Superior Piezoelectric Properties Research Articles

Phase transition and piezoelectric properties of lead-free (Bi1/2Na1/2)TiO3–BaTiO3 ceramics

(1−x)(Bi0.5Na0.5)TiO3–xBaTiO3 ceramics (x=0.03, 0.06, 0.08, 0.12, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, and 0.90) were fabricated by a conventional solid-state reaction and their phase transitions and piezoelectric properties were investigated using XRD analyses, Curie temperature, the frequency dependance of dielectric constant, and P–E curves. A complete solid solution with a perovskite structure was formed in the whole composition range of BNT–BT and more than two phase transitions arising from a compositional change were found. With increasing BaTiO3 content, the sequence of phase transitions from a rhombohedral structure to unknown tetragonal structures and finally a tetragonal structure with the space group P4mm has been established. While the rhombohedral–tetragonal phase transition led to superior piezoelectric properties in BNT–BT ceramics, other phase transitions between tetragonal structures had a little effect on piezoelectric properties. The d33, εr, kp, kt, and Qm and values lied in ranges of 40–130pC/N, 400–900, 10–30%, 15–30%, and 50–250, respectively.

Computational prediction and characterization of single-layer CrS2

Using first-principles calculations, we predict a previously unreported bulk CrS2 phase that is stable against competing phases and a low energy dynamically stable single-layer CrS2 phase. We characterize the electronic, optical, and piezoelectric properties of this single-layer material. Like single-layer MoS2, CrS2 has a direct bandgap and valley polarization. The optical bandgap of CrS2 is 1.3 eV, close to the ideal bandgap of 1.4 eV for photovoltaic applications. Applying compressive strain increases the bandgap and optical absorbance, transforming it into a promising photocatalyst for solar water splitting. Finally, we show that single-layer CrS2 possesses superior piezoelectric properties to single-layer MoS2.

Orientation-dependent piezoelectricity and domain characteristics of tetragonal Pb(Zr0.3,Ti0.7)0.98Nb0.02O3 thin films on Nb-doped SrTiO3 substrates

For a better understanding of piezoelectricity in epitaxial film systems, epitaxially grown tetragonal Pb(Zr0.3Ti0.7)0.98Nb0.02O3 (PNZT) thin films with three primary crystallographic orientations were studied with a focus on their piezoelectric behaviors and domain configuration. Using piezoresponse force microscopy, the (001)-oriented epitaxial films were found to show superior piezoelectric properties compared with the (110)- and (111)-oriented films. This can be attributed to the structural characteristics of the tetragonal PNZT phase after applying an electrical field. Island-distributed domain shapes were also mapped for all three orientations.

Characterization and Piezoelectric Properties of Bismuth Sodium Titanate Prepared by the Hydrothermal Synthesis Method

Bismuth sodium titanate (Na1/2Bi1/2)TiO3 powders were prepared by the hydrothermal route with starting chemicals containing Ti (OC4H9)4, Bi (NO3)35H2O as Bi and Ti sources at 180°C for 48 h in a PTFE-lined autoclave. XRD result confirms the formation of a pure pervoskite structure for the synthesized powders. SEM observation shows that the powders consist of spherical particles in the range of 0.2~1.0 μm, exhibiting a mean particle size of 0.5 μm. Compared with (Na1/2Bi1/2)TiO3 ceramics made by the conventional solid state reaction method, the specimen made by the hydrothermal synthesis method has superior piezoelectric properties with its piezoelectric constant d33 attaining a relatively high value of 78 pC/N.

Crystal Growth and Characterization of (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub>-BaTiO<sub>3</sub> Single Crystals Obtained by the Top-Seeded Solution Growth Method under High-Pressure Oxygen Atmosphere

A single crystal of ferroelectric 0.88(Bi,Na)TiO30.12BaTiO3 (BNTBT) solid solution with tetragonal P4mm structure was grown by the top-seeded solution growth (TSSG) method at a high oxygen pressure (PO2) of 0.9 MPa. The crystals grown by the high-PO2 TSSG method exhibited a large remanent polarization (Pr) of 54 μC/cm2, which leads to a spontaneous polarization of 54 μC/cm2. The large Pr compared with that of crystals grown at PO2 = 0.1 MPa is suggested to originate from a low oxygen vacancy concentration for the crystals grown at a higher PO2. The high-PO2 TSSG method was demonstrated to be effective for obtaining BNTBT crystals with superior polarization and piezoelectric properties.

A novel piezoelectric composite with spiral structure

A novel 0.25PZN–0.75PLZT ceramic/epoxy resin composite consisting of a spiral ceramic skeleton was fabricated by a roll forming–curling method and the effect of the volume fraction of ceramics was studied. These, composites with spiral structure exhibited unique characteristics, such as superior piezoelectric properties and hydrostatic pressure sensitivity. The optimal properties were obtained when the volume fraction of ceramics was 40%: Kt=61.3%, εr=988 and FOM=37.5×10−12m2/N. The results made the ceramic/epoxy resin composite a candidate for sensor applications.

