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Sample records for pyroelectricity

  1. Pyroelectric Quantum Well Energy Harvesters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the investigation of pyroelectric energy harvesters with enhanced efficiencies through quantum wells induced by a multilayer design.  Pyroelectric...

  2. Dynamics of pyroelectric accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ghaderi, R.; Davani, F. Abbasi, E-mail: fabbasi@sbu.ac.ir [Radiation Application Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2015-01-26

    Pyroelectric crystals are used to produce high energy electron beams. We have derived a method to model electric potential generation on LiTaO{sub 3} crystal during heating cycle. In this method, effect of heat transfer on the potential generation is investigated by some experiments. In addition, electron emission from the crystal surface is modeled by measurements and analysis. These spectral data are used to present a dynamic equation of electric potential with respect to thickness of the crystal and variation of its temperature. The dynamic equation's results for different thicknesses are compared with measured data. As a result, to attain more energetic electrons, best thickness of the crystals could be extracted from the equation. This allows for better understanding of pyroelectric crystals and help to study about current and energy of accelerated electrons.

  3. Radiation generation with pyroelectric crystals

    Science.gov (United States)

    Geuther, Jeffrey A.

    2007-12-01

    Pyroelectric crystals heated or cooled in vacuum have been used to produce low-energy x-ray devices since 1992. In the course of this thesis, experiments with lithium tantalate (LiTaO3) and lithium niobate (LiNbO 3) were performed to extend the usefulness of pyroelectric radiation sources. Paired-crystal x-ray generators were shown to double the x-ray energy and yield, and allow the k-shell fluorescence of any metal up to thorium (Z = 90). It was demonstrated that the electron emission from a single pyroelectric crystal could be transmitted through a beryllium window to allow the electron beam to be extracted from the vacuum chamber. The electron emission current and energy were measured, and a mathematical model was developed to predict emission current and energy. Magnetic deflection experiments were used to verify that the electric field produced by the pyroelectric effect in lithium tantalate was sufficient to ionize gas. Finally, a paired-crystal system was used to ionize a deuterium fill gas near a metallic tip mounted to a pyroelectric crystal, and accelerate these ions into a deuterated target mounted to the opposing crystal. This technique was used to produce a compact, low-power fusion neutron source driven by pyroelectric crystals.

  4. Experiments to Demonstrate Piezoelectric and Pyroelectric Effects

    Science.gov (United States)

    Erhart, Jirí

    2013-01-01

    Piezoelectric and pyroelectric materials are used in many current applications. The purpose of this paper is to explain the basic properties of pyroelectric and piezoelectric effects and demonstrate them in simple experiments. Pyroelectricity is presented on lead zirconium titanate (PZT) ceramics as an electric charge generated by the temperature…

  5. MEMS based pyroelectric thermal energy harvester

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Scott R; Datskos, Panagiotis G

    2013-08-27

    A pyroelectric thermal energy harvesting apparatus for generating an electric current includes a cantilevered layered pyroelectric capacitor extending between a first surface and a second surface, where the first surface includes a temperature difference from the second surface. The layered pyroelectric capacitor includes a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer. In addition, a pair of proof masses is affixed at a distal end of the layered pyroelectric capacitor to face the first surface and the second surface, wherein the proof masses oscillate between the first surface and the second surface such that a pyroelectric current is generated in the pyroelectric capacitor due to temperature cycling when the proof masses alternately contact the first surface and the second surface.

  6. A Strip Cell in Pyroelectric Devices

    Directory of Open Access Journals (Sweden)

    An-Shen Siao

    2016-03-01

    Full Text Available The pyroelectric effect affords the opportunity to convert temporal temperature fluctuations into usable electrical energy in order to develop abundantly available waste heat. A strip pyroelectric cell, used to enhance temperature variation rates by lateral temperature gradients and to reduce cell capacitance to further promote the induced voltage, is described as a means of improving pyroelectric energy transformation. A precision dicing saw was successfully applied in fabricating the pyroelectric cell with a strip form. The strip pyroelectric cell with a high-narrow cross section is able to greatly absorb thermal energy via the side walls of the strips, thereby inducing lateral temperature gradients and increasing temperature variation rates in a thicker pyroelectric cell. Both simulation and experimentation show that the strip pyroelectric cell improves the electrical outputs of pyroelectric cells and enhances the efficiency of pyroelectric harvesters. The strip-type pyroelectric cell has a larger temperature variation when compared to the trenched electrode and the original type, by about 1.9 and 2.4 times, respectively. The measured electrical output of the strip type demonstrates a conspicuous increase in stored energy as compared to the trenched electrode and the original type, by of about 15.6 and 19.8 times, respectively.

  7. Ferroelectric ceramics in a pyroelectric accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Shchagin, A. V., E-mail: shchagin@kipt.kharkov.ua [Kharkov Institute of Physics and Technology, Kharkov 61108 (Ukraine); Belgorod State University, Belgorod 308015 (Russian Federation); Miroshnik, V. S.; Volkov, V. I. [Kharkov Institute of Physics and Technology, Kharkov 61108 (Ukraine); Oleinik, A. N. [Belgorod State University, Belgorod 308015 (Russian Federation)

    2015-12-07

    The applicability of polarized ferroelectric ceramics as a pyroelectric in a pyroelectric accelerator is shown by experiments. The spectra of X-ray radiation of energy up to tens of keV, generated by accelerated electrons, have been measured on heating and cooling of the ceramics in vacuum. It is suggested that curved layers of polarized ferroelectric ceramics be used as elements of ceramic pyroelectric accelerators. Besides, nanotubes and nanowires manufactured from ferroelectric ceramics are proposed for the use in nanometer-scale ceramic pyroelectric nanoaccelerators for future applications in nanotechnologies.

  8. Study on Pyroelectric Harvesters with Various Geometry

    Directory of Open Access Journals (Sweden)

    An-Shen Siao

    2015-08-01

    Full Text Available Pyroelectric harvesters convert time-dependent temperature variations into electric current. The appropriate geometry of the pyroelectric cells, coupled with the optimal period of temperature fluctuations, is key to driving the optimal load resistance, which enhances the performance of pyroelectric harvesters. The induced charge increases when the thickness of the pyroelectric cells decreases. Moreover, the induced charge is extremely reduced for the thinner pyroelectric cell when not used for the optimal period. The maximum harvested power is achieved when a 100 μm-thick PZT (Lead zirconate titanate cell is used to drive the optimal load resistance of about 40 MΩ. Moreover, the harvested power is greatly reduced when the working resistance diverges even slightly from the optimal load resistance. The stored voltage generated from the 75 μm-thick PZT cell is less than that from the 400 μm-thick PZT cell for a period longer than 64 s. Although the thinner PZT cell is advantageous in that it enhances the efficiency of the pyroelectric harvester, the much thinner 75 μm-thick PZT cell and the divergence from the optimal period further diminish the performance of the pyroelectric cell. Therefore, the designers of pyroelectric harvesters need to consider the coupling effect between the geometry of the pyroelectric cells and the optimal period of temperature fluctuations to drive the optimal load resistance.

  9. Pyroelectric Harvesters for Generating Cyclic Energy

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2015-04-01

    Full Text Available Pyroelectric energy conversion is a novel energy process which directly transforms waste heat energy from cyclic heating into electricity via the pyroelectric effect. Application of a periodic temperature profile to pyroelectric cells is necessary to achieve temperature variation rates for generating an electrical output. The critical consideration in the periodic temperature profile is the frequency or work cycle which is related to the properties and dimensions of the air layer; radiation power and material properties, as well as the dimensions and structure of the pyroelectric cells. This article aims to optimize pyroelectric harvesters by matching all these requirements. The optimal induced charge per period increases about 157% and the efficient period band decreases about 77%, when the thickness of the PZT cell decreases from 200 μm to 50 μm, about a 75% reduction. Moreover, when using the thinner PZT cell for harvesting the pyroelectric energy it is not easy to focus on a narrow band with the efficient period. However, the optimal output voltage and stored energy per period decrease about 50% and 74%, respectively, because the electrical capacitance of the 50 μm thick pyroelectric cell is about four times greater than that of the 200 μm thick pyroelectric cell. In addition, an experiment is used to verify that the work cycle to be able to critically affect the efficiency of PZT pyroelectric harvesters. Periods in the range between 3.6 s and 12.2 s are useful for harvesting thermal cyclic energy by pyroelectricity. The optimal frequency or work cycle can be applied in the design of a rotating shutter in order to control the heated and unheated periods of the pyroelectric cells to further enhance the amount of stored energy.

  10. Pyroelectric Energy Harvesting: Model and Experiments

    Science.gov (United States)

    2016-05-01

    characterization of the pyroelectric sample was performed with a Radiant Precision Premier II Ferroelectric Tester. The Radiant Vision software...enables many electrical measurements including ferroelectric hysteresis loops, leakage, and capacitance tests. The Radiant system uses a current...conversion cycles. 5.1 Static Testing The pyroelectric sample was tested under static temperature conditions using the heater element and a Radiant

  11. Pyroelectric energy conversion: optimization principles.

    Science.gov (United States)

    Sebald, Gael; Lefeuvre, Elie; Guyomar, Daniel

    2008-03-01

    In the framework of microgenerators, we present in this paper the key points for energy harvesting from temperature using ferroelectric materials. Thermoelectric devices profit from temperature spatial gradients, whereas ferroelectric materials require temporal fluctuation of temperature, thus leading to different applications targets. Ferroelectric materials may harvest perfectly the available thermal energy whatever the materials properties (limited by Carnot conversion efficiency) whereas thermoelectric material's efficiency is limited by materials properties (ZT figure of merit). However, it is shown that the necessary electric fields for Carnot cycles are far beyond the breakdown limit of bulk ferroelectric materials. Thin films may be an excellent solution for rising up to ultra-high electric fields and outstanding efficiency. Different thermodynamic cycles are presented in the paper: principles, advantages, and drawbacks. Using the Carnot cycle, the harvested energy would be independent of materials properties. However, using more realistic cycles, the energy conversion effectiveness remains dependent on the materials properties as discussed in the paper. A particular coupling factor is defined to quantify and check the effectiveness of pyroelectric energy harvesting. It is defined similarly to an electromechanical coupling factor as k2=p2theta0/(epsilontheta33cE), where p, theta0, epsilontheta33, cE are pyroelectric coefficient, maximum working temperature, dielectric permittivity, and specific heat, respectively. The importance of the electrothermal coupling factor is shown and discussed as an energy harvesting figure of merit. It gives the effectiveness of all techniques of energy harvesting (except the Carnot cycle). It is finally shown that we could reach very high efficiency using 1110.75Pb(Mg1/3Nb2/3)-0.25PbTiO3 single crystals and synchronized switch harvesting on inductor (almost 50% of Carnot efficiency). Finally, practical implementation key

  12. The pyroelectric constant and dielectric coefficient measurement of pyroelectric thin films

    CERN Document Server

    Altintas, E

    1998-01-01

    Pyroelectric coefficient measurements were made in various temperature for poled and unpoled form of PVDF which is pyroelectric material. For these experiments the quasi-static techniques was used. PVDF samples were poled in various electric strengths and relation between poling field strength and pyroelectric coefficient was investigated. It was observed that as poling field strength was increased, the pyroelectric coefficient increased as well. The other study was the effect of poling temperature on pyroelectricity. The best result was obtained when PVDF sample was poled at 340 K. This temperature value is about the Curie temperature of PVDF is and given in the literature. For poled and unpoled samples, there was an increase in pyroelectric coefficient with the increase of measurement temperature up to T sub c. The dielectric permittivity and dielectric loss measurement of PVDF which is a semi-crystalline polymer was taken in the 125-375 K temperature and 100-20 khz frequency interval. The measurements show...

