Impedance spectroscopic studies of ferroelectric Pb2Sb3DyTi5O18 ceramic

Abstract

The electrical properties of polycrystalline Pb₂Sb₃DyTi₅O₁₈ were investigated by complex impedance spectroscopy. The dielectric relaxation was found to be of polydispersive non-Debye type, and relaxation frequency shifts to higher frequencies with increasing temperature. Evidence of temperature dependent electrical relaxation phenomena as well as the negative temperature coefficient of resistance (NTCR) character of the sample have also been observed. The ac conductivity obeys the universal power law and dispersion in conductivity was observed in the lower frequency region. Also, the frequency dependent ac conductivity at different temperatures indicated that the conduction process is thermally activated. The activation energy was estimated to be 0·62 eV from the temperature variation of dc conductivity.     

Effects of microwave heating on dielectric and piezoelectric properties of PZT ceramic tapes

Commercial lead zirconate titanate (PZT) perovskite powders were used to fabricate ceramic tape and then sintered by microwave and conventional methods. Both dielectric and piezoelectric properties of PZT ceramic tapes were studied in terms of sintering process. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) show the PZT perovskite phase with smaller grain size and dense microstructure can be obtained at a lower sintering temperature by microwave process. It was also observed that shrinkage ratio and bulk density of the tapes sintered at 800 °C were obtained about 19% and 7.46 g/cm³ by the microwave heating method, respectively, that is corresponding to those values of sintered PZT tapes at 950 °C by conventional process. Moreover, the dielectric constant and maximum permittivity are increased about 30% as compared with conventional processing method. The experimental results demonstrated that the characteristics of the PZT tapes could be significantly improved by microwave heating method. These results demonstrate that such a simple approach can upswing the piezoelectric and dielectric properties of these tapes by using microwave process with a short heating time.     

Effect of sol composition on dielectric and ferroelectric properties of PZT composite films

Crack free calcium modified PZT composite films have been synthesized using modified sol-gel process by depositing the slurries prepared by mixing powder of composition PbZr_0.52Ti_0.48O₃ and sol of composition Pb_(1−x)Ca_xZr_0.52Ti_0.48O₃ (where x = 0, 0.06, 0.1) on Pt(1 1 1)/Ti/SiO₂/Si substrate. The infilteration process has also been employed which resulted in dense microstructure of the films. Thickness of the films as measured by SEM of cross section of the films was more than 25 μm. The XRD patterns of the resultant films consisted of pure perovskite phase and no peak related to either pyrochlore phase or Pt substrate was observed. The room temperature dielectric constant and loss were compared. The temperature dependence of dielectric constant revealed that T_C of all the films was same, i.e., 351 °C, in spite of different compositions of the sol used. Well saturated PE-loops of the films show that the films were ferroelectric in nature.     

Effect of sintering aid and repeated sol infiltrations on the dielectric and piezoelectric properties of a PZT composite thick film

Thick PZT films have been produced using a combination of spin coating of a composite slurry and subsequent infiltration of PZT producing sol. The effect of adding a Cu₂O–PbO sintering aid and repeated sol infiltrations have been studied with the aim of producing dense PZT films. Relative permittivity has been shown to increase with the addition of sintering aid and increased levels of sol infiltration. Measurements of piezoelectric properties indicate that sol infiltrations have no effect on d₃₃ once a critical density has been exceeded. A sample with approximately 10% closed porosity was obtained following the incorporation of sintering aid and four infiltration steps per layer. This resulted in a mean relative permittivity of approximately 700 and a d₃₃ of 62 pC/N (poling conditions: 8 V/μm for 5 min at 200 °C).     

Impact of ionizing radiation on structural,dielectric, and piezoelectric properties of Sr modified PZT

Ion irradiation effects on piezoceramic (Pb_0.94 Sr_0.04) (Zr_0.52 Ti_0.48)O₃ (PSZT) are investigated by using 4 MeV carbon (C), 9 MeV copper (Cu), and 20 MeV gold (Au) ions. The energies of incident ions are selected in order to target the same range of all incident ions in the material, while producing different amounts of vacancies. The ion irradiation is performed with fluences of 1×10¹³, 1×10¹⁴, and 1×10¹⁵ ions/cm² using Tandem Pelletron accelerator (5UDH-2). Post irradiation changes in PSZT are investigated via various structural, dielectric, and piezoelectric measurement techniques. Results divulge that the irradiation process disturbs the crystallinity along with reduction in X-ray diffraction (XRD) peak intensities owing to strain induced structural defects. A small decrease in dielectric constant is observed due to trapped charges, which screen the depolarization after irradiation. However, a significant decrease is detected in piezoelectric charge coefficients (d₃₃) and piezoelectric voltage coefficients (g₃₃) due to switching of micro domains of PSZT as a result of energy observed during irradiation process. These results indicate that ion irradiation has damaging effects on the properties of PSZT. The discussed information may be utilized to assess performance of PSZT based devices under radiation rich environments such as space.     

