Lead Zinc Niobate Research Articles

Polaron-mediated transport and relaxation phenomena in the lead zinc niobate (PZN) modified bismuth ferrite solid solution

To investigate the dielectric and conductivity properties of PZN modified BF solid solution high temperature mixed oxide technique is employed. The material is subjected to analysis using XRD, SEM, and impedance spectroscopy. A polycrystalline PZN-BF sample with an average crystallite size of 63.3 nm has been formed. The scanning electron micrographs show that the grains and grain boundaries are distributed suitably. dielectric characteristics of the 0.1PZN-0.9BF compound are studied at frequencies ranging from 1 kHz to 1 MHz and temperatures ranging from ambient temperature to 400 °C. The confined mobility of charge carriers causes nearly continuous loss (NCL) behavior at low temperatures (<200 °C). High-temperature relaxation resulting from charge carrier hopping induces maximum loss and elevated conductivity. Rendering to the Overlapping Large Polaron Tunnelling (OLPT) model of conductivity, the transport mechanism in this modified BiFeO3 (BF) compound is facilitated by the short-range hopping of polarons. The NTCR behavior from Arrhenius plot of ac conductivity and temperature independent conductivity relaxation from loss modulus (M'') analysis are demonstrated. Sensors, actuators, and optoelectronic devices can benefit from the PZN-modified BF compound's electrical and dielectric characteristics, which have been studied in detail.

Effect of sintering temperature on phase formation and dielectric property of modified PLZT ceramics with addition of BT and PZN

ABSTRACT The modified-lead lanthanum zirconate titanate (PLZT) ceramics with the addition of barium titanate (BT) and lead zinc niobate (PZN) were prepared. PLZT 9/65/35–BT ceramics changed from ferroelectric rhombohedral phase to paraelectric cubic phase as the content of BT was increased. The optimized dielectric constant at room temperature and frequency of 1 kHz could be obtained when 5 mol% BT was added and the ceramic was sintered at 1275 °C (ϵr = 10463, tanδ = 0.0125). PLZT 8/40/60–PZN ceramics had a perovskite structure with a decrease of unit cell volume as the content of PZN was increased. The optimized dielectric constant at room temperature and frequency of 1 kHz could be obtained when 20 mol% PZN was added and the ceramic was sintered at 1250 °C (ϵr = 14290, tanδ = 0.0081).

A brief review on the status of binary and ternary relaxor-PT materials

Compare lead zirconate titanate (PZT), a new generation relaxor-PT material that shows significantly improved properties with very high electromechanical coupling and piezoelectric coefficients, which makes them optimistic piezoelectric materials for various applications like sensors, transducers, and actuators. In this paper, we discuss the status of binary relaxor-PT materials such as lead zinc niobate - lead titanate (PZN–PT), lead magnesium niobate - lead titanate (PMN–PT), lead scandium niobate - lead titanate (PSN-PT), lead indium niobate - lead titanate (PIN-PT), and lead nickel niobate - lead titanate (PNN-PT) and ternary relaxor-PT materials lead indium niobate -lead magnesium niobate - lead titanate (PIN-PMN-PT), lead indium niobate - lead zinc niobate - lead titanate (PIN-PZN-PT), lead zinc niobate - lead magnesium niobate - lead titanate (PZN-PMN-PT), and lead scandium niobate - lead magnesium niobate - lead titanate (PSN-PMN-PT).

Large tunability of frequency in Fe0.5Co0.5-ZnO/PZN-PT nanogranular films with high resistivity

Abstract The soft magnetic films (SMFs) using in monolithic microwave integrated circuits (MMICs) are suffered from the lower ferromagnetic resonance frequency f FMR and resistivity. In this study, Fe0.5Co0.5-ZnO films with high resistivity were fabricated by a compositional gradient sputtering on (0 1 1) lead zinc niobate–lead titanate (PZN-PT) substrates. It is interesting to note that the resistivity of the ZnO-doped Fe0.5Co0.5 films is 10–30 times larger than that of pure Fe0.5Co0.5 films. An ultrahigh f FMR of 10.48 GHz were achieved at electric field of 8 kV/cm without bias magnetic field. The excellent microwave ferromagnetic performances in as-deposited films can be attributed to two reasons: (1) the large uniaxial anisotropy field induced by gradient composition of doping ZnO, (2) the strong magnetoelectric coupling between the ferromagnetic/ferrielectric interfaces under the condition of high resistivity in Fe0.5Co0.5-ZnO films.