  13. Wind-driven pyroelectric energy harvesting device

    Science.gov (United States)

    Xie, Mengying; Zabek, Daniel; Bowen, Chris; Abdelmageed, Mostafa; Arafa, Mustafa

    2016-12-01

    Pyroelectric materials have recently received attention for harvesting waste heat owing to their potential to convert temperature fluctuations into useful electrical energy. One of the main challenges in designing pyroelectric energy harvesters is to provide a means to induce a temporal heat variation in a pyroelectric material autonomously from a steady heat source. To address this issue, we propose a new form of wind-driven pyroelectric energy harvester, in which a propeller is set in rotational motion by an incoming wind stream. The speed of the propeller’s shaft is reduced by a gearbox to drive a slider-crank mechanism, in which a pyroelectric material is placed on the slider. Thermal cycling is obtained as the reciprocating slider moves the pyroelectric material across alternative hot and cold zones created by a stationary heat lamp and ambient temperature, respectively. The open-circuit voltage and closed-circuit current are investigated in the time domain at various wind speeds. The device was experimentally tested under wind speeds ranging from 1.1 to 1.6 m s-1 and charged an external 100 nF capacitor through a signal conditioning circuit to demonstrate its effectiveness for energy harvesting. Unlike conventional wind turbines, the energy harvested by the pyroelectric material is decoupled from the wind flow and no mechanical power is drawn from the transmission; hence the system can operate at low wind speeds (<2 m s-1).

  14. Virtual experiment of pyroelectric fusion

    Energy Technology Data Exchange (ETDEWEB)

    Nasseri, Mohammad Mehdi, E-mail: mnasseri@aeoi.org.ir

    2015-11-01

    The virtual experiment of pyroelectric fusion was conducted by Geant4 simulator. Despite the limitations of the code for simulating the pyroelectric fusion experiment precisely, the following interesting results were obtained. Two crystals were separated by a certain distance. A constant electric field with varying intensities was applied between the crystals. As initial particles, deuterium ions were emitted to deuterated polypropylene (CD{sub 2}). This virtual experiment showed that the number of ions that hit the target, for different distances between the crystals, increases with the increase of the intensity of the electric field; however, further increase of the electric field results in the reduction of the number of hit ions, which attains a constant value of about 57% of the initial number of ions. For a (D, D) fusion reaction to occur, the distance between the two crystals should be <1.5 cm and for a (D, T) fusion reaction to occur, this distance could be up to 2 cm. The energy spectra of ions for low and high electric fields were narrow and long and wide and short, respectively.

  15. Energy harvesting with piezoelectric and pyroelectric materials

    CERN Document Server

    Muensit, Nantakan

    2011-01-01

    The purpose of this book is to present the current state of knowledge in the field of energy harvesting using piezoelectric and pyroelectric materials. The book is addressed to students and academics engaged in research in the fields of energy harvesting, material sciences and engineering. Scientists and engineers who are working in the area of energy conservation and renewable energy resources should find it useful as well. Explanations of fundamental physical properties such as piezoelectricity and pyroelectricity are included to aid the understanding of the non-specialist. Specific technolo

  16. The pyroelectric vidicon - Ten years on

    Science.gov (United States)

    Burgess, D.; Nixon, R.; Ritchie, J.

    1986-01-01

    A technology development status evaluation is presented for British high performance pyroelectric vidicon, IR-sensitive TV cameras, the first tubes and cameras of which were demonstrated over a decade ago. Attention is given to the improvements that had to be instituted in camera design in order to obtain optimum performance from the vidicon tubes. A rotating disk chopper and flicker processing were incorporated into the camera's design. Pyroelectric cameras have been extensively applied in industry and the police and military services for fire detection and in rescue operations.

  17. Pyroelectric coupling in thin film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Karpov, Victor G.; Shvydka, Diana [Department of Physics and Astronomy, University of Toledo, OH (United States)

    2007-07-15

    We propose a theory of thin film photovoltaics in which one of the polycrystalline films is made of a pyroelectric material grains such as CdS. That film is shown to generate strong polarization improving the device open circuit voltage. Implications and supporting facts for the major photovoltaic types based on CdTe and CuIn(Ga)Se{sub 2} absorber layers are discussed. Band diagram of a pyroelectric (CdS) based PV junction. Arrows represent the charge carrier photo-generation. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Pyroelectric Charge Release in Rhombohedral PZT

    NARCIS (Netherlands)

    Noheda, Beatriz; Duan, Ning; Cereceda, Noé; Gonzalo, Julio A.

    1998-01-01

    A new experimental set-up controlled by computer has been made to measure the pyroelectric charge of ferroelectric materials with a relatively high conductivity at slow rates of temperature variation. It allowed us to obtain the polarisation vs. temperature behaviour of PZT with various compositions

  19. Multi-Frequency Band Pyroelectric Sensors

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2014-11-01

    Full Text Available A methodology is proposed for designing a multi-frequency band pyroelectric sensor which can detect subjects with various frequencies or velocities. A structure with dual pyroelectric layers, consisting of a thinner sputtered ZnO layer and a thicker aerosol ZnO layer, proved helpful in the development of the proposed sensor. The thinner sputtered ZnO layer with a small thermal capacity and a rapid response accomplishes a high-frequency sensing task, while the thicker aerosol ZnO layer with a large thermal capacity and a tardy response is responsible for low-frequency sensing tasks. A multi-frequency band pyroelectric sensor is successfully designed, analyzed and fabricated in the present study. The range of the multi-frequency sensing can be estimated by means of the proposed design and analysis to match the thicknesses of the sputtered and the aerosol ZnO layers. The fabricated multi-frequency band pyroelectric sensor with a 1 μm thick sputtered ZnO layer and a 20 μm thick aerosol ZnO layer can sense a frequency band from 4000 to 40,000 Hz without tardy response and low voltage responsivity.

  20. Pyroelectric nanogenerators for harvesting thermoelectric energy.

    Science.gov (United States)

    Yang, Ya; Guo, Wenxi; Pradel, Ken C; Zhu, Guang; Zhou, Yusheng; Zhang, Yan; Hu, Youfan; Lin, Long; Wang, Zhong Lin

    2012-06-13

    Harvesting thermoelectric energy mainly relies on the Seebeck effect that utilizes a temperature difference between two ends of the device for driving the diffusion of charge carriers. However, in an environment that the temperature is spatially uniform without a gradient, the pyroelectric effect has to be the choice, which is based on the spontaneous polarization in certain anisotropic solids due to a time-dependent temperature variation. Using this effect, we experimentally demonstrate the first application of pyroelectric ZnO nanowire arrays for converting heat energy into electricity. The coupling of the pyroelectric and semiconducting properties in ZnO creates a polarization electric field and charge separation along the ZnO nanowire as a result of the time-dependent change in temperature. The fabricated nanogenerator has a good stability, and the characteristic coefficient of heat flow conversion into electricity is estimated to be ∼0.05-0.08 Vm(2)/W. Our study has the potential of using pyroelectric nanowires to convert wasted energy into electricity for powering nanodevices.

  1. Study on Pyroelectric Harvesters Integrating Solar Radiation with Wind Power

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2015-07-01

    Full Text Available Pyroelectric harvesters use temperature fluctuations to generate electrical outputs. Solar radiation and waste heat are rich energy sources that can be harvested. Pyroelectric energy converters offer a novel and direct energy-conversion technology by transforming time-dependent temperatures directly into electricity. Moreover, the great challenge for pyroelectric energy harvesting lies in finding promising temperature variations or an alternating thermal loading in real situations. Hence, in this article, a novel pyroelectric harvester integrating solar radiation with wind power by the pyroelectric effect is proposed. Solar radiation is a thermal source, and wind is a dynamic potential. A disk generator is used for harvesting wind power. A mechanism is considered to convert the rotary energy of the disk generator to drive a shutter for generating temperature variations in pyroelectric cells using a planetary gear system. The optimal period of the pyroelectric cells is 35 s to harvest the stored energy, about 70 μJ, while the rotary velocity of the disk generator is about 31 RPM and the wind speed is about 1 m/s. In this state, the stored energy acquired from the pyroelectric harvester is about 75% more than that from the disk generator. Although the generated energy of the proposed pyroelectric harvester is less than that of the disk generator, the pyroelectric harvester plays a complementary role when the disk generator is inactive in situations of low wind speed.

  2. Improvement of Pyroelectric Cells for Thermal Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Jing-Chih Ciou

    2012-01-01

    Full Text Available This study proposes trenching piezoelectric (PZT material in a thicker PZT pyroelectric cell to improve the temperature variation rate to enhance the efficiency of thermal energy-harvesting conversion by pyroelectricity. A thicker pyroelectric cell is beneficial in generating electricity pyroelectrically, but it hinders rapid temperature variations. Therefore, the PZT sheet was fabricated to produce deeper trenches to cause lateral temperature gradients induced by the trenched electrode, enhancing the temperature variation rate under homogeneous heat irradiation. When the trenched electrode type with an electrode width of 200 μm and a cutting depth of 150 μm was used to fabricate a PZT pyroelectric cell with a 200 μm thick PZT sheet, the temperature variation rate was improved by about 55%. Therefore, the trenched electrode design did indeed enhance the temperature variation rate and the efficiency of pyroelectric energy converters.

  3. Responsivity Calibration of Pyroelectric Terahertz Detectors

    CERN Document Server

    Berry, Christopher W; Jarrahi, Mona

    2014-01-01

    There has been a significant advancement in terahertz radiation sources in the past decade, making milliwatt terahertz power levels accessible in both continuous-wave and pulsed operation. Such high-power terahertz radiation sources circumvent the need for cryogenic-cooled terahertz detectors such as semiconductor bolometers and necessitate the need for new types of calibrated, room-temperature terahertz detectors. Among various types of room-temperature terahertz detectors, pyroelectric detectors are one of the most widely used detectors, which can offer wide dynamic range, broad detection bandwidth, and high sensitivity levels. In this article, we describe the calibration process of a commercially available pyroelectric detector (Spectrum Detector, Inc, SPI-A-65 THz), which incorporates a 5 mm diameter LiTaO3 detector with an organic terahertz absorber coating.

