Longitudinal Piezoelectric Coefficient D33 Research Articles

A high performance nanocellulose-PVDF based piezoelectric nanogenerator based on the highly active CNF@ZnO via electrospinning technology

Piezoelectric polymer composites have attracted much attention due to their high piezoelectric properties and excellent flexibility. In this work, cellulose nanofiber (CNF) was loaded with ZnO by an improved two-step hydrothermal method to obtain CNF@ZnO composites, which have the advantage at high-efficiency one-step film formation and displays considerable piezoelectric performance. Under the optimized hydrothermal conditions, ZnO can be uniformly loaded on CNF sbstrate. The piezoelectric response of CNF at scattered state and micro-nano scale has been successfully characterized to be 5.85 pm·V−1 via piezoelectric force microscopy (PFM), which can be increased to 9.49 pm·V−1 after loaded with ZnO. The obtained CNF@ZnO was dispersed in polyvinylidene fluoride (PVDF) to prepare a large-format tough PVDF/CNF@ZnO composite membrane (E-PVDF/CZ) by electrospinning. CNF@ZnO can effectively increase β phase in PVDF to be 87.36%, and its piezoelectric response was further enhanced to be 24.65 pm·V−1, along with longitudinal piezoelectric coefficient (d33) of 31±2.07 pC·N−1 higher than that of E-PVDF (20.25±2.05 pC·N−1). It also exhibits excellent mechanical performance and flexibility with the tensile strengthen of 16.12±2.35 MPa and elongation at break of 16.21±2.17%. Under the force of 45 N, the open-circuit voltage (VOC) and short-circuit current (ISC) of E-PVDF/CZ are as high as 11.8 V and 452 nA, respectively. Finally, the prepared flexible sensor has an VOC up to 31.2 V under the fist hitting state, while it is about 1.68 V stimulated by water droplets which can also weakly light a LED. The strategy will exactly facilitate the cellulose material in the application in energy harvesting and environmental monitoring.

Temperature-Dependent Ferroelectric Properties and Aging Behavior of Freeze-Cast Bismuth Ferrite-Barium Titanate Ceramics.

Lead-free BiFeO3-BaTiO3 (BF-BT) piezoceramics have sparked considerable interest in recent years due to their high piezoelectric performance and high Curie temperature. In this paper, we show how the addition of highly aligned porosity (between 40 and 60 vol %) improves the piezoelectric performance, sensing, and energy harvesting figures of merit in freeze-cast 0.70BiFeO3-0.30BaTiO3 piezoceramics compared to conventionally processed, nominally dense samples of the same composition. The dense and porous BF-BT ceramics had similar longitudinal piezoelectric coefficients (d33) immediately after poling, yet the dense samples were observed to age faster than those of porous ceramics. After 24 h, for example, the porous samples had significantly higher d33 values ranging from 112 to 124 pC/N, compared to 85 pC/N for the dense samples. Porous samples exhibited 3 and 5 times higher longitudinal piezoelectric voltage coefficient g33 and energy harvesting figure of merit d33g33 than dense samples due to the unexpected increase in d33 and decrease in relative permittivity with porosity. Spontaneous polarization (Ps) and remnant polarization (Pr) decrease as the porosity content increased from 37 to 59 vol %, as expected due to the lower volume of active material; however, normalized polarization values with respect to porosity level showed a slight increase in the porous materials relative to the dense BF-BT. Furthermore, the porous ceramics showed improved temperature-dependent strain-field response compared to the dense. As a result, these porous materials show excellent potential for use in high temperature sensing and harvesting applications.

Surface potential modulation for improved mechanical energy harvesting and sensing in 3D printed biopolymer thermoelectret

This study presents the development of a special class of electret known as thermoelectret, made with polylactic acid (PLA), prepared via 3D printing technology followed by a heat-assisted corona discharged technique. We show that the bimodal surface polarity (i.e., ± 1 kV) is possible to achieve over the top and bottom surfaces of 3D printed PLA thermoelectret that enable a wide range of potential applications, such as mechanical energy harvesting to wearable biomedical sensors. Besides this, the enhanced surface potential leads to a giant longitudinal piezoelectric coefficient (d33) of 350 ± 15 pC/N, which is typically 10 times higher than the best-known piezoelectric polymer, polyvinylidene fluoride-trifluoro ethylene (PVDF-TrFE). To utilize this benefit, a 3D-printed thermoelectret-based mechanical energy harvester (3D-TEH) has been developed that delivers an outstanding power density of ⁓ 25 mW/m2, which makes it a suitable candidate for the self-power pressure sensor. As a proof of concept, we have demonstrated that 3D-TEH is capable of recording the bone-joints motions, coughing action, and human foot-pressure distribution that signify its potential application as a self-powered bio-medical sensor.

