Effect of Pb(Fe1/2Nb1/2)O3 modification on dielectric and piezoelectric properties of Pb(Mg1/3Nb2/3)O3-PbZr0.52Ti0.48O3 ceramics

10 mol% Pb(Fe_1/2Nb_1/2)O₃ (PFN) modified Pb(Mg_1/3Nb_2/3)O₃-PbZr_0.52Ti_0.48O₃ (PMN-PZT) relaxor ferroelectric ceramics with compositions of (0.9 − x)PMN-0.1PFN-xPZT (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9) were prepared. X-ray diffraction investigations indicated that as-prepared ceramics were of pure perovskite phase and the sample with composition of x = 0.8 was close to morphotropic phase boundary (MPB) between rhombohedral and tetragonal phase. Dielectric properties of the as-prepared ceramics were measured, and the Curie temperature (T_c) increased sharply with increasing PZT content and could be higher than 300 °C around morphotropic phase boundary (MPB) area. At 1 kHz, the sample with composition of x = 0.1 had the largest room temperature dielectric constant ?_r = 3519 and maximum dielectric constant ?_m = 20,475 at T_m, while the sample with composition of x = 0.3 possessed the maximum dielectric relaxor factor of γ = 1.94. The largest d₃₃ = 318 pC/N could be obtained from as-prepared ceramics at x = 0.9. The maximum remnant polarization (P_r = 28.3 μC/cm²) was obtained from as-prepared ceramics at x = 0.4.     

Effect of MnO2 addition on the piezoelectric properties in Pb(Mg1/3Nb2/3)O3 relaxor ferroelectrics

The effects of MnO₂ addition on the piezoelectric properties in Pb(Mg_1/3Nb_2/3)O₃ relaxor ferroelectrics were studied in the ferroelectricity-dominated temperature range from −40 to 30°C. Dielectric, piezoelectric, and electrostrictive properties were examined to clarify the effect of MnO₂ addition. As an added amount of MnO₂ increases, the dielectric constant decreases and the mechanical quality factor increases in Pb(Mg_1/3Nb_2/3)O₃. From the experimental results, it has been found that Mn behaves as a ferroelectric domain pinning element.     

Microstructural evolution and dielectric properties of Cu-deficient and Cu-excess CaCu3Ti4O12 ceramics

The microstructural evolution and dielectric properties of CaCu_3−xTi₄O_12−x (3 − x = 2.8-3.05) ceramics were investigated. Normal grain growth behavior was observed at Cu/Ca ≤ 2.9, while abnormal grain growth was observed at Cu/Ca ≥ 2.95. A CuO-rich intergranular liquid phase at Cu/Ca ≥ 2.95 and angular grain morphology were the main reasons for abnormal grain growth. However, the abundant intergranular liquid at Cu/Ca = 3.05 significantly affected the relative dielectric permittivity and dielectric loss. The CuO composition is the key parameter that determines the microstructure and dielectric properties of CCTO ceramics.     

Electric-field-induced strain and piezoelectric properties of a high Curie temperature Pb(In1/2Nb1/2)O3-PbTiO3 single crystal

The temperature dependence of dielectric and piezoelectric properties, electric-field-induced strains of 0.66 Pb(In_1/2Nb_1/2)O₃-0.34 PbTiO₃ single crystals, which were grown directly from melt by using the modified Bridgman technique with the allomeric Pb(Mg_2/3Nb_1/3)O₃-PbTiO₃ seed crystals, were determined as a function of crystallographic orientation with respect to the prototypic (cubic) axes. Ultrahigh piezoelectric response (d₃₃∼2000 pC/N, k₃₃∼94%) and strain levels up to 0.8%, comparable to rhombohedral (1−x)Pb(Mg_2/3Nb_1/3)O₃-xPbTiO₃ and (1−x)Pb(Zn_2/3Nb_1/3)O₃-xPbTiO₃ single crystals, were observed for the 〈0 0 1〉-oriented crystals. Strain levels up to 0.47% and piezoelectric constant d₃₃∼1600 pC/N could be achieved being related to an electric-field-induced rhombohedral-orthorhombic phase transition for the 〈1 1 0〉-oriented crystals. In addition, high electromechanical coefficients k₃₃ (∼88%) can be achieved even heating to 110 °C. High T_C (∼200 °C), large electromechanical coefficients k₃₃ (∼94%) and low dielectric loss factor (∼1%), along with large strain make the crystals promising candidates for a wide range of electromechanical transducers.     