Effects of pore size and orientation on dielectric and piezoelectric properties of 1-3 type porous PZT ceramics

Porous PZT ceramics have drawn an increasing amount of interest in recent years due to their superior properties compared with the dense material. However, researchers have usually dedicated effort to 0-3 and 3-3 type porous PZT ceramics and little attention has been focused on 1-3 type. The 1-3 type porous PZT ceramics with high porosity were fabricated in this study by freeze-casting process. All samples possessed high piezoelectric coefficient (d₃₃) with high porosity owing to the special one-dimensional ordered porous structure along the poling direction. The d₃₃ values increased by either improving the pore channel orientation level or decreasing pore size. The relative permittivity improved only with the enhancement of pore channel orientation level. The acoustic impedances ranged from 1.45 to 1.35 MRayls which could match well with those of biological tissue or water; therefore, this material would be beneficial in hydrophone applications.     

Effect of Samarium substitution on dielectric properties of (Pb)(Zr, Ti, Fe, Nb)O3 type ceramic system

The influence of Samarium substitution on the dielectric properties of modified PZT composition with representative formula [Pb_1−xSm_xZr_0.588Ti_0.392Fe_0.01Nb_0.01O₃] system is reported. Samarium (Sm) was varied from 0 to 0.01/FU in the present system in a step of 0.0025. The samples were prepared by the traditional solid state reaction process. XRD analysis showed all the samples to be single phase with tetragonal structure. Dielectric properties were studied in detail as a function of frequency and temperature (from room temperature (RT) 30 to 400 °C). All compositions show phase transition and the transition temperature (T_C) is found to decrease with increase in Sm substitution. Room temperature dielectric constant shows an increasing trend while loss improves with Sm doping.     

Densification and dielectric properties of strontium bismuth tantalate ceramics

Abstract

The effects of B₂O₃ doping on the sintering processes and dielectric properties of SrBi₂Ta₂O₉ were investigated in this study. The sinterability of SrBi₂Ta₂O₉ was significantly enhanced by doping B₂O₃ due to the formation of liquid phase at elevated temperatures. The addition of B₂O₃ also led to inhibited thermal decomposition and enhanced grain growth of SrBi₂Ta₂O₉. The amount of doped B₂O₃ was found to substantially influence the dielectric constants of SrBi₂Ta₂O₉ ceramics. When a proper amount of B₂O₃ was added, the dielectric constants greatly increased. For facilitating the densification process and improving the dielectric properties of SrBi₂Ta₂O₉, it is important to control the doping amount of B₂O₃.     

Effect of particle size and ZnO addition on microwave dielectric properties of nanocrystalline (Zr0.8Sn0.2) TiO4 ceramics

Abstract

Polycrystalline samples of (Zr_0.8Sn_0.2)TiO₄ have been synthesised by solid state reaction method. The effects of ball milling and the addition of ZnO (1–2.5 wt-%) on the microwave dielectric properties of (Zr_0.8Sn_0.2)TiO₄ ceramics are investigated. As the ball milling time increases, the density of the (Zr_0.8Sn_0.2)TiO₄ ceramics increases. The influence of ZnO as a sintering aid on the sintering temperature of (Zr_0.8Sn_0.2)TiO₄ is also studied. As the weight percentage of ZnO increases, the density increases up to 1.5 wt-% of ZnO and thereafter it starts decreasing. The dielectric constant εγ _r and the product of quality factor Q and resonant frequency f_o of TE_{01 °} mode (Qxf_o ) followed the same trend with increasing density, irrespective of whether the density increased with ball milling time or by addition of ZnO. The value of Qxf _o is found to increase with increasing grain size. The microwave dielectric constant and the Qxf _o values were respectively ranged from 32 to 39.3 and from 32 000 to 49 600 at 10.5 GHz for (Zr_0.8Sn_0.2)TiO₄ ceramics. Furthermore, the influence of the processing parameters on the microwave dielectric properties of (Zr_0.8Sn_0.2)TiO₄ is discussed.     

