Columbite Precursor Method Research Articles

Effect of Processing on the Dielectric and Piezoelectric Properties of Pb(Mg1/3,Nb2/3)O3-32.5PbTiO3 Ceramics Prepared without Excess PbO

The morphotropic phase boundary (MPB) composition of (1−x)Pb(Mg1/3,Nb2/3)O3-xPbTiO3 (x = 0.32) was synthesized by the columbite precursor method without the use of any excess PbO for densification. Ceramics were prepared using two atmospheres viz. sintering in air and oxygen, respectively to study the effect of these different processing conditions on the sintering process. High-density ceramics were formed when samples were sintered in an oxygen environment. The high density and absence of excess PbO, resulted in excellent dielectric, ferroelectric and piezoelectric properties. Dielectric constants on the order of ∼41,500 were recorded at the Tc. A maximum strain level of ∼0.17% at ∼30 kV/cm, associated with a piezoelectric constant (d33) of 785 pC/N was obtained on the samples having the highest density.

Dielectric, piezoelectric and pyroelectric properties of PMN–PT (68:32) system

Solid solution of 32 mol% of Lead Titanate in PMN–PT system has been prepared by columbite precursor method. Room temperature X-ray diffraction study reveals the formation of perovskite phase with tetragonal structure. Dielectric measurements have been carried out at different frequencies (0.1 kHz–1 MHz) as a function of temperature (RT to 235 °C). The phase transition was found to be of diffused type. The polarization studies show ferroelectric nature of the material with a high value of remnant polarization ( P r) ∼21 μC/cm 2 and spontaneous polarization ( P s) ∼29 μC/cm 2. Strain versus electric field ( S– E) behavior shows piezoelectric nature of the material with high value of maximum strain 0.14% at 60 kV/cm. Pyroelectric coefficient at room temperature has been found to be 3×10 −2 μC/cm 2 K.

The effect of substitution of WO 3 on relaxation behavior of Pb(Mg 1/3Nb 2/3)O 3–PbTiO 3 ceramics

0.67Pb(Mg 1/3Nb 2/3)O 3 (PMN)–0.33PbTiO 3 (PT) ferroelectric ceramics has been selected as base component. Different content of B-site substitute (0.1, 0.5 and 1 mol%) were used to modify the base component. The specimens were synthesized by the columbite precursor method, and pure perovskite phase were obtained for all the specimens. The dielectric behavior was examined to investigate the relaxor behavior of each component. It is found that the specimen undoped and modified with 0.1 mol% WO 3 nearly behave as normal ferroelectric ceramics, while with the content of WO 3 increasing, the degree of relaxor behavior for the composition increases. Thus, B-site substitute WO 3 has a strong effect of inducing relaxor behavior of PMN–PT ferroelectric ceramics near morphotropic phase boundary (MPB).

Electrical properties of Pb(Mg 1/3Nb 2/3)O 3–PbTiO 3 ceramics modified with WO 3

Ferroelectrics 0.67Pb (Mg 1/3Nb 2/3)O 3–0.33PbTiO 3 (PMN–PT) + x mol% WO 3 ( x=0.1, 0.5, 1, 2) were prepared by columbite precursor method. Electrical properties of WO 3-modified ferroelectrics were investigated. X-ray diffraction (XRD) was used to identify crystal structure, and pyrochlore phase were observed in 0.67Pb (Mg 1/3Nb 2/3)O 3–0.33PbTiO 3+2 mol% WO 3. Dielectric peak temperature decreased with WO 3 doping, indicating that W 6+ incorporated into PMN–PT lattice. Lattice constant, pyrochlore phase and grain size contribute to the variation of K max. Both piezoelectric constant ( d 33) and electromechanical coupling factors ( k p) were enhanced by doping 0.1 mol% WO 3, which results from the introduction of “soft” characteristics into PMN–PT, while further WO 3 addition was detrimental. We consider that the two factors, introduction of “soft” characteristics and the formation of pyrochlore phase, appear to act together to cause the variation of piezoelectric properties of 0.67PMN–0.33PT ceramics doping with WO 3.

