Phase diagram and properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 polycrystalline ceramics

yPb(In_1/2Nb_1/2)O₃-(1 − x − y)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (yPIN-(1 − x − y)PMN-xPT) polycrystalline ceramics with morphotropic phase boundary (MPB) compositions were synthesized using columbite precursor method. X-ray diffraction results indicated that the MPB of PIN-PMN-PT was located around PT = 0.33-0.36, confirmed by their respective dielectric, piezoelectric and electromechanical properties. The optimum properties were found for the MPB composition 0.36PIN-0.30PMN-0.34PT, with dielectric permittivity ?_r of 2970, piezoelectric coefficient d₃₃ of 450 pC/N, planar electromechanical coupling k_p of 49%, remanent polarization P_r of 31.6 μC/cm² and T_C of 245 °C. According to the results of dielectric and pyroelectric measurements, the Curie temperature T_C and rhombohedral to tetragonal phase transition temperature T_R-T were obtained, and the “flat” MPB for PIN-PMN-PT was achieved, indicating that the strongly curved MPB in PMN-PT system was improved by adding PIN component, offering the possibility to grow single crystals with high electromechanical properties and expanded temperature usage range (limited by T_R-T).     

Anisotropic field induced phase transitions and negative electrocaloric effect in rhombohedral Mn doped Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals

The electrocaloric effect (ECE) of Mn doped Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT:Mn) single crystals with particular emphasis on the impact of crystallographic orientations and phase transitions were investigated systematically. Orientation-dependent phase transitions have been demonstrated by the dielectric and strain behaviors. Intriguingly, the negative ECE of –0.02?°C and –0.002?°C were obtained firstly in [001]-oriented PIN-PMN-PT:Mn crystals near the rhombohedral→tetragonal phase transformation and in [011]-oriented crystals near the rhombohedral→orthorhombic phase transformation, respectively. However, only the positive ECE was found in [111]-oriented crystals near the tetragonal→rhombohedral phase transition. Additionally, the maximum ECE temperature changes calculated in [001]-, [011]- and [111]-oriented crystals were 0.33?°C, 0.46?°C and 0.38?°C, respectively. Our results suggest that the negative ECE is attributed to electric field-induced phase transitions, whose critical field decreases with the increase of temperature. The phase transition-mediated coexistence of positive and negative effects in the relaxor-ferroelectric single crystals is beneficial to enhance the efficiency of the solid-state cooling devices.     

Fabrication and characterization of (Pb(Mg1/3Nb2/3)O3, Pb(Yb1/2Nb1/2)O3, PbTiO3) ternary system ceramics

New ternary compositions in the Pb(Mg_1/3Nb_2/3)O₃-Pb(Yb_1/2Nb_1/2)O₃–PbTiO₃ (PMN-PYbN-PT) system were prepared using 0.5Pb(Yb_1/2Nb_1/2)O₃-0.5PbTiO₃ (PYbNT) and (1-x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (x = 0.26; PMNT26 or x = 0.325; PMNT32.5) powders synthesized via the columbite method. Dense (≥ 96% of theoretical density) ceramics with PMN/PYbN mole ratios of 25/75 (R-25), 50/50 (R-50) and 75/25 (R-75T and R-75R) were fabricated by reactive sintering at 1000 °C for 4 h. Therefore, incorporation of PYbNT to PMNT successfully decreased sintering temperature of PMNT from 1200 °C-1250 °C to 1000 °C. Samples with higher density and perovskite ratio together with lower weight loss possessed higher dielectric and piezoelectric values in each composition. The R-75 samples had remanent polarization (P_r) values of 34-36 μC/cm² and piezoelectric charge coefficient (d₃₃) of 560 pC/N. The sharp phase transition PMNT as a function of temperature became broader or more diffuse with increasing PYbNT content. However, PYbNT addition to PMNT increased Curie temperature (T_c) from 183 °C (for PMNT32.5) to 220-242 °C (for R-75T and R-75R) to 336 °C (for R-25). Therefore, these ternary compositions can be tailored for various high temperature applications due to the relatively higher T_c with enhanced piezoelectric and dielectric properties as compared to PMNT.     