Effect of grain size on phase transition,dielectric and pyroelectric properties of BST ceramics

Grain size effect on phase transition, dielectric and pyroelectric properties of BST ceramics under DC bias field was reported for the first time. With the grain size increased by one order of magnitude, phase transition diffuseness parameters δ and γ decreased from 282 to 63 and 1.64–1.33, respectively. This resulted in the dielectric constant maximum increased by 65%, the pyroelectric coefficient maximum and corresponding figure of merit were quadrupled and tripled, respectively. The physical essence of the great size effect can be attributed to a combination of surface effect, mechanical stress effect and extrinsic effect of grain boundary. A well understanding of the grain size effect and its mechanism will be useful for the BaTiO₃-based ceramics and other ferroelectrics.     

Temperature dependence of macroscopic and microscopic PZT properties studied by thermo-mechanical analysis,dielectric measurements and X-ray diffraction

The main objective of the paper is to point out the influence of composition and of poling state (poled and unpoled samples) on the evolution of various parameters (?_r, dilatation coefficients, lattice parameters) at different scales (lattice, bulk) using X-ray diffraction (XRD), thermo-mechanical analysis (TMA) and dielectric methods. The transition temperatures have been determined from the above measurements and compared. The composition has an influence on the transition temperature and not on the dilatation coefficient value. The poling state influences only the macroscopic dilatation evolution and not the value of the transition temperature. A scale effect is only observed on majoritary tetragonal compositions which show different values of transition temperatures from microscopic and macroscopic methods.     

Experimental and theoretical dielectric studies of PVDF/PZT nanocomposite thin films

Poly(vinylidene fluoride)/lead zirconate titanate nanocomposite thin films (PVDF/PZT-NPs) were successfully prepared by mixing fine Pb(Zr_0.52,Ti_0.48)O₃ nanoparticles (PZT-NPs) into a PVDF solution under ultrasonication. The mixture was spin coated onto glass substrate and then cured at 110 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to characterize the structure and properties of the obtained thin-film nanocomposites. The dielectric properties of the PVDF/PZT-NPs were analyzed in detail with respect to frequency. In comparison with pure poly (vinylidene fluoride), the dielectric constant of the nanocomposite (15 vol.% PZT-NPs) was significantly increased, whereas the loss tangent was unchanged in the frequency range of 100 Hz to 30 MHz. The nanocomposites exhibited good dielectric stability over a wide frequency range. Different theoretical approaches were employed to predict the effective dielectric constants of the thin film nanocomposite systems, and the estimated results were compared with the experimental data.     

添加剂对锆钛酸铅二元系压电陶瓷性能的影响

对添加剂按电价进行了分类，讨论了各类添加剂对锫钛酸铅二元系压电陶瓷性能的影响，分析了各类添加剂能对锆钛酸铅二元系压电陶瓷进行改性的原因。研究表明各种添加剂的加入量都有一个适宜的范围。     

Effect of electrode interfaces on peak-drift switching current of PZT thin films

In this study, we investigated the impact of electrodes on the structural, crystal orientation, and electrical characteristics of lead zirconate titanate [Pb(Zr_0.52Ti_0.48)O₃, PZT] thin films, that were deposited on Pt, Au, and LaNiO₃ (LNO) electrodes through sol-gel processes. The peak voltage, that is, the voltage corresponding to the maximum switching current point, was developed to depict the novel peak-drift electric characteristics in ferroelectric thin films. It increases in the positive ferroelectric peak voltage, and decreases in the negative peak voltage with an increase in the driving voltage amplitude. Based on space-charge-limited bulk conduction, we evaluated the peak-drift phenomenon, Schottky contact and their influences on the switching current. When polarization orientation is reversed, the Schottky contact disappears at one side of the PZT/electrode, and forms at the other side synchronously. Our results indicate that the formation of a Schottky contact affects the shape of the switching curves, and its disappearance influences the magnitude of the current characteristics.     

Effect of solvent on structure and optical properties of PZT nanoparticles prepared by sol-gel method, in infrared region

Single-phase perovskite Pb(Zr_0.52,Ti_0.48) nanoparticles, PZT-NPs were prepared by the sol-gel method with two different solvents, 2-methoxyethanol, EGME, and poly ethylene glycol, PEG. X-ray diffraction (XRD) was used to study of the structure of the PZT-NPs. Fourier transform infrared spectroscopy (FTIR) was used to measure the infrared reflectivity spectrum in the range of 4000-280 cm⁻¹. Infrared active vibration modes of BO₆ octahedral (ν₁ and ν₂) were observed for PZT-NPs below 600 cm⁻¹. The third vibration mode of Pb against the TiO₃ group, ν₃, occurred below the experimentally accessible range. The Kramers-Kronig method (K-K) and classical dispersion theory were applied to analyze the data and calculation of the optical constants such as reflective index (N(ω))and permittivity (?(ω)). The results showed that the structure and optical properties of PZT-NPs were changed by different type of solvent.     

