G33 Value Research Articles

Fabrication of Piezoelectric Composites Using High-Temperature Dielectrophoresis

In this paper, we present a method to create a highly sensitive piezoelectric quasi 1–3 composite using a thermoplastic material filled with a piezoelectric powder. An up-scalable high-temperature dielectrophoresis (DEP) process is used to manufacture the quasi 1–3 piezoelectric polymer-ceramic composites. For this work, thermoplastic cyclic butylene terephthalate (CBT) is used as a polymer matrix and PZT (lead zirconium titanate) ceramic powder is chosen as the piezoelectric active filler material. At high temperatures, the polymer is melted to provide a liquid medium to align the piezoelectric particles using the DEP process inside the molten matrix. The resulting distribution of aligned particles is frozen upon cooling the composite down to room temperature in as little as 10 min. A maximum piezoelectric voltage sensitivity (g33) value of 54 ± 4 mV·m/N is reported for the composite with 10 vol% PZT, which is twice the value calculated for PZT based ceramics.

Building high transduction coefficient BiScO3–PbTiO3 piezoceramic and its power generation characteristics

Improving the power generation characteristics of piezoelectric energy harvesters requires the construction of piezoelectric ceramics with high transduction coefficient (d33 × g33), which remains a big challenge. In this paper, guided by piezoelectric energy harvester applications, the relationship between the composition, microstructure and transduction coefficient of (1 − x)BiScO3–xPbTiO3 material is systematically studied. The results demonstrated that the sample with a composition of x = 0.64 not only has a high Curie temperature (426 °C) which is beneficial to improve the working stability of the device, but also has a very high d33 × g33 value (15,110 × 10−15 m2/N), which is significantly superior to the commercial PZT system. Excellent electrical performance can be attributed to the fact that the composition of x = 0.64 located near MPB has a very high piezoelectric charge constant (505 pC/N) at the same time with moderate dielectric constant (1907). The cantilever-type energy harvester made of optimized composition generated a high output power density of 2.93 μW/mm3 at room temperature, which charged a commercial 47 μF electrolytic capacitor to 22 V in just 220 s and lighted up 72 LEDs for 0.1~0.2 s. Further, x = 0.64 harvester exhibited a large output voltage of 2.76 V even at 350 °C, suggesting its potential use for powering high temperature wireless sensors.

A wide temperature insensitive piezoceramics for high‐temperature energy harvesting

AbstractOne of the key challenges in the development of high‐temperature energy harvesting (HTEH) technology is to clarify the relationship between temperature‐dependent material parameters and device power generation capabilities. However, at present, the research on temperature stability of piezoceramics mainly relies on thermal annealing technology, which cannot follow the actual temperature dependence of the piezoelectricity, and it is even more difficult to predict the temperature stability of HTEH. To shed light on this field, here, (1−x)BiScO3–xPbTiO3 system was chosen for building HTEH material, and the temperature‐dependent electrical parameters, such as d33, εr, and g33, have been measured by multiple in situ techniques. It was found that the synergistic effect of d33 and εr with temperature helps to obtain a stable g33 value in a wide temperature range. Moreover, in the mode of the cantilever‐type energy harvester, a stable output voltage was obtained at x = 0.64 harvester with <20% change over a broad temperature range of 100‐250°C, and it was verified that the temperature stability of g33 is crucial to the operation stability of HTEH devices.

Large enhancement of transduction coefficient in PZN-PZT energy harvesting system through introducing low-εr PIN relaxor

Designing piezoceramics with a large transduction coefficient (d33×g33) is key to improving the power generation of piezoelectric energy harvesters (PEHs). However, in popular PEH materials such as Pb(Zn1/3Nb2/3)O3-Pb(Zr1/2Ti1/2)O3 (PZN-PZT), the same trend in the variation of d33 and εr makes it difficult to achieve a large d33 × g33. In this work, we introduced low-εr Pb(In1/2Nb1/2)O3 (PIN) into the PZN-PZT matrix to pull down the εr of the quaternary system. This simultaneously stabilized d33 in a certain range due to the refinement of the domain structure and increased the electrostrictive coefficient (Q33), and consequently the d33 × g33 value increased to 16081 × 10−15 m2/N for the optimal composition. We assembled a cantilever beam type PEH from the preferred material with a power density up to 3.37 μW/mm3 at 1 g acceleration, and demonstrated its use to charge an electrolytic capacitor to drive commercial blue LEDs and a speed sensor.

