Effect Of PZT Research Articles

Can nano PZT-OPC composites be used as a smart γ-ray attenuator?

Nano PbZr0.52Ti0.48O3-ordinary Portland cement (PZT-OPC) composites were fabricated by a ball milling technique with different PZT content (30, 50, 70, and 90% by weight). The prepared samples were annealed at 600 °C. The structure, morphology, thermal and electrical properties of these annealed samples were investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The effects of PZT on dielectric and piezoelectric properties of the composites were investigated. γ-ray spectroscopy was used to measure the γ-ray attenuation coefficients of the annealed nanocomposite samples using the 661.7 keV γ-ray of 137Cs source. The microstructure changes of the prepared composite samples were investigated using the positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques. The XRD patterns show both PZT and cement peaks. Also, these patterns indicate the presence of PZT retards the hydration process of the Portland cement. The FTIR spectra show the major absorption bands for both PZT and cement. SEM images show the binding between calcium silicate hydrate and PZT which may be a better factor for improving the mechanical properties of the cement. TGA curves show a higher thermal weight loss for 50% PZT-OPC composite sample. The PZT-OPC composite sample with 50% PZT content shows the highest γ-ray mass attenuation coefficient compared with the other composite samples. The positron annihilation spectroscopy (PAS) results show that the size of large voids and the concentration of small defects increase by increasing PZT content. Also, these results reveal that the core electrons slightly reduced by increasing PZT content. The results indicate that the dielectric constant and piezoelectric coefficient values slightly and rapidly increase for composite samples with PZT content <50% and >50%, respectively. Finally, the 50% PZT-OPC composite sample showed novel shielding and acceptable piezoelectric properties to be used as a smart shield.

Preparation and Properties of Epoxy Piezoelectric Vibration Reduction Composites

The epoxy resin (E-51) was used as polymer matrix, conductive carbon black (CB) as conductive filler, and PZT was used to prepare a composite by curing. The effects of PZT and CB content on the properties of PZT/ CB/ EP piezoelectric composite were studied. When the PZT content reaches 40 wt%, the optimized vibration attenuation properties of PZT/CB/EP materials could be achieved with a loss factor of 0.9 from room temperature to 60 °C. With the increase of PZT content, the bending strength of PZT/CB/EP piezoelectric composite vibration reduction material firstly increased from 45 MPa to 65 MPa and then decreased to 38 MPa. At room temperature, the dielectric constant increased from 7 to 50, and the dielectric loss increased from 0.1 to 0.5.

Rietveld analysis, magnetic, transport, and optical properties of (1 − x)BiFeO3–(x)Pb(Zr0.52Ti0.48)O3 ceramics prepared by sol–gel route

Pb(Zr0.52Ti0.48)O3 (PZT)-modified samples of BiFeO3 (BFO) were synthesized by a sol–gel method in composition range 0.0 ≤ x ≤ 0.15 to see the effect of PZT on structural, optical, dielectric, and magnetic properties of BFO ceramics. It is demonstrated that the PZT-modified BFO can expressively improve the dielectric and magnetic properties. Structural analysis was carried out with the Rietveld FullProf program, revealed that changes in lattice parameters and stability of rhombohedral structure with R3c symmetry up to x = 0.15 dilution of PZT. Structural distortion and strain were calculated by the Williamson–Hall approach. Moreover, a significant improvement in magnetization at room temperature was achieved for PZT-modified samples ascribed to the disturbance in the spin cycloid arrangement of Fe ions. PZT-modified BFO samples are showing better dielectric properties than undoped BFO attributed to suppression of Bi and oxygen vacancies. Our results demonstrate that the significant role of PZT can be seen in conductivity vs. 1000/T plots and the appearance of dissimilar kinds of conduction mechanisms in the different linear regions. Optical studies were performed in the 1 eV–4.5 eV spectral range and the calculated optical bandgap was found to decrease with PZT doping. The results of infrared spectroscopy show shifts of IR phonon modes in the lower wavenumber side.