Piezoelectric properties of new MnO 2-added 0.2 PZN–0.8 PZT ceramic

The development of a new piezoelectric material, 0.5 wt.%MnO 2-added (Pb 0.95Sr 0.05)((Zn 1/3Nb 2/3) 0.20(Zr 0.50Ti 0.50) 0.80)O 3 ceramics (PZNST), optimized for use in multilayer piezoelectric transformer application is described. The requirements to such a material are high mechanical quality factor of Q m, electromechanical coupling factor of k p, Curie temperature of T c and low dielectric dissipation factor of tan δ, and at the same time a relative low sintering temperature. The dielectric and piezoelectric properties of the new developed material, PZNST, have been investigated on different sintering temperature (900–1100 °C). The pure perovskite phase was formed by the columbite precursor method. The optimum values of Q m, k p, tan δ, ε r, T c and d 33 were 1360, 0.62, 0.002, 1240, 320 °C and 325 pC/N, respectively, at calcination of 850 °C and sintering of 1000 °C temperature.

Diffusion‐Induced Interface Migration and Mechanical Property Improvement in the Lead Magnesium Niobate–Lead Titanate System

Diffusion–induced interface migration (DIIM) is a technique for modifying the microstructure and mechanical properties of ceramics. In the present study, we investigated DIIM in 0.65Pb(Mg1/3Nb2/3)O3·0.35PbTiO3 (mol fraction) (PMN–PT) ceramics and its effect on mechanical properties. PMN–PT samples were fabricated using the Columbite precursor method and then surface–modified by heat treatment after packing with PbTiO3 powder to induce DIIM. Evaluation of mechanical properties using Hertzian indentation and Vickers indentation showed that the critical load for yielding and surface hardness of the PbTiO3–packed PMN–PT samples were higher than those of the unpacked samples. Thus, the mechanical properties were improved in the samples with a DIIM layer. These results showed that the reliability of mechanical properties of PMN–PT samples is improved by inducing DIIM at the surface.

Effects of depressor addition on electrical properties of Pb(Mg 1/3Nb 2/3)O 3–PbTiO 3 dielectric ceramics

To develop inorganic dielectric materials for layer insulating materials with high dielectric constant and low dielectric loss of next-generation system-in-a-package, Pb(Mg 1/3Nb 2/3)O 3–PbTiO 3 (PMNT) and PMNT-Pb(Mg 1/2W 1/2)O 3–Pb(Fe 1/2 Ta 1/2)O 3 (PMNT–PMW–PFT; PMNT–PMWFT) ceramics were fabricated by the columbite precursor method. The addition of 1.0 mass% excess MgO to PMNT 94/6 was effective in restraining the formation of the pyrochlore phase and stabilizing the perovskite phase. When the mixing proportion (mol%) of PMNT 94/6/PMWFT 85/15 was 80/20, good dielectric properties with relative permittivity, ε r of 4660 and dielectric loss, tan δ of 0.06% at 1 MHz were obtained. By varying the mixing proportion of PMW/PFT in PMWFT, which plays an important role of depressor to PMNT, 0.8PMNT 94/6·0.2PMWFT 70/30 ceramics having high ε r of 5810, low tan δ of 0.07% at 1 MHz and their flat frequency characteristics were obtained by means of the effects of depressor addition to PMNT.

Chemical Heterogeneity in PMN–35PT Ceramics and Effects on Dielectric and Piezoelectric Properties

Pb[(Mg1/3Nb2/3)0.65Ti0.35]O3 (PMN–35PT) powder was prepared using the columbite precursor method. Fully dense compacts were formed by hot‐pressing the powder at 950°C, and then the compacts were annealed at 1150°C for 5 and 10 h, respectively. Dielectric and piezoelectric properties of the as‐hot‐pressed and annealed samples were measured and correlated with microstructure. The as‐hot‐pressed material exhibited relaxor–ferroelectric‐like behavior, with a relatively low dielectric constant maximum measured at 1 kHz (Km@1kHz) of 8160. Annealing resulted in a transition to weak normal‐ferroelectric behavior, a shift in the dielectric maximum temperature from 190°C to 169°C, and a dramatic increase of Km@1kHz to a maximum value of 41 720 for the longer anneal. The as‐hot‐pressed microstructure was chemically heterogeneous, characterized by submicrometer‐sized regions of varying magnesium, niobium, and titanium content that likely originated from chemical heterogeneities that were present in the as‐prepared PMN‐PT powder. The as‐hot‐pressed properties have been explained as being the integrated response of many discrete ferroelectric responses as dictated for each of these regions by the local chemistry. The transition on annealing has been explained in terms of chemical homogenization to a near‐morphotropic phase‐boundary composition that is intrinsically weak normal‐ferroelectric. Differences in polarization‐versus‐electric‐field and strain‐versus‐electric‐field behavior between the hot‐pressed and annealed materials have been discussed in terms of differences in domain mobility.