Fabrication and characterization of flexible piezoelectric composites with natural rubber matrix

This work aims to fabricate and characterize flexible piezoelectric composites with natural rubber (NR) matrix. Different amounts of Pb(Mg1/3Nb2/3)0.65Ti0.35O3 (PMNT) powders were added in NR matrices. Porosity, tensile strength and percent elongation at break of composites tended to decrease with increasing PMNT content. The dielectric constant of the NR materials was found to be 3.5. It was raised up to 4.2, 5.0, 4.5, 4.8 and 5.1 when 60, 80, 100, 120 and 150 phr PMNT powders were added. However, dielectric loss of NR materials did not change with PMNT additions. Among this composite system, the NR/100PMNT composite showed the best piezoelectric properties, which its output voltage, piezoelectric coefficient (d33) and piezoelectric voltage coefficient (g33) values were equal to 1.61 V, 2.1 × 10−4 pC/N and 5.4 × 10−6 V⋅m/N, respectively. This composition composite is a promising material suitable for further improvement to be used as piezoelectric generators in energy harvesting applications.

Relationship between piezoelectric properties of ceramics and output performance of 33-mode piezoelectric energy harvesters

Ring-type 33-mode piezoelectric energy harvesters (PEHs) were fabricated using Pb(Zr,Ti)O3- and (Na,K)NbO3-based piezoelectric ceramics. The relationship between the output performance of the PEH and the piezoelectric properties of the ceramics was investigated. Ring-type PEHs were selected for this investigation because they can be mounted on a specimen holder at the same position, ensuring structurally reliable output performance. The × Qm/ value, which was reported as a figure of merit (FOM) of the PEH under resonance condition, could not adequately explain the output performances of the 33-mode PEH with a specimen holder much larger than the size of the specimen. The d33 × g33 value, which is a FOM derived from the theoretical output power of the 33-mode PEH, can explain the variation of the output power of the 33-mode PEH with a large specimen holder. However, since the variation of the output power was more accurately explained by the d33 × g33 × value, this was suggested as a new FOM of the output power of the ring-type 33-mode PEH with a large specimen holder.

Effects of MnO2 doping on the electrical properties of BCZT ceramics prepared by seed-induced method

The effects of MnO2 doping on the electrical properties of Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) ceramics prepared by adding 1.0 mol% BCZT seed were studied Results were found that the ceramics showed pure perovskite phase phase for all samples. Density and grain size values were in the range of 5.45–5.57 g/cm3 and 6.79–9.85 μm, respectively. The highest values of εr and Pr measured at room temperatures were 3900 and 8.22 μC/cm2, respectively which were obtained for the sample of 1.0 mol% MnO2. Tan δ of all ceramic samples was lower than 0.02. In addition, d33 and g33 values were changed with MnO2 content.

Recent progress on piezoelectric energy harvesting: structures and materials

With the rapid development of advanced technology, piezoelectric energy harvesting (PEH) with the advantage of simple structure, polluted relatively free, easily minimization, and integration has been used to collect the extensive mechanical energy in our living environment holding great promise to power the self-sustainable system and portable electronics. In this paper, attempts have been made to review the progress of piezoelectric materials and devices used for energy harvesting. The review focused on three parts: structure of piezoelectric devices (cantilever, cymbal, and stacks); theoretical mode, including vibration mode (d31 and d33) and its responding theories of different devices; and piezoelectric materials, among which the electric performance of Pb(ZrTi)O3-based, lead-free-based, and composites applied in bulk/micro/nano-PEH devices were introduced in details. It is suggested that a new structure of PEH should be designed by combining advantages of cantilever, stacks, and cymbal structure. Besides, high d33 × g33 value and low e of piezoelectric materials are required in order to generate high electric output power for bulk/micro/nano-PEH. Additionally, lead-free piezoelectric ceramics is a candidate for manufacturing PEH devices, and nano-composite materials should be developed to further improve the flexibility of piezoelectric materials.