Structural investigation and dielectric studies on Mn substituted Pb(Zr0.65Ti0.35)O3 perovskite ceramics

Polycrystalline samples of manganese substituted lead zirconium titanate (PZMT) with general formula Pb(Zr_0.65−xMn_xTi_0.35)O₃ ceramics have been synthesised by high temperature solid state reaction technique. X-ray diffraction (XRD) patterns were recorded at room temperature to study the crystal structure employing Rietveld technique. All the patterns could be refined to R3c space group with rhombohedral symmetry. Bond lengths and angles have been calculated from refined parameters. Microstructural properties of the materials were analysed by scanning electron microscope (SEM) and compositional analysis were carried out by energy dispersive spectrum (EDS) measurements. All the materials exhibit ferroelectric to paraelectric transition. The Curie temperature (T_c) increases with the Mn concentration. We have observed that dielectric constant decreases and AC conductivity increases with the frequency. The correlation between lattice parameters and T_c for the present samples has been observed.     

Effect of the slurry composition on the piezoelectric properties of PZT ceramics fabricated via materials extrusion 3D printing

Herein, the effect of the binder content in lead zirconate titanate (PZT) slurry has been systematically studied to improve the piezoelectric properties of PZT ceramics prepared via material extrusion 3D printing. For smooth printing, a slurry with a binder concentration ranging from 6 to 12 wt% was proposed. The porosity of the green body first decreased and then increased with an increase in the binder concentration, and the minimum porosity was obtained when the binder concentration reached 10 wt%. Samples with increased density were obtained after debinding and lead-rich atmosphere sintering. PZT piezoceramics fabricated using a binder content of 10 wt% exhibit the maximum relative density (96.9%), largest piezoelectric constant (342.6 pC/N) and dielectric constant (1621). Based on the above process, the wood pile structure and helical twentytetrahedral structural components were successfully fabricated using the material extrusion process. This research lays the foundation for the engineering application of 3D printing to fabricate high-performance piezoceramics with complex shapes.     

Effect of heating rate on the physicomechanical properties of siliceous ceramics

The effect of heating rate on the density, water absorption, and the Young’s modulus of ceramic materials based on clays of different mineralogic compositions is studied. It is established that the optimum heating rate depends on the mineralogic composition and the functional parameters of ceramics.     

Piezoelectric properties and damping behavior of highly loaded PZT/polyurethane particulate composites

In this study, using a solution casting process, thermoplastic polyurethane elastomer (TPU) composites containing different contents of lead zirconate titanate (PZT) ferroelectric particles were produced. The damping treatment of composites at high volume of fillers was investigated. SEM micrographs showed that PZT particles had a proper distribution in the PU matrix. Differential scanning calorimetry (DSC) thermograms indicates that melting enthalpy decreases by raising PZT filler content. The results of the dynamic mechanical thermal analysis (DMTA) proved that the magnitude of loss factor (tan δ) strongly depends on PZT content, and it decreased from 0.51 to 0.27 as PZT content increased. The value of E₀ increases to 0.32 GPa in the composite reinforced with 50 v% of PZT. The role of PZT on the acoustic behavior of TPU was measured using the acoustic absorption coefficient (a). The results showed that as PZT content increased from 0 to 50%, the acoustic absorption coefficient reached 0.25 at 6000 Hz frequency. The composites of PZT/PU with 0–3 connectivity were poled, and the optimal poling conditions that could be applied without sample breakdown were studied. Moreover, we prepared composites containing 70 vol% PZT particles by modifying the particles. Modification of PZT particles caused a decrease in both d₃₃ and g₃₃ constants of the PZT/PU composites.     

Effect of pressure on electric generation of PZT(30/70) and PZT(52/48) ceramics near phase transition pressure

Impact experiment of Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics were conducted by empolying shock reverberation techniques within 3-7 GPa and X-ray diffraction patterns of these materials have been measured at pressure up to 32 GPa with a diamond anvil cell and synchrotron radiation. To refine the crystal structure, Rietveld analysis was performed and bulk moduli were calculated using Birch-Murnaghan equation of state. We found a tetragonal phase transforming to a cubic phase in Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics at ∼7.4 GPa and ∼4 GPa respectively. For dynamic pressure experiment, a metal flyer accelerated by a gas gun facility impacts into PZT ceramics to investigate electric energy. As pressure increased, output voltage of Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics slightly increased below ∼7 GPa and ∼4 GPa. But the voltage increased near ∼7 GPa and ∼4 GPa. From the result, we could confirm that the phase transition influenced the considerable effect on the electrical power generation.