Temperature dependence of electrical and electromechanical properties of Pb(Mg1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr,Ti)O3 thin films

The electrical and electromechanical properties of Pb(Mg_1/3Nb_2/3)O₃–Pb(Ni_1/3Nb_2/3)O₃–Pb(Zr,Ti)O₃ (PMN–PNN–PZT, PMN/PNN/PZT = 20/10/70) on Pt/Ti/SiO₂/Si substrates by chemical solution deposition was investigated. The PMN–PNN–PZT films annealed at 650 °C exhibited slim polarization hysteresis curves and a high dielectric constant of 2100 at room temperature. A broad dielectric maximum at approximately 140–170 °C was observed. The field-induced displacement was measured by scanning probe microscopy, the bipolar displacement was not hysteretic, and the effective piezoelectric coefficient (d₃₃) was 66 × 10⁻¹² m/V. The effective d₃₃ decreased with temperature, but the value at 100 °C remained 45 × 10⁻¹² m/V.     

Linear response fluorescent temperature-sensing properties based on Stark sublevels of Er3+-doped Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Yb1/2Nb1/2)O3 ceramics

The Er³⁺ doped 0.84(PMN-PT)?0.14PYN ceramics were employed as a temperature-sensing material. The obtained compounds exhibit strong visible upconversion (UC) fluorescence under a 980-nm diode laser excitation. On account of the Stark split effect, the ²H_11/2, ⁴S_3/2, and ⁴F_9/2 levels of Er³⁺ split into two Stark sublevels, respectively. The fluorescence intensity ratios (FIR) between these sublevels were calculated in a temperature range of 133–573?K, and a linear FIR vs. temperature relation has been found. FIR of A/B shows a wide temperature sensing range with a relatively low sensitivity of 0.003?K^?1. Meanwhile E/C illustrates the highest sensitivity of 0.0134?K^?1 but in the smallest temperature range 453–573?K. FIR technique provides us a optical thermometric method with constant sensitivity in a wide temperature range.     

Investigation of ternary system Pb(Sn,Ti)O3-Pb(Mg1/3Nb2/3)O3 with morphotropic phase boundary compositions

(1 − x)Pb(Sn_1−yTi_y)O₃-xPb(Mg_1/3Nb_2/3)O₃ (x = 0.1-0.4, y = 0.45-0.65) ternary system was prepared using two-step columbite precursor method. Phase structure of the synthesized ceramics was studied by using X-ray powder diffraction and the morphotropic phase boundary (MPB) curve of the ternary system was confirmed. The isothermal map of Curie temperature (T_C) in the phase diagram was obtained based on the dielectric-temperature measurements. The coercive field E_C and internal bias field E_i were found to increase with increasing PT content, while decrease with increasing PMN content. The optimum properties were achieved in the MPB composition 0.8Pb(Sn_0.45Ti_0.55)O₃-0.2Pb(Mg_1/3Nb_2/3)O₃, with dielectric permittivity ?_r, piezoelectric coefficient d₃₃, planar electromechanical coupling k_p, mechanical quality factor Q_m and T_C of being on the order of 3040, 530pC/N, 55.5%, 320 and 190 °C, respectively, exhibiting potential usage for high power application.     

Microstructural, electrical and magnetic properties of multiferroic CoFe2O4/0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 nanocomposite thin films

Bilayered CoFe₂O₄/0.68Pb(Mg_1/3Nb_2/3)O₃-0.32PbTiO₃ nanocomposite films are successfully prepared on Pt/Ti/SiO₂/Si substrate via simple sol-gel process. X-ray diffraction result reveals that there exists no chemical reaction or phase diffusion between the CoFe₂O₄ and 0.68Pb(Mg_1/3Nb_2/3)O₃-0.32PbTiO₃ phases. The microstructure is characterized by scanning/transmission electron microscopy (STEM). The composite thin films exhibit both strong ferroelectric and ferromagnetic responses at room temperature. The maximal magnetoelectric coupling coefficient of the nanocomposite films reaches up to 25 mV/cm Oe, occurs at a lower bias magnetic field (H_dc) of 550 Oe.     

