Nanocrystalline Lead Zirconate Titanate Research Articles

PZT 50/50 nanocrystalline powders with tetragonal structure prepared via gel combustion route: Effect of heat treatment on phase and chemical compositions

Comparative structural and thermal investigations of a process of formation of nanocrystalline lead zirconate titanate Pb(Zr0.50Ti0.50)O3 (PZT 50/50) powders, with a tetragonal structure, prepared via a gel combustion route under different thermal treatment conditions, were conducted. The thermal behaviour of a gel and an as-formed combustion product (powdered precursor) was studied using TGA/DTA techniques. The XRD study of the powdered precursor calcined at various temperatures, in combination with the TGA/DTA data, resulted in the establishment of the optimal temperature mode for obtaining a single-phase PZT 50/50 nanopowder. A possible mechanism for the formation of the PZT 50/50 phase during gel combustion has been proposed.Formation of a single-phase PZT powder with a given molar ratio of Pb/Zr/Ti = 1/0.5/0.5 was verified by XRD, μ-XRF and EDS methods. The results of XRD and FTIR spectroscopy indicated the tetragonal crystal structure of the PZT powder. The nanocrystalline nature of PZT 50/50 was confirmed by both XRD and SEM data. SEM studies revealed that the prepared nanopowders had a homogeneous, porous, coral-like microstructure with an average grain size in the range of 90–100 nm. According to the simultaneous thermal analysis (TGA/DSC) results, thermal stability of the PZT 50/50 nanopowder was observed up to 1000 °C. Local capacitance and the distribution of its values were measured on the surface of the PZT 50/50 coating, formed on Pt/Al2O3/Pt substrate using the screen printing technique, using scanning capacitance microscopy (SCM).

Influence of PbO phase content on structural and optical properties of PZT nanopowders

Nanocrystalline lead zirconate titanate (PZT) powders were synthesized via a modified Pechini method. The effect of heat treatment temperature on the microstructural properties was studied using X-ray powder diffraction. The explored temperatures were identified from the TGA/DSC measurement and it is found that the crystallization starts from 550 °C. Rietveld refinement was applied to study structural changes and to quantitatively assess the fractional content of lead monoxide, identified in nano-PZT powders. Lebail method was carried out to the XRD pattern to accurately determine the peak broadening and position. Size-Strain Plot and various Williamson-Hall methods were used to calculate the lattice microstrain and crystallite size. The minimum strain was noticed in the pure tetragonal-PZT sample. TEM technique was also employed to study nanopowders and to confirm the formation of small-sized particles. The energy band gap was determined by diffused reflectance measurements and found to range from 3.17 to 3.29 eV.

Raman Spectroscopy Studies of Nanocrystalline Lead Zirconate Titanate as Functions of Particle Size and Pressure

The Raman studies of lead zirconate titanate with varied grain size from 27.5 nm to 983 nm were performed under pressure up to 32 GPa to elucidate the scenario of phase transition pressures of lead zirconate titanate, which lies in the morphotropic phase boundary. The coexistence of ferroelectric rhombohedral and tetragonal phases at ambient condition changed to the coexistence of tetragonal and cubic phases at intermediate pressure and finally, transited to paraelectric cubic phase at elevated pressure. The pressure evolution of Raman spectra results indicated that the phase transition pressure increased with the reduction of the particle size.

Solvothermal Synthesis of Size-Controlled Lead Zirconate Titanate Particles

Nanocrystalline lead zirconate titanate (PZT) powders have been synthesized by solvothermal method, in which a mixed solvent of ethanol and water was used as reactive medium and Pb (NO3)2, ZrOCl2·8H2O, C16H36O4Ti, KOH and NH3·H2O were used as raw materials. It was found that PZT particle sizes decreased from 2 μm to 100 nm with the ratio of Vethanol/Vwater increasing from 1/2 to 2/1 under a KOH concentration of 4 mol/L at 200 °C for 4 h. It indicated that the Vethanol/Vwater of mixed solvent played an important role in controlling the morphology and size of PZT crystals, as well as reaction temperature.