Dielectric and piezoelectric properties of 2-2 connectivity lead-free piezoelectric ceramic Bi0.5Na0.5TiO3/Portland cement composites

In this paper, 2-2 connectivity pattern lead-free piezoelectric ceramic Bi0.5Na0.5TiO3/Portland cement composites with ≈ 30–70 vol% of Bi0.5Na0.5TiO3 ceramic has been successfully fabricated. Dielectric and piezoelectric properties of the composites were investigated. The results showed that Bi0.5Na0.5TiO3 ceramic content has an effect on dielectric property of the composite, that is the dielectric constant value increased as Bi0.5Na0.5TiO3 ceramic content increased while the dielectric loss value reduced at higher Bi0.5Na0.5TiO3 ceramic content. The piezoelectric coefficient (d33) values of composites obtained were in the range of 48 pC/N to 73 pC/N. Moreover, composite with Bi0.5Na0.5TiO3 ceramic content of ≈ 30 vol% exhibited highest piezoelectric voltage coefficient (g33) value of 26.06 mV m/N. Therefore, these promising results showed that the 2–2 connectivity pattern lead-free piezoelectric ceramic Bi0.5Na0.5TiO3/Portland cement composite has the potential to be used as a sensor for structural health monitoring application.

Dielectric, ferroelectric and piezoelectric properties of (Ba0.7Ca0.3)Ti1-xCuxO3-x ceramics

(Ba0.7Ca0.3)Ti1-xCuxO3-x ceramics (where x = 0, 0.01, 0.02 and 0.03) were prepared employing a conventional solid state sintering technique. X-ray diffraction patterns and Ti K-edge X-ray Absorption Near-Edge Structure (XANES) spectra indicated a structural distortion of Cu-doped ceramics. Depending on Cu content, the features of normal ferroelectric and diffuse dielectric phase transition could be induced by the Cu addition. The temperature where maximum dielectric existed was decreased upon increase of Cu concentration. The creation of oxygen vacancies and defect dipoles caused double-like P-E loop in host material. The decrease of d33, g33 and kp values was observed in correlation with decrease of Pr in doped ceramics. The results here suggested that the electrical properties of this ceramic system may be largely tunable by Cu dopant and could be an attractive material for high-dielectric response devices.

A composite approach boosts transduction coefficients of piezoceramics for energy harvesting

Piezoelectric energy harvesting is a hotspot in the field of new energy, the core goal of which is to prepare piezoceramics with a high transduction coefficient (d33×g33). The traditional solid–solution design strategy usually causes the same variation trend of d33 and εr, resulting in a low d33×g33 value. In this work, a composite design strategy was proposed that uses PZN–PZT/ZnAl2O4 as an example. By introducing ZnAl2O4, which is nonferroelectric with low εr, to the PZN–PZT piezoelectric matrix, εr decreased rapidly while d33 remained relatively stable. This behavior was ascribed to the increase of Q33 caused by an interfacial effect facilitating the formation of micro-domain structure.

PZT/PLZT - elastomer composites with improved piezoelectric voltage coefficient

Lead Zirconate Titanate (PZT) and Lanthanum-modified Lead Zirconate Titanate (PLZT) ceramic sensor materials are widely used because of their excellent piezoelectric coefficients. These materials are brittle, high density and have low achievable piezoelectric voltage coefficients. The density of the sintered ceramics shall be reduced by burnable polymeric sponge method. The achievable porosity level in this case is nearly 60 – 90%. However, the porous ceramic structure with 3-3 connectivity produced by this method is very fragile in nature. The strength of the porous structure is improved with Sylgard®-184 (silicone elastomer) by vacuum impregnation method maintaining the dynamic vacuum level in the range of -650 mm Hg. The elastomer Sylgard®-184 is having low density, low dielectric constant and high compliance (as a resultant stiffness of the composites is increased). To obtain a net dipole moment, the impregnated ceramic composites were subjected to poling treatment with varying conditions of D.C. field and temperature. The properties of the poled PZT/PLZT - elastomer composites were characterized with LCR meter for measuring the dielectric constant values (k), d33 meter used for measuring piezo-electric charge coefficient values (d33) and piezo-electric voltage coefficient (g33) values which were derived from d33 values. The voltage coefficient (g33) values of these composites are increased by 10 fold as compared to the conventional solid ceramics demonstrates that it is possible to fabricate a conformable detector.