Effect of PMN modification on structure and electrical response of xPMN–(1−x)PZT ceramic systems

The structural and electrical properties of xPb(Mg1/3Nb2/3)O3–(1−x)Pb(Zr,Ti)O3 ternary ceramic system with the composition near to the morphotropic phase boundary (MPB) and of xPb(Mg1/3Nb2/3)O3–(1−x)Pb(Zr0.47Ti0.53)O3 ceramics were investigated as a function of the Pb(Mg1/3Nb2/3)O3 (PMN) content by scanning electron microscopy (SEM), X-ray diffraction (XRD), dielectric and piezoelectric spectroscopy and polarization-electric field measurement technique. Studies were performed on the samples prepared by a columbite precursor method for x=0.125, 0.25 and 0.5. Room temperature SEM investigations revealed common trends in the grain structure with increasing PMN content. XRD analysis demonstrated that with increasing PMN content in xPb(Mg1/3Nb2/3)O3–(1−x)Pb(Zr0.47Ti0.53)O3, the structural change occurred from the tetragonal to the pseudocubic phase at room temperature. Changes in the dielectric and ferroelectric behavior were then related to these structural trends and further correlated with the piezoelectric properties. The results of ferroelectric hysteresis measurements, in conjunction with dielectric spectroscopy, demonstrated an intermediate, relaxor-like behavior between normal and relaxor ferroelectrics in the solid solution system, depending on the PMN content.

Study of the structure and dielectric relaxation behavior of Pb(Ni 1/3Nb 2/3)–PbTiO 3 ferroelectric ceramics

Relaxor-type ferroelectric ceramics, (1− x)Pb(Ni 1/3Nb 2/3)O 3– xPbTiO 3 ( x=0.28–0.42) were synthesized by the columbite precursor method. The phase structure and dielectric properties were investigated. X-ray diffraction results demonstrate that a region with both pseudocubic and tetragonal phase in existence lies in the composition range x=0.34–0.38, which is the morphotropic phase boundary (MPB). Examination of the dielectric behavior indicates that the ceramics exhibit abnormal high dielectric constant near the MPB composition. In addition, the transformation of (1− x)PNN– xPT from relaxor to normal ferroelectric behavior with the PT content increasing is successive.

Dielectric and ferroelectric properties of Pb(Ni 1/3Nb 2/3)O 3–PbTiO 3 ferroelectic ceramic near the morphotropic phase boundary

(1− x)Pb(Ni 1/3Nb 2/3)O 3– xPbTiO 3 ( x=0.28–0.42) system ferroelectric ceramics were synthesized by the columbite precursor method. The phase structure and dielecric, ferroelectric properties were investigated. X-ray diffraction (XRD) results demonstrate that the morphotrophic phase boundary (MPB) lies in the composition range x=0.34–0.38. Examination of the dielectric behavior indicates that the ceramics exhibited very high dielectric constant near the MPB composition. In addition, the ferroelectric properties of the ceramics were found also quite well around the MPB.

Low-temperature properties of lead nickel-niobate ceramics

Single-phase perovskite ceramics of Pb(Ni 1/3Nb 2/3)O 3 (PNN) are prepared by the columbite precursor method. Dielectric studies show that ceramic Pb(Ni 1/3Nb 2/3)O 3 is a typical relaxor ferroelectric with properties similar to those of its single-crystals. Low-temperature pyroelectric properties and electromechanical coupling coefficients suggest PNN to be an attractive material for low-temperature applications.

Low-temperature property investigation of the lead indium-niobate–lead nickel-niobate solid solution

The complex perovskite solid solution (1−x) Pb(In1/2Nb1/2)O3–(x) Pb(Ni1/3Nb2/3)O3 has been successfully prepared by the Columbite precursor method. The temperature dependencies of the dielectric constant and pyroelectric coefficient were measured between −261 and 200°C. Relaxor ferroelectric behavior has been noticed in all compositions across the solid solution. The room-temperature electrostrictive coefficient, Q33, was 1.83×10−2C2/m4 for x=0.10. No room-temperature piezoelectric activity was detected; however, upon cooling to −261°C the maximum coupling coefficients kp=29%, kt=11%, and k33=31% were observed for the composition x=1.00.