Electric-field-induced phase transition and electrocaloric effect in PZT near morphotropic phase boundary

We study the effect of the direction of the applied field on the phase transformations and electrocaloric (EC) effect in bulk Pb(Zr0.52Ti0.48)O3 (PZT52/48) using a Landau-Ginzburg-Devonshire (LGD) thermodynamic frame. The results show that the phase transitions and EC response are strongly anisotropic. The larger EC effect can be obtained for field applied along [111] direction compared to the [001]and [011] directions in the considered temperature range. A negative EC effect has been found at the triclinic (TR)-monoclinic (MB) transition region for fields applied along the [011] direction, whereas only a normal EC effect exists for the other two field directions ([001] and [111]).

Dynamic/static displacement sensor based on magnetoelectric composites

This study presents a dynamic/static displacement sensor based on both end fixed Terfenol-D/PZT (lead zirconate titanate) magnetoelectric composites. Owing to the fixed boundary condition, the magnetostriction of Terfenol-D under the magnetic field is limited and the stress acts on PZT through mechanical coupling, and finally, an induced voltage is generated due to the piezoelectric effect in PZT. The magnetic field applied on the magnetoelectric composites varies with the displacement of the permanent magnet which represents the displacement to be measured. In that case, the determination of displacement can be transformed into determining the variation of the magnetic field. The experimental results manifest that the frequency of magnetoelectric voltage is the same as the frequency of displacement. The dynamic displacement sensitivity of this sensor increases with the increase in the input frequency in the low frequency range and the decrease in the length of the air gap. The sensitivity is 6.549 mV/μm with a 0.75 mm air gap for dynamic displacement at 10 Hz and 0.84 μV/μm with a 2.5 mm air gap and an external magnetic field at 1 kHz for static displacement. It can be concluded that the displacement measuring mechanism based on the magnetoelectric effect is a promising robust and accurate method.

Enhanced Self‐Powered UV Photoresponse of Ferroelectric PZT Materials by Pyroelectric Effect

AbstractSemiconductor materials based UV photodetectors can be operated via photovoltaic effect by converting UV light into electric signals. Recent studies have been focused on how to fabricate excellent semiconductor materials based photodetectors through construction of heterojunctions, which may not be suitable for practical large‐scale devices due to the high cost and sophisticated fabrication process. Here, by utilizing naturally existing temperature change of UV illumination and the pyroelectric effect of ferroelectric materials, a novel self‐powered UV photodetector based on Pb(Zr,Ti)O3 (PZT) material is presented through a simple fabricating process, which can be well utilized to detect 365 nm UV light by using light‐induced temperature variation. Under a temperature change rate of 2.40 K s−1, the voltage response and the corresponding responsivity can be enhanced by larger than 6600% as compared with that of individual UV light illumination. This study provides a feasible solution to realize self‐powered UV light detection by utilizing light‐induced pyroelectric effect in PZT.

Design and fabrication of high electron mobility transistor devices with gallium nitride-based

Gallium nitride (GaN) and its family of materials (including GaN, InN, AlN and their alloys) are known as the third generation of semiconductor, which has important applications in optoelectronics and microelectronics. In the structure of GaN-based high electron mobility transistor (HEMT) device, there is a relatively large conduction band offset in the AlGaN/GaN heterojunction structure, and it can produce a strong spontaneous and piezoelectric polarization effect in the vicinity of the heterojunction, which can also accumulate high concentrations of two-dimensional electron gas (2DEG) under the condition of no need of intentionally doping at the interface. The surface of Heterojunction AlGaN/GaN interface will form a 2DEG channel, and the 2DEG in potential well is controlled by the gate voltage, also the 2DEG layer is very close to the surface, which is sensitive to the state of the surface. When the surface state changes, it can cause a change in the 2DEG density, thus the concentration of 2DEG can be adjusted by changing the surface states, thereby changing the current between the source and drain. GaN-based HEMT serves as a gate control device, which has a high concentration of 2DEG and is sensitive to the surface state at the AlGaN/GaN heterojunction. According to the basic structure and advantages of the GaN-based HEMT device, the ferroelectric thin film PZT is deposited on the metal gate serving as a light sensitive layer. When the light is incident on the gate, the photo-sensing layer PZT generates the photovoltaic effect, which causes the surface charge of the photosensitive layer to change, and also causes the 2DEG to change, so the input current changes. In this paper, firstly, a new “M/F/M/S” structure is proposed by introducing a photosensitive material PZT on a GaN-based HEMT gate electrode and combining the PZT of a ferroelectric thin film with photovoltaic effect. Secondly, the HEMT device is fabricated on the AlGaN/GaN epitaxial wafer of sapphire substrate, and the photosensitive unit PZT is prepared on the gate, and thus the HEMT device with photosensitive is realized. Finally, the carrier concentration in the channel is regulated by the photovoltaic effect of PZT and 365 nm UV and visible light are detected through changing the source-drain current. The comparative tests under the conditions with and without a photosensitive gate HEMT device show that when the voltage Vgs is smaller, the saturation drain-source current Ids measured under the irradiation of visible light in the former condition is not reduced compared with that in the latter condition, and the increment of Ids measured in the former condition is 5.2 mA larger than in the latter condition. Therefore it can be seen that the PZT can act on the gate GaN-based HEMT device under the irradiation of visible and ultraviolet light and adjust the channel current.