Thermal conductivity of (1-x)BaTiO3-xPb(Zn1/3Nb2/3)O3 ceramics (x = 0, 0.025, 0.05, 0.075, 0.1, 0.125 and 0.15)

Barium titanate BaTiO3 (BT) is one of the widely applied lead-free ferroelectric materials due to relatively high permittivity and low cost. Lead zinc-niobate Pb(Zn1/3Nb2/3)O3 (PZN) belongs to a class of disordered and inhomogeneous materials, i.e. is a relaxor. Low-lead (1-x)BT-xPZN ceramics (x = 0, 0.025, 0.05, 0.075, 0.1, 0.125 and 0.15) were prepared by two-step conventional oxide mixed sintering process. Thermal conductivity (κ) of these ceramics was measured for the first time (except for x = 0) from room temperature to 200 °C. It was shown that the thermal conductivity decreases with both decreasing temperature and with increasing PZN content. κ(T) curves show anomaly at Curie temperature, which is connected with change of specific heat. Obtained results indicated that thermal conductivity of investigated samples is mainly related to phonons scattering by lattice defects and by atomic mass fluctuation resulted from PZN incorporation to BT.

Effect of gold nanoparticles on lead zinc niobate–barium titanate structure by X-ray absorption spectroscopy

ABSTRACTThe 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs sintering was carried out for 3 – 5 h at various temperatures ranging from 1100 to 1150°C. The effect of AuNPs on 0.93PZN-0.07BT local structure and dielectric properties were investigated. The Au K-edge XANES spectrum indicated that AuNPs are not substituted into 0.93PZN-0.07BT structure. The dielectric constants and dielectric loss of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs after sintering at 1050°C for 3–5 h are higher and lower than that of 0.93PZN-0.07BT ceramics without AuNPs after sintering at 1100°C for 3–5 h, respectively, which can be described by assuming the connectivity series between the ceramics and the metal phases. In addition, Curie temperature shifting of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs due to the higher degree of chemical heterogeneity caused by the AuNPs addition. Therefore, the including of AuNPs into 0.93PZN-0.07BT ceramics can be improving dielectric properties with lower temperature and shorter time in sintering process.

Giant electrocaloric effect in lead zinc niobate titanate single crystal

Abstract Dielectric properties of (100) oriented 0.91Pb(Zn 1/3 Nb 2/3 )O 3 -0.09PbTiO 3 single crystal has been studied in heating and cooling process. In heating process, the temperature of transformation from ferroelectric rhombohedral to ferroelectric tetragonal phase is about 96 °C, and the temperature of transformation from ferroelectric tetragonal to paraelectric phase is about 190 °C. But in cooling process, both of them decrease to 64 °C and 117 °C, respectively. Thermally stimulated discharging current explains the transformation between microdomain and macrodomain of the 0.91Pb(Zn 1/3 Nb 2/3 )O 3 -0.09PbTiO 3 single crystal. Polarization–electric field hysteresis loops are conducted and typical ferroelectric hysteresis loops are observed. At 20 °C and 15 kV/cm, the ferroelectric properties with the values of P s , P r and E c are found to be 47.52 μC/cm 2 , 45.24 μC/cm 2 and 7.20 kV/cm, respectively. Near the temperature of phase transition, Remnant polarizations are reduced significantly. The largest adiabatic temperature change of the electrocaloric effect is 0.9 K in 15 kV/cm; that is, the temperature change per unit of applied electric field reaches 0.6 × 10 −6 K m/V.

Effect of atmosphere on the formation of perovskite phase in 0.90Pb(Zn1/3Nb2/3)O3-0.10PbTiO3 (PZN-10PT) powders

Lead zinc niobate (PZN) and lead titanate (PT) solid solutions close to the morphotropic phase boundary (MPB) exhibit unusually large dielectric and piezoelectric constants. PZN-PT ceramics with a composition close to the MPB processed by the conventional route yield ceramics with a pyrochlore structure. In the last few decades, attempts to synthesize PZN-PT powders with perovskite structure via traditional ceramic methods and novel chemical processing routes have failed. In the present research, an analysis was made of the effect of the calcination atmosphere on the formation of perovskite phase in PZN-10PT powders. To this end, thermal analyses were carried out in four different atmospheres: oxygen, air, argon and nitrogen. The powders were calcined at the temperatures at which the DTA curves presented peaks, and the resulting phases were identified by X-ray diffraction.

