PbO Atmosphere Research Articles

Effect of rare-earth (La and Eu) doping on ferroelectric and magnetic properties of magnetoelectric Pb(Fe0.5Nb0.5)O3

Polycrystalline Pb(Fe0.5Nb0.5)O3 (PFN) samples have been synthesized to study the effect of rare-earth ions, La and Eu, on multiferroic physical properties. The synthesis of materials in controlled PbO atmosphere accounted for the pyrochlore free ceramics with tetragonal structure. Small amount (1 at.%) of rare-earth doping resulted in a shrinkage of unit cell volume. The dielectric studies indicated a decrease in phase transition temperature from 375 K to 356 K for La doped ceramics. A well-saturated ferroelectric polarization with a remanent polarization of 8.9 μC/cm2 was observed for undoped PFN while the doping affected in the large leakage current and higher coercivity. We observed no significant effect of doping on magnetic transition temperatures at low temperatures. Doping with La resulted in reduced magnetoelectric coefficient compared to the undoped value of 9.2 mV/cmOe, due to the poor poling ability.

Large-scale fabrication of titanium-rich perovskite PZT submicro/nano wires and their electromechanical properties

We report a 2-step approach to prepare tetragonal perovskite PbZr(0.1)Ti(0.9)O(3) submicro/nano wires in gram scale and with over 95% wire content. Non-perovskite precursor wires were first fabricated by hydrothermal processing. A subsequent annealing in a PbO atmosphere at 600 degrees C converted these wires into perovskite structures which retain the one-dimensional shape. Binding of the perovksite nanowires to a conductive substrate could be achieved by a similar heat treatment of the non-perovskite precursor wires on a flat Pt coated substrate. Taking advantage of the strong mechanical attachment and good electrical contact between the wires and the metallic layer, piezoresponse force microscopy (PFM) was used to measure the local piezoelectric and ferroelectric properties of the individual wires. Enhanced piezoelectric response relative to sputtered epitaxial PbZr(0.2)Ti(0.8)O(3) film and squared hysterisis loop with sharp switching indicate pronounced electro-mechanical and ferroelectric behavior. The 90 degree domain structure of the as-prepared perovskite PZT wires was confirmed by both PFM and transmission electron microscopy investigations.

Effect of Pb(Zn1/3Nb2/3)O3 Additions on Phase Structure, Ferroelectric and Dielectric Properties of PbZrO3 Ceramics

Polycrystalline samples of (1-x)PbZrO 3 −xPb(Zn 1/3 Nb 2/3 )O 3 , where x = 0.0–0.3, were prepared by the columbite method. Sintering was performed at 1,250°C for 2–4 h in PbO atmosphere. The X-ray diffraction (XRD) was used to investigate pure phase perovskite in sintered ceramics. Moreover, dielectric and ferroelectric properties have been determined via dielectric spectroscopy and hysteresis loop measurement, respectively. Complete solid solutions of the perovskite phase of PZ−PZN ceramics were obtained in all compositions. The phase transformation from orthorhombic to rhombohedral was observed at composition 0.2 < x < 0.3. Furthermore, a change from antiferroelectric behavior in the PZ ceramic to normal ferroelectric behavior in PZ−PZN ceramics was observed in composition 0.1 < x < 0.2. These results clearly show the significance of added PZN in reducing the antiferroelectric behavior in PZ ceramic.

Templated Grain Growth of &lt;001&gt; Textured PMN‐28PT Using SrTiO3 Templates

Highly textured PMN‐28PT (0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3) ceramics were produced by templated grain growth on &lt;001&gt; oriented platelet‐shaped SrTiO3 template particles with an aspect ratio of 10–15. The templates were aligned in PMN‐28PT matrix powder via tape casting and fired in an O2–PbO atmosphere at 1150°C for up to 15 h. This resulted in textured ceramics with a 40 micrometer grain size and without residual templates. The volume fraction of textured material ( f ) and the orientation parameter (r) were quantified by fitting X‐ray diffraction rocking curve data to the March–Dollase equation. Processing conditions were optimized to achieve the best possible values of f and r for the chosen templates and matrix powder. A texture fraction of at least 81 vol% and an orientation parameter of 0.2 were achieved when all random matrix grains were consumed (a perfect textured ceramic would show a texture fraction of 100 vol% and an orientation parameter of 0).

Simultaneous synthesis and single-step sintering of lead magnesium niobate ceramic using mixed nanopowders

A high density single-phase lead magnesium niobate ceramic with the highest peak dielectric constant reported so far, has been synthesized and sintered simultaneously via a modified mixed oxide route, using mixed oxide nanopowder and single-step sintering. The mixed nanopowder was sintered at 1200 °C in air and PbO atmospheres. By comparison, samples sintered in air, gained pyrochlore structure, while those samples sintered in PbO atmosphere had pure perovskite structure. Pellets sintered for 2.5 h exhibited best dielectric properties with peak dielectric constant of 18,672 at the frequency of 1 kHz at −13 °C. The dielectric properties, compressibility, phase formation, densification, and microstructure of the samples were investigated.