Cyclotriphosphazene fibre reinforced poly(benzoxazine-co-ε-caprolactam) nanocomposites for flame retardant applications

Cyclophosphazene nanotube (PZT) incorporated poly(benzoxazine-co-ɛ-caprolactam) (P(BZ-co-CPL)) nanocomposites were developed for improving flame retardant properties. The effects of PZT on the flammability properties of P(BZ-co-CPL) matrix were evaluated through UL-94 flammability test and limiting oxygen index (LOI). The UL-94 results of P(BZ-co-CPL)/PZT hybrid nanocomposites showed V-1 rating, whereas neat P(BZ-co-CPL) showed burning rating. The LOI values are increased from 25.4 to 31.4 for 1.5 wt% PZT incorporated P(BZ-co-CPL) nanocomposite systems. SEM was used to study the char morphology of P(BZ-co-CPL)/PZT after being exposed to UL-94 flammability test. Data from thermal studies indicate that the PZT incorporated P(BZ-co-CPL) systems possess better Tg and thermal degradation behavior when compared to the neat P(BZ-co-CPL). The values of dielectric constant are decreased with increasing temperature. From the values, it is ascertained that the P(BZ-co-CPL)/PZT systems exhibit stable dielectric behavior with regard to variation in temperature. The TEM images ascertain the uniform dispersion of PZT in the P(BZ-co-CPL) matrix.

Large Longitudinal Magnetoelectric Effect in Clamping Structure of TbDyFe Flake, Pb(Zr,Ti)O&lt;sub&gt;3&lt;/sub&gt; Ring

Longitudinal magnetoelectric (ME) effect has been studied in a clamping structure of a magnetostrictive TbDyFe (Terfenol-D), a piezoelectric Pb(Zr,Ti)O3(PZT) ceramic ring. The ME coupling originates from the magnetic-mechanical-electric transform of the magnetostrictive effect in Terfenol-D and the piezoelectric effect in PZT by endpoint bonding, without adhesive layer. In such a clamping structure, Large induced voltage was measured without amplifier, Large longitudinal ME coefficient of 0.12V cm-1Oe-1was obtained at f =1 kHz, which is about 3 times larger than transverse ME coefficient of conventional layered Terfenol-D/PZT composites under the same measuring conditions. The ME coefficient reaches a maximum value at the dc bias magnetic field (Hdc) =280 Oe, which is lower than Hdc =350 Oe in conventional layered composites. The results show that large ME coupling can be achieved without adhesive layer, and longitudinal ME effect can be better than transverse ME effect.

PZT / MWNTs / EP Piezoelectric Damping Composites Conductivity and Dynamic Mechanical Analysis

According to piezoelectricity and electrical conductivity theory, the ternary system piezoelectric damping composites containing piezoelectric ceramic powder (PZT) / multi-walled carbon nanotubes (MWNTs) / epoxy resin (EP) were developed. Through the conductive and mechanical performance test of composites, the paper showed the piezoelectric damping energy dissipation mechanism of polymer composites. Results indicated that: the loss factor of materials would increase with the increasing of PZT content. When the content of PZT exceeded a certain value, tanδ would increase dramatically. When the content of MWNTs is 2%, tanδ reached a high value. This meant composites played the role of shock absorbing by conducting electricity from piezoelectric effect of PZT to external circuit.