Phase formation behavior of perovskite ferroelectric lead zirconate titanate - lead zinc niobate powders by X-ray absorption spectroscopy

ABSTRACTLead zirconate titanate - lead zinc niobate (PZT-PZN) powders were prepared by a modified mixed-oxide synthetic route via a combination of Zn2Nb34O87 precursor and vibro-milling techniques. The effects of calcination temperature and chemical composition on phase formation were investigated by x-ray absorption spectroscopy. The Zn K-edge x-ray absorption near edge structure (XANES) was simulated with PZT-PZN in pyrochlore phase and perovskite phase. The comparison between simulated and measured XANES shows the increasing perovskite phase formation of PZT-PZN with increasing calcination temperature and the optimization of calcination temperature lead to 100% yield of PZT-PZN in perovskite phase. In addition, the Zn K-edge x-ray absorption near edge structure (XANES) was simulated with various compositions of PZT in PZT-PZN. The comparison between simulated and measured XANES shows the increasing perovskite phase formation of PZT-PZN with increasing composition of PZT. The results show the optimization of calcination conditions lead to formation of PZT-PZN in perovskite phase.

Local Structure and Phase Formation of Lead Zinc Niobate Powders by X-Ray Absorption Spectroscopy

This work is aimed at synthesizing lead zinc niobate powders which consist of pyrochlore phases by modified solid-state reaction via a rapid vibro-milling in difference three synthesis routes: mixed oxide precursor (PZN-M) , columbite precuresor (PZN-C) and lead niobate precuresor (PZN-P). It involves the fabrication of PZN powder and study of phase formation and local structural environment of Zn ions by using X-ray Diffraction (XRD) and X-Ray Absorption Spectroscopy (XAS) techniques that compared the amount of pyrochlore phases with perovskite phase.

Hybrid fabrication of piezoelectric thick films using a sol-infiltration and photosensitive direct-patterning technique

We propose a hybrid fabrication technique for piezoelectric thick films using sol-infiltration and a direct-patterning process. To achieve the demands of high-density and direct-patterning at a low sintering temperature, a photosensitive lead zirconate titanate (PZT) solution was infiltrated into a lead zinc niobate–lead zirconate titanate (PZN–PZT) thick film. The direct-patterned PZT films were formed on a locally screen-printed thick film, using a photomask and UV light. By optimizing the thickness of the photosensitive PZT layer, the hybrid films that were prepared with a 120-s soaking time of PZT sol showed a very dense and uniform microstructure with a large grain size at a low sintering temperature of 800 °C. It also had enhanced electrical properties. The measured remnant polarization (Pr) and coercive field (Ec) were 14.61 μC cm−2 and 24.16 kV cm−1, respectively. The Pr value was over four times greater than those of the screen-printed films. We fabricated array-type piezoelectric resonators with direct-patterned PZN–PZT thick films to show the ability of the direct-patterning of the PZT thick film on a silicon wafer for actuator and sensor application, especially for mass production.

Thermal, dielectric and ferroelectric properties of 0.925BaTiO3–0.075Pb(Zn1/3Nb2/3)O3 ceramic

New low-lead content 0.925BaTiO3–0.075PbZn1/3Nb2/3O3 (0.925BT–0.075PZN) ceramic was fabricated by the spark-plasma-sintering method. X-ray diffraction measurements showed that the obtained specimen possesses a pure perovskite structure. The microstructure investigation indicated a dense ceramic structure with 95% relative density determined by the Archimedes method. Composition undergoes a sequence of phase transitions as pure barium titanate (BT). Dielectric study revealed that the electric permittivity decreases at its maximum and the phase transition shifts to a higher temperature after lead zinc niobate doping of BT. Besides, the dielectric dispersion and polarization increases and decreases, respectively. Obtained results were discussed in term of the difference between ionic size and its mass and local elastic and electric fields. The results show that investigated ceramic is one of the promising low-lead materials for electronic applications.

Driving ferromagnetic resonance frequency of FeCoB/PZN-PT multiferroic heterostructures to Ku-band via two-step climbing: composition gradient sputtering and magnetoelectric coupling.