Structural and Electrical Properties of Lead Zirconate Titanate Thick Films Fabricated by Screen-Printing Method

Ferroelectric Pb(Zr0.6Ti0.4)O3 (PZT(60/40)) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The Pt bottom electrodes were screen-printed on the alumina substrate. The PZT(60/40) thick films were annealed at 1050°C for 10min in PbO atmosphere. Pb(Zr0.4Ti0.6)O3 (PZT(40/60)) precursor solution, which prepared by sol-gel method, was spin-coated on the PZT thick films to obtain a densification. These PZT multilayered thick films were annealed at 650°C for 2 h in PbO atmosphere. The upper electrodes were fabricated by screen printing the Ag paste and then firing at 590°C for 10min. Its structural and electrical properties of the PZT thick films with the treatment of PZT(40/60) precursor solution coating were investigated. The coating and drying procedure was repeated 4 times. And then the PZT(40/60) precursor solution was spin-coated on the multilayered thick films. A concentration of a coating solution was 1.5 mol/L and the number of coating was repeated from 0~15. The porosity of the thick films was decreased with increasing the number of coatings. All PZT multilayered thick films showed the XRD patterns of typical peroveskite polycrystalline structure. The relative dielectric constant of the PZT-15 (15: number of solution coatings) thick film were 370. And the PZT-15 thick film shows the remanent polarization of 23.5 μC/cm2 and coercive field of 18.0 kV/cm, respectively.

Structure and electrical properties of Mn-modified Pb((Zn 1/3Nb 2/3) 0.20 (Zr 0.50Ti 0.50) 0.80)O 3 ceramics sintered in a protective powder atmosphere

The effects of PbO atmosphere on structure and electrical properties of Mn-modified Pb((Zn 1/3Nb 2/3) 0.20(Zr 0.50Ti 0.50) 0.80)O 3 ceramics were investigated. Specimens were prepared with and without a PbZrO 3 protective ambient, by columbite two-stage process in a temperature region from 1050 to 1200 °C. The results indicated that PbZrO 3 powder is favored to the liquid-state sintering process of specimens in PbO vapor pressure equilibrium. The specimens sintered with PbZrO 3 powder showed the homogenous and intergranular microstructure; whereas, the specimens sintered without PbZrO 3 powder demonstrated the inhomogenous and transgranular microstructure. Without protective PbZrO 3 powder, the flow of PbO from the compact to the exterior resulted in the formation of amorphous phase in grain boundaries, which deteriorated the electric properties seriously. By the use of PbO protective atmosphere, the excellent piezoelectric and dielectric properties ( Q m = 1160, tan δ = 0.004, K p=0.54) were obtained at 1100 °C for 2 h.

Effects of the Particle Size and the Firing Atmosphere on Electrical Properties in PNN-PZT Thick Films

Pb(Ni 1/3 Nb 2/3 )O3─PbZrO3─PbTiO3 (PNN-PZT) thick films were screen-printed on platinized alumina substrates and fired at 800–1000°C under PbO atmosphere or in air. Effects of the starting particle size and the firing atmosphere on the microstructure and electrical properties of the thick films were investigated. Attrition milling produced smaller particle size than ball milling. Thick films prepared from attrition-milled powders showed more uniform microstructure at all firing temperatures and also denser microstructure and better electrical properties at firing temperature above 900°C than thick films prepared from ball-milled powders. PbO atmosphere improved electrical properties of thick films prepared from attrition-milled powders while little influenced on those of thick films prepared from ball-milled powders. Electrical properties of the thick film prepared from attrition-milled powders and fired at 900°C under PbO atmosphere were as follows: dielectric constant of 604, remanent polarization of 17.4 μ C/cm2 and coercive field of 60.6 kV/cm.

Chemically Induced Interface Migration in PZT System During Controlling of PbO Content

Chemically induced interface migration (CIIM) in Pb[(Co1/3Nb2/3)0.1Zr0.6Ti0.3]O3 (PCNZT) ceramics was investigated while controlling the PbO content. After sintering, stoichiometric samples were heat-treated in a PbO atmosphere allowing diffusion of PbO into grain boundaries (alloying), while the samples with excess PbO were heat-treated in air in order to promote PbO evaporation (dealloying). In both cases, an interface moving against their curvature was observed. Because of the zigzag structure of the grain boundaries, the mechanical properties improved.

