PLZT Powders Research Articles

Enhancing piezoelectricity of PLZT ceramics by bismuth stearate coating via water-soluble defatted powder injection molding

Lead zirconate titanate-based piezoelectric ceramics (Pb0·91La0·06(Zr0·58Ti0.42)0.975Nb0·02O3, PLZT) were prepared by water-soluble defatted powder injection molding using bismuth stearate as surfactant. The effects of bismuth stearate surfactant amount on the feed viscosity, water degreasing rate and electrical properties were studied. The results showed that the bismuth stearate coating reduces agglomeration between the PLZT powders and decreases the viscosity of the feed. During sintering, bismuth stearate is decomposed into bismuth oxide, which acts as sintering aid to increase the density of the sintered bismuth stearate-coated PLZT ceramics. Bi3+ dissolves into the perovskite crystal lattice, which increases the tetragonality factor and the content of tetragonal phase, and improves the dielectric, ferroelectric and piezoelectric properties of the bismuth stearate-coated PLZT ceramics. This study provides a novel modification method for the production of injection molded ceramics using a water-soluble binder system.

Photostriction properties of PLZT (4/52/48) ceramics sintered by SPS

In this paper, the preparation and sintering process of Lanthanum-modified lead zirconate titanate ceramics (PLZT 4/52/48) powders and ceramics were investigated. The PLZT powders were prepared by co-precipitation and sol-gel methods. It is confirmed that PLZT powders synthesized by sol-gel method had smaller grains and better dispersion. The atmosphere sintering and spark plasma sintering（SPS）technique were used to sinter the PLZT ceramics separately. After sintering, the physical, electrical, and optical properties of the PLZT ceramics sintered by different methods were tested. The results show that the SPS sintering can increase the densification degree (reaching 99.5%)of the PLZT ceramics, which improved the transparency, ferroelectric, piezoelectric and optical properties of PLZT ceramics. It is found that when the light intensity reached 600 mW/cm2, the maximum photo-induced strain of the SPS sintered ceramic was as high as 10. 84 × 10−3, which was almost 1.4 times larger than that of the atmosphere-sintered sample. Obviously, the sol-gel method and SPS process can enhance the comprehensive performance of PLZT ceramics.

Micro-structural, dielectric, ferroelectric and piezoelectric properties of mechanically processed (Pb1−xLax)(Zr0.60Ti0.40)O3 ceramics

In this work, (Pb1−xLax)(Zr0.60Ti0.40)O3 (PLZT x/60/40, x = at.%) ceramics were prepared by using high energy mechanical ball milling followed by cold isostatic pressing (CIP), investigated for their micro-structural, dielectirc, ferroelectric and piezoelectric properties. Mechanical activation results in the highly reactive nature of the nano size milled PLZT powders, which enables the partial perovskite phase formation, confirmed by room temperature XRD patterns. CIP leads to a higher density with a closely packed dense microstructure of sintered PLZT ceramics shown in SEM images. The grain size of PLZT x/60/40 ceramics was found to be decreasing with increasing La3+ content. The highest relative density of ~ 97% was found to be for PLZT 8/60/40 ceramics with grain size of ~ 1.35 µm. The PLZT 8/60/40 system also shows the highest dielectric constant of ~ 1976, remnant polarization of 29.1 µC/cm2, piezoelectric coefficients (d33 $$~ \cong ~$$ 570 pC/N, g33 $$~ \cong ~$$ 28.03 × 10−3 Vm/N) and electromechanical coupling factors (kp = k33 = 64.1% and k31 = 54%). The elastic compliances for the PLZT x/60/40 ceramics were also obtained.

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.