RF/microwave soft magnetic films (SMFs) are key materials for miniaturization and multifunctionalization of monolithic microwave integrated circuits (MMICs) and their components, which demand that the SMFs should have higher self-bias ferromagnetic resonance frequency fFMR, and can be fabricated in an IC compatible process. However, self-biased metallic SMFs working at X-band or higher frequency were rarely reported, even though there are urgent demands. In this paper, we report an IC compatible process with two-step superposition to prepare SMFs, where the FeCoB SMFs were deposited on (011) lead zinc niobate–lead titanate substrates using a composition gradient sputtering method. As a result, a giant magnetic anisotropy field of 1498 Oe, 1–2 orders of magnitude larger than that by conventional magnetic annealing method, and an ultrahigh fFMR of up to 12.96 GHz reaching Ku-band, were obtained at zero magnetic bias field in the as-deposited films. These ultrahigh microwave performances can be attributed to the superposition of two effects: uniaxial stress induced by composition gradient and magnetoelectric coupling. This two-step superposition method paves a way for SMFs to surpass X-band by two-step or multi-step, where a variety of magnetic anisotropy field enhancing methods can be cumulated together to get higher ferromagnetic resonance frequency.

Multiferroic oxide composites: synthesis, characterisation and applications

The nature of mechanical strain mediated electromagnetic coupling in multiferroic composites has been studied extensively in recent years. This review is on composites with ferromagnetic or ferrimagnetic oxides and ferroelectrics. Systems studied so far include samples with spinel ferrites, hexagonal ferrites or lanthanum manganites for the ferromagnetic phase and barium titanate, lead zirconate titanate (PZT), lead magnesium niobate–lead titanate (PMN-PT) or lead zinc niobate–lead titanate (PZN-PT) for the ferroelectric phase. Bilayer and multilayer heterostructures, bulk composites, core shell nanoparticles and core shell nanotubes and nanowires were investigated for their response to magnetic fields, termed direct magnetoelectric effect (DME). Several systems show a giant low frequency DME and resonance enhancement at bending and electromechanical resonance. The response of the composites to an electric field, called converse ME effect, is found to be strong in several ferrite–ferroelectric composites. The potential for use of the composites for pico-Tesla magnetic sensors and high frequency electric field tunable ferrite signal processing devices are also addressed in this review.

Thermodynamics of Ferroelectric Solid Solutions with Morphotropic Phase Boundaries

A thermodynamic analysis is presented for the diffusionless phase diagrams of ferroelectric solid solutions that display a morphotropic phase boundary (MPB) separating adjacent tetragonal and rhombohedral phases. Equations are developed for the shape of the MPB, the locations of triple and tricritical points, and for the line along which the anisotropy of polarization vanishes. The appearance of lower symmetry orthorhombic and monoclinic phases is considered and the topologies of energy surfaces in the region of the phase diagram where these phases may stabilize are illustrated. The theory is applied to the solid solution of lead zirconate with lead titanate (PZT) and relationships between polar anisotropy and the transformation strain, dielectric susceptibility and piezoelectric properties, are discussed. The analysis is used to reproduce phase boundary lines for solid solutions of lead titanate with lead magnesium niobate (PMN‐PT) and lead zinc niobate (PZN‐PT) and composition–temperature diagrams along isopleths in the ternary system PMN‐PZT are estimated. The anisotropies of polarization in solid solutions based on lead titanate and barium titanate are contrasted. The results provide a thermodynamic framework useful for guiding experimental investigations of ferroelectric solid solutions and for generating energy functions used in constitutive modeling and phase field simulations of microstructure and properties.

Role of dopant induced defects on the properties of Nd and Cr doped PZNT single crystals

Abstract The dielectric, ferroelectric and piezoelectric properties of rare-earth Nd-doped lead zinc niobate–lead titanate (Nd:PZNT) and transition metal Cr-doped lead zinc niobate–lead titanate (Cr:PZNT) single crystals have been investigated. Formation of pure perovskite phases was confirmed from powder X-ray diffraction. Lattice parameters have been obtained by Rietveld refinement. Both Nd and Cr doped crystals showed a diffuse phase transition and frequency dispersive phenomena supporting the enhancement in relaxor behavior. The variation in the values of dielectric constant ( ɛ r ), AC conductivity and piezoelectric charge coefficient ( d 33 ) due to the creation of oxygen vacancies and lead vacancies as a result of doping is investigated in detail. Hysteresis behavior of the doped crystals is explained by considering the possible switching mechanism of domains and the formation of defect dipoles.

