O3 Piezoelectric Ceramics Research Articles

Temperature dependent phase structure and enhanced electrical properties of CaZrO3-modified (K,Na,Li) (Nb,Ta)O3 lead-free piezoelectric ceramics

A series of lead-free (K0·49Na0·49Li0.02) (Nb0·8Ta0.2)O3 (KNLNT) piezoelectric ceramics modified by CaZrO3 (denoted as KNLNT-xCaZrO3, x = 0–0.05) were synthesized using a conventional solid-state approach. Herein, the influence of CaZrO3 doping on the crystal structure, ferroelectric properties, dielectric properties as well as piezoelectric properties were systematically investigated. The XRD analysis shows that all the proposed samples present pure perovskite phase, revealing the phase structure transition from an orthorhombic to a pseudocubic phase at a threshold value of x is 0.01 and 0.03. Moreover, the in-situ XRD characterization was applied to investigate the transformation process of phase structure: the pseudocubic-tetragonal (TP-T) phase transition temperature has been decreased to room temperature at x = 0.04. In addition, the results were further confirmed by the temperature-dependent dielectric properties. For the microstructure, the typical strip-like domains and nanoscale domains can be found in transmission electron microscopy (TEM) images. Due to the coexistence of orthorhombic and pseudocubic with x = 0.03, the remnant polarization has an anomaly, and large strain value and large signal d33* value is obtained under a 20 kV/cm electric field, which is about 0.106% and 532 pm/V.

Excellent piezoelectric property and thermal stability of Pb(Sc, Nb)O3-Pb(Hf, Ti)O3ceramic

xPb(Sc1/2Nb1/2)O3–(1 − x)Pb(Hf1−yTiy)O3 piezoelectric ceramics were prepared by solid-state route, and the phase structures and piezoelectric properties of ceramics were systematically investigated. Results showed that the sample with the composition of x = 0.07 and y = 0.53 possessed higher phase coexistence between the rhombohedral and tetragonal, and exhibited the optimal properties among different constituent systems, i.e., TC = 355 °C, d33 = 400 pC/N, εr = 1390, and tan δ = 1.05%. Furthermore, the effects of temperature on d33, leakage current density, P-E loop, and unipolar strain were studied for xPb(Sc1/2Nb1/2)O3–(1 − x)Pb(Hf0.47Ti0.53)O3 samples. The sample with x = 0.07 revealed better temperature stability as well, the reason of which was analyzed in detail. The study indicates that the 0.07Pb(Sc1/2Nb1/2)O3–0.93Pb(Hf0.47Ti0.53)O3 piezoelectric ceramic has excellently comprehensive properties suitable for application in higher temperature condition.

Influence of component content on the properties of PSZN-PSNN-PSZT ceramics

In this paper, (Pb0.9Sr0.1)(Zn1/3Nb2/3)(0.06+x)(Ni1/3Nb2/3)0.16(Zr0.52Ti0.48)(0.78-x)O3 (PSZN-PSNN-PSZT, x = 0, 0.02, 0.04, 0.06, 0.08) piezoelectric ceramics were prepared by traditional solid-state reaction method. The samples were studied on microstructure, phase structure, electrical properties and dielectric relaxation. All as-prepared PSZN-PSNN-PSZT ceramics present single phase of perovskite structure. Experimental results show that the variation trend of the R phase percentage content is consistent with the trend of d33. Also, increasing PSZN content will inhibit the growth of sample grains. The temperature-dependent of dielectric performance testing results present that all the samples possess obvious relaxation behavior. The best overall performance of the samples are obtained at x = 0.06, where its d33 = 920pC/N, kp = 0.71, Pr = 24.54 μC cm−2, γ = 1.98, ε r = 6856, tanδ = 3.3%, Tc = 133 ℃. The PSZN-PSNN-PSZT ceramics are potential candidate materials due to its simple preparation process, the high dielectric and piezoelectric properties.