Tailoring the functional properties of PLZT-BaTiO3 composite ceramics by core-shell approach

In the present work, composite ceramics of BaTiO3 with La0.08Pb0.92Ti0.20Zr0.80O3 were prepared from powders synthesized by two different methods: (a) PLZT@BT ceramics from core-shell powders with PLZT-core and BaTiO3 shell and (b) PLZT-BT ceramic composites from mixed PLZT and BaTiO3 powders. In core-shell ceramics, a thin conductive layer of BaPbO3 was formed that resulted in an increased effective permittivity with relatively low losses (tan δ < 0.7 in kHz regions). The extrinsic contributions play an important role in both ceramics, but they are more evident in core-shell samples due to the large number of interfaces. These results show that novel functional properties can be tailored by the controlled chemical reaction at interfaces.

Technology and dielectric properties of the PLZT-NZF composites

ABSTRACTThe aims of the study were to design and obtain ferroelectric-ferromagnetic ceramic composites based on ferrite powder and PLZT powder. The synthesis of the composition of the PLZT material of chemical formula Pb0.98La0.02(Zr0.90Ti0.10)0.995O3 was carried out by conventional technology. The composite constituted 90% of PLZT powder and 10% of ferrite powder (Ni0.64Zn0.36Fe2O4).The article presents the technology and the results of a XRD measurement, a microstructure and the dielectric properties of the composite samples. This type of multiferroic materials and ferroelectric-ferrimagnetic composites can be used to develop a new class of transducers/sensors integrating electro-magnetic interaction in a single device.

Lanthanum induced diffuse phase transition in high energy mechanochemically processed and poled PLZT 8/60/40 ceramics

La+3 substitution based piezoelectric material, (Pb0.92La0.08) (Zr0.60Ti0.40)O3 also known as PLZT 8/60/40, was prepared by high energy mechano-chemical ball milling. The highly reactive nature of the nano size (∼15–40 nm) milled PLZT powders enable the partial perovskite phase (confirmed by X-ray diffraction) at room temperature itself. Compaction of these fine scale nano powders by the cold isostatic pressing technique leads to a higher density >98% with a close packed dense microstructure that can be seen in SEM images for sintered ceramics. Dielectric measurements for the electrically poled PLZT 8/60/40 ceramics suggest that the lanthanum substitution affects the nature of ferroelectric phase transition of PZT showing a deviation from normal to the diffuse type phase transition (DPT). The parameters of this DPT, such as degree of deviation from Curie–Weiss law (ΔTm), diffuseness empirical parameters γ and ΔTdiff were calculated at various frequencies from 1 kHz to 500 kHz. The large value of γ (1 < γ < 2) and ΔTdiff at said frequencies confirms the deviation from normal phase transition and the high degree of disorderliness in the material. To support this study, polarization vs. electric field and electromechanical coupling factor (kp) measurements were also performed on PLZT 8/60/40 ceramics within the temperature range of 30 °C–170 °C and 30 °C–210 °C respectively. The effect of temperature on the ferroelectric properties was also studied.

Excellent electrostrictive properties of low temperature sintered PZT ceramics with high concentration LiBiO2 sintering aid

The effect of LiBiO2 (LBO) additive on the sintering of Pb0.97La0.03(Zr0.53Ti0.47)0.9925O3 (PLZT) ceramics was carefully investigated. 6.0wt% LBO added PLZT powders could be fully densified to 98% relative density at a temperature as low as 950°C. It is worthy to notice that there are distinct enhancements in piezoelectric and electrostrictive properties by increasing the soaking time from 2h to 7h, which could mainly originate from the improvement of crystallinity and grain size of PLZT ceramics. By controlling the soaking time and concentration of LBO addition, PLZT ceramics sintered at 950°C could exhibit high curie temperature of 240°C and very high S11 of 0.22% under 3.0kV/mm, which is even better than that of traditionally sintered PZT-5, PMN–PZT, and this is very promising for actuators designed in multilayer structure in high temperature environment.