Epitaxial growth of spinel cobalt ferrite films on MgAl2O4 substrates by direct liquid injection chemical vapor deposition

The direct liquid injection chemical vapor deposition (DLI-CVD) technique has been used for the growth of cobalt ferrite (CFO) films on (100)-oriented MgAl2O4 (MAO) substrates. Smooth and highly epitaxial cobalt ferrite thin films, with the epitaxial relationship MAO(100)[001]∥CFO(100)[001], are obtained under optimized deposition conditions. The films exhibit bulk-like structural and magnetic properties with an out-of-plane lattice constant of 8.370Å and a saturation magnetization of 420kA/m at room temperature. The Raman spectra of films on MgAl2O4 support the fact that the Fe3+- and the Co2+-ions are distributed in an ordered fashion on the B-site of the inverse spinel structure. The DLI-CVD technique has been extended for the growth of smooth and highly oriented cobalt ferrite thin films on a variety of other substrates, including MgO, and piezoelectric lead magnesium niobate–lead titanate and lead zinc niobate–lead titanate substrates.

Probing local structure of pyrochlore lead zinc niobate with synchrotron x-ray absorption spectroscopy technique

Local structure of lead zinc niobate (PZN) ceramic, synthesized via B-site oxide precursor route in atmospheric pressure, was investigated using synchrotron x-ray absorption spectroscopy (XAS) technique. The x-ray absorption near-edge structure (XANES) simulation was first carried out. The XANES simulation results indicate that the PZN ceramic is in pyrochlore phase having Zn2+ substituted on Nb5+ site. Afterwards, the extended x-ray absorption fine structure (EXAFS) analysis was performed to extract the bond length information between Zn2+ and its neighboring atoms. From the EXAFS fitting, the bond length between Zn2+ and Pb2+ in the pyrochlore phase was found to be longer than the previously reported bond length in the perovskite phase. Further, with the radial distribution information of Zn2+'s neighboring atoms, the formation energies along the precursor-to-pyrochlore and precursor-to-perovskite reaction paths were calculated using the density functional theory (DFT). The calculated results show that the formation energy of the perovskite phase is noticeably higher than that of the pyrochlore phase, which is influenced by the presence of energetic Pb2+ lone pair, as the perovskite phase has shorter Zn2+ to Pb2+ bonding. This therefore suggests the steric hindrance of Pb2+ lone pair and the mutual interactions between Pb2+ lone pair and Zn2+ are main causes of the instability of lead zinc niobate in the perovskite structure and confirm the efficacy of XAS and DFT analysis in revealing local structural details of complex pyrochlore materials.

Large E-field tunability of microwave ferromagnetic properties in Fe50Co50-Hf/lead zinc niobate–lead titanate multiferroic laminates

Fe50Co50-Hf films were deposited on the (011)-cut single crystal lead zinc niobate–lead titanate (PZN-PT) substrates by a composition gradient sputtering (CGS) method. Strong converse magnetoelectric (ME) coupling was observed in the multiferroic laminates of CGS Fe50Co50-Hf/PZN-PT, which exhibited a large electric field (E-field) tunability of microwave magnetic properties. With the increase of E-field strength from 0 to 8 kV/cm, the ferromagnetic resonance (FMR) fields Hr shifted upwards by 270.2 Oe and downwards by 237.7 Oe along hard axis and easy axis directions, being equivalent to 33.8 and 29.7 Oe cm/kV, respectively. Accordingly, the self-biased ferromagnetic resonance frequency fFMR significantly enhanced from 4.0 to 6.5 GHz with an increment of ΔfFMR = 2.5 GHz under a zero-bias magnetic field, and the magnetic damping constant α decreases from 0.0280 to 0.0185. The strong ME coupling between CGS Fe50Co50-Hf film and PZN-PT substrate not only enhanced the fFMR but also reduced the magnetic loss at microwave frequencies, which gives great opportunity in fabrication of tunable microwave devices.

Synthesis, Formation and Characterization of Lead Zirconate Titanate–Lead Zinc Niobate Powders

xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Zn1/3Nb2/3)O3 or xPZT-(1−x)PZN (x = 0.85–0.95)powders were prepared by a modified mixed-oxide synthetic route via a combination of Zn2Nb34O87 precursor and rapid vibro-milling techniques. Effects of calcination temperature on phase formation, morphology, particle size and chemical composition of perovskite ferroelectric powders in the solid solution of PZT-PZN system were investigated. Perovskite phase transition from a tetragonal to a coexistence of tetragonal and rhombohedral phases occurred as composition and firing temperature change. The tetragonality factor and degree of spherical grain shape were observed to increase with increasing PZT content. Moreover, the degree of agglomeration and averaged particle size of the PZT-PZN powders were also found to increase at higher calcination temperatures.