Structure and dielectric behavior of (1-x)Pb(Sc1/2Ta1/2)O3-xPb(In1/2Nb1/2)O3 solid solution

A solid solution system of (1-x)Pb(Sc_1/2Ta_1/2)O₃-xPb(In_1/2Nb_1/2)O₃ (x = 0.2, 0.4, 0.6, and 0.8) was synthesized by conventional solid-state reaction technique. The optimum sintering temperatures of ceramics with x = 0.2, 0.4, 0.6, and 0.8 were 1400?°C, 1400?°C, 1300?°C, and 1200?°C, respectively. At these temperatures, the densest samples and the maximum dielectric constant were obtained. With increasing x, the percentage of pyrochlore phase increased, indicating a decrease in the solubility of solid solution. For x = 0.2, with the sintering temperature increasing, the ordering degree decreased while the dielectric constant increased. For x = 0.6 and 0.8, at the highest sintering temperature, the most pyrochlore phase appeared and the minimum dielectric constant was obtained. In addition, the relaxor characteristics of solid solution ceramics were systematically investigated. It was found that the dielectric maximum decreased and the temperature at dielectric maximum shifted to higher temperature with x increasing. All compositions exhibited the second-order phase transition due to the analysis of dielectric behaviors on heating and cooling. Interestingly, the difference in dielectric maximum between heating and cooling became larger with PIN content increasing. The diffuseness exponents of all compositions were calculated to be in the range of 1.53–1.66, suggesting the typical relaxor. The polarization-electric field (P-E) hysteresis loops of all solid solutions showed the shapes of slim loop. Meanwhile, the coercive field and remnant polarization of all compositions were analyzed in detail.     

Temperature induced dielectric polarization evolution in polycrystalline Pb(Cd1/3Nb2/3)O3

The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), dilatometric and dielectric measurements performed for the same polycrystalline Pb(Cd_1/3Nb_2/3)O₃ (PCN) sample are presented. These results reveal the complex character of polycrystalline PCN dielectric properties; in particular, no structural phase transition (PT) was observed. The thermal expansion coefficient indicates glass-like behaviour of PCN. The frequency and temperature dependencies of complex dielectric permittivity were measured and analyzed in terms of diffused/relaxor transition of the ferroelectric polarization. Temperature induced evolution of the relative dielectric permittivity was found to involve two processes. Dielectric permittivity changes, originating from thermally induced evolution of thermal equilibrium of interactions between main structural lattice and two sub-lattices present in the sample were interpreted in terms of thermal evolution of polar cluster sizes in the region of relaxor/glass-like transition.     

Structural and electrical properties of 0.56Pb(Ni1/3Nb2/3)O3-0.10Pb(Zn1/3Nb2/3)O3-0.34PbTiO3 ceramics prepared by different ceramic processings

The ternary system of 0.56Pb(Ni_1/3Nb_2/3)O₃-0.10Pb(Zn_1/3Nb_2/3)O₃-0.34PbTiO₃ (0.56PNN-0.10PZN-0.34PT) ceramics were prepared by conventional solid-state reaction method via straight mixed oxide method, columbite precursor method and B-site oxide mixing route. X-ray diffraction (XRD) measurement demonstrated that both the tetragonal and rhombohedral phases coexist in the B-site oxide mixing route prepared ceramics accompanied by the largest content of perovskite phase of 95.18%. The 0.56PNN-0.10PZN-0.34PT ceramics prepared by the straight mixed oxide method and the B-site oxide mixing route exhibit rather homogeneous microstructure. As a comparison, in the columbite precursor method prepared ceramics nebulous granules and octahedral or other polyhedral morphology grains are observed. All the sintered ceramics exhibit diffused ferroelectric phase transition where the dielectric response peaks are broad, diffused and strongly frequency dependent. However, the temperature of dielectric maximum (T_m) increases greatly from 398.0 K of the 0.56PNN-0.10PZN-0.34PT ceramics prepared by the B-site oxide mixing route to 423.3 K of the ones prepared by the straight mixed oxide method. Saturated and symmetric P-E hysteresis loops are observed in all the sintered ceramics, where the B-site oxide mixing route prepared ceramics exhibit large value of remanent polarization (P_r) of 17.13 μC/cm² and the least value of coercive field (E_c) of 11.99 kV/cm. Piezoelectric constant (d₃₃) exhibits the largest value of 449 pC/N for the ceramics prepared by the B-site oxide mixing route. Such results are related to the phase composition, density and porosity of the ceramics.     

Synthesis and properties of (BaxPb1−x)(Zn1/3Nb2/3)O3 relaxor ferroelectric ceramics using a reaction-sintering process

(Ba_xPb_1−x)(Zn_1/3Nb_2/3)O₃ (BPZN; x = 0.06–0.1) relaxor ferroelectric ceramics produced using a reaction-sintering process were investigated. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. BPZN ceramics of 100% perovskite phase were obtained. Highly dense BPZN ceramics with a density higher than 98.5% of theoretical density could be obtained. Maximum dielectric constant K_max 13,500 (at 75 °C), 19,600 (at 50 °C) and 14,800 (at 28 °C) at 1 kHz could be obtained in 6BPZN, 8BPZN and 10BPZN, respectively. Dielectric maximum temperature (T_max) in BPZN ceramics via reaction-sintering process is lower than BPZN ceramics prepared via B-site precursor route.     