Novel manufacturing method for highly flexible poly(lactic acid) foams and ferroelectrets

Poly (lactic acid) (PLA) foams have demonstrated a high variety of functional characteristics, still, the rigidity of this cellular material remains a major limiting factor when it comes to implementation options. In this contribution, PLA foams with outstanding flexibility were created for the first time by a new approach of uniaxial stretching and immediate relaxation following supercritical CO2-assisted extrusion foaming. Instead of improving the resilience of the PLA raw material, structural elasticity of the foam was achieved via altering the deformation mechanism from cell wall collapse or rupture towards reversible and extensive flexural strain. In addition, PLA foams with excellent piezoelectric properties were also achieved via high-voltage corona poling, giving additional function to the lens-like anisotropic foam cells. This foaming technology creates the opportunity to produce PLA piezoelectrets in a way entirely different from the state-of-the-art methods. Correlation between the tensile as well as compression elongations and moduli, cell morphology and longitudinal piezoelectric coefficients (d33) of electretized foam samples were studied. Unprecedented reversible tensile elongations of up to 16% and total elongations of up to 35% were reached, as well as considerable d33 values in the range of 50–320 pC/N were obtained for PLA ferroelectrets.

Dielectric and piezoelectric properties of cement-containing piezoelectric composites: Experiments and modeling

In this work, porous honeycomb lead zirconate titanate (PZT) ceramics with one dimensional ordered pore channels were fabricated by the ionotropic gelation of sodium alginate/PZT suspension with SrCl2 solution, then the piezoelectric cement/PZT paste with different mass fraction of PZT component were cast into the porous ceramics to produce cement-containing piezoelectric composites. The influences of PZT mass fraction of piezoelectric cement/PZT paste on the microscopic morphology were studied. The relative permittivity (εr) and longitudinal piezoelectric strain coefficient (d33) of piezoelectric composites were measured and predicted by experiments and modified “unit cell” model respectively, while both results displayed consistency. The composites presented typical electromechanical coupling behavior for the direct and inverse piezoelectric effect of PZT component, when the PZT mass fraction increased to 50 wt%, the cement-containing piezoelectric composites acquired the greatest thickness electromechanical coupling coefficient (Kt) value of 55.69% and acoustic impedance (Z) value of 10.00 MRayls, making it an appropriate candidate material in the structure health monitoring system.

Effect of electrically induced cracks on the properties of PZT thin film capacitors

We present a study of the effect of electrically induced cracks on both the ferroelectric and piezoelectric properties of Pt/PbZr0.52Ti0.48O3 (PZT)/Pt capacitors and correlations with domain structures of PZT films. Above a threshold bipolar electric field, cracks appear inside the PZT layer thickness leading to an increase in the ferroelectric polarization (+50% for the remnant polarization, from 16 to 25 μC/cm2) and the longitudinal piezoelectric coefficient d33,f (from ∼150 to ∼220 pm/V). The use of x-ray diffraction during in situ biasing provides direct evidence for a modification of the PZT crystalline structure as well as the a/c domain configuration. After cracking, the fraction of c-domains is strongly increased, thus contributing to higher polarization and larger strain in the out-of-plane direction.

Flash Sintered Potassium Sodium Niobate: High-Performance Piezoelectric Ceramics at Low Thermal Budget Processing.

Alternative sintering technologies promise to overcome issues associated with conventional ceramic sintering such as high thermal budgets and CO2 footprint. The sintering process becomes even more relevant for alkali-based piezoelectric ceramics such as K0.5Na0.5NbO3 (KNN) typically fired above 1100 °C for several hours that induces secondary phase formation and, thereby, degrades their electrical characteristics. Here, an ability of KNN ceramics to be of high performance is successfully demonstrated, using an electric field- and current-assisted Flash sintering technique at 900 °C only. Reported for the first time, Flash sintered KNN ceramics have room-temperature remnant polarization Pr = 21 μC/cm2 and longitudinal piezoelectric coefficient d33 = 117 pC/N, slightly superior to that of conventional ones due to the reduced content of secondary phases. High-performance KNN ceramics Flash sintered at a low-thermal budget have implications for the development of innovative low carbon technologies, electroceramics stakeholders, and piezoelectric energy harvesters.