Pyroelectric and Electrocaloric Properties of PZT- and BT-Based Ceramics

Thermal energy harvesting using non-linear pyroelectric effects in PZT with different Tc, PLZT, Ba(Zr0.2Ti0.8)O3 and (Ba0.8Sr0.2)TiO3 ceramics, and PMN-PT crystals were investigated. PLZT ceramics with Tc of 140°C exhibited large energy generation of 54.8 J/L/cycle with temperature variations from 30°C to 200°C and field variations from 0 to 20 kV/cm. Ba(Zr0.2Ti0.8)O3 ceramics with Tc of 40°C exhibited energy generation of 58.6 J/L/cycle with temperature variations from 30°C to 125°C and field variations from 0 to 20 kV/cm. The electrocaloric temperature changes ΔT due to applied ΔE were measured. PLZT(7/65/35) ceramics exhibited ΔT of 0.2 K at room temperature under a bipolar switching field of 20 kV/cm.

Large magnetoelectric effect in mechanically mediated structure of TbFe2, Pb(Zr,Ti)O3, and nonmagnetic flakes

Magnetoelectric (ME) effect has been studied in a structure of a magnetostrictive TbFe2 alloy, two piezoelectric Pb(Zr,Ti)O3 (PZT) ceramics, and two nonmagnetic flakes. The ME coupling originates from the magnetic-mechanical-electric transform of the magnetostrictive effect in TbFe2 and the piezoelectric effect in PZT by end bonding, instead of interface bonding. Large ME coefficients of 10.5 and 9.9 V cm−1 Oe−1 were obtained at the first planar acoustic and third bending resonance frequencies, which are larger than that of conventional layered TbFe2/PZT composites. The results show that the large ME coupling can be achieved without interface coupling.

Modulation Effect of Lead Zirconate Titanate for Zinc Oxide Channel Resistance in Ferroelectric Field Effect Transistor

In this work, bottom-gate-type ferroelectric field effect transistors (FeFET) are fabricated. Sol-gel prepared aluminum doped zinc oxide (ZnO) and Lead Zirconate Titanate (PZT) are applied as channel and gate dielectric respectively. Uniform and dense ZnO is fabricated and good conductivity is obtained. Polarization of PZT is found to decrease after Al doped ZnO is prepared on it. Obvious modulation effects of PZT on the channel are found. Capacitance of the channel and gate dielectric stacked structure is tested. And channel resistance is found to change with the direction of remnant polarization in PZT. Mechanisms of the modulation effects are investigated.

Zr-shift at the origin of the exceptional piezoelectric properties ofPbZr0.52Ti0.48O3

In spite of intensive experimental and theoretical studies, no model at the atomic scale has been proposed to explain the large piezoelectric effect in ${\text{PbZr}}_{0.52}{\text{Ti}}_{0.48}{\text{O}}_{3}$ (PZT) compared to the low piezoelectric response in the simple end-member lead titanate ${\text{PbTiO}}_{3}$. X-ray absorption spectroscopy (XAS) appears as the technique of choice not only to clarify the role of Zr, but also to quantify the Zr displacement through the Ferroelectric-Paraelectric $(F\text{\ensuremath{-}}P)$ transition. We clearly show evidence of the polar character of the Zr-atoms in PZT with a Zr-shift which will produce a small polarization. Such an atomic configuration for one type of atoms leads to relatively easy switching, i.e., relatively low electric field to align the Zr-polar atoms, which will create a favorable energetic situation for the cooperative switching of the strongly polar Ti-O dipole and would therefore account for the large piezoelectric effect in PZT.

Piezo and dielectric properties of PHB–PZT composite

AbstractFlexible piezoelectric composite films made of poly(3‐hydroxybutyrate) (PHB) in powder form and lead zirconate titanate (PZT) ceramic powder were obtained by mixing both powders and pressing at 180°C. The effect of PZT on PHB crystallization was investigated using differential scanning calorimetry (DSC). The relative dielectric constant and dielectric loss factor were analyzed by dielectric spectroscopy and the α‐relaxation of amorphous phase of PHB was observed. After suitable polarization, the composite film displayed piezoelectric activity indicating the possibility of using that material as a sensor. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Microwave Heating Characteristic of Multilayered Structures in a Slngle-Mode Cavity

In this study, nonconductor (PZT), semiconductor (Si) and conductor (Pt/Ti) whose permittivity andpermeability are distinctive are prepared into various multilayered structures for exploring the heating behavior of microwave (2.45Hz) in a single-mode cavity. The heating efficiency of the semiconductor and conductor was much higher at the maximum of H field than that of E field. At the H maximum, the Si layer was useful to generate high temperature and the Pt/Ti accelerated the heating rate. At the E maximum, the Si layer was also in favor of obtaining high temperature, but the Pt/Ti layer partially suppressed the microwave heating. The effect of PZT on the heating processing was not obviously observed at the maximum of both H and E fields.