  4. Radiatively heated high voltage pyroelectric crystal pulser

    Energy Technology Data Exchange (ETDEWEB)

    Antolak, A.J., E-mail: antolak@sandia.gov [Sandia National Laboratories, Livermore, CA 94550 (United States); Chen, A.X. [Sandia National Laboratories, Livermore, CA 94550 (United States); Leung, K.-N. [Sandia National Laboratories, Livermore, CA 94550 (United States); Nuclear Engineering Department, University of California, Berkeley (United States); Morse, D.H.; Raber, T.N. [Sandia National Laboratories, Livermore, CA 94550 (United States)

    2014-01-21

    Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

  5. Highly stretchable piezoelectric-pyroelectric hybrid nanogenerator.

    Science.gov (United States)

    Lee, Ju-Hyuck; Lee, Keun Young; Gupta, Manoj Kumar; Kim, Tae Yun; Lee, Dae-Yeong; Oh, Junho; Ryu, Changkook; Yoo, Won Jong; Kang, Chong-Yun; Yoon, Seok-Jin; Yoo, Ji-Beom; Kim, Sang-Woo

    2014-02-01

    A highly stretchable hybrid nanogenerator has been developed using a micro-patterned piezoelectric polymer P(VDF-TrFE), PDMS-CNT composite, and graphene nanosheets. Mechanical and thermal energies are simultaneously harvested from a single cell of the device. The hybrid nanogenerator exhibits high robustness behavior even after 30% stretching and generates very stable piezoelectric and pyroelectric power outputs due to micro-pattern designing. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Self Assembly and Pyroelectric Poling for Organics

    Science.gov (United States)

    2015-07-06

    ozone or nitrogen oxides) and energetic species from corona discharge . These problems can strongly inhibit the efficient poling and large-scale...respectively. In this idealized model , a modest temperature change (10 to 50 °C) will lead to a considerably large electrostatic field in a thin film dielectric...measurement); (e) contact poling. 4. Systematically analyze electrostatics models to quantify electric field generation from commonly used pyroelectric

  7. Improved Ambient Pressure Pyroelectric Ion Source

    Science.gov (United States)

    Beegle, Luther W.; Kim, Hugh I.; Kanik, Isik; Ryu, Ernest K.; Beckett, Brett

    2011-01-01

    The detection of volatile vapors of unknown species in a complex field environment is required in many different applications. Mass spectroscopic techniques require subsystems including an ionization unit and sample transport mechanism. All of these subsystems must have low mass, small volume, low power, and be rugged. A volatile molecular detector, an ambient pressure pyroelectric ion source (APPIS) that met these requirements, was recently reported by Caltech researchers to be used in in situ environments.

  8. Electronic detection of ultra-heavy nuclei by pyroelectric materials

    Science.gov (United States)

    Simpson, J. A.; Tuzzolino, A. J.

    1983-01-01

    A recent prediction by the authors that pyroelectric materials may be capable of detecting ultra-heavy nuclei has been confirmed. Charge pulse signals from pyroelectric crystals of lithium tantalate exposed to Au ions and a pulsed beam of Ni-58 ions, and from pyroelectric films of polyvinylidene fluoride exposed to a pulsed beam of Ni-58 ions, have been measured using pulse electronics with time constants in the microsecond range. These studies show that pyroelectric materials, in general, are capable of detecting incident nuclei having very high mass and charge. In particular, pyroelectric polymers, such as polyvinylidene fluoride, are readily available as inexpensive flexible films. This new class of charged particle detector could eventually find applications in large-area experiments for detection and trajectory determination of low-energy, ultra-heavy nuclei.

  9. The flexoelectric effect associated size dependent pyroelectricity in solid dielectrics

    Directory of Open Access Journals (Sweden)

    Gang Bai

    2015-09-01

    Full Text Available A phenomenological thermodynamic theory is used to investigate the effect of strain gradient on the pyroelectric effect in centrosymmetric dielectric solids. Direct pyroelectricity can exist as external mechanical stress is applied to non-pyroelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective pyroelectric coefficient was analyzed in truncated pyramids. It is found to be controlled by size, ambient temperature, stress, and aspect ratio and depends mainly on temperature sensitivity of flexoelectric coefficient (TSFC and strain gradient of the truncated pyramids dielectric solids. These results show that the pyroelectric property of Ba0.67Sr0.33TiO3 above Tc similar to PZT and other lead-based ferroelectrics can be obtained. This feature might widely broaden the selection of materials for infrared detectors with preferable properties.

  10. The Electronic Structure and Secondary Pyroelectric Properties of Lithium Tetraborate

    Directory of Open Access Journals (Sweden)

    Peter A. Dowben

    2010-09-01

    Full Text Available We review the pyroelectric properties and electronic structure of Li2B4O7(110 and Li2B4O7(100 surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li2B4O7 so that the pyroelectric coefficient is nonzero but roughly 103 smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness  contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected. The time dependent surface photovoltaic charging suggests that surface charging is dependent on crystal orientation and doping, as well as temperature.

  11. The flexoelectric effect associated size dependent pyroelectricity in solid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Gang, E-mail: baigang@njupt.edu.cn [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Liu, Zhiguo [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Xie, Qiyun; Guo, Yanyan; Li, Wei [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Yan, Xiaobing [College of Electronic and information Engineering, Hebei University, Baoding 071002 (China)

    2015-09-15

    A phenomenological thermodynamic theory is used to investigate the effect of strain gradient on the pyroelectric effect in centrosymmetric dielectric solids. Direct pyroelectricity can exist as external mechanical stress is applied to non-pyroelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective pyroelectric coefficient was analyzed in truncated pyramids. It is found to be controlled by size, ambient temperature, stress, and aspect ratio and depends mainly on temperature sensitivity of flexoelectric coefficient (TSFC) and strain gradient of the truncated pyramids dielectric solids. These results show that the pyroelectric property of Ba{sub 0.67}Sr{sub 0.33}TiO{sub 3} above T{sub c} similar to PZT and other lead-based ferroelectrics can be obtained. This feature might widely broaden the selection of materials for infrared detectors with preferable properties.

  12. The off-axis pyroelectric effect observed for lithium tetraborate

    Energy Technology Data Exchange (ETDEWEB)

    Ketsman, I. [Dept. of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); Wooten, D. [Air Force Institute of Technology, 2950 Hobson Way, Wright Patterson Air Force Base, OH 45433-7765 (United States); Xiao, Jie [Dept. of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); Losovyj, Ya.B. [Dept. of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Burak, Ya.V.; Adamiv, V.T. [Institute of Physical Optics, 23 Dragomanov Street, Lviv 79005 (Ukraine); Sokolov, A. [Dept. of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); Petrosky, J.; McClory, J. [Air Force Institute of Technology, 2950 Hobson Way, Wright Patterson Air Force Base, OH 45433-7765 (United States); Dowben, P.A., E-mail: pdowben@unl.ed [Dept. of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States)

    2010-01-25

    We find a pyroelectric current along the <110> direction of stoichiometric Li{sub 2}B{sub 4}O{sub 7} so that the pyroelectric coefficient is nonzero but roughly 10{sup -3} smaller than along the <001> direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the <110> direction can be correlated with anomalies in the elastic stiffness C{sub 33}{sup D} contributing to concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected. The time dependent surface photovoltaic charging suggests that an inverse piezoelectric effect occurs at the (110) surface but not the (100) surface. Both effects along the <110> direction or at the (110) surface are distinct the conventional as a bulk pyroelectric effect.

  13. Thermally induced atmospheric pressure gas discharges using pyroelectric crystals

    Science.gov (United States)

    Johnson, Michael J.; Linczer, John; Go, David B.

    2014-12-01

    Using a heated pyroelectric crystal, an atmospheric pressure gas discharge was generated through the input of heat. When put through a change in temperature, the polarization of a pyroelectric can change significantly, creating a substantial electric potential at its surface. When configured with a grounded sharp counter electrode, a large inhomogeneous electric field forms in the interstitial gas to initiate a corona-like discharge. Under constant heating conditions, gaseous ions drifting to the pyroelectric accumulate and screen the electric field, extinguishing the discharge. By thermally cycling the pyroelectric, negative and positive discharges are generated during heating and cooling, respectively, with peak currents on the order of 80 nA. Time-integrated visualization confirmed the generation of both a corona-like discharge and a surface discharge on the pyroelectric. Parametric studies identified that thermal cycling conditions significantly influence discharge formation for this new atmospheric pressure discharge approach.

  14. Study of pyroelectric activity of PZT/PVDF-HFP composite

    Directory of Open Access Journals (Sweden)

    Luiz Francisco Malmonge

    2003-12-01

    Full Text Available Flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT powder and poly(vinylidene fluoride-hexafluoropropylene (PVDF-HFP copolymer. The pyroelectric and the piezoelectric longitudinal (d33 coefficients were measured. A 50/50 vol.% PZT/PVDF-HFP composite resulted in piezo and pyroelectric coefficients of d33 = 25.0 pC/N and p = 4.5 × 10-4 C/m²K at 70 °C, respectively. Analysis of the complex permittivity in a wide range of frequency was carried out indicating lower permittivity of the composite in comparison with a permittivity of the PZT ceramic. The low value of the permittivity gives a high pyroelectric figure of merit indicating that this material can be used to build a temperature sensor in spite of the lower pyroelectric coefficient compared with PZT.

  15. Secondary pyroelectric and electrocaloric effects in thin films

    Science.gov (United States)

    Tong, Trong

    The pyroelectric and electrocaloric effect play an important role in many applications such as energy harvesting and solid-state cooling. This dissertation focuses on the characterization of the pyroelectric and electric coefficient in thin film using novel laser-based technique. The implementation of the systems is described in detail, and heat transport models are developed to interpret the experimental data. The temperature oscillation caused by the modulated laser power or the entropy change are calculated over a wide range of the modulation frequency. These techniques are applied to characterize Pb(ZrTi)O3 and Ba(SrTi)O3 films growth by Pulse Laser Deposition (PLD) and sol-gel method. The secondary pyroelectric and electrocaloric contributions caused by clamping substrate effect are discussed. A wide range frequency analysis is applied to extract the secondary pyroelectric coefficient. The secondary pyroelectric effect is found to have the same dependence on applied field as the pyroelectric coefficient and is approximately 15% and 20% of the total response for PbZr 0.2Ti0.8O3 and Ba0.6Sr0.4TiO 3 grown by PLD, respectively. By comparing the pyroelectric and electrocaloric coefficient measured on the same devices, our result shows the secondary contribution to the electrocaloric coefficient has the opposite sign as the primary effect and therefore reduces the overall entropy change of Pb(ZrTi)O3 in an electric field. Finally, the sol-gel method is used to produce Pb(ZrTi)O 3 thin films. The sample fabrication is described in detail along with physical characterization and the pyroelectric measurement. Sol-gel PZT films are perovskite phase with (100) orientation. The pyroelectric coefficient is measured to be 135 microC m-2 K-1.

  16. Study of pyroelectric activity of PZT/PVDF-HFP composite

    OpenAIRE

    Luiz Francisco Malmonge; José Antonio Malmonge; Walter Katsumi Sakamoto

    2003-01-01

    Flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT) powder and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) copolymer. The pyroelectric and the piezoelectric longitudinal (d33) coefficients were measured. A 50/50 vol.% PZT/PVDF-HFP composite resulted in piezo and pyroelectric coefficients of d33 = 25.0 pC/N and p = 4.5 × 10-4 C/m²K at 70 °C, respectively. Analysis of the complex permittivity in a wide ran...