Electron emission from Pb(Zr0.65Ti0.35)O3 film cathode by pulse electric field

Pulse electric field induced electron emission from the Pb(Zr_0.65Ti_0.35)O₃ ferroelectric films has been investigated as a function of the film thickness from 0.2 to 4.0 μm and the upper electrode diameter from 200 to 1100 μm. The electron emission charge from the 3.0 μm film was several nC per pulse, which was comparable to that of the bulk ferroelectrics. However, the local dielectric breakdown occurred in the films below 1.0 μm without the electron emission, which was confirmed by the optical microscopy observation after the emission tests. As the upper electrode size decreased and the film thickness increased, electrons were more easily emitted without breakdown.     

Development of perovskite in Fe-substituted Pb(Zn1/3Ta2/3)O3 and dielectric characteristics

Pb(Zn_1/3Ta_2/3)O₃ ceramics, compositionally modified by the incorporation of Fe to the octahedral lattice sites, were prepared and characterized in terms of perovskite development, dielectric properties, as well as microstructure evolution. The powders of the B-site precursor compositions were synthesized separately and reacted with PbO to form Pb[(Zn_1/3Ta_2/3),(Fe_1/2Ta_1/2)]O₃. The perovskite contents increased continuously with the Fe concentration. The maximum dielectric constant values of the ceramics increased tremendously with the fraction of Fe, whereas the dielectric maximum temperatures were rather insensitive to the compositional change.     

Crystallographic and dielectric properties of barium-substituted Pb(Mg1/3Ta2/3)O3 ceramics

Ceramic powders of (Ba,Pb)Pb(Mg_1/3Ta_2/3)O₃ were prepared via a B-site precursor route. Crystal symmetries and lattice parameters were determined. Monophasic perovskite was developed after the two-step reaction process, in which the lattice parameters showed linear changes in the entire composition range. Dielectric responses of the ceramics with compositional and frequency changes were investigated. The results were also compared with the (Ba,Pb)(Zn_1/3Ta_2/3)O₃ data.     

Effects of Mn doping on the structure and electrical properties of high-temperature BiScO3-PbTiO3-Pb(Zn1/3Nb2/3)O3 piezoelectric ceramics

The effects of Mn addition on the structure, ferroelectric, and piezoelectric properties of the 0.35BiScO₃-0.60PbTiO₃-0.05Pb(Zn_1/3Nb_2/3)O₃ ceramics were studied. The results demonstrate that the addition of small amounts of Mn did not cause a remarkable change in crystal structure, but resulted in an evident evolution in microstructure and ferro-piezoelctric properties. The addition of Mn can induce combinatory “hard” and “soft” piezoelectric characteristics due to aliovalent substitutions. The optimal electrical properties are obtained in the 0.25 mol% Mn-doped composition with a high Curie temperature, indicating that Mn doping contributes to the electrical properties of the ceramics. It can be expected that the improved piezoelectric material can be a promising candidate for high-temperature piezoelectric applications.     

Comparative investigation of structure and dielectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 (65/35) and 10% PbZrO3-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (65/35) ceramics prepared by a modified precursor method

Relaxor ferroelectric Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (65/35) and 10% PbZrO₃-doped Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (65/35) ceramics were both prepared by a modified precursor method, which was based on the high-temperature synthesis of an oxide precursor that contained all the B-site cations for the consideration of B-site homogeneity. The dielectric properties of Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (65/35) ceramic was more of normal ferroelectric behavior, but the high dielectric constant (?_m = 34,200 at 1 kHz) and piezoelectric constant (d₃₃ = 709 pC/N) were observed for this composition close to the morphotropic phase boundary. Comparatively, introduction of 10% PbZrO₃ into Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (65/35) ceramics enhanced the diffuse phase transition as well as the rhombohedral to tetragonal phase transition temperature, while it also kept the high dielectric constant (?_m = 29,600 at 1 kHz) and piezoelectric constant (d₃₃ = 511 pC/N).     