Domain structures and dielectric properties resulting from tweed precursors of relaxor ferroelectric solid-solution single-crystal 24Pb(In1/2Nb1/2)O3-46Pb (Mg1/3Nb2/3)O3-30PbTio3

The domain structures of poled and depoled lead-based relaxor ferroelectric solid-solution single-crystal 24Pb(In(1/2)Nb(1/2))O(3)-46Pb (Mg(1/3)Nb(2/3))O(3)-30PbTio(3) are studied by polarized light microscopy, piezoresponse force microscopy (PFM), scanning electron microscopy (SEM), and dielectric spectroscopy. The domain structures in the nonergodic relaxor state are found by PFM to consist of tweed structures resulting from random fields from the competition between ferroelectric and antiferroelectric distortion, and planar defects found by SEM are treated as dislocations associated with strain accommodation, resulting in superior piezoelectric properties. This domain structure is found to be connected with hierarchical domain structures.

TEM MICROSTRUCTURE ANALYSIS FOR COMPRESSIVELY STRESSED Pb(Zr,Ti)O3 THIN FILMS BY CSD-DERIVED LaNiO3 BOTTOM ELECTRODES

Pb(Zr,Ti)O3 (PZT) possesses superior ferroelectric and piezoelectric properties arisen near a morphotropic phase boundary (MPB) composition, PbZr0.53Ti0.47O3 . We have prepared a PZT (MPB composition) thin film and perovskite-type LaNiO3 (LNO) electrodes on Si substrate by chemical solution deposition (CSD) method. The CSD-derived LNO bottom electrode applied compressive stress to the PZT film and enhanced the ferroelectric properties of the PZT film. TEM and SAED revealed that stress distribution and microstructures of the PZT/LNO/ Si films effectively influenced the ferroelectric properties.

High piezoelectricity 0–3 cement-based piezoelectric composites

0–3 cement-based piezoelectric composites were prepared with Portland cement as matrix, lead zirconate titanate (abbreviation PZT) as functional phase and powder with high dielectric constant and high specific surface area as enhanced phase. The composites were fabricated with compacted method and the compressive strength was 96MPa. Results indicated that, with 1.5kV/mm polarization voltage and steam curing, the 24h piezoelectric strain constant d33 was 32.4pC/N when the contents of PZT and enhanced phase were 60vol.% and 20wt.%, respectively; d33 exceeded 70pC/N after curing at room temperature and dry atmosphere for 38days; gradually, it reached a constant value 99.0pC/N after 90days. This exhibited superior piezoelectric properties.

Preparation of Pb(Mg1/3Nb2/3)O3-PbTiO3ceramics by reaction-sintering method and their electrical properties

Pure phase perovskite relaxor-based (1 – x )Pb(Mg 1/3 Nb 2/3 )O 3 – x PbTiO 3 (PMN–PT, x = 0.2–0.4) ferroelectric ceramics were prepared by the reaction-sintering method sintered at 1240–1250 °C. The synthesized ceramics exhibit rather homogeneous microstructure morphology and relatively high density. The content of PbTiO 3 (PT) exerts successive influences on sintering capability, phase structure and electrical properties of the PMN-PT ceramics. With the increase of the PT content, the crystal structure of the PMN–PT ceramics changes gradually from the rhombohedral phase, across the coexistence of rhombohedral phase and tetragonal phase, and to the tetragonal phase, accompanied by the change of the dielectric response character from typical relaxor ferroelectrics to normal ferroelectrics. The morphotropic phase boundary (MPB) of the PMN–PT system is determined locating at x = 0.3–0.34 based on the structure analysis and the electrical properties measurements, in which the PMN–PT ceramics with the MPB composition exhibit enhanced microstructure and excellent electrical properties, especially superior piezoelectric properties.

