addition, the feasibility of rotary micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photo-induced voltage of PLZT ceramic. The experimental results show that the photo-induced voltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

High piezoelectricity of PLZT ceramics with strong frequency-dielectric dispersion below depolarization temperature

Crystal structure, dielectric and piezoelectric properties of PLZT x/59/41 ceramics with 1 wt% Sb2O5 addition were studied systematically by X-ray diffraction and electrical measurements. X-ray diffraction analyses show that the crystal structure experiences a phase transition from rhombohedral to tetragonal as the La content increasing. The piezoelectric charge coefficient d33 increases dramatically as the La content increases from 5 mol% to 6.5 mol%. In the 6.5/59/41, the crystal structure is a mixture of cubic and tetragonal phases and the sample possesses a high piezoelectricity of d33 = 821 pC/N. Meanwhile, the dielectric response exhibits a strong frequency-dispersion not only before poling but also after poling below the depolarization temperature, indicating that domains remain at nanoscale all the time in 6/59/41 and 6.5/59/41 samples. Considering the continuity of dispersive behaviors, it is suggested that the nanodomains after poling are coupled in a metastable state and are probably responsible for the high piezoelectricity.

Spectroscopic investigations of Nd3+ doped PLZT ceramics on the basis of Judd-Ofelt theory

Transparent Nd doped PLZT ceramic was fabricated using uni-axial hot press. Spectroscopic investigation of Nd3+ (1.0at%) doped PLZT(8/65/35) ceramic was carried out using Judd–Ofelt theory. Based on this theory the calculated intensity parameters are; Ω2 = 2.22 × 10–20cm2, Ω4 = 1.31 × 10−20cm2, Ω6 = 2.32 × 10–20cm2. These intensity parameters are used to determine the emission probabilities, radiative lifetimes, and branching ratios of the 4F3/2→4IJ (J = 9/2, 11/2, 13/2, 15/2) transitions. The calculated radiative lifetime (179μs) is in good agreement with the measured life time (166μs). Finally, the emission cross-section of the potential laser transitions was also evaluated.

Effect of preparation process on properties of PLZT (9/65/35) transparent ceramics

Lead lanthanum zirconate titanate (PLZT 9/65/35) transparent ceramics were prepared by different methods. The excellent properties of the ceramics were obtained by partial co-precipitation method and microwave sintering, which reduced the sintering temperature from 1200 to 1000 °C, and shortened the sintering time from 180 to 20 min, compared with the traditional methods. The X-ray diffraction patterns confirm the presence of pure perovskite phase and highly crystalline of PLZT ceramics, i.e. the relative density was up to 96.5%. The dielectric constant of the ceramics were 3895. The hysteresis loop of PLZT ceramics prepared by partial co-precipitation method showed typical quadratic type, which would enable their applications in optical communication switches. The transparency of PLZT ceramics was investigated and the transmittance of 53.8% was obtained in PLZT at 850 nm.

Effects of Annealing on Ferroelectric, Optical and Electrically Controlled Light Scattering Properties of PLZT Transparent Ceramics

PLZT (X/70/30) ceramics with different La contents (X=7.45, 7.54, 7.63 mole%) were fabricated by hot-press sintering techniques. The effects of annealing on ferroelectric, optical and electrically controlled light scattering properties of PLZT transparent ceramics were examined and analyzed. The XRD patterns indicated that all the samples were crystallized into a pure perovskite phase without the second phase. The SEM exhibited fully dense, uniform microstructures with well-developed grains. The annealing treatment weakened the degree of squareness of the ferroelectric hysteresis loop, and even the anti-ferroelectric phase occurred as the La content increasing to X=7.63. The remnant polarization (Pr) and coercive electric field (Ec) decreased with the annealing treatment for all samples. The slow annealing treatment resulted in the lager increase of both transmittance and contrast ratio than those of the rapid annealing treatment at λ=632.8nm. The electrically controlled light scattering properties were obviously enhanced by the annealing treatment. Especially, the PLZT (7.63/70/30) ceramics exhibited the different electrically controlled light scattering performance which indicated it could hold high transmittance and symmetry in a wide electric field range with the slow annealing treatment.

Diffuse phase transition in mechanically activated (Pb1−xLax)(Zr0.60Ti0.40)O3 electro-ceramics

In this paper, the dielectric properties of (Pb1−xLax)(Zr0.60Ti0.40)O3 (referred to from now on as PLZT x/60/40) ceramics were investigated for the optimization of La substitution at the A-site of PZT ceramics. The PLZT x/60/40 ceramic powders were synthesized by mechanical activation and compaction of these fine scale nano powders was done using cold isostatic pressing. The present study suggests that lanthanum substitution affects the nature of the ferroelectric phase transition of PZT showing a deviation from normal to the diffuse type phase transition (DPT). The parameters of this DPT, such as the degree of deviation from Curie–Weiss law (ΔTm), diffuseness empirical parameters γ and ΔTdiff were calculated for different compositions of PLZT ceramics at 1 kHz. The large value of γ (1 < γ < 2) and ΔTdiff confirms the deviation from normal phase transition and the high degree of disorderliness in the material. It is also found that the Curie temperature Tc and maximum dielectric constant emax both decrease with increasing La3+ content. The maximum value of dielectric constant for the PLZT 8/60/40 ceramics was found to be ~1975.

