Field-induced successive phase transitions of Pb(Zn1/3Nb2/3)O3-x%PbTiO3 crystals

The field-induced structural phase transitions of Pb[(Zn_1/3Nb_2/3)_1−x Tix]O₃ (PZN-x%PT) with x = 0.09 and 0.045 were investigated by the high-resolution micro-Brillouin scattering. PZN-9%PT crystals undergo two first order phase transitions, while PZN-4.5%PT undergo a second order phase transition under the zero-field cooling. Under the field-cooling, the higher phase transition of PZN-9%PT changed into a second order phase transition and the temperature range of a tetragonal phase was widened. Whereas a lower phase transition kept the nature of a first order phase transition. On the other hand, elastic anomaly was appeared on phase transition of PZN-4.5%PT under the field cooling.     

Dielectric properties and morphotropic phase boundaries in the xPb(Zn1/3Nb2/3)O3−(1−x)Pb(Zr0.5Ti0.5O3 pseudo-binary system

Ceramics in the xPb(Zn_1/3Nb_2/3)O₃−(1−x)Pb(Zr_0.5Ti_0.5)O₃ [xPZN–(1−x)PZT] solid solution system are expected to display excellent dielectric, piezoelectric, and ferroelectric properties in compositions close to the morphotropic phase boundary (MPB). The dielectric behavior of ceramics with x = 0.1−0.6 has been characterized in order to identify the MPB compositions in this system. Combined with X-ray diffraction results, ferroelectric hysteresis measurements, and Raman reflectivity analysis, it was consistently shown that an MPB exists between x = 0.2 and x = 0.3 in this binary system. When x ≤ 0.2, the tetragonal phase dominates at ambient temperatures. In the range of x ≥ 0.3, the rhombohedral phase dominates. For this rhombohedral phase, electrical measurements reveal a profound frequency dispersion in the dielectric response when x ≥ 0.6, suggesting a transition from normal ferroelectric to relaxor ferroelectric between 0.5 ≤ x ≤ 0.6. Excellent piezoelectric properties were found in 0.3PZN–0.7PZT, the composition closest to the MPB with a rhombohedral structure. The results are summarized in a PZN–PZT binary phase diagram.     

Switching Current Measurements in Pb(Zn1/3 Nb2/3)O3-PbTiO3 Relaxor Ferroelectric Single Crystals

Switching current measurements have been carried out on relaxor ferroelectric single crystal-PZN, and the solid solution 0.86PZN-0.04PT and 0.91PZN-0.09PT for crystallographic directions [001] and [111]. The experiments showed the presence of two maximum points in the switching current for 0.86PZN-0.04PT and 0.91PZN-0.09PT that can be attributed to the co-existence of two phases. The switching time inverse shows a two-fold linear dependence on applied field for both [001] and [111]. This suggests that the polarization reversal in the relaxor systems is related to the mobility of the domains. The switching time in relaxor ferroelectric is long (millisecs) compared to the reported data on normal ferroelectric Barium titanate (microsecs). The switching time is dependent on the composition of the crystal along both [001] and [111]. Along [111], the switching time decreases as the PT component increases in the crystal while along [001], the switching time increases as the PT increases.     

Piezoelectric and dielectric characteristics of low temperature sintering Pb(Ni1/3Nb2/3)O3-Pb(Mn1/3Nb2/3)O3-Pb(Zr1/2Ti1/2)O3 ceramics for multilayer piezoelectric actuator

In this study, in order to develop the composition ceramics for multilayer piezoelectric actuator, PNN substituted PMN-PZT ceramics were fabricated using Li₂CO₃ and Na₂CO₃ as sintering aids, and their piezoelectric and dielectric characteristics were investigated. With the increase of the amount of PNN substitution, dielectric constant (εr), electromechanical coupling factor (k _p), and piezoelectric constant (d ₃₃) of specimens showed the maximum value at each sintering temperature, and crystal structure changed from tetragonal to rhombohedral. At the sintering temperature of 950^∘C, the density, εr, k _p, d ₃₃, Q_m and Tc of 12 mol% PNN substituted PMN-PNN-PZT composition ceramics showed the optimal values of 7.79 g/cm³, 1160, 0.599, 419pC/N, 894 and 332^∘C, respectively, for low loss multilayer piezoelectric actuator application.     