  17. Piezoelectric and pyroelectric effects of a crystalline polymer

    Science.gov (United States)

    Kundu, Nikhil K.; Kundu, Malay

    1990-01-01

    Polyvinylidene flouride (PVDF) is a crystalline polymer to both piezoelectric and pyroelectric nature. Piezoelectricity produces electrical signals when mechanically deformed, and pyroelectricity is the electrical polarization induced by thermal absorption in crystals. To demonstrate the piezoelectric effect PVDF is subjected to impact loads which produce electrical charges proportional to mechanical stresses. A heat source was used to demonstrate the pyroelectric nature of PVDF. The rise in temperature due to absorbed energy by the polymer produces electrical output. The qualitative test results obtained are graphically reproduced.

  18. Effect of space exposure on pyroelectric infrared detectors (A0135)

    Science.gov (United States)

    Robertson, J. B.; Clark, I. O.; Crouch, R. K.

    1984-01-01

    The effects of long-duration space exposure and launch environment on the performance of pyroelectric detectors which is important for the prediction of performance degradation, setting exposure limits, or determining shielding requirements was investigated. Air pollution monitoring and thermal mapping of the Earth, which includes the remote sensing of aerosols and limb scanning infrared radiometer projects, requires photodetection in the 6- to 20 micro m region of the spectrum. Pyroelectric detectors can detect radiation in the 1- to 100 micro m region while operating at room temperature. This makes tahe pyroelectric detector a prime candidate to fill the thermal infrared detector requirements.

  19. A Novel Compact Pyroelectric X-Ray and Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Yaron Danon

    2007-08-31

    This research was focused on the utilization of pyroelectric crystals for generation of radiation. When in constant temperature pyroelectric crystals are spontaneously polarized. The polarization causes internal charges to accumulate near the crystal faces and masking charges from the environment are attracted to the crystal faces and neutralize the charge. When a pyroelectric crystal is heated or cooled it becomes depolarized and the surface charges become available. If the heating or cooling is done on a crystal in vacuum where no masking charges are available, the crystal becomes a charged capacitor and because of its small capacitance large potential develops across the faces of the crystal.

  20. Therapeutic dose from a pyroelectric electron accelerator.

    Science.gov (United States)

    Fullem, T Z; Fazel, K C; Geuther, J A; Danon, Y

    2009-11-01

    Simple heating of pyroelectric crystals has been used as the basis for compact sources of X rays, electrons, ions and neutrons. We report on the evaluation of the feasibility of using a portable pyroelectric electron accelerator to deliver a therapeutic dose to tissue. Such a device could be mass produced as a handheld, battery-powered instrument. Experiments were conducted with several crystal sizes in which the crystal was heated inside a vacuum chamber and the emitted electrons were allowed to penetrate a thin beryllium window into the surrounding air. A Faraday cup was used to count the number of electrons that exited the window. The energy of these electrons was determined by measuring the energy spectrum of the X rays that resulted from the electron interactions with the Faraday cup. Based on these measurements, the dose that this source could deliver to tissue was calculated using Monte Carlo calculations. It was found that 10(13) electrons with a peak energy of the order of 100 keV were emitted from the beryllium window and could deliver a dose of 1664 Gy to a 2-cm-diameter, 110-microm-deep region of tissue located 1.5 cm from the window with air between the window and the tissue. This dose level is high enough to consider this technology for medical applications in which shallow energy deposition is beneficial.

  1. Invited Review Article: Practical guide for pyroelectric measurementsa)

    Science.gov (United States)

    Lubomirsky, Igor; Stafsudd, Oscar

    2012-05-01

    The characterization of pyroelectric materials is a necessary stage in the design of a large variety of pyroelectric-based devices ranging from intrusion alarms to IR cameras. The sample configurations and measurement techniques currently in use vary widely and require careful attention in order to avoid artifacts. In this review, we provide a practical guide to the measurement of the pyroelectric coefficient, paying particular attention to the new instrumental possibilities (fast sinusoidally modulated light sources, low impedance broad band current meters, and fast averaging oscilloscopes) that have become available during the last decade. Techniques applicable to bulk specimens, substrate-supported films, and self-supported films are described in detail. The most commonly used procedures are classified according to the type of thermal excitation: continuous ramping, heat pulse, and continuous oscillation. In the appendices, we describe the practical realization of these measurement schemes and provide mathematical descriptions for the extraction of the pyroelectric coefficient from the measured data.

  2. Evaluation of dome-input geometry for pyroelectric detectors

    Science.gov (United States)

    Zeng, J.; Hanssen, L. M.; Eppeldauer, G. P.

    2013-06-01

    Dome-input pyroelectric radiometers with different black coatings were developed to extend the spectral responsivity scale from near infrared (NIR) to 20 μm. The reflective dome with shiny gold-coating has been known to be an efficient light trap to enhance the detector absorptance and to minimize spectral responsivity variation. The enhancement of spectral responsivity using reflective dome relies on optical characterization of black coating on detector, reflectance of dome reflector, and input aperture dimension, etc. We report a comparison of spectral responsivity of dome-input pyroelectric radiometers measured with/without dome-trap from 2.4 μm to 14 μm using the Infrared Spectral Comparator Facility (IRSCF) at NIST. The results show 4 % to 8 % gain of responsivity for two dome-input pyroelectric detectors, with reduced structure of spectral responsivity. The uncertainty of dome-input pyroelectric radiometer calibrations is approximately 2 % (k = 2).

  3. Design of a VDF/TrFE Copolymer-on-silicon pyroelectric sensor

    NARCIS (Netherlands)

    Setiadi, D.; Regtien, P.P.L.

    1994-01-01

    This paper presents a design of a VDF/TrFE copolymer-on-silicon pyroelectric sensor. For an optimal design of a VDF/TrFE-on-silicon pyroelectric sensor, the one-dimensional diffusion equation is solved for the pyroelectric multilayer structure. The output current of the sensor is calculated. Improve

  4. Improving Pyroelectric Energy Harvesting Using a Sandblast Etching Technique

    Directory of Open Access Journals (Sweden)

    An-Shen Siao

    2013-09-01

    Full Text Available Large amounts of low-grade heat are emitted by various industries and exhausted into the environment. This heat energy can be used as a free source for pyroelectric power generation. A three-dimensional pattern helps to improve the temperature variation rates in pyroelectric elements by means of lateral temperature gradients induced on the sidewalls of the responsive elements. A novel method using sandblast etching is successfully applied in fabricating the complex pattern of a vortex-like electrode. Both experiment and simulation show that the proposed design of the vortex-like electrode improved the electrical output of the pyroelectric cells and enhanced the efficiency of pyroelectric harvesting converters. A three-dimensional finite element model is generated by commercial software for solving the transient temperature fields and exploring the temperature variation rate in the PZT pyroelectric cells with various designs. The vortex-like type has a larger temperature variation rate than the fully covered type, by about 53.9%.The measured electrical output of the vortex-like electrode exhibits an obvious increase in the generated charge and the measured current, as compared to the fully covered electrode, by of about 47.1% and 53.1%, respectively.

  5. Development of MEMS based pyroelectric thermal energy harvesters

    Science.gov (United States)

    Hunter, Scott R.; Lavrik, Nickolay V.; Bannuru, Thirumalesh; Mostafa, Salwa; Rajic, Slo; Datskos, Panos G.

    2011-06-01

    The efficient conversion of waste thermal energy into electrical energy is of considerable interest due to the huge sources of low-grade thermal energy available in technologically advanced societies. Our group at the Oak Ridge National Laboratory (ORNL) is developing a new type of high efficiency thermal waste heat energy converter that can be used to actively cool electronic devices, concentrated photovoltaic solar cells, computers and large waste heat producing systems, while generating electricity that can be used to power remote monitoring sensor systems, or recycled to provide electrical power. The energy harvester is a temperature cycled pyroelectric thermal-to-electrical energy harvester that can be used to generate electrical energy from thermal waste streams with temperature gradients of only a few degrees. The approach uses a resonantly driven pyroelectric capacitive bimorph cantilever structure that potentially has energy conversion efficiencies several times those of any previously demonstrated pyroelectric or thermoelectric thermal energy harvesters. The goals of this effort are to demonstrate the feasibility of fabricating high conversion efficiency MEMS based pyroelectric energy converters that can be fabricated into scalable arrays using well known microscale fabrication techniques and materials. These fabrication efforts are supported by detailed modeling studies of the pyroelectric energy converter structures to demonstrate the energy conversion efficiencies and electrical energy generation capabilities of these energy converters. This paper reports on the modeling, fabrication and testing of test structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy harvesters.

  6. A Meliorated Multi-Frequency Band Pyroelectric Sensor.

    Science.gov (United States)

    Hsiao, Chun-Ching; Liu, Sheng-Yi; Siao, An-Shen

    2015-07-06

    This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

  7. Abnormal Activity Detection Using Pyroelectric Infrared Sensors

    Directory of Open Access Journals (Sweden)

    Xiaomu Luo

    2016-06-01

    Full Text Available Healthy aging is one of the most important social issues. In this paper, we propose a method for abnormal activity detection without any manual labeling of the training samples. By leveraging the Field of View (FOV modulation, the spatio-temporal characteristic of human activity is encoded into low-dimension data stream generated by the ceiling-mounted Pyroelectric Infrared (PIR sensors. The similarity between normal training samples are measured based on Kullback-Leibler (KL divergence of each pair of them. The natural clustering of normal activities is discovered through a self-tuning spectral clustering algorithm with unsupervised model selection on the eigenvectors of a modified similarity matrix. Hidden Markov Models (HMMs are employed to model each cluster of normal activities and form feature vectors. One-Class Support Vector Machines (OSVMs are used to profile the normal activities and detect abnormal activities. To validate the efficacy of our method, we conducted experiments in real indoor environments. The encouraging results show that our method is able to detect abnormal activities given only the normal training samples, which aims to avoid the laborious and inconsistent data labeling process.

  8. Abnormal Activity Detection Using Pyroelectric Infrared Sensors.

    Science.gov (United States)

    Luo, Xiaomu; Tan, Huoyuan; Guan, Qiuju; Liu, Tong; Zhuo, Hankz Hankui; Shen, Baihua

    2016-06-03

    Healthy aging is one of the most important social issues. In this paper, we propose a method for abnormal activity detection without any manual labeling of the training samples. By leveraging the Field of View (FOV) modulation, the spatio-temporal characteristic of human activity is encoded into low-dimension data stream generated by the ceiling-mounted Pyroelectric Infrared (PIR) sensors. The similarity between normal training samples are measured based on Kullback-Leibler (KL) divergence of each pair of them. The natural clustering of normal activities is discovered through a self-tuning spectral clustering algorithm with unsupervised model selection on the eigenvectors of a modified similarity matrix. Hidden Markov Models (HMMs) are employed to model each cluster of normal activities and form feature vectors. One-Class Support Vector Machines (OSVMs) are used to profile the normal activities and detect abnormal activities. To validate the efficacy of our method, we conducted experiments in real indoor environments. The encouraging results show that our method is able to detect abnormal activities given only the normal training samples, which aims to avoid the laborious and inconsistent data labeling process.