Combustion synthesis and electromagnetic properties of nanocrystalline Pb(Zr0.52Ti0.48)O3

The properties of nanocrystalline lead zirconate titanate [PZT, Pb(Zr0.52Ti0.48)O3] thick films and pellets synthesized by self-propagating auto combustion route using sucrose as a fuel are reported. The X-ray diffraction reveals the formation of nanocrystalline tetragonal PZT having a particle size of 5.52 nm in thick films and 7.08 nm in bulk material. SEM images show the grain size of 300–400 nm with some agglomeration, as well as modified open grain boundaries and grain growth in the PZT thick film as compared to the bulk material. The DC electric resistivity of PZT shows semiconducting behavior. We also characterized the 8–18 GHz microwave insertion loss, absorption, complex permittivity, and microwave conductivity of synthesized materials. The real part of permittivity and dielectric loss were found to decrease with increasing frequency.

Synthesis and Characterization of Nanocrystalline PZT Powders by a Simple Sol-Gel Method

Nanocrystalline lead zirconate titanate (PZT) powders with composition at the morphotropic phase boundary (MPB) were synthesized by a simple aqueous based sol-gel method, using lead nitrate, zirconium nitrate and tetrabutyl titanate as the starting materials. The sol could be easily transformed into gel, firstly heated at 120°C for 10h, then at 180°C for 24h. The thermal decomposition process of the gel was investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The effect of citrate addition amount on the calcining temperature was discussed. The results reveal that pure perovskite phase PZT powders can be obtained at a calcining temperature as low as 600°C. The average grain size of the powders was determined by transmission electron microscope and X-ray diffraction. The influences of calcining temperature and the pH value of the solution on the grain size were investigated. The sintering temperature and electrical properties of the ceramics derived by nano-powders were compared with those prepared by the conventional ceramic processing. The result shows that using the nanopowder, the sintering temperature could be reduced by about 100°C and the ferroelectric properties were enhanced.

Synthesis and Characterization of Sol–Gel Derived PZT Nano Powder

Single phase nanocrystalline lead zirconate titanate (PZT) powder of composition Pb(Zr(0.52)Ti(0.48))O3 has been prepared by sol-gel process by using lead acetate trihydrate, zirconium propoxide and titanium propoxide as lead, zirconium and titanium precursor materials respectively. XRD, FTIR and TGA/DTA techniques are used to characterize structural, vibrational and thermal changes involved during the formation of PZT nanocrystalline powder with tetragonal phase. XRD pattern exhibits the polycrystalline nature of the powder heat treated at 800 degrees C with preferential orientation of (110) plane. Simultaneous TGA/DTA studies of the gel powder show endothermic and exothermic peaks corresponding to weight loss at different temperatures and increase in weight between 750 degrees C and 800 degrees C which confirms the improvement in crystallization. IR transmittance spectra of the powders heat treated at 650 degrees C and 750 degrees C show the coexistence of rhombohedral and teragonal phases and above this temperature only teragonal phase exists.

Size effect studies on nanocrystalline Pb(Zr 0.53Ti 0.47)O 3 synthesized by mechanical activation route

The nanocrystalline lead zirconate titanate (PZT) with the composition Pb(Zr 0.53Ti 0.47)O 3 has been synthesized by mechanical activation, without calcination at intermediate temperature. The PZT powder that has been mechanically activated for 10, 20 and 30 h shows crystallite size of 15, 12 and 8 nm, respectively. Size effect on PZT formation, tetragonality factor and dielectric constant has been investigated in detail. TEM and AFM studies have been carried out to confirm the formation of nanocrystalline PZT. The temperature dependence of dielectric constant at different frequencies was also measured, to study the size effects in PZT ferroelectrics. The nanocrystalline PZT obtained by this route has high dielectric constant at Curie temperature in comparison to that prepared conventionally.