Thermally stable piezoelectric performance in low-temperature sintered Pb0.95Ba0.01Sr0.04(Zr0.53Ti0.47)O3 ceramics with a low loss factor

ABSTRACT Herein, Pb0.95Ba0.01Sr0.04(Zr0.53Ti0.47)O3 piezoelectric ceramics comprising 0.25 wt% MnCO3, 1 wt% LiBiO2 and 0.06 wt% CuO (PBSZT-LBCu-Mn ceramics, abbreviated as Mn0.25) were prepared via a conventional method at a low firing temperature of ∼900 °C. The phase structure and temperature-dependent electrical properties were systematically investigated. The product composition possesses the following properties: normalised strain (d 33*) ∼362 pm/V, Curie temperature (T c) ∼336 °C, mechanical quality factor (Q m) ∼568, loss factor (tan δ) ∼0.0058 and relative dielectric constant (ϵ r) ∼872. The remnant polarisation (P r), maximum polarisation (P max) and coercive field (E c) slightly decreased as a function of increasing temperature, while the strain (S pol) was observed to increase. Additionally, d 33* values of 362 and 411 pm/V were achieved at 25 °C and 120 °C, respectively, with a change ratio <14%. The Mn0.25 ceramics exhibit low ϵ r and tan δ values, leading to small average power dissipation, which is beneficial for high-frequency actuator applications.

Aging effects on resonance frequency of Pb(Ti0.52Zr0.48)O3 piezoelectric ceramics for power ultrasonic transducers

The time-dependent resonance frequency at different heating temperatures was studied for the Pb(Ti0.52Zr0.48)O3 widely applied to power ultrasonic transducers. The prediction model for the changes of resonance frequency (Δfs) was developed using the response surface methodology based on central composite design. The results of significance and analysis of variance (ANOVA) tests have proved that the prediction model has an adequate approximation to the actual values. An evaluation of the interaction effects of temperature and time parameters, heating temperature (Tc), heating time (Tt), and aging time (ta) revealed a decreasing tendency towards the resonant frequency. As the Tc is increased, the Δfs shows three regions with different variation tendency. The Δfs is slightly decreased with increasing Tt and has slow-motion escalating trend with increasing ta. The irreparability variation of resonant frequency revealed in response surface plots shows that Tc and Tt have significant effects on the piezoelectric properties of Pb(Ti0.52Zr0.48)O3. The study of aging effects on resonance frequency at different temperatures could open a road to promote the practical application of PZT-based ceramics automatic tuning.

Crystal structure and actuation mechanisms in morphotropic phase boundary Pb(Zn1/3Nb2/3)O3‐Pb(Zr1/2Ti1/2)O3 piezoelectric ceramic

AbstractLead‐based Pb(Zn1/3Nb2/3)O3‐Pb(Zr1/2Ti1/2)O3 (PZN‐PZT) piezoelectric ceramics have been intensively studied owing to their excellent performance in multilayer actuators; however, the detailed crystal structure and actuation mechanisms are still not well understood. In this study, in situ electric‐field‐biasing high‐energy synchrotron X‐ray diffraction was employed to monitor the crystal structure evolution and to deconvolute contributions to the electrostrain in the morphotropic phase boundary composition of 0.3PZN–0.7PZT. An electric‐field‐induced reversible phase transition between the coexisting monoclinic and tetragonal phases was identified. The unit cell parameters of the monoclinic phase exhibit significantly greater response to the electric field than those of the tetragonal phase. The effective lattice strain, evaluated through peak profile fitting, and the macroscopic strain measurement were found to be in agreement. The high electrostrain is primarily caused by the electric‐field‐induced phase transition with concurrent intrinsic/extrinsic contributions. This work provides a deeper description of the crystal structure and actuation mechanisms in PZN‐PZT piezoelectric systems.

Effects of sintering temperature on structure and electrical properties of (Na0.48k0.473Li0.04Sr0.007)(Nb0.883Ta0.05Sb0.06Ti0.007)O3 piezoelectric ceramics

In this study, the effects of sintering temperature on microstructure, dielectric and piezoelectric properties are investigated for the non-stoichiometric (Na0.48K0.473Li0.04Sr0.007)(Nb0.883Ta0.05Sb0.06Ti0.007)O3 (NKLNTSST) piezoelectric ceramics. The results suggest that the piezoelectric properties are enhanced owing to the more normal ferroelectric characteristics, higher density, more uniform grains and presence of polymorphic phase transition regions, which are observed with an increase in the sintering temperature up to 1080?C. The piezoelectric properties are weakened owing to the larger degree of diffuse phase transition and more cationoxygen-vacancy pairs with an increase in the sintering temperature above 1080?C. The best piezoelectric properties including kp = 40%, d33 = 288 pC/N, ?max = 72.12, loss = 2.57%, Ec = 13.45 kV/cm and Pr = 10.23 ?C/cm2 are obtained at the sintering temperature of 1080?C.