  9. Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric- ferroelectric ceramics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.

  10. Pyroelectric sensor arrays for detection and thermal imaging

    Science.gov (United States)

    Holden, Anthony J.

    2013-06-01

    Penetration of uncooled (room temperature operation) thermal detector arrays into high volume commercial products depends on very low cost technology linked to high volume production. A series of innovative and revolutionary developments is now allowing arrays based on bulk pyroelectric ceramic material to enter the consumer marketplace providing everything from sophisticated security and people monitoring devices to hand held thermal imagers and visual IR thermometers for preventative maintenance and building inspection. Although uncooled resistive microbolometer detector technology has captured market share in higher cost thermal imager products we describe a pyroelectric ceramic technology which does not need micro electro-mechanical systems (MEMS) technology and vacuum packaging to give good performance. This is a breakthrough for very low cost sensors and imagers. Recent developments in a variety of products based on pyroelectric ceramic arrays are described and their performance and applicability compared and contrasted with competing technologies.

  11. Nano/microscale pyroelectric energy harvesting: challenges and opportunities

    Directory of Open Access Journals (Sweden)

    Devashish Lingam

    2013-12-01

    Full Text Available With the ever-growing demand for renewable energy sources, energy harvesting from natural resources has gained much attention. Energy sources such as heat and mechanical motion could be easily harvested based on pyroelectric, thermoelectric, and piezoelectric effects. The energy harvested from otherwise wasted energy in the environment can be utilized in self-powered micro and nano devices, and wearable electronics, which required only µW–mW power. This article reviews pyroelectric energy harvesting with an emphasis on recent developments in pyroelectric energy harvesting and devices at micro/nanoscale. Recent developments are presented and future challenges and opportunities for more efficient materials and devices with higher energy conversion efficiency are also discussed.

  12. Power maximization for pyroelectric, piezoelectric, and hybrid energy harvesting

    Science.gov (United States)

    Shaheen, Murtadha A.

    The goal of this dissertation consists of improving the efficiency of energy harvesting using pyroelectric and piezoelectric materials in a system by the proper characterization of electrical parameters, widening frequency, and coupling of both effects with the appropriate parameters. A new simple stand-alone method of characterizing the impedance of a pyroelectric cell has been demonstrated. This method utilizes a Pyroelectric single pole low pass filter technique, PSLPF. Utilizing the properties of a PSLPF, where a known input voltage is applied and capacitance C p and resistance Rp can be calculated at a frequency of 1 mHz to 1 Hz. This method demonstrates that for pyroelectric materials the impedance depends on two major factors: average working temperature, and the heating rate. Design and implementation of a hybrid approach using multiple piezoelectric cantilevers is presented. This is done to achieve mechanical and electrical tuning, along with bandwidth widening. In addition, a hybrid tuning technique with an improved adjusting capacitor method was applied. An toroid inductor of 700 mH is shunted in to the load resistance and shunt capacitance. Results show an extended frequency range up to 12 resonance frequencies (300% improvement) with improved power up to 197%. Finally, a hybrid piezoelectric and pyroelectric system is designed and tested. Using a voltage doubler, circuit for rectifying and collecting pyroelectric and piezoelectric voltages individually is proposed. The investigation showed that the hybrid energy is possible using the voltage doubler circuit from two independent sources for pyroelectrictity and piezoelectricity due to marked differences of optimal performance.

  13. Spatial solitons in biased photovoltaic photorefractive materials with the pyroelectric effect

    Energy Technology Data Exchange (ETDEWEB)

    Katti, Aavishkar; Yadav, R.A., E-mail: rayadav@bhu.ac.in

    2017-01-23

    Spatial solitons in biased photorefractive media due to the photovoltaic effect and the pyroelectric effect are investigated. The pyroelectric field considered is induced due to the heating by the incident beam's energy. These solitons can be called screening photovoltaic pyroelectric solitons. It is shown that the solitons can exist in the bright and dark realizations. The conditions for formation of these solitons are discussed. Relevant example is considered to illustrate the self trapping of such solitons. The external electric field interacts with the photovoltaic field and the pyroelectric field to either support or oppose the self trapping. - Highlights: • Effect of pyroelectric field on screening photovoltaic solitons is studied. • Illumination induced pyroelectric field is considered for the first time. • Self trapping depends on external, pyroelectric and photovoltaic space charge field.

  14. Improved Response of ZnO Films for Pyroelectric Devices

    Directory of Open Access Journals (Sweden)

    Shih-Yuan Yu

    2012-12-01

    Full Text Available Increasing the temperature variation rate is a useful method for enhancing the response of pyroelectric devices. A three-dimensional ZnO film was fabricated by the aerosol deposition (AD rapid process using the shadow mask method, which induces lateral temperature gradients on the sidewalls of the responsive element, thereby increasing the temperature variation rate. To enhance the quality of the film and reduce the concentration of defects, the film was further treated by laser annealing, and the integration of a comb-like top electrode enhanced the voltage response and reduced the response time of the resulting ZnO pyroelectric devices.

  15. Pyroelectric Energy Harvesting: With Thermodynamic-Based Cycles

    Directory of Open Access Journals (Sweden)

    Saber Mohammadi

    2012-01-01

    Full Text Available This work deals with energy harvesting from temperature variations using ferroelectric materials as a microgenerator. The previous researches show that direct pyroelectric energy harvesting is not effective, whereas thermodynamic-based cycles give higher energy. Also, at different temperatures some thermodynamic cycles exhibit different behaviours. In this paper pyroelectric energy harvesting using Lenoir and Ericsson thermodynamic cycles has been studied numerically and the two cycles were compared with each other. The material used is the PMN-25 PT single crystal that is a very interesting material in the framework of energy harvesting and sensor applications.

  16. An integrated charge amplifier for a pyroelectric sensor

    NARCIS (Netherlands)

    Setiadi, D.; Armitage, A.; Binnie, T.D.; Regtien, P.P.L.; Sarro, P.M.

    1997-01-01

    This paper presents an integrated charge amplifier that measures a small charge. This charge is generated by a pyroelectric detector. The charge amplifier consists of a single-stage c-annon source configuration with a passive feedback network. The charge amplifier has a bandwidth of 700 kHz and an o

  17. A Meliorated Multi-Frequency Band Pyroelectric Sensor

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2015-07-01

    Full Text Available This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

  18. Application of LiTaO3 pyroelectric crystal for pulsed neutron detection

    Science.gov (United States)

    Liang, W. F.; Lu, Y.; Wu, J.; Gao, H.; Li, M.

    2016-08-01

    The feasibility of a LiTaO3 pyroelectric crystal for pulsed neutron detection has been studied. The detector consists of a slice of electroded Z-cut LiTaO3 pyroelectric crystal, and no additional neutron converter is required owing to the Li contained in the crystal. The slight temperature increase caused by neutron radiation will lead to the release of bound charges and will give rise to a pyroelectric signal. The response of it has been studied both theoretically and experimentally. Our preliminary experiment on the CFBR-II reactor suggests that the LiTaO3 pyroelectric detector is promising for high intensity neutron - pulse measurement.

  19. Spatial solitons in biased photovoltaic photorefractive materials with the pyroelectric effect

    Science.gov (United States)

    Katti, Aavishkar; Yadav, R. A.

    2017-01-01

    Spatial solitons in biased photorefractive media due to the photovoltaic effect and the pyroelectric effect are investigated. The pyroelectric field considered is induced due to the heating by the incident beam's energy. These solitons can be called screening photovoltaic pyroelectric solitons. It is shown that the solitons can exist in the bright and dark realizations. The conditions for formation of these solitons are discussed. Relevant example is considered to illustrate the self trapping of such solitons. The external electric field interacts with the photovoltaic field and the pyroelectric field to either support or oppose the self trapping.

  20. Real-time assessment of a linear pyroelectric sensor array for object classication

    Science.gov (United States)

    White, William E., III; Brown, Jeremy B.; Chari, Srikant; Jacobs, Eddie L.

    2010-10-01

    Pyroelectric linear arrays can be used to generate profiles of targets. Simulations have shown that generated profiles can be used to classify human and animal targets. A pyroelectric array system was used to collect data and classify targets as either human or non-human in real time. The pyroelectric array system consists of a 128-element Dias 128LTI pyroelectric linear array, an F/0.86 germanium lens, and an 18F4550 pic microcontroller for A/D conversion and communication. The classifier used for object recognition was trained using data collected in petting zoos and tested using data collected at the US-Mexico border in Arizona.

  1. Fabrication of a ZnO Pyroelectric Sensor

    Directory of Open Access Journals (Sweden)

    Yuh-Chung Hu

    2008-01-01

    Full Text Available This paper proposes a two-step radio frequency (RF sputtering process to forma ZnO film for pyroelectric sensors. It is shown that the two-step sputtering process with alower power step followed by a higher power step can significantly improve the voltageresponsivity of the ZnO pyroelectric sensor. The improvement is attributed mainly to theformation of ZnO film with a strongly preferred orientation towards the c-axis.Furthermore, a nickel film deposited onto the uncovered parts of the ZnO film caneffectively improve the voltage responsivity at higher modulating frequencies since thenickel film can enhance the incident energy absorption of the ZnO layer.

  2. A virtual experiment on pyroelectric X-ray generator

    Energy Technology Data Exchange (ETDEWEB)

    Nasseri, Mohammad Mehdi, E-mail: mnasseri@aeoi.org.ir

    2015-09-01

    The production of pyroelectric type X-ray generators has a long term background. In case of using X-ray generators containing two pyroelectric crystals, some parameters have not been practically measured yet. This article aims to calculate such parameters by means of Geant4 Mont Carlo codes. The obtained edge energy of initial electrons was 3 keV at a constant pressure of 1mTorr and electric field of 250 kV/cm. The amplification coefficient production of electrons was increased reaching to a constant value of 2.7. The observed mean energy of produced gas ions was approximately 39 eV, equivalent to 5.7% of the emitted electrons. The efficiency of the generated X-ray was about 63% and did not show a considerable change as the energy of initial electrons increased.

  3. Fusion of Multiple Pyroelectric Characteristics for Human Body Identification

    Directory of Open Access Journals (Sweden)

    Wanchun Zhou

    2014-12-01

    Full Text Available Due to instability and poor identification ability of single pyroelectric infrared (PIR detector for human target identification, this paper proposes a new approach to fuse the information collected from multiple PIR sensors for human identification. Firstly, Fast Fourier Transform (FFT, Short Time Fourier Transform (STFT, Wavelet Transform (WT and Wavelet Packet Transform (WPT are adopted to extract features of the human body, which can be achieved by single PIR sensor. Then, we apply Principal Component Analysis (PCA and Support Vector Machine (SVM to reduce the characteristic dimensions and to classify the human targets, respectively. Finally, Fuzzy Comprehensive Evaluation (FCE is utilized to fuse recognition results from multiple PIR sensors to finalize human identification. The pyroelectric characteristics under scenarios with different people and/or different paths are analyzed by various experiments, and the recognition results with/without fusion procedure are also shown and compared. The experimental results demonstrate our scheme has improved efficiency for human identification.