Investigation of La-doped 0.25Pb(Zn1/3Nb2/3)O3-0.75Pb(ZrxTi1-x)O3 ceramics near morphotropic phase boundary

La-doped 0.25Pb(Zn_1/3Nb_2/3)O₃-0.75Pb(Zr_xTi_1-x)O₃ (x = 0.51–0.57) ceramics were prepared by a conventional mixed oxide method. The piezoelectric and dielectric properties of various compositions near the morphotropic phase boundary (MPB) were investigated. The MPB was determined by X-ray diffraction (XRD) patterns. The optimal properties were obtained in the specimen with Zr/Ti = 53/47: d₃₃ = 570 pC/N, k_p = 0.60, ε_r = 3900, tgδ = 1.9%, T_c = 204°C, P_r = 35.21 μC/cm², E_c = 11.62 kV/cm, which means it is a good candidate for applications.     

Random-Site Cation Ordering and Dielectric Properties of PbMg1/3Nb2/3O3-PbSc1/2Nb1/2O3

(1 ? x)PbMg_1/3Nb_2/3O₃-(x)PbSc_1/2Nb_1/2O₃ (PMN-PSN) solid solution crystals have been grown by the flux method in the whole concentration range. X-ray supercell reflections due to B-cation ordering were observed for as-grown crystals from the 0.1 ≤ x ≤ 0.65 compositional range. Though the ordered domains are rather large (～50 nm) the relaxor-like dielectric behavior is observed for compositions with x < 0.6. The diffusion of the dielectric permittivity maximum in as-grown crystals is the lowest at x = 0.6 and increases towards the end members of solid solution. Such behavior is explained within a Bragg-Williams approach by employing the random layer model. At x ～ 0.6 the excitation energy determined from the Vogel-Fulcher relation exhibits a jump which we regard to changing the kind of the polar regions from PbMg_1/3Nb_2/3O₃ to PbSc_1/2Nb_1/2O₃ related type.     

Piezoelectric properties of the Pb(Sc1/2Nb1/2) O3-Pb(Mg1/3Nb2/3) O3-PbTiO3 ternary ceramic materials near the morphotropic phase boundary

Abstract

The physical and electrical properties of xPb(Sc_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃(PSMNT 100x/100y/100z) ternary ceramic materials near the morphotropic phase boundary (MPB) were investigated. The MPB follows on almost linear region between the PSMNT 58/00/42 and PSMNT 00/68/32 MPB compositions of the binary systems. The maximum piezoelectric constant, d ₃₃ = 680 pC/N, were found at PSMNT 29/33/38, where ε^T ₃₃/ε₀ = 3,800, and electromechanical coupling factors, (k _p = 70%, k₃₁ = 43%, and k ₃₃ = 76%) and T _c = 207°C were obtained. The maximum electromechanical coupling factors, (k _p = 72%, k ₃₁ = 45%, and k ₃₃ = 77%) were found at PSMNT 29/34/37, where ε^T ₃₃/ε₀ = 3,000, d ₃₃ = 640 pC/N, and T _c = 205°C were obtained. These values are better than those of PZT.     

IR detectors using Pb(Mg1/3Nb2/3)O3 and Pb(Sc1/2Ta1/2)O3 ceramics under DC bias

Recently, one type of thermal-type IR detector, the pyroelectric sensor, has become of great interest in commercial applications, because of its ability to operate without cooling, its constant detectivity independent of wavelength, and its low cost. The conventional pyroelectric materials are usually normal ferroelectric materials with a first and second phase transition. The working temperatures are sufficiently below the Curie temperature T_c for stable responsivity to temperature. Electric field induced-type pyroelectric sensors have also been proposed. Relaxor ferroelectric materials such as Pb(Mg_1/3Nb_2/3)O₃ (PMN) and Pb(Sc_1/2Ta_1/2)O₃ (PST), which have a glassy Curie temperature near room temperature, are used in this type of sensor. This paper describes the sensor properties of electric field induced-type pyroelectric sensors prepared by using PMN and PST ceramics as compared with the conventional type sensors. Material evaluations of PMN and PST ceramics were made to determine their dielectric and pyroelectric properties. PMN shows excellent induced pyroelectric properties for the sensors over a wide range of temperatures. On the other hand, PST seems to be inadequate for an IR detector because of a very narrow high-response temperature range. The sensors with PMN and PST ceramics show enhanced pyroelectric activities under dc bias field. The measured sensor voltage responsivities agree with the calculated values for the PMN case. The electric field induced-type infrared sensor with thick or thin film materials seems to be satisfactory as linear array IR detectors for thermal imaging, with application of a higher electric field.     