Fabrication and performance of PNN-PZT piezoelectric ceramics obtained by low-temperature sintering

Abstract The Pb(Ni1/3Nb2/3)O3-Pb(Zr x Ti1−x )O3 (PNN-PZT) piezoelectric ceramics with CuO and LiBiO2 doping were successfully fabricated by the low-temperature solid-state reaction to effectively restrain the PbO volatilization. The microstructure and electrical properties of the PNN-PZT ceramics were characterized. The experimental results reveal that the PNN-PZT ceramics are composed of a pure perovskite structure in which the rhombohedral and tetragonal phases coexist. Meanwhile, the good electric properties, including low dielectric loss, outstanding diffusion phase transition and palpable dielectric relaxation, are exhibited in PNN-PZT ceramics with 0.2 wt.% CuO and 1 wt.% LiBiO2 addition. This piezoceramic composition possibly provides a reference for the application of multi-layer piezoelectric actuators.

Study of domain configurations in (Bi,Na)ZrO3-modified (K,Na)(Nb,Sb)O3 piezoelectric ceramics by acid-etching at different temperatures

Domain structure often greatly affects piezoelectric performance of a ferroelectric ceramic. Accordingly, a convenient method that can well characterize the domain structure at various temperatures is highly desired for understanding the underlying mechanism. An improved acid-etching technique was recently developed for such purpose. Domain structure of poled 0.96(K0.48Na0.52)(Nb0.96Sb0.04)O3–0.04(Bi0.50Na0.50)ZrO3 ceramics with a large piezoelectric coefficient d33 of 535 pC/N was systematically investigated at three typical temperatures. It was found that domain configurations change significantly with temperature. Hierarchical nanodomain structure is widely observed in domain patterns acid-etched at 25 °C, due to the orthorhombic-tetragonal phase coexistence. By contrast, the majority part of those acid-etched at − 60 °C are simply some long parallel stripes, while a small amount of banded structure appears in broad stripes inside some grains. A nearly 63° intersectional angle is seen between two adjacent sets of parallel stripes in the domain pattern of a cuboid-shaped grain, indicating that orthorhombic phase remains down to − 60 °C. The domain patterns acid-etched at 80 °C become even simpler, mainly consisting of long parallel stripes that are several hundred nanometers wide and have quite straight edges. Fundamental issues associating with the possible domain configurations and the acid-etching were discussed on the simple mathematical basis.

Enhanced electrical properties of lead-free (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 piezoelectric ceramics by optimizing phase ratio and sintering temperature

It is challenging for material chemists to develop lead-free ceramics due to the toxicity of lead for human health and environment. (Ba, Ca)(Ti, Zr)O3 and (Ba, Ca)(Ti, Sn)O3 lead-free piezoelectric ceramics have attracted much attention due to their superior piezoelectric properties. In this study, Ca2+, Zr4+ and Sn4+ were simultaneously doped at A-sites and B-sites, respectively, to clarify the structure and enhance the electrical performance. (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 (BCxTZS) lead-free piezoelectric ceramics were successfully fabricated by conventional solid-state reactive sintering method. The effects of Ca2+ content (x) and sintering temperature on microstructure, phase structure and electrical properties of BCxTZS were investigated. Herein, BCxTZS ceramics are the coexistence of R-O phases as 0.01 ≤ x ≤ 0.02, and they become O-T phases as 0.02 < x ≤ 0.08. The excellent electrical performances with d33 = 511 pC N−1, kp = 43% and Qm = 126 were achieved by optimizing the phase ratio and sintering temperature. The superior d33 along with the comparable Qm with PZT ceramics indicates that BCxTZS ceramics are promising lead-free piezoelectric ceramics.