Modified tunable dielectric properties by addition of MgO on BaZr0.25Ti0.75O3 ceramics

Phase composition, microstructure and tunable dielectric properties of (1 − x)BaZr_0.25Ti_0.75O₃-xMgO (BZTM) composite ceramics fabricated by solid-state reaction were investigated. It was found Mg not only existed in the matrix as MgO, there was also trace amount of Mg²⁺ ions dissolved in the BZT grains, which led to Curie temperature of the BZTM composites ceramics shifting to below −100 °C. Dielectric permittivity of the BZTM composite ceramics was reduced from thousands to hundreds by manipulating the content of MgO. Johnson's phenomenological equation based on Devonshire's theory was used to describe the nonlinear dielectric permittivity of the ceramics with increasing applied DC field. With increasing content of MgO, anharmonic constant α_(T) increased monotonously. Dielectric permittivity was 672, while dielectric tunability was as high as 30.0% at 30 kV/cm and dielectric loss was around 0.0016 for the 0.6BaZr_0.25Ti_0.75O₃-0.4MgO sample at 10 kHz and room temperature.     

Low temperature sintering and microwave dielectric properties of SmAlO3 ceramics

The effects of sintering aids on the microstructures and microwave dielectric properties of SmAlO₃ ceramics were investigated. CuO and ZnO were selected as sintering aids to lower the sintering temperature of SmAlO₃ ceramics. With the additions, the sintering temperature of SmAlO₃ can be effectively reduced from 1650 to 1430°C. The crystalline phase exhibited no phase differences at low addition level while Sm₄Al₂O₉ appeared as a second phase as the doping level was over 0.5 wt.%. In spite of the additions, the dielectric constants showed no significant change and ranged 19-21. However, the quality factor Q×f was strongly dependent upon the type and amount of additions. The Q×f values of 51,000 and 41,000 GHz could be obtained at 1430°C with 0.25 wt.% CuO and ZnO additions, respectively. The temperature coefficients depended on the additions and varied from −40 to −65 ppm/°C. Results of X-ray diffractions, EDS analysis and scanning electron microscopy were also presented.     

Growth and electrical performance of Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Fe1/2Nb1/2)O3 single crystals

For the first time, we have grown ferroelectric single crystals Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃-Pb(Fe_1/2Nb_1/2)O₃ (PMN-PT-PFN) from the melt by the simple slow cooling process. The chemical composition of the single crystals PMN-PT-PFN (0.59/0.31/0.10) is near the morphotropic phase boundary (MPB). X-ray diffraction (XRD) was used to study phase structure of the as-grown crystals, energy dispersive X-ray spectrometer (EDS) and electron probe micro-analyzer (EPMA) were employed to confirm the chemical composition and element distribution of the as-grown crystals, respectively. The ferroelectric, dielectric and piezoelectric properties of the as-grown PMN-PT-PFN (0.59/0.31/0.10) single crystal oriented along the (0 0 1) axis were measured, which showed that the remnant polarization (P_r), coercive electric fields (E_c), the Curie temperature (T_c) and the piezoelectric coefficient (d₃₃) were 50.2 μC/cm², 13.9 kV/cm, 158 °C and about 1800 pC/N, respectively. All the results indicated that the PMN-PT-PFN (0.59/0.31/0.10) single crystals are promising for applying to field of high frequency.     

Hydrothermal temperature effect on magnetoelectric coupling of Ni/Pb(Zr0.52Ti0.48)O3 bilayers

Magnetoelectric (ME) Ni/Pb(Zr_0.52Ti_0.48)O₃ bilayers have been prepared by hydrothermal method. The structure and ferroelectric properties of the Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films prepared at various hydrothermal temperatures are characterized by X-ray diffraction and ferroelectric testing. With the hydrothermal temperature increasing the grain size of the PZT thin films gradually decreases leading to a gradual increase of the coercive field and a decrease of the remnant polarization of the Ni/PZT bilayers. The ME voltage coefficient of the Ni/PZT bilayers gradually decreases as hydrothermal temperature increases. The large ME coefficient makes these Ni/PZT bilayers possible for applications in multifunctional devices such as electromagnetic sensor, transducers and microwave devices.     

Laser annealing of Pb(Zr0.52Ti0.48)O3 thin films for the pyroelectric detectors

Lead zirconate titanate (Pb(Zr_0.52Ti_0.48)O₃, PZT) thin films fabricated by magnetron sputtering technique on the Pt/Ti/SiO₂/Si substrates at room temperature, were annealed by means of CO₂ laser with resulting average substrate temperature below 500 °C. The crystal structure, surface morphology and pyroelectric properties of the PZT films before and after annealing were investigated by X-ray diffraction, atomic force microscopy, and pyroelectric measurements. The results show that the annealed PZT thin film with a laser energy density of 490 W/cm² for 25 s has a typical perovskite phase, uniform crystalline particles with a size of about 90 nm, and a high pyroelectric coefficient with 1.15 × 10^− 8 Ccm^− 2 K^− 1.     