  4. Wireless intelligent alarm technology with pyroelectric infrared sensor

    Science.gov (United States)

    Chen, Xiao

    2009-07-01

    Aiming at the defects of monitoring conducted by man in the conventional practice, we study the passive intelligent automatic alarm technology based on the pyroelectric infrared sensor and wireless communication technology. The designed passive infrared wireless alarm is composed of pyroelectric infrared sensors, infrared special chip BISS0001 and their peripheral circuits. When someone enters into the detecting and monitoring range, the alarm will detect the infrared ray of the human radiation by the contactless form and detect the signals of circuit output. Then it translates them into low frequency signals relative with human sports speed, distance and direction, produce corresponding output signals through amplifying by the back state controller, switch on the work power of the wireless transmitting circuit and make it emit the alarm signals. The system enhances the monitoring level and effects and possesses many advantages such as wide detecting range, long detecting distance and high reliability.

  5. Pyroelectric materials as electronic pulse detectors of ultraheavy nuclei

    Science.gov (United States)

    Simpson, J. A.; Tuzzolino, A. J.

    1984-01-01

    The design and testing of ultraheavy-nucleus pulse detectors based on pyroelectric materials are reported, extending the preliminary findings of Tuzzolino (1983) and Simpson and Tuzzolino (1983). Uranium-ion beams of about 240 MeV/u are detected by a 39.5-micron-thick Si detector, degraded to about 175 MeV/u by Al absorbers, and then strike 700-micron-thick polyvinylidene fluoride or 1000-micron-thick LiTaO3 pyroelectric samples. Both detector systems are connected to a coincidence circuit via charge-sensitive preamplifiers, shaping amplifiers with 30-microsec effective time constants, and electronic discriminators. Sample spectra are shown, and the pulse heights measured are found to agree with theoretical calculations to within a factor of about 2. The response of the pyroelectric materials is found to be unaffected by exposure to about 10 Mrad of 2-7-MeV/u heavy ion radiation. With further study and improvement of the detection sensitivity, devices of this type could be applied to large-area space measurements of low ultraheavy-ion fluxes.

  6. Feasibility study of thermal energy harvesting using lead free pyroelectrics

    Science.gov (United States)

    Karim, Hasanul; Sarker, Md Rashedul H.; Shahriar, Shaimum; Arif Ishtiaque Shuvo, Mohammad; Delfin, Diego; Hodges, Deidra; (Bill Tseng, Tzu-Liang; Roberson, David; Love, Norman; Lin, Yirong

    2016-05-01

    Energy harvesting has significant potential for applications in energizing wireless sensors and charging energy storage devices. To date, one of the most widely investigated materials for mechanical and thermal energy harvesting is lead zirconate titanate (PZT). However, lead has detrimental effects on the environment and on health. Hence, alternative materials are required for this purpose. In this paper, a lead free material, lithium niobate (LNB) is investigated as a potential material for pyroelectric energy harvesting. Although its theoretical pyroelectric properties are lower compared to PZT, it has better properties than other lead free alternatives such as ZnO. In addition, LNB has a high Curie temperature of about 1142 °C, which makes it applicable for high temperature energy harvesting, where other pyroelectric ceramics are not suitable. Herein, an energy harvesting and storage system composed of a single crystal LNB and a porous carbon-based super-capacitor was investigated. It is found that with controlled heating and cooling, a single wafer of LNB (75 mm diameter and 0.5 mm thickness) could generate 437.72 nW cm-3 of power and it could be used to charge a super-capacitor with a charging rate of 2.63 mV (h cm3)-1.

  7. A VDF/TrFE copolymer on silicon pyroelectric sensor: design considerations and experiments

    NARCIS (Netherlands)

    Setiadi, D.; Regtien, P.P.L.

    1995-01-01

    For an optimal design of a VDF/TrFE (vinylidene fluoride trifluoroethylene) copolymer-on-silicon pyroelectric sensor, the one-dimensional diffusion equation is solved for the pyroelectric multilayer structure. Output current and voltage of the sensor are calculated. Improvement of the sensor can be

  8. Pyroelectric effect and polarization instability in self-assembled diphenylalanine microtubes

    Science.gov (United States)

    Esin, A.; Baturin, I.; Nikitin, T.; Vasilev, S.; Salehli, F.; Shur, V. Ya.; Kholkin, A. L.

    2016-10-01

    The natural ability of peptides and proteins to self-assemble into elongated fibrils is associated with several neurogenerative diseases. Diphenylalanine (FF) tubular structures that have the same structural motif as in Aβ-amyloid peptide (involved in Alzheimer's disease) are shown to possess remarkable physical properties ranging from piezoelectricity to electrochemical activities. In this work, we also discover a significant pyroelectric activity and measure the temperature dependence of the pyroelectric coefficient in the temperature range of 20-100 °C. Pyroelectric activity decreases with temperature contrary to most ferroelectric materials and significant relaxation of pyrocurrent is observed on cooling after heating above 50 °C. This unusual behavior is assigned to the temperature-induced disorder of water molecules inside the nanochannels. Pyroelectric coefficient and current and voltage figures of merit are estimated and future applications of pyroelectric peptide nanostructures in biomedical applications are outlined.

  9. Potassium dihydrogen phosphate and potassium tantalate niobate pyroelectric materials and far-infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, H. B. [Lawrence Berkeley Lab., CA (United States); [California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1993-10-01

    This thesis discusses characterization of two ferroelectric materials and the fabrication of bolometers. Potassium tantalate niobate (KTN) and potassium dihydrogen phosphate (KDP) are chosen because they can be optimized for operation near 100K. Chap. 2 reviews the physics underlying pyroelectric materials and its subclass of ferroelectric materials. Aspects of pyroelectric detection are discussed in Chap. 3 including measurement circuit, noise sources, and effects of materials properties on pyroelectric response. Chap. 4 discusses materials selection and specific characteristics of KTN and KDP; Chap. 5 describes materials preparation; and Chap. 6 presents detector configuration and a thermal analysis of the pyroelectric detector. Electrical techniques used to characterize the materials and devices and results are discussed in Chap. 7 followed by conclusions on feasibility of KDP and KTN pyroelectric detectors in Chap. 8.

  10. FT-infrared and pyroelectric studies on calix[8]arene Langmuir-Blodgett films

    CERN Document Server

    Oliviere, P A R

    2001-01-01

    that the remaining acid groups form either facing dimers with the amine or sideways dimers between themselves. The spectra do not change with temperature. This demonstrates that the films are thermally stable. Additionally, this invariance shows that the pyroelectric activity in these films does not arise from a change in the proton transfer as has been previously postulated. Theoretical calculations undertaken predict that the source of the dipole change required for the level of pyroelectric activity seen is likely to be a change in distance between the acid and amine groups. Further observations, quantitatively examined by curve fitting techniques, show that the greater the number of proton-transferred pairs, the lower the pyroelectric coefficient. Thus, only the temperature-dependent separation of the acid and amine pairs which have not undergone proton transfer is responsible for the pyroelectric activity in these systems. Pyroelectric activity is exhibited by materials which possess a spontaneous temper...

  11. Neutron interrogation systems using pyroelectric crystals and methods of preparation thereof

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Vincent; Meyer, Glenn A.; Falabella, Steven; Guethlein, Gary; Rusnak, Brian; Sampayan, Stephen; Spadaccini, Christopher M.; Wang, Li-Fang; Harris, John; Morse, Jeff

    2017-08-01

    According to one embodiment, an apparatus includes a pyroelectric crystal, a deuterated or tritiated target, an ion source, and a common support coupled to the pyroelectric crystal, the deuterated or tritiated target, and the ion source. In another embodiment, a method includes producing a voltage of negative polarity on a surface of a deuterated or tritiated target in response to a temperature change of a pyroelectric crystal, pulsing a deuterium ion source to produce a deuterium ion beam, accelerating the deuterium ion beam to the deuterated or tritiated target to produce a neutron beam, and directing the ion beam onto the deuterated or tritiated target to make neutrons using a voltage of the pyroelectric crystal and/or an HGI surrounding the pyroelectric crystal. The directionality of the neutron beam is controlled by changing the accelerating voltage of the system. Other apparatuses and methods are presented as well.

  12. Temperature Field Analysis for PZT Pyroelectric Cells for Thermal Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Chi-Yuan Lee

    2011-11-01

    Full Text Available This paper proposes the idea of etching PZT to improve the temperature variation rate of a thicker PZT sheet in order to enhance the energy conversion efficiency when used as pyroelectric cells. A partially covered electrode was proven to display a higher output response than a fully covered electrode did. A mesh top electrode monitored the temperature variation rate and the electrode area. The mesh electrode width affected the distribution of the temperature variation rate in a thinner pyroelectric material. However, a pyroelectric cell with a thicker pyroelectric material was beneficial in generating electricity pyroelectrically. The PZT sheet was further etched to produce deeper cavities and a smaller electrode width to induce lateral temperature gradients on the sidewalls of cavities under homogeneous heat irradiation, enhancing the temperature variation rate.

  13. Long—Range Effects on the Pyroelectric Coefficient of Ferroelectric Superlattice

    Institute of Scientific and Technical Information of China (English)

    DONGWen; WUYin-Zhong; 等

    2002-01-01

    Long-range effects on the pyroelectric coefficient of a ferroelectric superlattice consisting of two different ferroelectric materials are investigated based on the transverse Ising model.The effects of the interfacial coupling and the thickness of one period on the pyroelectric coefficient of the ferroelectric superlattics are studied by taking into account the long-range interaction.It is found that with the increase of the strength of the long-range interaction,the pyroelectric coefficient decreases when the temperature is lower than the phase transition temperature;the mumber of the pyroelectric peaks decreases gradually and the phase transition temperature increases,It is also found that with the decrease of the interfacial coupling and the thickness of one period.the phase transition temperature and the number of the pyroelectric peaks decrease.

  14. Pyroelectric response in crystalline hafnium zirconium oxide (Hf1-xZrxO2) thin films

    Science.gov (United States)

    Smith, S. W.; Kitahara, A. R.; Rodriguez, M. A.; Henry, M. D.; Brumbach, M. T.; Ihlefeld, J. F.

    2017-02-01

    Pyroelectric coefficients were measured for 20 nm thick crystalline hafnium zirconium oxide (Hf1-xZrxO2) thin films across a composition range of 0 ≤ x ≤ 1. Pyroelectric currents were collected near room temperature under zero applied bias and a sinusoidal oscillating temperature profile to separate the influence of non-pyroelectric currents. The pyroelectric coefficient was observed to correlate with zirconium content, increased orthorhombic/tetragonal phase content, and maximum polarization response. The largest measured absolute value was 48 μCm-2 K-1 for a composition with x = 0.64, while no pyroelectric response was measured for compositions which displayed no remanent polarization (x = 0, 0.91, and 1).