Heating rate effect on dielectric, ferroelectric and piezoelectric properties of Bi0.45La0.05Na0.40K0.10Ti0.98Zr0.02O3 Pb-free piezoelectric ceramic for actuator applications

In this present work, the effect of heating/coolling rate on the electrical properties such as ferroelectric, dielectric and electrostrictive properties of Pb-free Bi0.45La0.05Na0.40K0.10-Ti0.98Zr0.02O3 or BLNKZT piezoelectric ceramics has been systematically investigated. The BLNKZT ceramics were prepared via a conventional solid state reaction method and sintered at 1125 °C for 2 h, which applied the heating/cooling rates of 5, 10 and 15 °C/min in order to clarify the optimal parameter for densification and good electrical properties. The XRD pattern exhibited a complete single perovskite structure with a pseudo-cubic phase at the rate of 5 °C/min sample and tranformed to tetragonal-rich phase at the rate of 15 °C/min. The SEM micrograph of all BLNKZT ceramics showed a cubic-like grain shape. The P-E hysteresis loop was measured at the temperatures ranging from −40 to 120 °C. With increasing temperature, the Pr and Ec values distinctly decreased and the P-E loops tended to deform and showed pinch loops. The maximum strain (Smax) value of 0.10% and calculated normalized strain (d*33) of 167 pm/V (measured at 60 kV/cm) were obtained for ceramic sintered with the heating/cooling rates of 5 °C/min.

The influence of different pore forming agents on piezoelectric and dielectric properties of porous PZT-PCN ceramics

Abstract In this study, the researcher developed porous lead zirconate titanate-lead cobalt niobate 0.8Pb (Zr1/2Ti1/2)O3-0.2Pb(Co1/3Nb2/3)O3 (PZT-PCN) piezoelectric ceramics with varying porosity using PVC Stearic Acid (SA) and PMMA as pore forming agents (PFA) by burnable plastic sphere process (BURPS). The study investigated the effect of PFA on the microstructure, dielectric and piezoelectric properties pertaining to porous PZT-PCN ceramics. The density decreased as the content of pore formers increased. This resulted in increasing of the porosity. The values of both relative permittivity (Ɛr) and longitudinal piezoelectric coefficient (d33) were shown to have decreased by increasing the porosity. The results showed the hydrostatic of merit (dhgh) of PZT-PCN with density of about 4.4 g/cm3 reached 2732 × 10−15 m2/N, which demonstrates that porous PZT-PCN ceramic is a promising material for biomedical diagnostic devices.

Dielectric, ferroelectric, piezoelectric properties, and impedance spectroscopy of (Ba0.85Ca0.15)(Ti0.9 Zr0.1)O3-x% (K0.5Bi0.5)TiO3 lead-free ceramics

The influence of (K0.5Bi0.5)TiO3 on structure, microstructure and piezoelectric properties of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) piezoelectric ceramics was investigated. Impedance spectroscopy was used to get better understanding of the electrical properties of the materials as a function of temperature and frequency. The XRD results indicate the presence of the morphotropic phase in the BCTZ–xKBT system. Dielectric and complex impedance spectroscopic studies were carried out over wide frequency (i.e. 102–106 Hz) and temperature (30–500 °C) ranges. The diffuseness of the dielectric peak was found to increase with increasing KBT proportion. The nature of frequency dependence of AC conductivity of BCTZ-KBT follows the Jonscher power law and calculated DC conductivity follows Arrhenius behavior. The Nyquist plots suggest the contribution of grains and grain boundaries to the electrical behavior of the materials. The ceramic with x = 0.25 mol% KBT demonstrates good properties: d33 = 226 PC/N, Tc = 110 °C, kp = 27.85%, εr =10,566, tanδ = 2.3%.