Multiferroic ceramics Pb(Fe1/2Nb1/2)O3 doped by Li

We present the results of obtaining and investigating multiferroic ceramics Pb(Fe_1/2Nb_1/2)O₃ (PFN) and PFN doped by various amounts of Li (PFN:Li). Ceramics have been obtained from oxides by two-step synthesis. For obtained samples the X-ray diffraction patterns, microstructure, DC electric conductivity, the temperature dependencies of dielectric permittivity and dielectric losses, electromechanical properties and hysteresis loops have been investigated. Obtained results have shown that the introduction of Li decreases electric conductivity and improves dielectric and electromechanical parameters important for applications.     

High energy storage,structure evolution and dielectric properties of complex perovskite solid solution (1-x) NaNbO3-xBi (Zn2/3Nb1/3) O3

Journal of Electroceramics - NaNbO3-based lead-free ceramics show great potential in energy storage and piezoelectric applications due to the antiferroelectric and ferroelectric features. However,...     

Pb((Mg0.7Zn0.3)1/3Nb2/3)O3 Relaxor Ferroelectric Ceramics by a Reaction-Sintering Process

Pb((Mg_1/3Nb_2/3)_0.7(Zn_1/3Nb_2/3)_0.3)O₃ (PMZN) relaxor ferroelectric ceramics produced by a reaction-sintering process were investigated. Without any calcination, the mixture of PbO, Mg(NO₃)₂, Zn(NO₃)₂ and Nb₂O₅ was pressed into pellets and sintered directly. PMZN ceramics of 100% perovskite phase were obtained. Density of 8.11 g/cm³ (> 98% of theoretical value) was obtained after sintered at 1200C for 2 h. 3–9 m grain size was obtained in PMZN ceramics sintered at 1180C–1250C for two hours by reaction-sintering process.Dielectric constant at room temperature under 1 kHz reaches 18200 after sintered at 1200C for 2 h.     

Preparation and electrical properties of 0.4Pb(Zn1/3Nb2/3)O3-0.6Pb(Zr0.4Ti0.6)O3 thin films by 2-step annealing method

Films of (1−x)Pb(Zn_1/3Nb_2/3)O₃-xPb(Zr_0.4Ti_0.6) O₃ (x = 0.6, 40PZN-60PZT) were deposited on Pt/TiO₂/ SiO₂/Si substrate through spin coating. Using a combination of homogeneous precursor solution preparation and two-step pyrolysis process, we were able to obtain the 40PZN-60PZT thin films of perovskite phase virtually without pyrochlore phase precipitation after annealing above 650^∘C. But since annealing done at the high temperatures for extended time can cause diffusion of Pt, TiO₂ and Si, and precipitation of nonstoichiometric PbO, we adopted 2-step annealing method to circumvent these problems. The 2-step annealed films show dense microstructure than the 1-step films annealed at higher temperature. Furthermore, the root-mean-square surface roughness of 220 nm thick films which are annealed at 720^∘C for 1 min and then annealed at 650^∘C for 5 min was found to be 3.9 nm by atomic force microscopy as compared to the 12 nm surface roughness of the film annealed only at 720^∘C for 5 min. The electrical properties of 2-step annealed films are virtually same and those of the 1-step annealed films annealed at high temperature. The film 2-step annealed at 720^∘C for brief 1 min and with subsequent annealing at 650^∘C for 5 min showed a saturated hysteresis loop at an applied voltage of 5 V with remanent polarization (P _r) and coercive voltage (V _c) of 25.3 μC/cm² and 0.66 V respectively. The leakage current density was lower than 10⁻⁵A/cm² at an applied voltage of 5 V.     

