Figure 4-7. Open-circuit output voltage increases linearly with induced stress in the PZT film. ________ 96 Figure 4-8. (A) Rectifying circuit used for determination of power delivered to different load resistors. (B) The measured output power delivered to different load resistances ranging from 10 kΩ to 50 MΩ with a peak stress of approximately 145 MPa. The output power is gradually building up with resistance increase. Up to 0.1 μW was generated when the energy harvester was connected to a 10 MΩ load. _____________ 97 Figure 5-1. The light intensity spectrum of the Novacentrix bulb generated at 600 V level pulse setting (black), with a peak emission in the violet regime. The dried PZT film light absorbance spectral curve (blue) has significant overlap with bulb emission, with the greatest absorbance in the ultraviolet (< 400 nm). However, the ITO glass slide has the greatest absorbance in the ultraviolet region. This could affect the effective energy transferred to the PZT film. ____________________________________________ 102 Figure 5-2. The setup for photonic sintering the PZT film with poling. The PZT film was sandwiched between top and bottom electrodes. Photonic flashes were transferred through the transparent top ITO glass electrode to create a rapid temperature transient in the film. Simultaneously, the electric field is continuously applied to the sample to reorient the electric dipoles in the PZT film. _________________ 103 Figure 5-3. The COMSOL simulation to estimate the temperature change in the PZT film and substrate during the photonic sintering. The top surface of the PZT film reached ~ 950 °C, which is high enough to sinter the PZT powders. However, the film-substrate interface increased up to ~ 720 °C, which is lower than the required sintering temperature (~ 800 °C). _________________________________________ 106 Figure 5-4. Before and after sintering with electric field poling. An approximately 6 μm thick PZT film was achieved prior to sintering. After the photonic sintering, a well sintered PZT thick film was obtained. Notice the particles size was increased due to the thermal expansion and powders merging. _________ 107 Figure 6-1. SimPulse modeling result of the temperature change for the simulation of 6 μm PZT film on the 20 μm Kapton substrate under the sintering condition: voltage = 400 V; pulse duration = 650 μs;
environmental/health issue as the waste contains high levels of lead). Other less wasteful high temperature processing routes based on sintering of ce- ramic particles—such as screen printing and electrophoresis—are of limited applicability due to the requirement for refractory substrates  which are difficult to integrate into MEMS processing routes . Even at moderate temperatures, where silicon substrates can be used, the increased diffusion kinetics mean that very thick and robust diffusion barrier/electrode systems are required [6, 7]. This is of particular importance in systems containing Pb (i.e. the majority of piezoelectric applications) as the formation of undesir- able liquid phase lead silicates can occur at temperatures greater than 700 ◦ C .
The work has a series of implications. The fact that, processing of PZT on copper has been demonstrated, implies that a copper base metal could be incorporated in a wide variety of PZT materials and applications. For example, the approach could be used for capacitors, embedded varactors, and piezoelectric-based sensors embedded directly into printed circuit boards. Furthermore, it could be adapted to the potentially large market volume PMN-PT (lead magnesium niobate – lead titanate) relaxor solid solutions, which are utilized for multilayer actuators and particular dielectric applications. Additionally, the results suggest that a route can be engineered to achieve PZT/Cu multilayer actuator stacks as long as thermal expansion mismatch issues can be addressed. An important advantage of copper as an electrode in high frequency applications is the reduction of series resistance (due to the low copper resistivity and the thickness of the foil).
PZT thick films are favorable for making high performancepiezoelectric micro devices such as high resolution piezoelectric ultrasonic transducers and micro wave front corrector. However, the preparation of PZT thick films still have challenges. By mechanical grinding PZT bulk materials, the thickness of 100μm is almost reaching its processing limit and the yield is only 5%. The following process of bonding and patterning is also very difficult. The thin film preparing method such as sputtering and chemical vapor deposition has the limitation of low deposition rate and easy cracking, the thickness of the films produced is under 5μm. . The thick films (10~100μm) can be fabricated using screen printing method by printing the PZT slurry paste on the screen template . This method is based on sintering of oxide ceramic particles, requiring temperatures normally above 850℃, which are likely to damage substrates and electrodes.