Low temperature firing of PZT thick films prepared by screen printing method

PZT thick films were prepared on alumina substrate by screen printing method. The paste was made from PbTiO 3–PbZrO 3–Pb(Mn 1/3Nb 2/3)O 3 ternary system with 1 wt.% excess PbO and organic vehicles. Screen-printed thick films were fired at 750–950 °C for 1 h either in air or PbO atmosphere (PbZrO 3+10 mol%ZrO 2). Pyrochlore phase was observed in PZT thick films fired in air at 950 °C in addition to a perovskite phase, while only a perovskite phase was formed in PbO atmosphere. PZT thick films fired in PbO atmosphere showed denser microstructure and better ferroelectric properties than those fired in air. The PZT thick film fired at 800 °C in PbO atmosphere showed very well developed P–E hysteresis, remanent polarization of 28.0 μC/cm 2 and coercive field of 52.7 kV/cm. The PZT thick film fired at 800 °C in PbO atmosphere can be applied to fabrications of piezoelectric microactuators or microsensors using Si micromachining technology.

The Effect of Sintering Atmosphere on the Dielectric Constant and Density of PMN Ceramics

Lead magnesium niobate (PMN) is a ferroelectric compound with relaxor characteristics. PMN powder prepared by semi-wet hydroxide route was compacted and sintered at 1000 C in air and PbO atmosphere. The loss of PbO, during sintering, leads to the formation of pyrochlore phase which lowers the dielectric constant and density of PMN ceramics. The effect of sintering atmosphere on the dielectric properties and the density of PMN ceramics is reported in this study.

Effect of post sinter annealing on the dielectric constants of PMN and PFN

Lead magnesium niobate (PMN) and lead iron niobate (PFN) are the ferroelectric ceramics having perovskite structure. Both of these compounds have high dielectric constant (10 000–20 000) and the change in their dielectric constant with respect to temperature is gradual, showing diffused phase transition peaks at −12°C (PMN) and 110C (PFN) respectively. The dielectric properties of these compounds depend very much on their microstructural features i.e. grain size, grain boundary thickness etc. In this study, the PMN and PFN powders prepared by semi-wet hydroxide route were sintered in PbO atmosphere at 1000–1150°C. The sintered pellets were heated in air at 1000°C for 1/2 to 1 h. Their dielectric properties with respect to temperature were studied and the effect of post sinter annealing on their dielectric constants was analysed.

Effect of Manganese Oxide Doping on the Dielectric Properties of Lead Iron Niobate Ceramics

Lead Iron Niobate (PFN) powder, prepared by semi-wet-hydroxide route, was doped with different concentrations of Mn2O3. The powders were compacted into pellets and these were then sintered at 1000°C in PbO atmosphere. The dielectric constant and loss tangent of these ceramics were measured in the temperature range, 25°-130°C. The effects of different concentrations of Mn2O3 doping on the microstructure, dielectric constant, loss tangent and Curie temperature of PFN are reported in this study.

Thick films on alumina substrates for piezoelectric devices applications

PZT and Bismuth Titanate thick films on alumina substrate are prepared. Grain size, temperature and time dependence of sintering is studied. Influence of PbO excess and atmosphere on piezoelectric properties is reported. For Bismuth Titanate materials high temperature measurements and deposits on metallic substrate are carried out.

1501 PNN-PSN ペロブスカイトセラミックスの合成とアクチュエータ特性

Relaxor-type ferroelectric perovskites Pb(Ni_<1/3>Nb_<2/3>)O_3-Pb(Sc_<1/2>Nb_<1/2>)O_3(PNN-PSN), though very difficult to obtain in single phase by the usual mixed oxide method, were prepared by a process consisting of heat treatment and then acid treatment of the oxide mixture containing PbO in amount greater than in the perovskite composition. For the crystallization of perovskite phase without the formation of pyrochlore phase and therefore with desirable composition, it was essential that the mole ratio of PbO to the perovskite composition is 2 : 1 or more and the calcination temperature is 950℃ or more. Removing the excess PbO by leaching with a 1N acetic acid solution, then the ceramic sintering was made at 1200-1360℃ in a PbO atmosphere. From the measurement of the dielectric constant against temperature, it was found that the Curie temperature linearly increased from PNN (-150℃) to PSN (100℃). The dielectric constant peak turned from broad to sharp and became higher with increasing PSN content. The actuator function was highly improved by the introduction of PbTiO_3 (PT) into PNN-PSN.