Phase Development and Electrical Properties of Pb(Yb 1/2 Nb 1/2 )O 3 -PbTiO 3 Epitaxial Films

The growth and electrical properties of Pb(Yb 1/2 Nb 1/2 )O 3 -PbTiO 3 (PYbN-PT) epitaxial films were investigated. PYbN-PT epitaxial films with SrRuO 3 bottom electrodes were grown by pulsed laser deposition. Optimization of the growth conditions for the PYbN-PT epitaxial films was carried out on (100) SrRuO 3 /(100) LaAlO 3 substrates using the (50/50) composition target. It was found that formation of pyrochlore phase could be caused not only by low growth temperatures or lead deficiency, but also by poor surface condition of the SrRuO 3 bottom electrodes. (001) PYbN-PT epitaxial films with good crystalline quality were obtained for a range of deposition rates (60-100 nm/min) and temperatures (620-680 °C) after vacuum annealing the SrRuO 3 bottom electrodes. The ferroelectric and piezoelectric properties of 1 w m-thick PYbN-PT epitaxial films with (50/50) and (60/40) compositions and with (001) and (111) orientations were investigated using (100) LaAlO 3 , (100) SrTiO 3 , and (111) SrTiO 3 substrates with SrRuO 3 bottom electrodes. The highest remanent polarization (29 w C/cm 2 ) and effective piezoelectric coefficient e 31.f ( m 14 C/m 2 ) were observed in the (001) PYbN-PT (50/50) film. The transition temperature of the (001) PYbN-PT (50/50) film was about 380 °C. Because of the degradation of the target during the deposition, a 3 w m-thick film was prepared by three depositions (1 w m each layer). The 3 w m-thick film exhibited a higher e 31.f coefficient of m 19 C/m 2.     

Low temperature sintering and microwave dielectric properties of Ba3Ti5Nb6O28 with B2O3 and CuO additions

The low sintering temperature and the good dielectric properties such as high dielectric constant (ε _r ), high quality factor (Q × f), and small temperature coefficient of resonant frequency (TCF) are required for the application of chip passive components in wireless communication low temperature co-fired ceramics (LTCC). In the present study, the sintering behaviors and dielectric properties of Ba₃Ti₅Nb₆O₂₈ ceramics were investigated as a function of B₂O₃-CuO content. The pure Ba₃Ti₅Nb₆O₂₈ system showed a high sintering temperature (1250^∘C) and had the good microwave dielectric properties: Q × f of 10,600 GHz, ε _r of 37, TCF of −12 ppm/^∘C. The addition of B₂O₃-CuO was revealed to lower the sintering temperature of Ba₃Ti₅Nb₆O₂₈, 900^∘C and to enhance the microwave dielectric properties: Q × f of 32,500 GHz, ε _r of 40, TCF of 9 ppm/^∘C. From the X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) studies, these phenomena were explained in terms of the reduction of oxygen vacancies and the formation of secondary phases having the good microwave dielectric properties.     

Effects of Al2O3 on the piezoelectric properties of Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics

Piezoelectric properties of Al₂O₃-doped Pb(Mn_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃ ceramics were investigated. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by X-ray diffractometer for all the specimens doped with Al₂O₃. The highest sintered density of 7.8 g/cm³ was obtained for 0.2 wt% Al₂O₃-doped specimen. Grain size increased by doping Al₂O₃ up to 0.3 wt%, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants increased by doping Al₂O₃ up to 0.2 wt%, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in O^{2 −} ion sites and the substitution of Al³⁺ ions.     

Pulsed Laser Deposited Ba(Mg1/3Ta2/3)O3 Microwave Dielectric Thin Films

Ba(Mg_1/3Ta_2/3)O₃ (BMT) microwave dielectric thin films were successfully synthesized by a modified pulsed laser deposition (PLD) process, which includes low temperature (200°C) deposition and high temperature (>500°C) annealing. Crystalline structured BMT thin films were obtained when the PLD-deposited films were post-annealed at a temperature higher than 500°C in oxygen atmosphere. The characteristics of BMT thin film, including crystallinity, grain size, film roughness, and dielectric properties were improved with annealing temperature, achieving dielectric constant K = 23.5 and dissipation factor tan δ = 0.015 (at 1 MHz) for the 800°C-annealed films.     