126nm photons. This radiation correspond to a 9.8eV energy transition between the and states of the excimers to their stable ground states. It is clear that the higher the transition, the more it is likely that some impurities present energy levels located between the transient states. As such, the excimer generation of 126nm from a discharge in argon is a lot more exposed to purity problems than that of lower transition excimers (e.g., xenon at 7.2eV). Also, it has been shown that in the case of xenon most of the purity problems could be overcome by completely sealing the discharge gas in a quartz tube. Here, since the gas is directly in contact with the chamber volume, impurities trapped on the walls of the chamber may be released and alter severely the intensity of the spectrum. For instance, at the early stages of the development of this lamp, an unexplained peak at 300-305nm was measured in the spectrum of the lamp output. This peak was persistent with respect to lower background pressures, as well as higher cylinder purity. Eventually, it occurred that it was caused by the presence of a few tens of centimetres of PTFE piping in the argon feeding line, i.e. between the cylinder and the lamp chamber. As argon is know to be extremely non reactive at room temperature, and also since no degasing of the piping materials is likely to happen at high pressures (few atm), this shows well how dramatically anultra low concentration of impurities can alter the spectrum output of such lamps. Also, unlike for the xenon cylindrical lamp, the development of this device did not consider the possible implementation of water cooling facilities. As a result, not only the photo-emission decreases due to the temperature increase (phonon losses), but also the heat generated by the lamp promotes impurities to degas from the chamber walls and to affect the spectrum output.
could be attributed to the lead loss experienced by the PZT layer when fired in the belt furnace. However, the firing temperature was only slightly above that at which lead migration occurs and therefore unlikely to have a large influence on the stoichiometry of the bulk device. This would indicate that any change in the domain structure of the bulk device would be minimal but could be a factor in the extra reduction observed.
Both transducers have been mounted in the suitable cases and then it will be exposed to artificial and actual rain. Two cantilever configurations have been used for measurement purpose i.e. single edge bound and circle edge bound. PVDF module was set as for cantilever single edge approach. Once the rain drops hit the transducers ’ edge it will generate an electrical potential due to bending stress applied to it. On the other hand, circle bound configuration has been applied to PZT transducer on which the raindrop knockout on the transducer’s surface. Hence, it generates an electrical potential at the electrode terminal of the transducer. Figure-4 illustrated the devoted cantilever configuration for the experiment.
promising route , and magnetic proximity coupling through a deposited Fe overlayer has been shown to lead to an increased Curie temperature T C . Nevertheless, the QAHE was not observed in Mn-doped material, probably also because an increasing interstitial incorporation of Mn is observed with increasing doping concentration . Cr remains the most promising dopant to achieve the QAHE , as it incorporates substitutionally on the Bi site  and leads to long-range ferromagnetic order at ∼8.5 K . Recently, it has been shown that TIs proximity coupled to a ferrimagnetic insulator show an increased T C , suggesting the great potential of
The PZT Series products have been designed to a very high level of performance, with features unavailable in any other product. All of the amplifiers have variable crossovers built in, with added touches such as subsonic filter, bass equalization and a remote Level control module(some models) that allows subwoofer Level control from the drivers seat.
Abstract: Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper.
Si-based light emitter is one of the most important com- ponents for Si-based photonic integration. Although many progresses have been made for silicon-based light emitter in recent years [1-4], it is still a big challenge to overcome the inefficient band-to-band radiative recom- bination of silicon. With large band offset and strong quantum confinement, the self-assembled QDs are promising structure to enhance the optical characteris- tics . In the past two decades, the self-assembled Ge QDs on Si substrates, which are compatible with com- plementary metal-oxide semiconductor processes, have been widely studied for Si-based optoelectronic device applications [6,7]. Unfortunately, the Ge QDs on Si can only provide a good confinement for the holes, which is hard to capture the electrons. Lacking of electrons for radiative recombination in Ge QDs limits its emission efficiency. A lot of efforts had been made to investigate luminescence of Ge QDs/Si(001) multilayer structure [8-10]. However, the radiative recombination in Ge QDs is still weak, even observed at lowtemperature [8,9,11]. How to increase the radiative recombination of
The Curie temperature was determined from the inflection point of M vs. 1/T plot. The Curie temperature, T C for the partially ordered (S=0.3) case was found about 625K (352°C). The result of T C as a function of the ordering parameter, S is shown in Fig. 3. The ordering parameter was estimated according to ref. . It was observed that