Effect of surface disorder on the domain structure of PLZT ceramics

ABSTRACTPb1-xLax(Zr0.65Ti0.35)1-x/4O3 (PLZT x/65/35) ceramics were studied by Piezoresponse Force Microscopy in order to understand the origin of domain structure as a function of La content. We show that the domain topology is mainly determined by the composition and grain size. The characteristic correlation length decreases with increasing La content, being sensitive also to the synthesis method. The behavior of the correlation length is linked to the macroscopic properties, showing a strong increase of disorder with La doping. The roughness exponent for the domain wall in PLZT 9/65/35 is close to 2/3 indicating 1D character of domain walls in relaxors.

Influence of poling voltage on optical absorption spectra, thermal properties, and structure of PLZT ceramics

ABSTRACTThe evolution of the optical absorption spectra, thermal properties and structure of Pb1-xLax(ZryTi1-y)1-x/4O3 ferroelectric ceramics, which are widely known due to extended use in electronics, are studied when ceramics are submitted to different poling voltages. Structure analysis was done using XRD, Scanning Electronic Microscopy, and Rietveld Refinement. XRD and Rietveld Refinement attest phase transition upon poling. Thermal properties are investigated using Inverse photothermal technique. Thermal diffusivity results show an increment as poling voltage increase. Photoacoustic Spectroscopy is used to determine optical absorption spectra, revealing higher optical transmission through material when higher voltages are applied.

Effects of Mn doping on dielectric properties of ferroelectric relaxor PLZT ceramics

A series of PLZT (8/65/35) ceramics with different Mn2O3 concentration (0.01, 0.1, 0.3, 1.0, and 3.0% by weight) have been synthesized to figure out its influence on their dielectric properties. The complex dielectric permittivity ε* = ε′−iε″ as function of frequency and temperature as well as polarisation loops P(E) have been studied as a function of Mn concentration.It was found that Mn doping is restrained the Vogel-Fulcher law held in the unmodified PLZT compound producing essential change of the dependence of ε* on temperature and frequency and of the shape of P(E). The observed effects are explained by gradual involvement of Debye and Maxwell-Wagner polarisation mechanisms in relaxation processes with the growth of the concentration of Mn concentration admixture. A decrease of the ε'(T) maximum value and shift of the maximum to higher temperatures is observed.The observed effects are attributed to impacts of Mn2+ and Mn3+ ions: formation of oxygen vacancies paired with Mn2+ as dipoles and Jahn-Teller distortion prompted by Mn3+ ions.

Effect of anisotropy on the ferroelectric, optical, and electro-optic properties of PLZT transparent ceramics prepared by uniaxial hot-press sintering techniques

PLZT (X/70/30) ceramics with different La contents (X = 7.45, 7.51,7.57, 7.63) were fabricated to study the effect of anisotropy on ferroelectric, optical, and electro-optic properties in parallel and normal to the uniaxial hot-press sintering direction (abbreviated as parallel and normal), respectively. All samples show the square hysteresis loops but the tetragonality with ferroelectricity is more evident in a parallel direction than that in normal direction. The high transmittances (≥60%, 0.35mm, visible to near infrared light) are obtained. However, the transmittances and the light scattering contrast ratios are higher in the normal direction. The PLZT (7.63/70/30) ceramic exhibits the more stable electrically controlled light scattering behavior in parallel direction and its contrast ratio reaches to the maximum 1.37 in a normal direction in this system.

PLZT(8/65/35) 세라믹스의 소결온도에 따른 유전 및 전기열량 특성

PLZT(8/65/35) 세라믹스의 소결온도에 따른 유전 및 전기열량 특성

Excitation and emission of Pr3+:PLZT ceramics

Excitation and emission spectra of Pr3+:PLZT ceramics have been studied. Several emission bands were measured under blue laser excitation, which correspond to 3P0→3H4, 1D2→3H4, 3P0→3H4 and 3P0→3F2 transitions of trivalent Pr3+. Their integrated emission intensities were determined. The blue-to-red luminescence intensity ratios of Pr3+ depend significantly on free sintering/hot pressing methods used for PLZT fabrication and activator concentration. Luminescence decay curves for the 1D2 state of Pr3+:PLZT ceramics are also presented and discussed.

Evidence of Normal to Anti Ferroelectric Phase Transition of PLZT Transparent Ceramics of Different Zr/Ti Ratio

The lanthanum-modified lead zirconate titanate transparent ceramics with different Zr/Ti ratio were prepared by the hot pressing sintering method. A single perovskive structure with a dense microsctructure was obtained and the transgranular fracture of PLZT ceramics tended to be more serious As the Zr/Ti ratio increases, the transmittance of PLZT ceramics tended to be higher and the transgranular fracture became more serious. The P-E loops changed froe a square hysteresis loop to a double tending slim hysteresis loop. Besides,the S-E loops changed from a approximate parabolic shape to a butterfly shape. These two loops confirm the transition from normal ferroelectric to anti ferroelectric phase occured with the Zr/Ti ratio increasing.