Improved Electrical and Mechanical Properties of Niti/TiO<i><sub>x</sub></i>/PZT/TiO<i><sub>x</sub></i> Thin Film Heterostructures

Nickel-titanium (NiTi) alloys are high-performance shape memory alloy actuator materials [1]. These alloys are metals possessing a memory, which can be triggered thermally or mechanically. Thin film of nickel-titanium shape memory alloy (SMA) is an excellent candidate for micro electric mechanical systems (MEMS). On the other hand, PZT is well known for its superior ferroelectric, dielectric and piezoelectric properties [2]. Integrating a ferroelectric (PZT) with ferroelastic (NiTi) material is technically interesting as the resulting heterostructure may then produce the properties associated with both of the materials and enhances the performance of MEMS based devices [3]. An important issue in the synthesis of NiTi/PZT hybrid heterostructure is the formation of appropriate crystalline phases of each material. The interdiffusions present at the interface of NiTi and PZT layer makes it difficult to obtain the optimal properties of both the components suitably at lower thickness values. With the miniaturization of active thin film devices, particularly for MEMS applications, it is desirable to obtain the best properties at lower thickness values. Therefore, in the present study, we have tried to lower the thickness of top NiTi films with the help of thin TiOx buffer layer between PZT and NiTi films. As expected, the excellent structural, electrical and mechanical properties of the NiTi/PZT heterostructure were achieved at lower thickness values.

Growth and Piezoelectric Properties of Melilite ABC3O7 Crystals

Single ABC3O7 crystals with the melilite structure, including SrLaGa3O7, SrGdGa3O7, and BaLaGa3O7, have been successfully grown by the Czochralski method. A complete set of room temperature elastic, dielectric, and piezoelectric constants was determined using resonance techniques and impedance analysis. Our results indicate that the crystals exhibit superior piezoelectric and elastic properties. The electrical resistivity was found to be on the order of 6 × 1013 ohm·cm at room temperature. The dielectric permittivity e11, piezoelectric constant d14, and electromechanical coupling coefficient k′12 were found to be on the order of 15–17, 12–15 pC/N, and 16–19%, respectively. For an ABC3O7 group member such as SrLaGa3O7, the melting temperature was measured to be 1588 °C, below which the crystal maintains good thermal stability. Consequently, the piezoelectric properties were studied as a function of temperature over the range of −50 to 120 °C. The frequency vs temperature coefficient was determined to be −1...

Stress-controlled Pb(Zr0.52Ti0.48)O3 thick films by thermal expansion mismatch between substrate and Pb(Zr0.52Ti0.48)O3 film

Polycrystalline Pb(Zr0.52Ti0.48)O3 (PZT) thick films (thickness ∼10 μm) were successfully fabricated by using a novel aerosol deposition technique on Si wafer, sapphire, and single crystal yitria stabilized zirconia (YSZ) wafer substrates with Pt electrodes and their dielectric, ferroelectric, and piezoelectric properties, and in-plane stresses were investigated. The films with different stress conditions were simply controlled by the coefficient of thermal expansion (CTE) misfit of PZT films and substrates. The results showed that the films bearing in-plane compressive stress deposited on the YSZ and sapphire substrates have superior dielectric, ferroelectric (∼90%), and piezoelectric (>200%) properties over that of the Si wafer. Among these three substrates, YSZ shows superior properties of the PZT films. However, films on Si wafer with tensile stress present lower properties. We believed that in-plane compressive stresses within the films are benefited, the formation of c-domain parallel to the thickness direction resulting in the higher piezoelectric properties. These results suggest that the properties of polycrystalline PZT thick films can be adjusted by simply choosing the substrates with different CTEs.

Electromechanical properties and anisotropy of single- and multi-domain 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 single crystals

Complete sets of elastic, piezoelectric, and dielectric constants of 0.72Pb(Mg(1∕3)Nb(2∕3))O(3)-0.28PbTiO(3) single crystal poled along [111](c) (single domain) as well as non-polar axes [001](c) and [011](c) (multidomain) have been measured under natural conditions. These data allowed us to evaluate accurately the extrinsic contributions to the superior piezoelectric properties. Very large extrinsic contributions to the unusual anisotropies in multidomain crystals are confirmed. We found that the instability of domain structures is the origin of the low mechanical quality factor Q for the multidomain relaxor-based ferroelectric single crystals. Our results can provide useful guidance in future design of domain engineered materials.

Ta 치환에 따른 비납계 (Na0.53K0.47)(Nb1-xTax)O3세라믹의 압전 및 유전 특성

Pb(Zr,Ti)O 3 (PZT) based ceramics with superior piezoelectric properties have been extensively used in various domestic and industrial appliances. However, PZT ceramics causing environmental contamination and health problems need to be eventually replaced by any of Pb-free materials. (Na 0.53 K 0.47 )(Nb 1?x Ta x )O 3 (NKNT), one of Pb-free piezoelectric ceramics, has long been known but its properties are not fully understood and developed. In this study, dielectric and piezoelectric properties of Pb-free NKNT ceramics were studied with Ta substitution for B-site at x=0~0.6. It was found that polymorphic phase transition (PPT) between orthorhombic and tetragonal phases was notably influenced by Ta substitution. The highest piezoelectric coefficient (d 33 ) of 284 pC/N was occurred at x = 0.45.