Enhanced piezoelectric performance of PVDF/BiCl3/ZnO nanofiber-based piezoelectric nanogenerator

A unique bismuth chloride (BiCl3)/zinc oxide (ZnO)/poly(vinylidene fluoride) (PVDF) nanofiber-based highly flexible piezoelectric nanogenerator (PENG) is prepared via electrospinning technique. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) are used to characterize the β-phase content and crystallinity of the PVDF based nanofibers, respectively. Then, we analyze four types nanofiber-based PENG (PVDF, PVDF/ZnO(2%), PVDF/BiCl3(2%), and PVDF/BiCl3/ZnO(2%)) and the influence factors of piezoelectric properties are addressed systematically. It is found that the longitudinal piezoelectric coefficient (d33) of PVDF/BiCl3/ZnO(2%) nanofiber-based PENG is up to 3.8 pC/N and an open-circuit voltage (VOC) of 12 V is also got. Finally, the practical applicability of the developed PENG is demonstrated by placing it on elbow and knee joint to monitor human body movement, which shows a maximum peak VOC of 3 V (for elbow) and 0.6 V (for knee) by bending and stretching between specific angles. The high-performance flexible PENG can be used as highly sensitive self-powered sensor, and it also can be used for wearable sensors for detecting some vital signals including breathing, heartbeating, which shows its possible applications in wearable electronics.

Microscopic piezoelectric behavior of clamped and membrane (001) PMN-30PT thin films

Bulk single-crystal relaxor-ferroelectrics, like Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), are widely known for their large piezoelectricity. This is attributed to polarization rotation, which is facilitated by the presence of various crystal symmetries for compositions near a morphotropic phase boundary. Relaxor-ferroelectric thin films, which are necessary for low-voltage applications, suffer a reduction in their piezoelectric response due to clamping by the passive substrate. To understand the microscopic behavior of this adverse phenomenon, we employ the AC electric field driven in-operando synchrotron x-ray diffraction on patterned device structures to investigate the piezoelectric domain behavior under an electric field for both a clamped (001) PMN-PT thin film on Si and a (001) PMN-PT membrane released from its substrate. In the clamped film, the substrate inhibits the field-induced rhombohedral (R) to tetragonal (T) phase transition resulting in a reversible R to Monoclinic (M) transition with a reduced longitudinal piezoelectric coefficient d33 < 100 pm/V. Releasing the film from the substrate results in recovery of the R to T transition and results in a d33 > 1000 pm/V. Using diffraction with spatial mapping, we find that lateral constraints imposed by the boundary between the active and inactive materials also inhibit the R to T transition. Phase-field calculations on both clamped and released PMN-PT thin films simulate our experimental findings. Resolving the suppression of thin film piezoelectric response is critical to their application in piezo-driven technologies.

Fabrication and properties of 3-3 type PZT-ordinary Portland cement composites

In this study, porous lead zirconate titanate (PZT) ceramics with porosity ranging from 46.4% to 82.3% were produced by the gel casting technology of particle-stabilized ceramic foams with the solid loading of 5–25 vol%, then the Portland cement paste was cast in porous PZT ceramics with continuous vibration to fabricate 3-3 type cement-based piezoelectric composites. The microstructure, dielectric, piezoelectric, and electromechanical coupling properties of the composites were characterized. With the increase in initial solid loading of PZT slurry, both the porosity, open porosity and pore size of porous PZT ceramics decreased correspondingly, which have prevented the filling of cement paste into the porous ceramics and led to the increment of PZT content in the composites. Increase in the PZT content contributed to the relative permittivity (εr) and longitudinal piezoelectric strain coefficient (d33), and a resultant reduction in piezoelectric voltage coefficient (g33). The prepared composites possessed a maximal thickness electromechanical coupling coefficient (Kt) value of 41.22%, higher than that of planar electromechanical coupling coefficient (Kp), indicating enhanced thickness mode oscillations of the composite. With the increase in PZT volume fraction, the PZT-cement composites turned from typical 3-3 structure to appoximate sandwich structure gradually, leading to more energy loss during electromechanical process and obvious decrease of the mechanical quality factor (Qm). The acoustic impedance (Z) of specimens ranged from 6.69 to 8.27 MRayls, close to that of cement materials (∼10 MRayls), making them promising candidate for application in civil engineering.