Metastable face-centered cubic lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT) nanocrystals synthesized by auto-ignition of metal–polymer gel

Nanocrystalline lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT) have been synthesized in powder form by a single-step auto-ignition of metal–polymer gel precursor. The nanocrystalline powders were characterized using analytical transmission electron microscopy (TEM) equipped with an energy-dispersive x-ray spectrometer (EDXS) for composition analysis. For both PZT and PLZT, nanoparticles of sizes as low as 1–5 nm along with larger nanoparticles of sizes up to 30 nm are observed in the TEM. The selected-area diffraction (SAD) patterns from the nanoparticles revealed a face-centered cubic (fcc) crystal structure for both PZT and PLZT with a lattice parameter of ∼0.51 nm. The formation of PZT and PLZT nanoparticles of sizes below 5 nm with metastable fcc crystal structure has been observed for the first time. It is concluded that, as the crystal size decreases, the system assumes crystal structures of higher symmetry initially through small changes in lattice parameters and, in extreme cases, through chemical disorder for ultrafine nanoparticles.

Nonaqueous Synthesis of Amorphous Powder Precursors for Nanocrystalline PbTiO3, Pb(Zr,Ti)O3, and PbZrO3

A novel, facile nonaqueous synthesis route to nanocrystalline lead zirconate titanate (PZT) powders is presented. Simple mixing of lead acetylacetonate with titanium and/or zirconium alkoxides in 2-butanone, followed by a solvothermal treatment at 200 °C, produced amorphous, nanosized precursor powders. According to X-ray diffraction and transmission electron microscopy investigations, calcination at comparably low temperatures yielded highly crystalline, phase-pure powders consisting of monocrystalline particles in the size range of about 10−30 nm. Thermogravimetric and infrared analyses of the as-prepared samples showed a content of organic species of about 10 wt %, which are decomposed between 200 and 330 °C. The lack of further weight loss above 400 °C proves the absence of PbO evaporation, a major drawback of previous PZT preparations. Crack-free thin films were obtained by simply casting a dispersion of precursor powders on a silicon substrate followed by thermal treatment. Scanning electron microsc...

Free-Standing Lead Zirconate Titanate Nanoparticles: Low-Temperature Synthesis and Densification

Nanocrystalline lead zirconate titanate (PZT) powder with an average particle size between 70 and 110 nm was synthesized using the citrate nitrate (C/N) autocombustion method. Phase-pure perovskite...

Novel Synthesis Route to Make Nanocrystalline Lead Zirconate Titanate Powder

The present research describes synthesis of perovskite lead zirconate titanate (PZT) nanocrystalline mesoporous powders from the aqueous solutions of Pb2+, Zr4+, and Ti4+ metal ions using sucrose as a template material. Sucrose retains the metal ions in solution through complex formation. Dehydration and thermal decomposition of the metal ion–sucrose mass produces a large amount of gas, which helps to create porosity and high surface area in the final products. The particle size of the synthesized powder is between 50 and 60 nm, with a average specific surface area between 20 and 25 m2/g. The surface area increases as the amount of sucrose increases. Nanocrystalline PZT powder with high surface area can be useful for low-temperature sintering.

Low Temperature Processing of Nanocrystalline Lead Zirconate Titanate (PZT) Thick Films and Ceramics by a Modified Sol-Gel Route

Dispersing fine particles into a sol-gel matrix is a promising process to get a thick 0–3 composite coating layer. In this paper, we have further improved this modified sol-gel process by nanocrystalline composite technique to realize the low temperature annealing. Dense Pb(Zr, Ti)O3 (PZT) thick films of 10 to 50 µm in thickness have been obtained on the platinum-coated silicon substrates by spin-coating at sintering temperature of 600–700°C and fully developed submicron-sized grains have been demonstrated in screen-printing piezoelectric films on alumina substrates at sintering temperature of 700–800°C. The dependence of various properties such as microstructure, crystallization, ferroelectric and dielectric properties of such made thick films on the processing parameters have been investigated. For a 10 µm-thick film spin-coated on silicon wafer, the dielectric loss and relative permittivity are 0.010 and 1024, respectively, at 1 kHz. The remanent polarization (Pr) and the coercive field (Ec) are 13.6 µC/cm2 and 34.5 kV/cm, respectively. Obviously, such made thick film has comparable properties with bulk PZT ceramic. This novel technique can be extensively used in sol-gel, screen-printing, tape-casting, even in traditional ceramic process to reduce the process temperature.