Thickness dependent growth and ferroelectric/dielectric properties of phase-pure 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 thin film derived from a modified sol-gel process

Annealing parameter and thickness are two significant factors affecting microstructure and electrical performance of sol-gel derived 0.65Pb(Mg_1/3Nb_2/3)O₃?0.35PbTiO₃ (0.65PMN-0.35PT) thin film. In this paper, various durations are firstly selected for the investigations on annealing parameter of 0.65PMN-0.35PT thin film. Enhanced insulating and ferroelectric properties can be obtained for the film annealed for 1 min due to its phase-pure and homogeneous perovskite structure. Based on this, a series of 0.65PMN-0.35PT thin films with various thicknesses by modifying deposition layer are synthesized annealed for 1 min and the effects of thickness on crystalline, insulating, ferroelectric and dielectric properties are characterized. It reveals that thickness-dependent behavior can be noticed for 0.65PMN-0.35PT thin film with the results that the 8-layered film possesses a relative large remanent polarization (P_r) of 23.34 μC/cm², and reduced leakage current density of 10^?9 A/cm² with low dissipation factor (tanδ) of 0.03 can be achieved for the 14-layered film.     

Fabrication and piezoelectric properties of BaTiO3/BaTiO3-Bi(Mg1/2Ti1/2)O3-BiFeO3 composites

We fabricated xBaTiO₃ (BT)/(1-x)[BaTiO₃-Bi(Mg_1/2Ti_1/2)O₃-BiFeO₃] (BT-BMT-BF)?+?0.1?wt%MnCO₃ composites by spark plasma sintering and investigated the effect of BT content x, BT powder size, and BT-BMT-BF composition on piezoelectric properties. For xBT/(1-x)(0.3BT-0.1BMT-0.6BF) +?0.1?wt%MnCO₃ (x?=?0–0.75) composites with a 0.5-µm BT powder, the dielectric constant was increased with x, and the relative density was decreased at x?=?0.67 and 0.75, creating optimum BT content of x?=?0.50 with a piezoelectric constant d₃₃ of 107?pC/N. When a larger 1.5-µm BT powder was utilized for the composite with x?=?0.50, the d₃₃ value increased to 150?pC/N due to the grain size effect of the BT grains. To compensate for a compositional change from the optimum 0.3BT-0.1BMT-0.6BF due to partial diffusion between the BT and 0.3BT-0.1BMT-0.6BF grains, a 0.5BT/0.5(0.275BT-0.1BMT-0.625BF)?+?0.1?wt%MnCO₃ composite with the 1.5-µm BT powder was fabricated. We obtained an increased d₃₃ value of 166?pC/N. These results provided a useful composite design to enhance the piezoelectric properties.     

Evolution of polar nano-regions under electric field around ferro-paraelectric transition temperature and its contribution to piezoelectric property in Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 crystal

As one of the most pronounced structural features, polar nano-regions (PNRs) is believed to have significant contribution to the outstanding piezoelectric property of relaxor-based ferroelectrics. However, direct experimental investigation on the connection between the PNRs behavior under electric field and piezoelectric responses is still insufficient. In this work, by the combined use of piezoresponse force microscopy, polarization light microscopy, and the electrical property measurements, we investigate the structure evolution from macro-domains to PNRs around ferro-paraelectric phase transition temperature (T_m, 140?°C) in Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ single crystal. Most importantly, based on the corresponding analysis of unipolar strain-electric-field (S-E) curves at different temperatures and the direct observation of electric-field-induced structure evolution at T_m, we intensively investigate the response of PNRs to electric field and its contribution to piezoelectric property. We conclude that, under electric field, the active PNRs around T_m first serve as polar seeds to induce macro-domains from the non-polar matrix, then promote the switching of macro-domains. The large-field strain coefficient d₃₃^* in these two processes can achieve maximum of about 5410?pm/V and 61710?pm/V at T_m, and gradually decreases at higher temperature with lower PNRs content.     