Bulk Ferroelectric Metamaterial with Enhanced Piezoelectric and Biomimetic Mechanical Properties from Additive Manufacturing.

Three-dimensional (3D) ferroelectric materials are electromechanical building blocks for achieving human-machine interfacing, energy sustainability, and enhanced therapeutics. However, current natural or synthetic materials cannot offer both a high piezoelectric response and desired mechanical toughness at the same time to meet the practicality. Here, a lamellar ferroelectric metamaterial was created with a ceramic-like piezoelectric property and a bone-like fracture toughness through a low-voltage-assisted 3D printing technology. The one-step printed bulk structure, consisting of periodically intercalated soft ferroelectric and hard electrode layers, exhibited a significantly enhanced longitudinal piezoelectric charge coefficient (d33) of over 150 pC N-1, as well as a superior fracture resistance of ∼5.5 MPa·m1/2, more than three times higher than conventional piezo-ceramics. The excellent printability together with the combination of both high piezoelectric and mechanical behaviors allowed us to create a bone-like structure with tunable anisotropic piezoelectricity and bone-comparable mechanical properties, showing a potential of manufacturing practical, high-performance, and smart biological systems.

Optimizing K0.5Na0.5NbO3 Single Crystal by Engineering Piezoelectric Anisotropy.

K0.5Na0.5NbO3 is considered as one of the most promising lead-free piezoelectric ceramics in the field of wearable electronics because of its excellent piezoelectric properties and environmental friendliness. In this work, the temperature-dependent longitudinal piezoelectric coefficient was investigated in K0.5Na0.5NbO3 single crystals via the Landau–Ginzburg–Devonshire theory. Results show that the piezoelectric anisotropy varies with the temperature and the maximum of deviates from the polar direction of the ferroelectric phase. In the tetragonal phase, parallels with cubic polarization direction near the tetragonal-cubic transition region, and then gradually switches toward the nonpolar direction with decreasing temperatures. The maximum of in the orthorhombic phase reveals a distinct varying trend in different crystal planes. As for the rhombohedral phase, slight fluctuation of the maximum of was observed and delivered a more stable temperature-dependent maximum and its corresponding angle θmax in comparison with tetragonal and orthorhombic phases. This work not only sheds some light on the temperature-dependent phase transitions, but also paves the way for the optimization of piezoelectric properties in piezoelectric materials and devices.

Tuning piezoelectric properties in elastomeric polyurethane nanocomposites utilizing cellulose nanocrystals

AbstractFlexible piezoelectric nanocomposites have been the subject of a lot of recent research due to the development and use of wearable electronic devices and the increasing need for new harvesting devices and sensors due to increasingly intelligent and interconnected cities. In this study, flexible piezoelectric nanocomposites using elastomeric polyurethane (PU) as matrix, and lead zirconate titanate (PZT) as active phase, were produced using cellulose nanocrystals (CNC) as the third phase. The study describes the effect of CNC insertion on the morphology, thermal, electrical, and piezoelectric properties of the nanocomposites. It points out that the CNCs not only act to cause greater dispersion of the ceramic grains in the matrix, but also to lead to greater polarization effectiveness of the ceramic grains, resulting in a longitudinal piezoelectric coefficient (d33) increase of more than 370%, as compared with biphasic composites dependent on the ceramic and nanocrystals content.