  15. Note: Portable rare-earth element analyzer using pyroelectric crystal

    Energy Technology Data Exchange (ETDEWEB)

    Imashuku, Susumu, E-mail: imashuku.susumu.2m@kyoto-u.ac.jp; Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun [Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  16. Investigation on the pyroelectric property of polycrystalline GdMnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X. [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Zhao, Y. G., E-mail: ygzhao@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Cui, Y. F.; Ye, L. D.; Zhao, D. Y.; Li, P. S.; Wang, J. W.; Zhu, M. H.; Zhang, H. Y. [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Rao, G. H., E-mail: rgh@guet.edu.cn [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2014-02-10

    Pyroelectric property of orthorhomic GdMnO{sub 3} polycrystalline samples was investigated. Two pyrocurrent peaks were observed with the sharp one near 20 K and the broad one at around 120 K. The dependences of these two peaks on magnetic field, heating rate, and poling voltage were explored systematically. The sharp peak is related to the ferroelectric transition, while the behavior of the broad one corresponds to dipole reorientation. Some key pyroelectric features are proposed to separate the spin-induced ferroelectricity from other effects. This work is helpful for understanding the pyroelectric property of multiferroic materials.

  17. Improper Ferroelectricity in Stuffed Aluminate Sodalites for Pyroelectric Energy Harvesting

    Science.gov (United States)

    Maeda, Yusaku; Wakamatsu, Toru; Konishi, Ayako; Moriwake, Hiroki; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Tanabe, Kenji; Terasaki, Ichiro; Taniguchi, Hiroki

    2017-03-01

    In the present study, we demonstrate ferroelectricity in stuffed aluminate sodalites (Ca1 -xSrx)8[AlO2]12(WO4)2 (x ≤0.2 ) (C1 -xSxAW ). Pyroelectric measurements clarify switchable spontaneous polarization in polycrystalline C1 -xSxAW , whose polarization values are on the order of 10-2 μ C /cm2 at room temperature. A weak anomaly in the dielectric permittivity at temperatures near the ferroelectric transition temperature suggests improper ferroelectricity of C1 -xSxAW for all investigated values of x . A comprehensive study involving synchrotron x-ray powder diffraction measurements, molecular dynamics simulations, and first-principles calculations clarifies that the ferroelectric phase transition of C1 -xSxAW is driven by the freezing of the fluctuations of WO4 tetrahedra in the voids of an [AlO2]12 12 - framework. The voltage response and electromechanical coupling factor of C1 -xSxAW estimated from the present results indicate that this material exhibits excellent performance as a pyroelectric energy harvester, suggesting that aluminate sodalites exhibit great promise as a class of materials for highly efficient energy-harvesting devices.

  18. Thermal Energy Harvesting Using Pyroelectric and Piezoelectric Effect

    Science.gov (United States)

    Kang, Miwon; Yeatman, Eric M.

    2016-11-01

    This paper presents a prototype of a thermal energy harvesting mechanism using both pyroelectric and piezoelectric effect. Thermal energy is one of abundant energy sources from various processes. Waste heat from a chip on a circuit board of the electronic device involves temperature differences from a few degrees C to over 100 °C. Therefore, 95 °C of a heat reservoir was used in this study. A repetitive time-dependant temperature variation is applied by a linear sliding table. The influence of heat conditions was investigated, by changing velocity and frequency of this linear sliding table. This energy harvesting mechanism employs Lead Zirconate Titanate (PZT-5H), a bimetal beam and two neodymium magnets. The pyroelectric effect is caused by a time-dependent temperature variation, and the piezoelectric effect is caused by stress from deformation of the bimetal. A maximum power output 0.54 μW is obtained at an optimal condition when the load resistance is 610 kΩ.

  19. Long-Range Effects on the Pyroelectric Coefficient of Ferroelectric Superlattice

    Institute of Scientific and Technical Information of China (English)

    DONG Wen; YAO Dong-Lai; WU Yin-Zhong; LI Zhen-Ya

    2002-01-01

    Long-range effects on the pyroelectric coefficient of a ferroelectric superlattice consisting of two differentferroelectric materials are investigated based on the transverse Ising model. The effects of the interfacial coupling andthe thickness of one period on the pyroelectric coefficient of the ferroelectric superlattice are studied by taking intoaccount the long-range interaction. It is found that with the increase of the strength of the long-range interaction, thepyroelectric coefficient decreases when the temperature is lower than the phase transition temperature; the number ofthe pyroelectric peaks decreases gradually and the phase transition temperature increases. It is also found that with thedecrease of the interfacial coupling and the thickness of one period, the phase transition temperature and the number ofthe pyroelectric peaks decrease.

  20. The pyroelectric coefficient of free standing GaN grown by HVPE

    Science.gov (United States)

    Jachalke, Sven; Hofmann, Patrick; Leibiger, Gunnar; Habel, Frank S.; Mehner, Erik; Leisegang, Tilmann; Meyer, Dirk C.; Mikolajick, Thomas

    2016-10-01

    The present study reports on the temperature dependent pyroelectric coefficient of free-standing and strain-free gallium nitride (GaN) grown by hydride vapor phase epitaxy (HVPE). The Sharp-Garn method is applied to extract the pyroelectric coefficient from the electrical current response of the crystals subjected to a sinusoidal temperature excitation in a range of 0 °C to 160 °C. To avoid compensation of the pyroelectric response by an internal conductivity, insulating GaN crystals were used by applying C, Mn, and Fe doping during HVPE growth. The different pyroelectric coefficients observed at room temperature due to the doping correlate well with the change of the lattice parameter c. The obtained data are compared to previously published theoretical and experimental values of thin film GaN and discussed in terms of a strained lattice.

  1. Dielectric and pyroelectric properties of lead zirconate titanate/polyurethane composites

    Science.gov (United States)

    Lam, K. S.; Wong, Y. W.; Tai, L. S.; Poon, Y. M.; Shin, F. G.

    2004-10-01

    0-3 composite ranging between 0 and 3, of ferroelectric ceramic lead zirconate titanate (PZT) and thermoplastic elastomer polyurethane (PU) were fabricated. The pyroelectric and dielectric properties of the hot-pressed thin film samples of various PZT volume fractions were measured. The experimental dielectric permittivities and losses agreed reasonably well with the Bruggeman model. The room temperature pyroelectric coefficients of the composites were found to increase linearly with PZT volume fraction and substantially larger than expected. For example, for a composite with 30% PZT, its pyroelectric coefficient is about 90μC/m2K at room temperature, which is more than tenfold of a PZT/PVDF composite of the same ceramic volume fraction. We propose a model in which the electrical conductivity of the composite system is taken into consideration to explain the linear relationship and the extraordinarily large pyroelectric coefficients obtained.

  2. Longitudinal and transverse pyroelectric effects in a chiral ferroelectric liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yablonskii, S. V., E-mail: yablonskii2005@yandex.ru; Bondarchuk, V. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Soto-Bustamante, E. A.; Romero-Hasler, P. N. [Universidad de Chile (Chile); Ozaki, M. [Osaka University, Department of Electronic Engineering, Faculty of Engineering (Japan); Yoshino, K. [Shimane Institute for Industrial Technology (Japan)

    2015-04-15

    In this study, we compare the results of experimental investigations of longitudinal and transverse pyroelectric effects in a chiral ferroelectric crystal. In a transverse geometry, we studied freely suspended liquid-crystal films. In both geometries, samples exhibited bistability, demonstrating stable pyroelectric signals of different polarities at zero voltage. It is shown that a bistable cell based on a freely suspended film requires 40 times less energy expenditures as compared to the conventional sandwich-type cell.

  3. Controlling dielectric and pyroelectric properties of compositionally graded ferroelectric rods by an applied pressure

    Science.gov (United States)

    Zheng, Yue; Woo, C. H.; Wang, Biao

    2007-06-01

    The polarization, charge offset, dielectric, and pyroelectric properties of a compositionally graded ferroelectric rod inside a high-pressure polyethylene tube are studied using a thermodynamic model based on the Landau-Ginzburg-Devonshire formulation. The calculated distribution of the polarization in the rod is nonuniform, and the corresponding charge offset, dielectric, and pyroelectric properties vary according to the applied pressure. This behavior may be used as a convenient means to control these properties for design optimization.

  4. Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

    Science.gov (United States)

    Park, Teahoon; Na, Jongbeom; Kim, Byeonggwan; Kim, Younghoon; Shin, Haijin; Kim, Eunkyoung

    2015-12-22

    Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display.

  5. Denoising Using Blind Source Separation for Pyroelectric Sensors

    Directory of Open Access Journals (Sweden)

    Huez Regis

    2001-01-01

    Full Text Available This paper deals with a process of denoising based on a Blind Source Separation (BSS method. This technique is inserted in an experimental device of nondestructive testing. Its excitation is a laser beam and its detectors are pyroelectric sensors. The latter are sensitive to the temperature. As they are also piezoelectric, they are particularly sensitive to the environmental noise. Therefore, it is necessary to denoise them. With this aim in view, a technique of blind source separation is implemented. One source corresponds to the incidental beam and the other sources are various noise. A judicious experimental device was designed in the laboratory. It fits to the requirements of the BSS technique, and it allows indeed a restoration of the incident signal.

  6. Determination of surface electric charge profile in pyroelectric crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ghaderi, R.; Davani, F. Abbasi, E-mail: fabbasi@sbu.ac.ir [Radiation Application Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2014-12-08

    Pyroelectric crystals are used to produce high energy self-focused electron beams. Here, an experimental analysis in combination with simulation studies will be reported to investigate possible sources of this effect. In the experiments, the surface of crystal was divided into six separated parts and the rate of surface electric charge production was measured accordingly. A non-steady and spatially non-uniform distribution of the surface charge generation was observed, in which it tends to a uniform distribution in the course of experiment. The obtained surface electric charges from the experiments were used to simulate the electric field and potential around the crystal by COMSOL Multiphysics. It was observed that emitted electrons from the crystal surface were focused, and the non-uniformity in spatial charge is responsible for this phenomenon.

  7. A temperature oscillation instrument to determine pyroelectric properties of materials at low frequencies: Towards elimination of lock-in methods

    NARCIS (Netherlands)

    Khanbareh, H.; Schelen, J.B.J.; Van der Zwaag, S.; Groen, W.A.

    2015-01-01

    Pyroelectric properties of materials can be accurately determined by applying a new digital signal processing method on the discrete sampled data obtained with a temperature oscillation technique. The pyroelectric coefficient is calculated from the component of the generated current 90∘ out of phase

  8. Mechanism of the Pyroelectric Response under Direct-Current Bias in La-Modified Lead Zirconate Titanate Stannate Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-Ling; WANG Gen-Shui; CHEN Xue-Feng; CAO Fei; DONG Xian-Lin; GU Yan; HE Hong-Liang; LIU Yu-Sheng

    2011-01-01

    Dielectric and pyroelectric properties ofPbo.97Lao.o2(Zro.42Sno.4oTio.i8)03 ceramics are investigated as functions of temperature and dc bias field. Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed. It is found that the sign, value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases. Polarization and depolarization processes under dc biases are analyzed. Besides the contribution of pind, the diffuse and decreased pyroelectric response under dc bias compared with that of an identical Geld poled sample without dc bias is mainly attributed to the depolarization process under dc bias.%@@ Dielectric and pyroelectric properties of Pbo.s7Lao.o2(Zro.42Sno.4OTio.is)O3 ceramics are investigated as functions of temperature and do bias field.Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed.It is found that the sign,value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases.Polarization and depolarization processes under do biases are analyzed.Besides the contribution of pind,the diffuse and decreased pyroelectric response under do bias compared with that of an identical field poled sample without do bias is mainly attributed to the depolarization process under do bias.