Dielectric and mechanical properties of PZN-PFN-BZN ternary system

The Ferroelectric relaxor ternary system 0.5PZN-(0.5 − x)PFN-xBZN was prepared using the columbite precursor method. The stability of the perovskite phase was studied as a function of BZN content in the system. It was observed that BZN is a good stabilizer of perovskite phase because of the high value of electronegativity difference between its cation and anion. It has also been observed that addition of BZN increases the dielectric maxima peak value and decrease the Curie temperature of the ceramics. The ternary composition 0.5PZN-0.425PFN-0.075BZN has been identified for MLCs applications. It has a Tc of around room temperature with a peak dielectric constant ≅6400 and tanδ ∼ 0.05. The mechanical properties of relaxor materials have also been studied and reported.

Effect of lanthanum-doping on the dielectric and piezoelectric properties of PZN-based MPB composition

In this paper, effect of lanthanum doping on the dielectric and piezoelectric properties of the morphotropic phase boundary (MPB) composition in the Pb(Zn1/3Nb2/3)O3-BaTiO3-PbTiO3 system is presented. Samples were prepared according to the formula Pb0.85−x Ba0.15La x [(Zn1/3Nb2/3)0.7Ti0.3]1−x/4O3 (0 < x < 0.3), where the compensation for La ions was achieved via the appearance of B-site vacancies. All the compositions were synthesized using columbite precursor method and sintered using inverted crucible approach. Results of x-ray diffraction demonstrate that the solid solubility limit of La2O3 in the PZN-based MPB composition is more than 30 mole%. Incorporation of La2O3 into A-site sublattice of perovskite structure stabilizes rhombohedral phase against tetragonal phase, as a consequence, the location of the MPB composition range is displaced toward PT-rich end. In addition, the lattice distortion degree, represented by either tetragonality for tetragonal phase or rhombohedrality for rhombohedral phase, is reduced. Increasing La2O3 content remarkably decreases both the dielectric permittivity maximum and the temperature of the dielectric permittivity maximum. However, addition of La2O3 obviously strengthens the degree of the frequency-dispersion, which is correlated with the weakened degree of ferroelectric couplings among oxygen octahedra. The degree of diffuse phase transition (DPT) is prominently enhanced with increasing La2O3, for which the underlying mechanism is explored. Moreover, the ever-increasing extent of departure from Curie-Weiss behaviour induced by the lanthanum doping is indicative of some changes with the respect to the scale of polar microregions inherent to relaxors. The longitudinal piezoelectric coefficient (d 33) is maximized at 1 mole% La2O3, which is attributed to the combined effect of phase coexistence and enhanced contribution from non-180° domain wall process associated with rhombohedral phase.

Study of the structure and dielectric relaxation behavior of Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric ceramics

(1–x)PMN–xPT[PMN, Pb(Mg1/3Nb2/3)O3; PT, PbTiO3] system ferroelectric ceramics with x = 0.30, 0.33, 0.35, and 0.38 were synthesized by the columbite precursor method. Their structure and dielectric behavior were investigated. X-ray diffraction results demonstrate that no two-phase region is presented, but a quasi-cubic to tetragonal phase boundary lies between x = 0.30 and 0.33. Examination of the dielectric behavior reveals that the transformation from relaxor to normal ferroelectric behavior across the morphotropic phase boundary (MPB) is successive and continuous. It is suggested that x 4 0.30 to 0.33 is the composition of MPB for the PMN–PT system. The MPB is also a boundary for the PMN–PT system to transform from relaxor to normal ferroelectrics.

Low temperature fabrication and impedance spectroscopy of PMN-PT ceramics

Single phase perovskite 0.9Pb(Mg 1/3Nb 2/3)O 3–0.1(PbTiO 3) ceramics were prepared using the columbite precursor method after optimizing the synthesis conditions. X-ray diffraction (XRD) studies were carried out to verify the phase formation at each processing step. Scanning electron microscopy (SEM) was employed to observe the microstructure of the sintered ceramics. Impedance and modulus spectroscopic data were used to gain an insight into the electrical properties of the samples and with a view to observing the relaxations in them.