Fabrication and characterization of a novel photoactive-based (0\u20133) piezocomposite material with potential as a functional material for additive manufacturing of piezoelectric sensors

The development of 3D-printed sensors and actuators from piezocomposite materials has increased in recent years due to the ease of production, low-cost and improved functionality additive manufacturing provides. The piezocomposite material developed in this work has the potential to be used as a functional material in stereolithographic additive manufacturing by combining the optical, viscoelastic properties of NOA 65 and the piezoelectric properties of Barium Titanate. The new (0–3) piezocomposite material consists of Norland Optical Adhesive 65 (NOA 65) as the polymer matrix and Barium Titanate (BaTiO3) with particles sizes (100 nm, 200 nm and 500 nm) as the dielectric filler. We synthesized thin film samples of the (0–3) piezocomposite with 60% w/w BaTiO3 using solution mixing and spin coating method to produce samples with layer thickness of 100 µm. Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) techniques were used to analyze the microstructure of the piezocomposite to determine the effect of different particles sizes of BaTiO3 on the structural and mechanical properties of the composite. The longitudinal piezoelectric coefficient d33 was also measured using the laser vibrometer technique. Both single point scans and full surface scans were carried out to obtain the average piezoelectric coefficient d33 of the composite material. The results of the SEM confirmed the (0–3) structure of the piezocomposite material with isolated BaTiO3 nanoparticles. It further showed the uniform distribution of the BaTiO3 nanoparticles across each of the samples. FTIR analysis showed that the filler nanoparticles had no effect on the native structure of the polymer matrix. The longitudinal piezoelectric coefficient d33 of the piezocomposite material was observed to increase with increasing BaTiO3 particle sizes, while the indentation modulus of the composite investigated using the method of Oliver and Pharr was observed to decrease with an increase in particle size. Results from the single point scans showed the composite with BaTiO3 particle size 100 nm, 200 nm and 500 nm having an average d33 of 2.1 pm/V, 3.0 pm/V and 3.9 pm/V while the average d33 obtained from the full surface scan of 1430 scan points showed 1.4 pm/V, 6.1 pm/V, 7.2 pm/V.

Analysis of Rosen type energy harvesting devices from porous piezoceramics with great longitudinal piezomodulus

AbstractThis paper describes analytical and numerical modeling of the energy harvesting device based on composite piezoelectric materials. The device is a nonuniformly polarized porous piezoceramic compound plate such as a Rosen‐type piezoelectric transformer with single bimorph section. The effective properties of porous piezoceramics with great longitudinal piezoelectric strain coefficient d33 were calculated in the ACELAN‐COMPOS finite element package. An analytical applied theory for a piecewise uniformly polarized piezoelectric generator was developed and compared with the results of finite element simulation performed in ACELAN package. An efficient design of a cantilever‐based energy harvesting device is proposed. The analysis of the considered devices depending on the percentage of porosity of piezoceramics and boundary conditions is carried out. It is shown that with an increase in the percentage of porosity, the output characteristics of energy harvesting devices improve. In addition, different boundary conditions were studied for specific PEG made of porous ceramics with non‐homogeneous polarization to find more effective scheme of fixing.

High performance high power textured piezoceramics

Crystallographic grain-oriented ceramics (also referred to as textured ceramics) are known to exhibit a high soft piezoelectric response. However, the role of texturing in hard piezoelectric materials is not well understood and it has been difficult to obtain a balance of hard and soft properties in the same material. Here, we investigate the hard and soft piezoelectric behavior of [001]PC-textured 0.05Pb(Mn1/3Sb2/3)O3-0.95[0.4Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3] (PMnS-PMN-PZT) ceramics to illustrate the influence of texturing degree. The results demonstrate that textured PMnS-PMN-PZT ceramics exhibit a 170% higher longitudinal mode piezoelectric coefficient (d33) with only 16% reduction in the mechanical quality factor (Qm). Random PMnS-PMN-PZT ceramics were found to exhibit a d33 of 259 pC/N and a Qm of 982, while textured ceramics sintered at the same temperature demonstrated a d33 of 445 and a Qm of 824. Electric field dependent x-ray diffraction is utilized to confirm the existence of internal bias generated from defect dipoles, providing the signature for hard behavior. Temperature dependent measurement of d33 and Qm for textured PMnS-PMN-PZT ceramics indicated high stability up to 120 °C.

PZT ceramic particles/polyurethane composites formalism for mechanical energy harvesting

More recently, the ferroelectric ceramic/polymer composites have been progressively replacing ferroelectric ceramics and polymers as they combine their interesting properties. Such as high compliance of polymers and high electromechanical coupling of ferroelectric ceramics those are required for piezoelectric transducer applications. At the same time, the ferroelectric ceramic/polymer composites formalism for predicting their energy-conversion capabilities is of both academic and industrial interest. The novelty of this paper is that the electrical power harvested by the PZT/PU polarized composite has been expressed in terms of the effective longitudinal piezoelectric coefficient (d33) of the composite via a parameter p related to the poling ratio. Besides, the parameter p, that is characterizing the PZT/PU composites with different longitudinal piezoelectric coefficients (d33), was evaluated. The other parameters of the electrical power expression were calculated using the Yamada model for the dielectric, piezoelectric and elastic constants. Finally, a good agreement was found between experience and model.