Microgeometry effect on the properties of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics

Porous Pb_0.99(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ ferroelectric ceramics with different pore size were prepared by solid-state sintering in air. The microstructural effect on the properties has been systematically investigated by SEM, ferroelectric hysteresis, strain-electric field curves and breakdown strength measurements. The results demonstrate that the microgeometry has a subtle effect on the ferroelectric and dielectric properties. However, the results also demonstrate that the electric field induced strain and the dielectric breakdown strength decreases with the increase of pore size.     

Pb(Zr0.52Ti0.48)O3/TiNi multilayered heterostructures on Si substrates for smart systems

Ferroelectric/shape memory alloy thin film multilayered heterostructures possess both sensing and actuating functions and are considered to be smart. In this article, Pb(Zr_0.52Ti_0.48)O₃ (PZT) ferroelectric thin films and Ti-riched TiNi shape memory alloy thin films have been deposited on Si and SiO₂/Si substrates in the 400-600 °C temperature range by pulsed laser deposition technique. Deposition processing, microstructure and surface morphology of these films are described. The TiNi films deposited at 500 °C had an austenitic B2 structure with preferred (110) orientation. The surfaces of the films were very smooth with the root-mean-square roughness on a unit cell level. The structure of the TiNi films had a significant influence on that of the subsequently deposited PZT films. The single B2 austenite phase of the TiNi favored the growth of perovskite PZT films. The PZT/TiNi heterostructures with the PZT and TiNi films respectively deposited at 600 and 500 °C exhibited a polarization-electric field hysteresis behavior with a leakage current of about 2 × 10^− 6 A/cm².     

Polarization fatigue and photoinduced current in (Pb0.72La0.28)Ti0.93O3 buffered Pb(Zr0.52Ti0.48)O3 films on platinized silicon

We report a study on the fatigue behavior of Pb(Zr_0.52Ti_0.48)TiO₃ (PZT) films deposited on Pt/Ti/SiO₂/Si substrates by a sol-gel method with single- and double-sided (Pb_0.72La_0.28)Ti_0.93O₃ (PLT) buffer layers, with an attempt to clarify the role of the top and bottom PLT buffer layers on the fatigue endurance (FE) of the PZT films. It is revealed that the existence of the PLT buffer layer and the level of driving alternating-current electric switching field strongly influence the fatigue properties. In terms of the existence of an asymmetric built-in electric field near the top and bottom interfaces between the film and metal electrode, we explain the observed fatigue properties.     

Quantitative dependence of the properties of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics on porosity

Porous Pb_0.99(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ ferroelectric ceramics with a pore size of the order of the crystalline grain size were prepared and the microstructure and the properties were investigated. Based on this microstructure, the net porosity of the ceramics can be attributed to the intentionally introduced extrinsic porosity and thus the quantitative dependence of ferroelectric and dielectric properties of the ceramics on the porosity can be established respectively. A good agreement with experimental measurements was obtained. Our work represents the first attempt to tailor the properties of ferroelectric ceramics via varying the porosity from the viewpoint of application.     

Chemical stability and dielectric properties of RO-La2O3-B2O3 (R = Ca, Mg, Zn)-based ceramics

New lanthanum borate (La₂O₃-B₂O₃) glasses modified with divalent oxides, such as CaO, MgO and ZnO were investigated as potential low temperature dielectrics by understanding compositional dependence of dielectric properties and chemical leaching resistance. Firing behavior, such as densification and crystallization, depended strongly on the glass composition and is found to influence the resultant dielectric performance. Specifically, the dielectric composition of 20ZnO-20La₂O₃-60B₂O₃ glass with 40 wt% Al₂O₃ as a filler showed distinct enhancements of dielectric properties, i.e., k ∼ 8.3 and Q ∼ 1091 at the resonant frequency of 17.1 GHz, as a result of 850 °C firing. The result was believed related to earlier densification and unexpected evolvements of ZnAl₂O₄ and La(BO₂)₃ phases during firing. The Mg-containing glass sample was most stable in strong acid solutions and did not show any significant changes in microstructure even after 300 min exposure. The Ca-containing glass sample was not regarded as a promising candidate for low temperature dielectrics from the observed low quality factor and weak chemical durability.