The structural origin of enhanced energy harvesting performance in piezoelectric perovskite

Energy harvesting, which can translate the wasted vibration energy into electric energy, is now a hot topic in the field of new energy, and the key point is to design high power piezoelectric ceramic according with the requirements of low-frequency vibration energy harvesting. In this study, high quality Co-modified 0.2Pb(Zn1/3Nb2/3)O3–0·8Pb(Zr0·50Ti0·50)O3 (PZN–PZT+Co) ceramics have been prepared by the two-stage method, and the energy harvesting characteristics were investigated. The results showed that the hierarchical nanodomain structure boosts the strong piezoelectric activity, leading to the high energy harvesting performance. The PZN–PZT+Co ceramic sintered at 1000°C exhibits an excellent d33×g33 value of 14080×10−15m2/N, which are much larger than that of commercial PZT-based ceramics. In the mode of the cantilever-type energy harvester, the output voltage and energy density of 33V, 4.4μW/mm3 were obtained at a low resonance frequency of 85Hz and acceleration of 10m/s2, showing potential application in piezoelectric energy harvester.

Polarization extension mechanism revealed through dynamic ferroelectric hysteresis and electric field driven structural distortions in lead free Na0.5Bi0.5TiO3 ceramic

The electric field amplitude (Eo) dependent dynamic ferroelectric hysteresis and polarization current density curves measured at room temperature for Na0.5Bi0.5TiO3 (NBT), showed three different stages of polarization reversal mechanism. The scaling relationship confirmed the dominance of domain wall motion at Stage I (i.e. upto Eo < 35 kV cm−1), followed by domain switching at Stage II (35 kV cm−1 < Eo < 60 kV cm−1). Interestingly, a unique behaviour with two sub stages was observed in Stage III (60 kV cm−1 < Eo < 90 kV cm−1), with two distinct switching mechanisms viz., polarization rotation at Stage III-A and polarization extension at Stage III-B. X-ray diffraction analysis based on the Rietveld refined atomic positional co-ordinates, in electrically poled system strongly favors the polarization extension mechanism proposed at Stage III-B. The measured Eo-dependent longitudinal piezoelectric response (d33 and g33) values match closely with our proposed polarization reversal mechanism.

Highly sensitive piezo particulate-polymer foam composites for robotic skin application

ABSTRACTTri-phase PZT-porous polyurethane (PU) composites are investigated with the aim of developing conformable, highly sensitive tactile sensors for application in Human-Machine Interactions. The main goal is to reduce the dielectric constant of the polymer matrix, and improve flexibility of traditional diphase piezo-composites, consisting of ceramic particles in a dense polymeric matrix, by adding a third (gaseous) phase to the system. The presence of the gaseous component in the polymer matrix in the form of well-distributed spherical inclusions effectively decreases the polymer dielectric permittivity, which improves the piezoelectric voltage coefficient of the composites significantly. The unique combination of dielectrophoretic structuring of PZT particles and the addition of a gaseous phase to the polymer resin results in the highest performance of the particulate composite sensors reported in the literature so far. The g33 values of the newly developed triphase composites are twice that of the structured di-phase PZT-dense PU composites (80 mV.m/N) and more than five times the g33 value of bulk PZT ceramics (24-28 mV.m/N).

Large area and flexible micro-porous piezoelectric materials for soft robotic skin

The need for flexible, highly sensitive tactile sensors that can fit onto curved surfaces is driving the conformable sensor materials research in the field of human–machine interactions. Here we report a new type of compliant piezoelectric active composite, a micro-porous polyurethane-PZT material, capable of generating a voltage output upon touch. The composites are synthesized with the aim of maximizing the piezoelectric sensitivity of particulate composite sensor materials. The goal is to reduce the dielectric constant of the polymer matrix and improve flexibility of conventional bulk piezo-composites, consisting of ceramic particles in a dense polymeric matrix, by adding a third (gaseous) phase to the system in the form of uniformly sized pores. The presence of the gaseous component in the polymer matrix in the form of well-distributed spherical inclusions effectively decreases the polymer dielectric permittivity, which increases the piezoelectric voltage sensitivity (g33) of the composite sensors significantly. The unique combination of dielectrophoretic structuring of PZT particles and the addition of a gaseous phase to the polymer resin results in the highest performance of the particulate composite sensors reported in the literature so far. The newly developed micro-porous composites show g33 value of 165mVm/N that is twice that of the structured PZT-bulk PU composites (80mVm/N) and more than five times the g33 value of bulk PZT ceramics (24–28mVm/N). The capability of the flexible freestanding sensors for application in touch sensing devices for soft robotics is demonstrated.