The principal factor regulating erythropoiesis is EPO (Krantz, 2000). Our data showed that Epo mRNA expression in the kidney was enhanced from day1 after lowtemperature exposure (Fig.4). In mice treated with EPO, the number of CFU-Es increases in the spleen and bone marrow (Hara and Ogawa, 1977). Therefore, it is suggested that the numbers of erythroid progenitors in the spleen and bone marrow increased in response to elevated circulating EPO level caused by enhanced renal EPO expression. The regulation of erythropoiesis and the red blood cell mass rely on the modulation of Epo gene expression in response to tissue oxygen tension (Fandrey and Bunn, 1993). The transcription factor HIF proteins mediate the hypoxia-induced transcription of oxygen-regulated genes, including Epo (Wang and Semenza, 1995). HIF-1 target genes are oxygen sensitive, partly because HIF-1α is rapidly degraded in normoxia but stable in hypoxia to promote transcriptions of the target genes (Bunn et al., 1998). We found that the expressions of Hif-1a and HIF-1 target genes were enhanced in the kidney at day4 after exposed to lowtemperature (Fig.4B,C). Although we did not determine HIF-1a protein level, our results suggested that elevated expression of HIF-1 target genes after lowtemperature exposure is induced by activation of HIF-1α protein. It is also suggested that enhanced Hif-1a gene expression and stabilization of HIF-1α protein is caused by lower renal oxygen tension. Lower oxygen tension would be caused by the high oxygen consumption necessary to produce heat during lowtemperature exposure. We did not detect enhanced expression of Epo mRNA or of the mRNAs of oxygen- regulated genes in the liver during lowtemperature exposure (data not shown). In rats exposed to low environmental temperature, hepatic blood flow increased, whereas renal blood flow did not change (Adán et al., 1994). It has been reported that the skin is a primary co-ordinator of the systemic hypoxic response and modulates cutaneous blood flow to regulate renal and hepatic EPO synthesis in mice (Boutin et al., 2008). In our model, it is suggested that hypoxia and the enhancement of Epo gene expression in the liver did not occur because of the increase in hepatic blood flow. Although Hif1-a mRNA levels did not increased at day1 after exposure to lowtemperature, renal Epo mRNA levels moderately increased at day1 (Fig.4A,B). Thyroid hormone (TH) plays an important role in the control of thermogenesis. During exposure to low ambient temperature, an increase of serum TH level and subsequent enhancement of heat production were reported previously (Rand et al., 1952; Kassenaar et al., 1956; Kassenaar et al., 1959; Gregerman, 1963; Silva, 2006). Additionally, it has been reported that TH enhances hypoxic-induced Epo expression in vitro Glut1
Piezoelectric Materials have played a pivotal role in the progress of Science and Technology since the First World War, being used historically as naturally occurring transducer for precise measurement or to transform energy from one form to the other while currently being used in the MEMS domain for sensing or energy harvesting. Thus this paper reviews piezoelectric materials and their applications in MEMS as thin films by categorizing the known materials in 3 types namely Naturally Occurring Materials, Piezoelectric Ceramics and Piezoelectric Polymers. Piezoelectric constants of the above mentioned materials are also enlisted.
photoactive dyes is presented. The material’s mechanical properties have been observed to follow the Sato and Furukawa model when increasing the NPs loading. Simulation techniques confirmed the experimental acoustic behaviour of the new 3D-printed sensor, which reproduces the behaviour observed on the locust TM, presenting higher amplitudes of motion at low frequencies on the thick region, and the opposite trend on the thin region, leading to acoustic frequency selection. The piezoelectric response of the 3D- printable material was successfully tested by both direct and converse piezoelectric processes, making it suitable for several applications in a cheaper and more time-efficient process. Further research is required to improve the d 33 coefficient of
Ω-cm respectively, for the PZT thin films annealed at the temperature 800 o C. The thermal conductivity of the bare sample has been estimated as 281.97 watt / mK, whereas for the PZT coated samples, annealed at different temperatures, a steady fall in thermal conductivity has been observed. The studies on the variation of thermal conductivity as with annealing temperature shows a non – linear decrease in thermal conductivity with the increase in annealing temperature. The hardness of the unannealed PZT thin film is determined as 130 VHN and the hardness of the PZT thin films is found to increase drastically with the increase in annealing temperature. The hardness is found to be maximum with the value 890 VHN and minimum with the value 160 VHN, for the PZT thin film annealed at the temperatures 800C and 500C respectively. The 2D and 3D AFM micrographs of the PZT thin film annealed at 800 C illustrates uniform grain growth, smooth and uniform surface pattern. SEM images also show that densification, compaction and crystallization with different annealing temperature. Further the surface studies indicate the presence of fine grains (average grain size 100 nm) and the average surface roughness is measured about 1.8 nm which is extremely least value.