Pressureless sintering of PMN–PT ceramics

PMN–PT ceramics with PMN to PT ratios of 60:40, 65:35, and 70:30 were prepared from PMN–PT powders synthesized by the columbite precursor method, and their sintering and grain growth characteristics at temperatures less than 1000°C were investigated. Results indicate that the PMN–PT ceramics can be pressureless-sintered to a relative density of approximately 96% at 950°C. However, full densification was prevented by the onset of abnormal grain growth. The addition of 0·5 wt% PbO to 65:35 PMN–PT ceramics lowered their sintering temperature to 900°C, but caused abnormal grain growth at lower temperatures. Preliminary TEM analyses indicate the presence of submicron-sized MgO particles at some ceramic microstructure triple points. Further studies will be required to understand abnormal grain growth behavior and to devise means for full densification.

Effect of Composition on the Electromechanical Properties of (1‐x)Pb(Mg1/3Nb2/3)O3−XPbTiO3 Ceramics

Ceramic lead magnesium niobate–lead titanate ((1‐x)PMN‐xPT) of different compositions has been prepared by the columbite precursor method. This study discusses compositions ranging from 0.94PMN–0.06PT to 0.60PM–N0.40PT, focusing on two areas of the (1‐x)PMNxPT system: compositions that exhibit electrostrictive behavior, and those that show piezoelectric behavior. In electrostrictive compositions where x is in the range of 0.06–0.20, the dielectric constant and electromechanical coupling factor dependencies on the bias field are evaluated. The optimal electromechanical properties are obtained with the composition 0.82PMN–0.18PT, measured at temperature T=Tm (the temperature of maximum dielectric constant) = 80°C and with a dc bias of 5 kV/cm. X–ray diffractometry is used to show that the (1‐x)PMN‐xPT system has a compositionally wide two–phase region and that 0.655PMN–0.345PT is the morphotropic phase boundary (MPB) composition. Electromechanical property evaluation shows that the optimal piezoelectric properties (piezoelectric charge coefficient (d33) value of 720 pC/N, dielectric constant (K) value of 5400, and electromechanical planar and thickness coupling coefficient (kp and kt, respectively) values of 62% and 46%, respectively) are obtained at the MPB composition.

The grain size, dielectric properties and impedance spectroscopy in a modified ternary system of Pb(Zr, Ti)O3

The Pb(Zr, Ti)O3 (PZT) modified ternary ceramics prepared by standard ceramic techniques were studied in the early 1970s. Recently much attention has been devoted to PbB9B0O3 –PbZrO3 –PbTiO3 ternary systems where cations B9 and B0 substitute for Ti or Zr ions in the perovskite phase. In another report [1] the Pb(Mg, Nb)O3 –PbTiO3 –PbZrO3 system where B9 ˆ Mg and B 0 ˆ Nb [2–4] was studied. The electrical and electromechanical properties were compared between the samples obtained by the standard ceramic technique and the samples obtained using columbite as the precursor. The densities, electromechanical couplings and dielectric constants of samples prepared using the columbite were better than those prepared using the simple ceramic method, for the same conditions. The kinetics of grain growth for the two methods were quite different; however, the lower dielectric constant of the samples prepared using the simple ceramic method was affected considerably by their lower density. The sintered ceramics were useful in application such as accelerometers and infrared sensors in which high values of d33 and dielectric constant are important parameters. Similar properties have been reported by chemical techniques [5, 6]. Both samples showed a perovskite rhombohedral phase (reticular parameters: a ˆ 4:063 A; AE ˆ 89:928). In this paper we analyse the temperature dependence of the dielectric properties for the same prepared system by using the better technique reported by Perez et al. [1] (columbite precursor method). The raw materials were mixed with MgNb2O6 powder in order to obtain the nominal composition Pb(Mg1=3Nb2=3)0:375Ti0:375Zr0:25O3 ‡ 0:5 mol% NiO‡MnO2 and were calcined at 900 8C for 2 h. The pressed powder were sintered at 1200 8C for 2 h. The dielectric losses were measured using a PM6303 RLC bridge, and alternating current impedance measurements were carried out using a Hewlett–Packard HP 4192 impedance analyser controlled by a HP-85 microcomputer. The frequency range was from 5 Hz to 13 MHz. The applied voltage was 1 V in each measurement. The dependence of the losses with the temperature, measured at 1 kHz, is shown in Fig. 1. This dependence shows that the substitution of (Zr, Ti) for Mg2‡ and Nb5‡ does not increase the conductivity of samples. The real values up to 100 8C permit us to consider these materials for application in electronic devices in the range in which there are