Dielectric and piezoelectric properties of PZT–cement composites

Lead zirconate titanate (PZT) and cement composites of 0–3 connectivity were produced using PZT of 30–90% by volume. The effects of PZT on dielectric and piezoelectric properties of the composites were then investigated. The dielectric constant (εr) of the composites was found to increase with increasing PZT content. The εr value of 90% PZT composite obtained was 291 which is noticeably higher than that of PC sample (εr = 79). The dielectric loss (tan δ) was found to decrease with PZT content and the tan δ value was lowest at 0.63 for 90% PZT composite. Piezoelectric coefficient (d33) was found to increase with PZT content as expected. However, the effects were most significant at two stages, first at 30% PZT volume content (14 pC/N) and then at very high PZT content (90% by volume) where d33 value reached 43 pC/N.

Effect of Ultra Thin Bottom Electrode on the Ferroelectric Properties of Pb(Zr,Ti)O3 Films Grown by Metal-Organic Chemical Vapor Deposition

ABSTRACT In order to fabricate highly integrated ferroelectric random access memory (FeRAM), three-dimensional (3D) trench structure should be employed. A capacitor stack, two electrodes and ferroelectric layer, fills the shallow trench. Thus the thickness of each layer is critical to realize 3D structure. It has been well known that that the degradation of ferroelectric layer when it is scaled down is very serious problem. In order to minimize such scaling effect of PZT, the thickness of electrode must be as thin as possible. In this study, we investigated the properties of Pb(Zr,Ti)O3 (PZT) deposited by metal organic chemical vapor deposition (MOCVD) on very thin Ir bottom electrode (40 nm). We found that the Ti film used as glue layer has serious effect on the leakage property of PZT thin film. The leakage problem was reduced by lowering the post annealing temperature.

SLD 동조 광원을 이용한 브라그 파장 측정 LPG 센서의 신호처리 시스템

A signal processing system of long period grating sensor that works in the optical wavelength domain is proposed. The system is based on a wavelength-swept semiconductor light source that includes an SLD and a F-P tunable filter. The hysteresis effects of PZT in the F-P filter is compensated by using an etalon filter and an athermal Fiber Bragg Grating. The detected signals from the photodiode are transmitted to a computer using an A/D converter and the result of the process is displayed in the monitor.

Influence of Buffer Layer Insertion and Annealing Mode upon Microstructures and Ferroelectric Characteristics of Sol-Gel-Derived Pb(Zrx, Ti1-x)O3 Thin Films

As a continuation of our previous work, PZT films with the Zr/Ti ratio varied from 40/60 to 70/30 were prepared by a sol-gel method, and the effects of PZT(120/52/48) buffer layer insertion and the annealing mode were investigated. The results indicate that, irrespective of the annealing mode, unbuffered PZT films with a Zr/Ti ratio of 40/60 to 60/40 exhibit (111)-preferred orientation, whereas buffer layer insertion induces growth with (100) orientation. This is in contrast to the case of PZT(70/30) film in which growth with (100) orientation is discernible even when the buffer layer is not inserted. AFM observations reveal that the PZT films with the buffer layer display slightly smoother surface microstructures than the unbuffered films. This is more clearly displayed in the case the film is subjected to RTA. Although the essential features of P-E hysteresis loops of the films are not significantly affected by the annealing mode, conventional furnace annealing generally leads to slightly larger remanent polarization (Pr) than RTA. Pr vs Zr/Ti ratio curves for PZT films with and without the buffer layer invariably give a peak at Zr/Ti=60/40. Fatigue life does not markedly improve even with an appropriate choice of the process factors in the film synthesis, which influence the microstructures and ferroelectric properties.