A factorial design approach for pressureless sintering in air of (Pb,La)(Zr,Ti)O 3 synthesized via coprecipitation of oxide–alkoxides

Using factorial design for guidance, (Pb,La)(Zr,Ti)O 3 (PLZT) ceramics of compositions 9.5/65/35 and 5/Z/T (Z/T = 60/40, 54/46, 40/60) were pressureless sintered in air. Theoretical bulk densities of up to 96% were achieved. The starting materials were obtained from the coprecipitation of the oxide–alkoxides. The relevant sintering parameters were initially screened with the 9.5/65/35 composition using a factorial design method to achieve high-density, high purity perovskite-phase, and small grain-size. The variables were ball-milling time, cold-press pressure, sintering time, sintering temperature, vacuum treatment, and PLZT to PbZrO 3 weight ratio. The optimized sintering conditions were then applied to the remaining PLZT compositions, as well as to a commercially purchased PLZT powder, PLZT 8/40/60 to yield similar ceramic qualities. The ceramic samples were characterized with SEM, XRD, and Raman spectroscopy, and their relative permittivity, ɛ r, and the piezoelectric constant, d 33, were measured.

Effect of oxidant-to-fuel ratios on phase formation of PLZT powder; prepared by gel-combustion

Single phase, PLZT powder was synthesized using gel-combustion route. It has been observed that fuel-to-oxidant ratio affects the initial phase formation. Higher fuel content leads to direct formation of crystalline perovskite PLZT powder due to substantial rise in the temperature during the redox reaction. Perovskite PLZT phase formation takes place at 550 °C, without any intermediate phase formation, for stoichiometric fuel-to-oxidant ratio. The crystallite size was found to be independent of fuel-to-oxidant ratio when the ash is heated above 700 °C.

Preparation and Dielectric Properties of 1-3 La Modified PZT/IPN Piezoelectric Composites

To prevent the potential cracking of gel fibers, La modified lead zirconate titanate (PLZT) ceramic fibers with diameter within 50µm were achieved by embedding into PLZT powders during the heat treatment. Then the 1-3 PLZT fiber/interpenetrating polymer network (IPN) piezoelectric composites were prepared by casting the IPN precursors onto the well aligned ceramic fibers. The influences of the heating temperatures and La amounts on the dielectric constant, dielectric loss with frequencies and piezoelectric constant of PLZT were investigated in detail. The morphologies of fibers and composites were observed by biological microscope. And also, the dielectric constant of PLZT fibers and PLZT fiber/IPN piezoelectric composites were detected.

Aqueous colloidal processing of PLZT ceramics near the morphotropic phase boundary

Single phase PLZT powder was fabricated using the mixed oxide approach, with a composition (6/60/40) lying on the rhombohedral-tetragonal (morphotropic) phase boundary. Aqueous suspensions showed an IEP of pH 9·7 in the absence of a polyelectrolyte surfactant. Inductively coupled plasma optical emission spectrometry analysis demonstrated considerable leaching of Pb2+ and La3+ ions under acidic conditions. The addition of an ammonium salt of poly(methacrylate), or PMA-NH4, decreased the IEP to pH 5-6. Suspensions were readily stabilised at basic pH using low PMA-NH4 concentration (<0·1 wt-% of solids). Concentrated suspensions exhibited shear thinning behaviour under low shear rates, with a transition to shear thickening at modest rates (i.e. 100 s−1). Excessive shear thickening imposed a maximum solids loading of 46 vol.-% on concentrated suspensions, which related to the somewhat ‘flake-like’ particle morphology. Slip casting resulted in green and sintered (1250°C for 30 min) densities of 56±1% and 98·3±0·6% of theoretical, respectively.