Ultra-high piezoelectric and dielectric properties of low-temperature-sintered lead hafnium titanate-lead niobium nickelate ceramics

Equimolar Li+ and Bi3+ co-doped 0.51Pb(Hf0.3Ti0.7)O3-0.49Pb(Nb2/3Ni1/3)O3 (PHT-PNN) piezoelectric ceramics were synthesized by conditional solid state method. The effects of Li+-Bi3+ co-doping on crystalline structure, morphological structure, piezoelectric and dielectric properties of PHT-PNN ceramics were systematically analyzed. Results revealed that Pb sites of PHT-PNN were replaced with Li+-Bi3+ after co-doping. Li+-Bi3+ co-doping also improved electrical performance of ceramics, formed liquid phase, and decreased sintering temperature during sintering process. Li+-Bi3+ co-doping resulted in ultra-high piezoelectric properties (e.g., d33 = 1025 pC/N and εr = 7974) for PHT-PNN/1.0 mol% Li+-Bi3+ ceramic sintered at 1100 °C. Furthermore, detailed mechanism responsible for improved piezoelectric response of Li+-Bi3+ co-doped ceramics was proposed. This study reports the synthesis of ultra-high performance piezoelectric ceramics with low-temperature co-firing properties, which is highly desirable for wide range of applications.

Upconversion photoluminescence modulation by electric field poling in Er3+ doped (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 piezoelectric ceramics

Luminescent piezoelectric materials promise a stratagem for controlling the optical process by electric field, which would benefit for future optoelectronic devices. Here, Er3+ doped (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 (BCZT: Er3+) piezoelectric ceramics are prepared to demonstrate the proof of concept. In addition to excellent intrinsic piezoelectricity and ferroelectricity, BCZT: Er3+ ceramics exhibit simultaneously strong green upconversion emissions under excitation of 980 nm. Remarkable photoluminescence (PL) quenching phenomenon as well as significant changes on relative intensities of stark lines are observed under external poling electric field. Furthermore, field dependent piezoelectric constant d33 and photoluminescence quenching ratio show similar variation trend and finally saturate for E > 3.5 kV/mm, which provides a noncontact strategy to monitor the piezoelectric constant d33. The PL quenching triggered by electric field in BCZT: Er3+ ceramics is ascribed to the decreased asymmetry originating from field-induced structural transformation from a significant fraction of the tetragonal phase to rhombohedral phase. Our work would be helpful for expanding the scope of luminescent piezoelectric materials and promising future optoelectronic and optical devices with cross-coupled physical properties.

Effect of Sintering Temperature on Mechanical and Electrical Properties of Lead-Free Bi&lt;sub&gt;0.5&lt;/sub&gt;(Na&lt;sub&gt;0.4&lt;/sub&gt;K&lt;sub&gt;0.1&lt;/sub&gt;)Ti&lt;sub&gt;0.98&lt;/sub&gt;Zr&lt;sub&gt;0.02&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Piezoelectric Ceramics

Effect of sintering temperatures on phase formation, mechanical and electrical properties of lead-free Bi0.5(Na0.8K0.2)0.5Ti0.98Zr0.02O3 or BNKTZ piezoelectric ceramics were investigated. The BNKTZ ceramics were prepared via a conventional solid-state sintering technique under various sintering temperature range 1100-1150°C for 2 h. The phase formation and microstructure of the ceramics were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) method, respectively. XRD analysis indicated that all samples exhibited a single perovskite structure and no secondary phase. SEM microscopy study revealed an increase in grain size with increasing sintering temperature. The maximum values of density and maximum dielectric constant of the ceramics sintered at 1125 °C were 5.79 g/cm3 and 3446, respectively. In addition, the ceramics sintered at 1125 °C showed highest mechanical properties (HV = 4.32 GPa, HK = 5.87 GPa, E = 143 GPa and KIC = 1.30 MPa.m1/2). The highest values of ferroelectric and piezoelectric were found at this sintering temperature.

Analyses for oxygen vacancies in (Na,K)NbO3-series piezoelectric ceramics by soft x-ray emission spectroscopy