High power density in a piezoelectric energy harvesting ceramic by optimizing the sintering temperature of nanocrystalline powders

Piezoelectric energy harvesting is the research hotspot in the field of new energy, and its core is to prepare piezoelectric ceramics with high transduction coefficient (d33×g33) and large mechanical quality factor (Qm) as well. In addition, the miniaturization of the piezoelectric energy harvester also requires the material to have a submicron fine grain structure. In this work, submicron-structured ternary system, MnO2-doped Pb(Zn1/3Nb2/3)O3-Pb(Zr0.5Ti0.5)O3 was constructed by pressureless sintering of nanocrystalline powders, which has been synthesized for the first time by high-energy ball milling route thereby evading the calcination stage. The microstructure and the energy harvesting characteristics were tailored through changing the sintering temperature. It was found that 1000°C sintered fine-grained specimen (mean grain size ∼0.95μm) showed the maximum d33×g33 value of 9627×10−15m2/N, meanwhile Qm was as large as 774, which was almost seven times larger than pure counterpart. In the mode of the cantilever-type energy harvester, a high power density of 1.5μW/mm3 were obtained for 1000°C sintered specimen at a low resonance frequency of 90Hz and acceleration of 10m/s2, which were further increased to 29.2μW/mm3 when the acceleration increased to 50m/s2, showing the potential applications as a next generation high power multilayer energy harvester.

Piezoelectric properties of Pb(Zr,Ti)O3-Pb(Ni,Nb)O3 ceramics and their application in energy harvesters

The piezoelectric properties of (1-x-y)PbZrO3-xPbTiO3-yPb(Ni1/3Nb2/3)O3 ceramics were investigated. Specimens with a large Pb(Ni1/3Nb2/3)O3 content, which have compositions close to the triple point, show small g33 and d33×g33 values because of their large εT33/ε0. These values increased with a decrease in y (amount of Pb(Ni1/3Nb2/3)O3) and the specimen with x=0.39 and y=0.29 showed the largest g33 of 43×10−3 V·m/N and d33×g33 of 25.2×10−12m2/N. Cantilever-type energy harvesters were fabricated using specimens with 0.38≤x≤0.41 and y=0.29. The output power densities of the energy harvesters were related to the d31×g31×k312 value of the piezoelectric ceramics. The energy harvester fabricated using a specimen with x=0.39 and y=0.29, which has a maximum d31×g31×k312 value, showed the maximum output power density of 1.01mW/cm3.

Microstructure and performance of 1–3 connectivity environmental friendly lead-free BNBK-Portland cement composites

The 1–3 connectivity lead-free piezoelectric composites were produced from the bismuth sodium titanate-bismuth potassium titanate-barium titanate (BNBK) ceramic and Portland cement (PC) by dice-and-fill method. Microstructure and performance of composites were investigated and compared with predicted models. The results indicated that the BNBK ceramic can improve the dielectric, piezoelectric coefficient and thickness electromechanical coupling coefficient properties in composites. At ≈40% BNBK ceramic content is the optimal BNBK content for an acoustic impedance match between composites and concrete. The dielectric constant and piezoelectric coefficient were close to the parallel model. The piezoelectric voltage coefficient of all composites was found to be higher than pure ceramic and the g33 value were found to be 26.55×10−3Vm/N and 21.74×10−3Vm/N for composite with 30% and 70% BNBK contents, respectively. The 1–3 BNBK-PC composites have good compatibility with concrete obtaining good performance for use in smart structures applications.

Relation between structure and piezoelectric properties of (1-x-y)PbZrO3-xPbTiO3-yPb(Ni1/3Nb2/3)O3 ceramics near triple point composition

The structural and piezoelectric properties of (1-x-y)PbZrO3-xPbTiO3-yPb(Ni1/3Nb2/3)O3 [(1-x-y)PZ-xPT-yPNN] ceramics near the triple point were investigated. The 0.16PZ-0.34PT-0.5PNN ceramic with a triple point composition exhibited a large d33, kp and ε33T/εo values of 855 pC/N, 0.68 and 5800, respectively. However, its g33 and d33 x g33 values were relatively small because of its large ε33T/εo. Similar results were obtained for specimens with rhombohedral-tetragonal or pseudocubic-tetragonal morphotropic phase boundary (MPB) compositions. However, specimens with a rhombohedral structure near the rhombohedral-tetragonal MPB exhibited large g33 and d33 x g33 values because of their large d33 and small ε33T/εo that can be explained by their polarization characteristics. In particular, 0.23PZ-0.36PT-0.41PNN ceramic exhibited large g33 and d33 x g33 values of 30.2×10−3 Vm/N and 22.6×10−12m2/N, respectively, thus making it a good candidate for piezoelectric energy harvesters and multilayer actuators.