Fabrication and electrical properties of Pb(Co1/3Nb2/3)O3 ceramics

Pb(Co_1/3Nb_2/3)O₃ (PCN) ceramics have been produced by sintering PCN powders synthesized from lead oxide (PbO) and cobalt niobate (CoNb₂O₆) with an effective method developed for minimizing the level of PbO loss during sintering. Attention has been focused on relationships between sintering conditions, phase formation, density, microstructural development, dielectric and ferroelectric properties of the sintered ceramics. From X-ray diffraction analysis, the optimum sintering temperature for the high purity PCN phase was found at approximately 1050 and 1100 °C. The densities of sintered PCN ceramics increased with increasing sintering temperature. However, it is also observed that at very high temperature the density began to decrease. PCN ceramic sintered at 1050 °C has small grain size with variation in grain shape. There is insignificant change of dielectric properties with sintering temperature. The P–E hysteresis loops observed at −70 °C are of slim-loop type with small remanent polarization values, which confirmed relaxor ferroelectric behavior of PCN ceramics.     

Effects of addition of Pb(Y1/2Nb1/2)O3 (PYN) on microstructure and piezoelectric properties of Pb(Zr0.53Ti0.47)O3

Pure and Pb(Y_1/2Nb_1/2)O₃ (PYN)-doped Pb(Zr_0.53Ti_0.47)O₃ have been characterized. The samples were prepared by conventional mixed-oxide ceramic technology. PYN dopant was added to PZT at content levels ranging from 1 to 2.5 mol%. The microstructures of the samples were examined using SEM and TEM. The average grain size was observed to decrease as the dopant content increased. Herringbone-like and wedge-shaped domain patterns were observed in all the samples. The piezoelectric properties of PZT were greatly improved by the addition of PYN. The highest piezoelectric constant d₃₁ was nearly twice that of pure PZT.     

Effects of Mg/Fe substitution on perovskite stabilization and dielectric properties of Pb(Zn1/2W1/2)O3

The effects of compositional modification by substituting Mg or Fe for Zn on the perovskite formation, crystallographic aspects, and dielectric properties of Pb(Zn_1/2W_1/2)O₃ were investigated. Microstructural evolutions in the sintered ceramics were also examined. Stabilization of the perovskite structure was accomplished by a much smaller concentration of Mg substitution. Lattice parameters of the perovskite decreased with increasing substituent fractions in general. By contrast, the permittivity values increased significantly with increasing Mg/Fe substitution.     

Effect of In, Ce and Bi dopings on sintering and dielectric properties of Ba(Zn1/3Nb2/3)O3 ceramics

In, Ce and Bi doped Ba(Zn_1/3Nb_2/3)O₃ (BZN) ceramics were prepared by conventional mixed oxide technique. In doping between 0.2 and 4.0 mol% increased the density of BZN at 1300 °C, Ce doping caused a decrease in density at 1250 °C. Levels of Bi₂O₃ up to 1.0 mol% had negative effect on densification, while high level doping could significantly improve the densification of the specimens. XRD of the samples indicated that In, Ce and Bi doping resulted in single phase formation at all concentrations, except 0.5 mol% Bi. SEM of Bi doped BZN indicated only single phase structure and Ce doping even at 0.2 mol% gave some secondary phases. In and Ce doping increased the dielectric constant from 41 to around 66 at 1 MHz. Bi doping decreased the dielectric constant to about 37 at 0.2 mol%, and then higher doping led to dielectric constant to increase to about 63.     

Influence of ceramic processing on dielectric properties of perovskite type compound: Pb(Mg1/3, Nb2/3)O3

Pb (Mg_1/3, Nb_2/3)O₃ perovskite type compound which can be sintered at low temperatures has a ligh dielectric permittivity and so can be used as multilayer ceramic capacitors. In this study we show that ceramic processes resulting in different mixtures of phases and different microstructures strongly influence the dielectric properties (dielectric permittivity, dissipation factor and resistivity). Only a careful characterization in each step of the process can allow the optimization of ceramics.     

Electron emission from Pb0.88La0.08(Zr0.65Ti0.35)O3 ferroelectric ceramics

The electron emission characteristics of PLZT 8/65/35 ferroelectric are studied. High current density has been obtained from PLZT 8/65/35 ferroelectric cathode. The source of the disturbance in the experiment is discussed and several methods to reduce the disturbance are proposed. It is discovered that there is a voltage threshold, and the electron emission will not occur until the amplitude of the pulse exceeds the threshold. Moreover, there are two current peaks in the FE electron emission curves, the primary peak remains stable in location and intensity, while the secondary one shows instability during repeating experiments.