(Na0.55K0.45)NbO3 (NKN) and acceptor-doped (Na0.55K0.45)(Nb1-xZr5x/4)O3 (NKNZ; x = 0.005 and 0.01) piezoelectric ceramics were fabricated by the conventional solid-state reaction method. Both ceramics were applied to a fatigue test for 106 cycles under an electric field at 3 kV/mm with unipolar drive. After the fatigue test, the maximum polarization of NKN and NKNZ (x = 0.005) was decreased by approximately 15 and 5%, respectively. Therefore, we found that the fatigue resistance properties of NKNZ ceramics, which substituted the Nb5+ ion with the Zr4+ ion, were improved. To study fatigue phenomena in piezoelectric ceramics, the chemical bond strength of both ceramics before and after the fatigue test was analyzed by soft X-ray emission spectroscopy (SXES), which has high energy resolution and is suitable for the evaluation of light elements in a local region with the micrometer order. We evaluated the formation of oxygen vacancies in as-sintered, poled, and fatigued ceramics by analyzing a chemical shift of the O Ka(3) peak appeared at approximately 175 eV in the SXES spectra. In NKN ceramics, the O Ka(3) peak was shifted to the higher energy side by the poling treatment and fatigue test. The peak position of fatigued NKN ceramics was close to that of the standard SrTiO3 sample. It was considered that the oxygen vacancies of the fatigued NKN ceramics had accumulated at grain boundaries instead of the oxygen moving. The improvement of the fatigue resistance for the NKNZ ceramics was attributed to the formation of a defect dipole connected with the oxygen vacancy and acceptor Zr ion.

Piezoelectric and thermophysical performances of La3+ and Ir4+ co-doped Ba0.95Ca0.05Ti0.94Zr0.06O3 ceramics

Abstract Rare earth element-doped piezoelectric ceramics exhibit excellent electrical properties. Platinum group elements can render them catalytically active and conductive. In this study, lead-free Ba0.95Ca0.05Ti0.94Zr0.06O3 piezoelectric ceramics doped with 0.12% lanthanum and iridium (varying contents, x) were sintered at 1260 °C. The thermal expansion coefficients and fracture strengths of these ceramics were affected by their strains and structural defects. With an increase in x, the diffuse phase transition weakened first and then accelerated (with further increase in x (> 0.75%)). The best ferroelectric properties were obtained at 400 ms and 25 kV/cm. The effects of the phase, structural defects, and internal stress on the electrical properties of the ceramics were systematically investigated. Relations of electrical properties, mechanical strength, and thermophysical performances were originally researched. In addition, the electrical properties (piezoelectric constants, ∼270 pC/N; mechanical quality factors, ∼70) and thermophysical performances (thermal expansion coefficient, ∼1.2 × 10−5 K−1) of the ceramics were found to be suitable for practical applications.

Influence of spark plasma sintering temperature on piezoelectric properties of PZT-PMnN piezoelectric ceramics

Being capable of interconverting electrical and mechanical energy, piezoelectric materials are essential for electromechanical devices. In this study, high-performance 0.95Pb(Zr0.52Ti0.48)O3–0.05Pb(Mn1/3Nb2/3)O3 (PZT-PMnN) piezoelectric ceramics were prepared by spark plasma sintering (SPS). We systematically investigated temperature-dependent electrical properties and phase structure of ceramics. The SPS temperature was found to be optimized at 950 °C. PZT-PMnN ceramic sintered at 950 °C possessed high piezoelectric performances, i.e. d33 of 411 pC/N and d33* of 556 pm/V. Furthermore, a high mechanical quality factor Qm (480) and low dielectric loss (0.19%) were obtained. Therefore, the spark-plasma-sintered PZT-PMnN ceramic is a promising candidate for applications.

Direct ink writing of macroporous lead‐free piezoelectric Ba0.85Ca0.15Zr0.1Ti0.9O3

AbstractDirect ink writing (DIW) has become a widespread additive manufacturing technique for material engineering, but its application in lead‐free Ba0.85Ca0.15Zr0.1Ti0.9O3 piezoelectric ceramics from aqueous systems has not been reported so far to our knowledge. The main obstacle is the high extent of hydrolysis reactions undergone by the starting powders when dispersed in water, hindering the attainment of stable water‐based colloidal suspensions. This paper reports on the preparation of stable aqueous inks from a deagglomerated and surface‐treated powder synthesized by solid‐state reaction and on DIW of macroporous lead‐free piezoelectrics. Based on zeta potential and rheological measurements, the optimal amounts of processing additives (dispersant, binder, and coagulating agent) were selected to transform the initial fluid suspension to a viscoelastic paste with sufficient stiffness and stability for the printing process. Dielectric and piezoelectric properties of samples sintered under different temperatures were also investigated.