DMA temperature sweeps were conducted in the total temperature range of -30 degree celsius to +100 degree celsius using a dynamic shear rheometer (Rheumatics, RDA II). For the temperature range -30 degree celsius to +90 degree celsius, parallel plates with diameter of 8 mm and gap 1.5 mm were used at a frequency of 10 rad/s. For the temperature range of +10 degree celsius to +100 degree celsius, plates with diameter -25 mm with gap 1 mm is used, and the frequency was set at 1 rad/s. The test started at lower temperatures and the temperature was increased by 2 degree celsius/min. A sinusoidal strain was applied and values of actual strain and torque were measured. Dynamic shear modulus |G*|, phase angle (δ) and |G*|/sin δ were calculated. Henceforth in this report, the dynamic shear modulus |G*| is called complex modulus G*. For performance grading of the binders, according to Superpave (AASHTO M320), time sweeps were carried out from +70 degree celsius to +88 degree celsius. The frequency used was 10 rad/s and values of G*/sin δ were calculated. Bitumen is a viscoelastic material, meaning that it shows viscous and elastic behavior simultaneously (Mezqer, 2002). In DMA, the ratio of peak stress to peak strain is defined as the complex modulus G*, which is a measure of the overall resistance to deformation of the sample repeatedly sheared. The phase difference between the stress and strain is defined as phase angle δ, which is a measure of the viscoelastic character of the sample. A phase angle of 90o represents a complete viscous fluid, behaving as water, and a phase angle of 0o represents an ideal elastic material behaving as a solid. At high temperatures, bituminous binders are more viscous showing high phase angle while at low temperatures they behave as elastic solids having a small phase angle. Both complex modulus and phase angle are functions of temperature and frequency which may be changed using additives like polymer or waxes. Testing was performed on binder mixture samples as well as on mixtures of filler and
700ºC. The thickness of film, t ≈ 237nm was determined using profilometery measurement. In order to avoid oxygen deficiency, a post-annealing at 700 ºC for 4 h was made in air. The crystal structure of the films was characterized by X-ray diffraction measurement (XRD) and data were refined by the Rietveld method. The electrical transport properties were measured by the four-point method in the range of 100-300K. Magnetoresistance measurement (MR) was used to measure the change in resistance under an external applied magnetic field up to 1 Tesla with temperature ranging from 80 to 300K using Hall measurement system (model Lake Shore 7604). The AC Susceptibility measurements were performed using a CryoBINDT model. Finally, the surface morphology of the LCMO film was characterized by Field Emission - Scanning Microscope (FE-SEM).
with hardeners : Mg 2+ ; Ni 2+ and softeners : Nb 5+ ; Sb 5+ ions) abbreviated as PZT-PMN-PNS quaternary system with varying Zr/Ti ratios in the range: 0.42 ≤ x ≤ 0.54 located near the morphotropic phase boundary (MPB) were prepared by conventional solid state process. The phase structure, dielectric and piezoelectric properties of the system were investigated. Phase analysis using X-ray diffraction (XRD) indicated that the phase structure of sintered PZT-PMN- PNS ceramics was transformed from tetragonal to rhombohedral, with Zr/Ti ratio increased in system. The MPB, in which the tetragonal and rhombohedral phases coexist, is in a composition range of Zr content from 48 to 52 mol%. Scanning electron micrographs of sintered ceramic surfaces (at 1180°C) showed the dense and uniform microstructure for composition close to MPB (Zr/Ti = 50/48) with apparent density of 7.9 g/cm 3 (≈ 98 % of the theoretic density). For 1.0 mol% (Mg, Nb) and 1.0 mol% (Ni, Sb) doped PZT composition with x = 50, electrical properties were significantly improved. The main parameters of Pb [Zr 0.50 Ti 0.48 (Mg 1/3 Nb 2/3 ) 0.01 (Ni 1/3 Sb 2/3 ) 0.01 ]O 3