Investigation of Electro-optic Light Modulators with PLZT Thin Films Prepared by Aerosol Deposition Method

We investigated a fabrication process and optical properties of electro-optic (EO) light modulators with Fabry-Perot structure, which consisted of PLZT [(Pb0.91, La0.09)(Zr0.65, Ti0.35)O3] thick films by aerosol deposition method. A supernatant elimination process for small size PLZT powder with diameter of 0.125-0.175 μm was effective in order to obtain a transparent film. In the fabricated Fabry-Perot type EO light modulator with a ITO (Indium Tin Oxide))/PLZT/ITO defect layer, a wavelength of resonant localized mode was shifted about 1.0 nm from 788 nm by applying an electric field of +400 kV/cm in reflectance mode, and consequently the reflectance difference of 7.2 % was observed. The Fabry-Perot type EO light modulator had the advantage of contrast of light in the reflection mode.

Pyroelectric and dielectric properties of lead lanthanum zirconate titanate (Pb0.92La0.08)(Zr0.65Ti0.35)O3-P(VDF/TFE)(0.98/0.02) nanocomposites

PLZT-P(VDF/TFE) 0-3compositeswithnanosized lead lanthanum zirconate titanate (Pb0.92La0.08)(Zr0.65Ti0.35)O3 (PLZT 8/65/35) ceramic powders of volume fraction Φ up to 0.2 were fabricated using PLZT powders imbedded in a copolymer P(VDF/TFE)(0.98/0.02) matrix. The PLZT nano- powders were prepared by the sol-gel technique. The PLZT-P (VDF/TFE) composite samples were prepared from ceramic and polymer powders by the hot-pressing method. Dielectric response was studied in the frequency range from 100 Hz to 1 MHz and at temperatures from 100 to 450 K. The pyro- electric properties were studied by dynamic method with modulation frequency from 1 to 100 Hz. The dielectric re- sponse of the ceramics-polymer composite was found to be a combination of the responses of the pure polymer and the ceramics: (1) the addition of the PLZT ceramics increases the value of the dielectric permittivity ɛ', (2) the composite shows the maximum of the permittivity coming from the PLZT ceramics, (3) the temperature dependences of the dielectric loss tgδ are characterized by the maximum attributed to the α-relaxation (glass transition) in the pure polymer. The py- roelectric coefficient of the composite increases from ∼20 μC/m 2 K in pure P(VDF/TFE) to ∼140 μC/m 2 Ki n the com- posites of Φ=0.15.

Dynamic dielectric response of PLZT-P(VDF/TFE) nanocomposites

Dynamic dielectric relaxation of polymer P(VDF/TFE)(0.98/0.02) loaded with lead lanthanum zirconate titanate (Pb0.92La0.08)(Zr0.65Ti0.35)O3(PLZT 8/65/35) ceramic nanopowders was studied in the frequency range from 100 Hz to 1 MHz and at temperatures from 100 K to 450 K. The PLZT nanopowders were prepared by the sol-gel method using: lead(II)acetate trihydrate, lanthanum acetate hydrate, zirconium(IV)propoxide and titanium(IV)propoxide. The crystallization process of PLZT powders was monitored by means of XRD analysis (Philips PW 3710) using Cu-Kα radiation in the range 20° ≤ 2Θ ≤ 60°. The powders were analyzed before and after burning of the organic remains. The morphology observations of the powders were made using Hitachi S-4700 scanning electron microscope (SEM), and the grain size distributions were measured on a Zetasizer Nano ZS by the DLS method. The PLZT-P(VDF/TFE) composite samples of 0-3 connectivity were prepared from ceramic and polymer powders by the hot-pressing method. The volume fraction of the ceramics Θ amounted 0.1, 0.15 and 0.2. The dielectric response of the ceramics-polymer composite was found as a combination of the responses of pure polymer and the ceramics: (i) the addition of the PLZT ceramics increases the value of the dielectric permittivity ϵ, (ii) the composite shows the maximum of the permittivity coming from the PLZT ceramics, (iii) the dielectric absorption spectrum of the composites is dominated by the α-relaxation in pure polymer.