Factors contributing to the local polar-structural heterogeneity and ultrahigh piezoelectricity in Sm-modified Pb(Mg1/3Nb2/3)O3–PbTiO3

Recently, an ultrahigh piezoelectricity (longitudinal piezoelectric coefficient d33 ~ 1500 pC/N) was reported in polycrystalline specimens of Sm-modified relaxor ferroelectric system Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) (Li et al 2018 Nat. Mater. 17 349). Here, we examine the factors associated with this anomalous phenomenon by carrying out a comparative structural, dielectric, ferroelectric and impedance spectroscopy on Sm-free 0.71PMN-0.29PT (piezoelectric coefficient d33 ~ 380 pC/N) and its Sm modified counterpart (d33 ~ 1160 pC/N). We found that, apart from inducing a Cm → P4mm inter-ferroelectric instability, Sm modification stabilizes a considerable degree of oxygen vacancies, with Sm exhibiting valence fluctuation. Based on our results, we argue that these defect types are the important source for creating structural-polar heterogeneity on the local scale, the interaction of which with the long-range ferroelectric order makes the system exhibit an ultrahigh piezoelectric response.

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.

Piezoelectric Response of ZnO Thin Films Grown By Plasma-Enhanced Atomic Layer Deposition

ZnO is a direct band gap semiconductor with attractive piezoelectrical, optical, and electrical properties, particularly appealing for a variety of functional devices. Especially the utilization of piezoelectric properties of ZnO nanostructures for transforming mechanical to electrical energy has attracted much research interest. For most of these so called nanogenerators, solution based deposition methods have been applied to create the desired nanostructures, often lacking a precise control of the deposition parameters. Atomic layer deposition, on the other hand, allows conformal and uniform deposition on high aspect ratio structures with Å-level thickness control. In this study, we investigate the piezoelectric response of ZnO thin films on flexible substrates as a starting point for piezoelectric nanostructures. The films are grown by plasma-enhanced atomic layer deposition (PE-ALD) to thicknesses below 100 nm by adapting diethylzinc and O2-plasma as reactants. In comparison to thermal ALD (where diethylzinc and water are used as reactants), PE-ALD allows the deposition of films with higher resistivity, an important property to minimize the leakage of piezoelectric charges. Commercially available Polyethylenterephthalat (PET) coated with Indium Tin Oxide (ITO) serves as the flexible substrate and bottom electrode, respectively. The deposition of ZnO thin films is carried out at substrate temperatures between room temperature and 100 °C, as a change in preferential crystal orientation from (100) to (002) can be observed in this temperature range. [1] The macroscopic piezoelectric characterization is performed in a home-built stamp station, in which a defined periodic force is exerted onto the samples and the generated piezoelectric charges are measured. Out of this, the longitudinal piezoelectric coefficient d33 can be obtained. Preliminary results show d33 coefficients > 7 pC/N, which is comparable to literature results. [2] The piezoelectric characterization is made for the different samples to understand how the d33 coefficient changes for films deposited at different substrate temperatures and thus having different crystal orientation. Since the [002] is the polar axis in the ZnO wurtzite crystal structure, films with preferred orientation in this direction are therefore expected to show higher d33 coefficients. The work lays the basis for developing functional piezoelectric generators and sensors in thin film form. However, the concepts can be easily transferred to depositions on lithographically defined templates in order to create nanostructured ZnO, which exhibits increased piezo response. [1] J.Pilz, A. Perrotta, G. Leising, A. M. Coclite, ZnO thin films grown by plasma-enhanced atomic layer deposition: material properties within and outside the “ALD window”, submitted. [2] M. Laurenti, S. Stassi, M. Lorenzoni, M. Fontana, G. Canavese, V. Cauda, C.F. Pirri, Evaluation of the piezoelectric properties and voltage generation of flexible zinc oxide thin films, Nanotechnology. 26 (2015) 215704. doi:10.1088/0957-4484/26/21/215704.