Effect of cement matrix and composite thickness on properties of 2-2 type cement-based piezoelectric composites

In this study, 2-2 type cement-based piezoelectric composites were fabricated by dice-and-fill technique. The effects of cement matrix and composite thickness on electrical and acoustic properties of the composite were analyzed. The results show that all the 2-2 type cement-based piezoelectric composites using different kinds of cement as matrix have superior piezoelectric and electromechanical properties. Cement matrix has little influence on the acoustic impedance of the composites, which fluctuates between 13.68 and 15.84 M rayl. With decreasing composite thickness, the piezoelectric strain factor d33, the dielectric factor ερ, and dielectric loss tan δ of the composites decrease, while the piezoelectric voltage factor g33, the thickness electromechanical coupling coefficient Kt, and the mechanical quality factor Qm increase. The acoustic impedance of the composites fluctuates around 14 M rayl with increasing the composite thickness, which is obviously less than that of the pure piezoelectric ceramic. Therefore, 2-2 type cement-based piezoelectric sensors suitable for civil engineering structure can be easily tailored by adjusting the composite thickness.

Effect of electrical and mechanical poling history on domain orientation and piezoelectric properties of soft and hard PZT ceramics

The superior piezoelectric properties of all polycrystalline ferroelectrics are based on the extent of non-180° domain wall motion under electrical and mechanical poling loads. To distinguish between 180° and non-180° domain wall motion in a soft-doped and a hard-doped lead zirconate titanate (PZT) ceramic, domain texture measurements were performed using x-ray and neutron diffraction after different loading procedures. Comparing the results to measurements of the remanent strain and piezoelectric coefficient allowed the differentiation between different microstructural contributions to the macroscopic parameters. Both types of ceramic showed similar behavior under electric field, but the hard-doped material was more susceptible to mechanical load. A considerable fraction of the piezoelectric coefficient originated from poling by the preferred orientation of 180° domains.

Piezoelectric actuated MEMS for use in microwave switching and filtering applications

AbstractThe paper reviews the developments made for designing and fabricating a piezoelectric driven actuator and its integration into coplanar wave guide (CPW) microwave structures. In the first part of this work the electromechanical properties of different lead–zirconate–titanate (PZT) thin films are investigated. A modified precursor route for chemical solution deposition (CSD) is introduced to minimize the thermal budget of the PZT by maintaining its superior piezoelectric properties. The second part deals with the fabrication of a piezoelectric driven actuator for use in RF switching applications. Advantages of bulk and surface micromachined devices are compared and a suitable actuator design is proposed. Based on these results, a piezoelectrically actuated shunt switch for use in CPW devices is developed and optimized, and the concept is confirmed by measurements. Finally, novel reconfigurable CPW band‐pass filters are presented, which demonstrate the usefulness of the developed shunt switches in microwave applications. magnified image Microwave switch Distribution of surface current density (background), image of copper contact (top) and micro switch schematic (bottom).

Effect of electrical and mechanical poling history on domain orientation and piezoelectric properties of soft and hard PZT ceramics

The superior piezoelectric properties of all polycrystalline ferroelectrics are based on the extent of non-180° domain wall motion under electrical and mechanical poling loads. To distinguish between 180° and non-180° domain wall motion in a soft-doped and a hard-doped lead zirconate titanate (PZT) ceramic, domain texture measurements were performed using x-ray and neutron diffraction after different loading procedures. Comparing the results to measurements of the remanent strain and piezoelectric coefficient allowed the differentiation between different microstructural contributions to the macroscopic parameters. Both types of ceramic showed similar behavior under electric field, but the hard-doped material was more susceptible to mechanical load. A considerable fraction of the piezoelectric coefficient originated from poling by the preferred orientation of 180° domains.

Vibration characteristics of micromachined piezoelectric diaphragms with a standing beam subjected to airflow

This paper presents a novel configuration consisting of a micromachined diaphragm and a standing beam for sensing airflow. A piezoelectric Pb(Zr,Ti)O 3 (PZT) film is deposited by spin-coating on the diaphragm to actuate and sense the vibration at its resonant frequency. A standing and extruded beam built on the diaphragm responds to the aerodynamic drag force, inducing mechanical strain, increasing the stiffness of the structure, and subsequently shifting the resonant frequency. The finite element method is used to demonstrate the first four mode shapes and predict the frequency shift of the proposed structure when subjected to airflow. The prototype microstructure is fabricated by combining the PZT sol–gel process and silicon micromachining. In particular, a two-step deep silicon etching process is developed to form the diaphragm structure with a standing silicon beam on it. Flip-chip bonding by solder balls is adopted to electrically connect the electrode pads to the circuit board. The characterization of the flip-chip bonded sensor chip exhibits superior piezoelectric and electrical properties. The wind tunnel test shows a 25 Hz resonant frequency shift for a wind speed of 10 m/s.