Preparation of PLZT Powders from Oxides via High-Energy Ball Milling Process

Lanthanum-modified lead zirconate-titanate (PLZT5/54/46) powders were prepared from the commercial PbO, La2O3, TiO2 and ZrO2 powders by high-energy ball milling process. The synthesized powders milled for different hours were characterized using XRD and SEM. Thedesigned PLZT perovskite phase was formed from the mixture of the starting materials after milling for 20 hours. PLZT(5/54/46) ceramics were obtained using the produced powders milled for 20 h followed by sintering at temperatures ranging from 1000 to1200°C. Ferroelectric property of the PLZT ceramics was also measured.

PLZT—Synthesis, sintering and ceramics microstructure

Producing of PLZT powders by original two-stage co-precipitation method from mixed solution of inorganic salts ZrOCl 2·8H 2O, TiCl 4, La(NO 3) 3·6H 2O, Pb(NO 3) 2, was carried out. The sequence of phases formed during PLZT synthesis has been studied by X-ray and DTA analysis. Ceramic samples were prepared by two-stage hot-pressing technology. Dielectric, ferroelectric and optical properties have been measured. Ceramic microstructures were studied by SEM with energy dispersive analytical capability (EDX). The fine-grained microstructure was quite uniform with the average grain size of 5–7 μm, without internal or grain boundary porosity. The optical transmittance of ceramic plates (thickness of 0.3 mm) measured at wavelength of 630 nm reached 67–69%.

Effects of Preparation Conditions on the Structural and Optical Properties of Spark Plasma‐Sintered PLZT (8/65/35) Ceramics

Transparent lanthanum‐doped lead zirconate titanate (PLZT) ceramics with high density were fabricated using spark plasma sintering (SPS), a recently developed hot‐pressing method. A wet–dry combination method was used to prepare the fine PLZT powders. The average grain size of the PLZT ceramics was less than 1 μm, because of a relatively low sintering temperature and a very short sintering time. The transmittance of PLZT ceramics increased with an increase of calcination temperature up to 700°C and then it slightly decreased with further increase of calcination temperature. The transmittance strongly depended on the SPS temperature and heat‐treatment temperature. The pellet sintered at 900°C for 10 min and heat treated at 800°C for 1 h with a thickness of 0.5 mm showed a transmittance of 31% at a wavelength of 700 nm. The relationships between the transmittance and the microstructure were investigated.

Characterization of Hydrothermally Synthesized PLZT for Pyroelectric Applications

PLZT fine powders have been synthesized by a hydrothermal process using lead acetate, lanthanum acetate, zirconium n-propoxide and titanium isopropoxide as starting materials. The synthesis was performed at 200°C for 8, 12 and 24 h. 4 M KOH was used as a mineralizer to adjust the pH to an optimum value for the mixed precursor solution. After hydrothermal treatment the solid portion was separated out, washed and dried at 100°C for 12 h, where PLZT fine powders were obtained. PLZT powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The PLZT powders were pressed and sintered to obtain high density ceramics, which then were investigated by XRD and SEM. The dielectric properties of the ceramics were investigated by measurements of dielectric constant and dielectric loss as a function of temperature at a fixed frequency.

Effects of powder preparation and sintering procedure on microstructure and dielectric properties of PLZT ceramics

PLZT ceramics belong to one of the very important groups of functional materials that make a basis for the production of a large range of electronic devices. The microstructure and properties of ceramics depend on the powder preparation and thermal processing conditions. Various techniques have been used to obtain chemically homogeneous and fine starting powders PLZT powders have been prepared by two different production routes: by a modified Pechini method, using a polymeric precursor method (PMM) and by a partial oxalate method. A two-step sintering process, including a hot pressing, was carried out at 1100 and 1200?C. Distinct phases obtained during the sintering process have been investigated by SEM and EDS techniques and dielectric properties such as permittivity and dielectric loss were measured in a frequency range from 1 to 20 kHz. A significant difference in microstructure and dielectric properties, depending on powder origin and sintering procedure, has been noticed.