A novel chemical route for the preparation of nanocrystalline PZT powder

Nanocrystalline lead zirconate titanate (PZT) powders were prepared starting from the solution of Ti (IV), Zr (IV), Pb (II) ions complexed with organic acids and amines. The complex solutions after complete evaporation decomposed and produced fluffy masses, which after calcination at lower temperature in comparison to solid-state method yield the desired phase of PZT. Various complexing agents such as oxalic acid, tartaric acid, ethylene diamine tetra acetic acid (EDTA), diethanolamine (DEA) have been used to influence the particle size and dielectric property in the PZT system. The precursors and the heat-treated powders are characterized by TG/DTA, XRD, and TEM analysis. The precursors obtained from the mixed solution of Ti (IV)–Zr (IV)–X/Pb (II)–EDTA (where X=oxalic acid, and tartaric acid) and Ti (IV)–Zr (IV)–Pb (II)–Y (where Y=Diethanolamine) produce pure PZT phase at 600°C, 400°C, 200°C, respectively. The corresponding average particle sizes are 60, 30, and 25 nm.

Pulsed laser deposition of nanocrystalline lead zirconate titanate thin films

Nanocrystalline ferroelectric thin films are obtained by pulsed laser deposition from a target prepared by sintering at approximately 700 °C nanosized powders of Pb(Zr0.52Ti0.48)O3 (PZT) with 1% weight addition of Nb2O2. The powder was prepared by spray-drying and it was calcinated at 500 °C. Film deposition is performed on Si(100) and Au/Si(100) substrates in a reactive oxygen atmosphere using a pulsed Nd-YAG laser with energy 0.3 J/pulse, wavelength 1064 nm, pulse duration 10 ns and frequency 10 Hz. The film samples are investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and dielectric measurements. The crystallite dimension of PZT films has been found through morphological analysis to be about 30-40 nm. A broadening of the dielectric constant peak at the ferroelectric transition temperature due to finite-size effects is observed. The critical coefficient γ in the Curie-Weiss law is found to be 1.85 which is indicative of a partially diffused phase transition.

Low‐Temperature Preparation of Nanocrystalline Lead Zirconate Titanate and Lead Lanthanum Zirconate Titanate Powders Using Triethanolamine

Nanocrystalline lead zirconate titanate (PZT) powders, with a Zr:Ti ratio of 60:40, have been prepared from a solution of triethanolamine (TEA) and Ti4+, Zr4+, and Pb2+ ions. The metal ions were in solution through complex formation with TEA. The soluble metal‐ion–TEA complex formed the precursor material when it was completely dehydrated. Heat treatment of the precursor at 450°C resulted in single‐phase PZT powders. The precursor and the heat‐treated powders have been characterized by using thermal analysis and X‐ray diffractometry (XRD) studies. The average particle size, as measured from X‐ray line broadening and transmission electron microscopy studies, was ∼20 nm. PZT powders modified with 3 mol% of lanthanum (PLZT) also were prepared through this route and were investigated via XRD studies. The dielectric constants of the PZT and PLZT powders were 12475 and 11262, and their corresponding Curie temperatures were 362° and 315°C, respectively.

Raman Phonon Modes and Ferroelectric Phase Transitions in Nanocrystalline Lead Zirconate Titanate

Micro-Raman spectra for PbZr x Ti 1-x O 3 (PZT) with grain sizes of 60 and 40 nm have been obtained. The results show that the E(TO 1 ) phonon mode of PbTiO 3 ('soft' mode) displays a decrease in frequency and an increase in linewidth with increasing Zr concentration. A discontinuous behavior in the phonon energy for the soft mode occurs at a morphotropic phase boundary (NPB) of x 0.4 and 0.2 for grain sizes of 60 and 40 nm, respectively, and it can be attributed to a phase transition from ferroelectric tetragonal to ferroelectric rhombohedral phase. The nonzero soft mode frequency near the MPB results from a level repulsion between an additional phonon mode at 10 cm -1 and the soft mode. Raman enhanced behavior has been found for the lowest phonon mode with Zr contents in the range of 0.3 to 0.6. The dependence of Raman phonon modes for PbZr 0.3 Ti 0.7 O 3 upon grain size has been analyzed and the results indicate a grain-size-induce(I phase transition at 13 nm.