Relationship between domain structure and film thickness in epitaxial PbTiO3 films deposited on MgO(001) by reactive sputtering

The epitaxial PbTiO3 thin films of different thickness were prepared on MgO(001) substrates by the reactive direct-current magnetron sputtering. The volume fraction of c domains, α, which was measured by x-ray diffractometry, increased rapidly from zero with the film thickness, being saturated at about 90% above 100 nm. The films were annealed in a PbO atmosphere at 700 °C for 8 h, and they were used to study the composition change in the Pb/(Pb + Ti) ratio and the relaxation of the residual intrinsic stress. The relationship between change of α and composition was weak. The stress state was calculated through the finite-element method. As for the small thickness, the tensile epitaxial stress overwhelmed compressive intrinsic and thermal stresses, and the domain structure was a-domain oriented. As for the large thickness, the compressive intrinsic stress together with the thermal stress overcame the tensile epitaxial stress, and the population turned into c domain.

Processing and properties of (1 − x)Pb(Mg 1/3Nb 2/3)O 3·xPbTiO 3 solid solutions from PbO- and MgO-excess compositions

Perovskite solid solutions (1 − x)Pb(Mg 1/3Nb 2/3)O 3·xPbTiO 3 with x between 0.06 and 0.14 were prepared by heat treatment followed by acid treatment of mixtures containing both PbO and MgO in amounts greater than in the perovskite composition. For example, heat treatment of 4PbO + 1.5MgO + 0.9Nb 2O 5 + 0.3TiO 2 mixture at 900°C for 1 h produced the perovskite with x = 0.1 without the formation of pyrochlore phase. The Pb(Mg 1/3Nb 2/3)O 3–PbTiO 3 (PMN–PT) solid solutions were crystallized into discrete cubes several micrometers in size. After sintering these particles at 1290°C for 2 h in a PbO atmosphere, the relative density of the ceramics was 93% or more. The ceramics with x = 0.08–0.1 showed a large electric field–induced strain near room temperature.

Preparation and Their Properties of Pb(Sc&lt;sub&gt;1/2&lt;/sub&gt;Ta&lt;sub&gt;1/2&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt;-Pb(Sc&lt;sub&gt;1/2&lt;/sub&gt;Nb&lt;sub&gt;1/2&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt; Solid-Solution Ceramics

{(1-x)Pb(Sc1/2Ta1/2)O3-xPb(Sc1/2Nb1/2)O3+0.5 mass% MnO2} (PST-PSN) solid-solution ceramics, where x=0.1-0.9, were prepared by normal sintering in a PbO atmosphere. The physical, dielectric and pyroelectric properties were evaluated using PST-PSN ceramics with x=0.1-0.9, respectively. All the obtained samples were high density sintered bodies with the low apparent porosities of less than 0.2%, ranging in bulk densities from 7.67×103 to 8.55×103kg/m3. The temperature dependence of the relative dielectric constant, εr for PST-PSN ceramics apparently exhibited the diffuse phase transition in all the compositions. Assuming that the volume specific heat, Cv of the present samples with x=0.4-0.9 are 2.5×106J/m3⋅K, x=0.4 PST-PSN sample exhibited the highest figures of merit, F. M. for voltage responsivity, Rv of around 8.5×10-14C⋅m/J and F. M. D* for specific detectivity, D* of around 5.9×10-11C⋅m/J, among the six samples studied here.

Microstructural development in sol-gel derived lead zirconate titanate thin films: The role of precursor stoichiometry and processing environment

The role of precursor stoichiometry and local firing environment on the microstructural development of sol-gel derived lead zirconate titanate (PZT) thin films was investigated. Typically, excess Pb is added to films to compensate for PbO volatilization during heat treatment. Here, it is shown that the use of stoichiometric precursors with either a PbO atmosphere powder or a PbO overcoat during the crystallization heat treatment is an attractive and viable alternative method for control of film stoichiometry. Using these approaches, we have fabricated single phase perovskite thin films with microstructures and electrical properties (Pr ∼ 36 μC/cm2 and Ec ∼ 45 kV /cm) comparable to those of films using optimized solution chemistries and excess Pb additions. The potential advantage of increasing PbO partial pressure, or activity, during firing versus excess Pb additions is discussed from the standpoint of a proposed crystallization scenario based on the kinetic competition between Pb loss and the nucleation and growth rates of the perovskite phase.

Preparation and ferroelectric properties of Pb(Zr, Ti)O3films by sol-gel processing

Abstract Pb(Zr x , Ti1-x )O3 (PZT) films were prepared on Ni metal plates by the sol-gel process using rapid thermal annealing (RTA). The PZT films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron probe micro analysis (EPMA). The electrical properties such as dielectric constant, remanent polarization, coercive field and leakage current were measured for PZT film with Zr/Ti ratio (70/30, 50/50) on Ni metal substrates. As the PZT films are treated in PbO atmosphere at 750°C for 1 h, the dielectric constant and remanent polarization increased. This result can be explained by the fact that the increase in ferroelectricity of the PZT film is caused by the electric polarizability of lead ion.