Processing and Electrical Properties of 0.5Pb(Yb1/2Nb1/2)O3-0.5PbTiO3 Ceramics

Pb(Yb_1/2Nb_1/2)O₃-PbTiO₃ ceramics at the morphotropic phase boundary (50:50) were sintered by conventional and reactive methods to 95% theoretical density and grain sizes <10 m. Excess PbO, added to enhance the densification, resulted in PbO-based non-ferroelectric phases that degraded the electrical properties. Volatilization of excess PbO by annealing the samples after sintering resulted in dense, perovskite samples and excellent electrical properties. The best electrical properties, obtained via reactive sintering, were a remanent polarization, P _r, of 0.36 C/m², a maximum dielectric constant of 31,000 (at the T _c = 371°C and 1 kHz), a piezoelectric charge coefficient, d ₃₃, of 508 pC/N, and an electromechanical coupling coefficient, k ₃₃, of 0.61.     

Structure and Properties of Hot-Pressed Pb(Lu1/2Nb1/2)O3-PbTiO3 Binary System Ceramics*

Solid solution series of the (1 - x)Pb(Lu_1/2Nb_1/2)O₃ - x PbTiO₃ binary system ceramics (PLuNT) were synthesized and hot-pressed (temperature 950°C to 1130°C, pressure 25 MPa); its structure, dielectric and piezoelectric properties were studied. Pure lutecium niobate PLuN (x = 0) has a pronounced long-range order in the B-sublattice and an antiferroelectric to paraelectric phase transition at ～258°C. The phase structure of the PLuNT system, at room temperature, changes from a pseudomonoclinic (psd-M, space group Bmm2) to tetragonal (T, space group P4mm). The pseudomonoclinic phase extends over the 0 ≤ x ≤ 0.38 interval within which the monoclinic angle β proceeds a minimum near to 90° at x ? 0.2. The morphotropic region covers the interval x = 0.38 - 0.49, the concentration ratio psd-M:T? 1 (the morphotropic phase boundary—MPB) corresponds to x = 0.41. Within the morphotropic region, a rather strong distortion of the unit cell—(c/a - 1)≥ 0.02, β ≥ 90.37º, characteristic of “hard” piezoelectrics is maintained. Dielectric dispersion and broadening of the phase transition, features typical to relaxors, are observed within the concentration interval of 0.1 ≤ x ≤ 0.3. The highest electromechanical coupling coefficients: k_p = 0.66, k_t = 0.48, k₃₁ = 0.34 of (1 - x) PLuN?xPT ceramics are attained in compositions near the MPB at x ≈ 0.41. Non-isovalent doping of PLuNT with La³⁺ in Pb sublattice shifts the MPB to lower values of x.     

Solid state crystal growth of BiScO3-Pb(Mg1/3Nb2/3)O3-PbTiO3

Single crystals 0.26BiScO₃-0.25Pb(Mg_1/3Nb_2/3)O₃-0.49PbTiO₃ [BSPMNT] have been grown for the first time by the solid-state crystal growth (SSCG) method. A <110> oriented Ba(Zr,Ti)O₃ crystal seed was embedded in a matrix of BSPMNT compact which was annealed at high temperatures to induce the single crystal growth. Various fluxes, including Bi₂O₃, LiBiO₂, PbO/LiBiO₂, and PbO/Bi₂O₃, were used and their effects on the microstructure of the annealed compacts and the single crystal growth behavior were investigated. In the annealed samples with PbO/Bi₂O₃ flux, a considerable single crystal growth occurred at 1050?°C (with thickness on the order of 500?C1000???m), without the formation of abnormally large grains in the matrix. The results were explained in terms of the effect of various fluxes, based on the grain growth theory.     

PHASE TRANSITION IN Pb(Mg1/3Nb2/3)0.68TiO0.32O3 SINGLE CRYSTAL

ABSTRACT

Phase transition of (001)-cut Pb(Mg_1/3Nb_2/3)_0.68Ti_0.32O₃(PMNT32%) single crystal have been investigated by polarizing light microscopy in the temperature ranged form room temperature to 200 K. The transformation from monoclinic (M_A) to cubic (C) phase through an intermedial monoclinic (M_C) phase, i.e. M_A-M_C-C, was observed in the heating run, and the C-M_C-M_A phase transition sequence was observed in the cooling run. The temperature-induced rotation of extinction position, which was the result of polarization rotation, was observed in M_C phase. It is interesting that tetragonal (T) phase has not been reached before the M_C phase turn into cubic phase. The existing phase diagram for PMNT system was improved by this experimental result. In addition, it was found the phase transition processes of M_C-M_A and cubic-M_C show distinct characters though both of they are first-order.