  9. A temperature oscillation instrument to determine pyroelectric properties of materials at low frequencies: Towards elimination of lock-in methods.

    NARCIS (Netherlands)

    Khanbareh, H.; Schelen, J.B.J.; van der Zwaag, S.; Groen, W.A.

    2015-01-01

    Pyroelectric properties of materials can be accurately determined by applying a new digital signal processing method on the discrete sampled data obtained with a temperature oscillation technique. The pyroelectric coefficient is calculated from the component of the generated current 90(∘) out of pha

  10. Application of LiTaO{sub 3} pyroelectric crystal for pulsed neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Liang, W.F., E-mail: liang_wen_feng@163.com [CAEP Key Laboratory of Neutron Physics, Mianyang 621900 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Lu, Y.; Wu, J.; Gao, H.; Li, M. [CAEP Key Laboratory of Neutron Physics, Mianyang 621900 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-08-11

    The feasibility of a LiTaO{sub 3} pyroelectric crystal for pulsed neutron detection has been studied. The detector consists of a slice of electroded Z-cut LiTaO{sub 3} pyroelectric crystal, and no additional neutron converter is required owing to the Li contained in the crystal. The slight temperature increase caused by neutron radiation will lead to the release of bound charges and will give rise to a pyroelectric signal. The response of it has been studied both theoretically and experimentally. Our preliminary experiment on the CFBR-II reactor suggests that the LiTaO{sub 3} pyroelectric detector is promising for high intensity neutron – pulse measurement. - Highlights: • LiTaO{sub 3} pyroelectric neutron detector can be used with no additional neutron converter. • Relationship between the pulsed neutron field and the voltage signal was obtained. • Experiment was carried out to test the response of LiTaO{sub 3} detector. • Feasibility of LiTaO{sub 3} for intense neutron pulse measurement was confirmed.

  11. High-frequency thermal-electrical cycles for pyroelectric energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, Bikram [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Damodaran, Anoop R. [Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Cho, Hanna [Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Martin, Lane W. [Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); King, William P., E-mail: wpk@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2014-11-21

    We report thermal to electrical energy conversion from a 150 nm thick BaTiO{sub 3} film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 μs. The rapid electric field changes as high as 11 × 10{sup 5 }kV/cm-s, and temperature change rates as high as 6 × 10{sup 5 }K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems.

  12. Energy harvesting from pavements via PVDF: hybrid piezo-pyroelectric effects

    Science.gov (United States)

    Tao, Junliang; Hu, Jie; Wu, Guangxi

    2016-04-01

    In the U.S., there are over 4 million miles (6 million km) of roadways and more than 250 million registered vehicles. The energy lost in the pavement system due to traffic-induced vibration and deformation is enormous. If effectively harvested, such energy can serve as an alternative sustainable energy source that can be easily integrated to the transportation system. The potential of PVDF, which is a piezoelectric polymer material, is investigated as a potential energy harvester integrated in pavement systems. The uniqueness of this study lies in that the electrical response of PVDF under coupled mechanical and thermal stimulations are studied. It is well known that most piezoelectric materials are also pyroelectric materials, which convert temperature change into electricity. However, the potential of PVDF as a hybrid piezo-pyroelectric energy harvester has been seldom studied. Through series of well controlled experiments, it is found that there exists interesting coupling phenomenon between piezoelectric and pyroelectric effects of PVDF: the voltage generated by simultaneous mechanical and thermal stimulations is the sum of voltages generated by separate stimulations. In addition, an estimation of power generation through piezoelectric and pyroelectric effect is conducted. Finally, the overall effects of temperature on hybrid piezo-pyroelectric energy harvesting are discussed.

  13. An infrared-driven flexible pyroelectric generator for non-contact energy harvester.

    Science.gov (United States)

    Zhao, Tingting; Jiang, Weitao; Liu, Hongzhong; Niu, Dong; Li, Xin; Liu, Weihua; Li, Xuan; Chen, Bangdao; Shi, Yongsheng; Yin, Lei; Lu, Bingheng

    2016-04-21

    In recent years, energy harvesting technologies, which can scavenge many kinds of energies from our living environment to power micro/nanodevices, have attracted increasing attention. However, remote energy transmission, flexibility and electric waveform controllability remain the key challenges for wireless power supply by an energy harvester. In this paper, we design a new infrared-driven non-contact pyroelectric generator for harvesting heat energy, which avoids direct contact between the pyroelectric generator and heat source and realizes remote energy transfer exploiting the photothermal and penetrability of infrared light. The output voltage (under the input impedance of 100 MOhm) and short-circuit current of the pyroelectric generator consisting of a CNT/PVDF/CNT layer (20 mm × 5 mm × 100 μm) can be as large as 1.2 V and 9 nA, respectively, under a 1.45 W cm(-2) near-infrared laser (808 nm). We also demonstrate the means by which the pyroelectric generator can modulate square waveforms with controllable periods through irradiation frequency, which is essential for signal sources and medical stimulators. The overshoot of square waveforms are in a range of 9.0%-13.1% with a rise time of 120 ms. The prepared pyroelectric generator can light a liquid crystal display (LCD) in a vacuum chamber from outside. This work paves the way for non-contact energy harvesting for some particular occasions where near-field energy control is not available.

  14. Pyroelectric properties and electrocaloric effect in TGS1-xPx single crystals

    Science.gov (United States)

    Sampathkumar, P.; Srinivasan, K.

    2016-10-01

    Triglycine sulfate (TGS) single crystals modified with phosphoric acid (TGS1-xPx) have been grown by slow evaporation technique at room temperature. Lattice parameters were identified by using single crystal x-ray diffractometer. The dielectric, pyroelectric, ferroelectric properties and electrocaloric effect have been investigated. Curie temperature of grown crystals was determined from dielectric constant measurements at various temperatures at a frequency of 1 kHz. The Curie temperature is found decreased for the TGS single crystals with the addition of phosphoric acid. Room temperature P-E hysteresis loops of TGS1-xPx single crystals are presented. The values of coercive field Ec, spontaneous polarization Ps and internal bias field Eb were obtained from the hysteresis loops. Discussion on pyroelectric properties as a function of temperature and applied electric field is presented. Figure of merits (FOMs) were determined to study the pyroelectric performance of the grown crystals. Among all compositions of x, x = 0.2 (i.e., TGS0.8P0.2) single crystals exhibited the largest pyroelectric coefficient and pyroelectric figure of merit at room temperature. From the above investigations the electrocaloric temperature change, ΔT of TGS1-xPx single crystals at selected applied fields and temperatures are obtained by indirect method and discussed.

  15. Infrared Responsivity of a Pyroelectric Detector with a Single-Wall Carbon Nanotube Coating

    Energy Technology Data Exchange (ETDEWEB)

    Theocharous, E.; Engtrakul, C.; Dillon, A. C.; Lehman, J.

    2008-08-01

    The performance of a 10 mm diameter pyroelectric detector coated with a single-wall carbon nanotube (SWCNT) was evaluated in the 0.8 to 20 {micro}m wavelength range. The relative spectral responsivity of this detector exhibits significant fluctuations over the wavelength range examined. This is consistent with independent absorbance measurements, which show that SWCNTs exhibit selective absorption bands in the visible and near-infrared. The performance of the detector in terms of noise equivalent power and detectivity in wavelength regions of high coating absorptivity was comparable with gold-black-coated pyroelectric detectors based on 50 {micro}m thick LiTaO{sub 3} crystals. The response of this detector was shown to be nonlinear for DC equivalent photocurrents >10{sup -9} A, and its spatial uniformity of response was comparable with other pyroelectric detectors utilizing gold-black coatings. The nonuniform spectral responsivity exhibited by the SWCNT-coated detector is expected to severely restrict the use of SWCNTs as black coatings for thermal detectors. However, the deposition of SWCNT coatings on a pyroelectric crystal followed by the study of the prominence of the spectral features in the relative spectral responsivity of the resultant pyroelectric detectors is shown to provide an effective method for quantifying the impurity content in SWCNT samples.

  16. Pyroelectric composite film for X-ray intensity detection

    Directory of Open Access Journals (Sweden)

    Walter Katsumi Sakamoto

    2012-04-01

    Full Text Available Composite material obtained with modified lead titanate (Pz34 ferroelectric ceramic and polyether-ether-ketone (PEEK polymer matrix was used as sensitive component to measure X-ray intensity in a novel detection system. The sensing element works as a thermal transducer, converting a non-quantified thermal flux into an output measurable quantity of electrical voltage. The samples were obtained up to 60 vol.% of ceramic, by hot pressing the mixture of Pz34 and PEEK powders at 368 °C and applying 12 MPa pressure for 2.0 hours. The sensor response varies from 2.70 to 0.80 V in the energy fluence rate range of 6.30 to 37.20 W.m-2. The absorbed incident energy was analyzed as a function of the ionizing energy. Furthermore, by measuring the pyroelectric activity of the composite film it was observed that there is no degradation of the sensor after the irradiation.

  17. Bullet Design and Fabrication of Dual Mode Pyroelectric Sensor: High Sensitive Energymeter for Nd: YAG Laser and Detector for Chopped He-Ne Laser

    Directory of Open Access Journals (Sweden)

    S. SATAPATHY

    2008-05-01

    Full Text Available Pyroelectric sensor using TGS has been designed and fabricated which can be operated in laser energy meter mode as well as pyroelectric detector mode. The amplifying circuit configuration has very good signal to noise ratio, very high input impedance and low drift. The pyroelectric sensor has been tested using Q-switched Nd: YAG laser and chopped He-Ne laser. The sensitivity of pyroelectric sensor in energymeter mode is 421.7V/J and the voltage responsivity of the pyroelectric sensor is 3.27 V/W in detector mode.

  18. Pyroelectric and dielectric properties of ferroelectric films with interposed dielectric buffer layers

    Science.gov (United States)

    Espinal, Y.; Kesim, M. T.; Misirlioglu, I. B.; Trolier-McKinstry, S.; Mantese, J. V.; Alpay, S. P.

    2014-12-01

    The dielectric and pyroelectric properties of c-domain ferroelectric films with linear dielectric buffer layers were investigated theoretically. Computations were carried out for multilayers consisting of PbZr0.2Ti0.8O3 with Al2O3, SiO2, Si3N4, HfO2, and TiO2 buffers on metalized Si. It is shown that the dielectric and pyroelectric properties of such multilayers can be increased by the presence of the buffer compared to ferroelectric monolayers. Calculations for PbZr0.2Ti0.8O3 films with 1% Al2O3 interposed between electrodes on Si show that the dielectric and pyroelectric coefficients are 310 and 0.070 μC cm-2 °C-1, respectively. Both values are higher than the intrinsic response of PbZr0.2Ti0.8O3 monolayer on Si.

  19. Layer thickness and period as design parameters to tailor pyroelectric properties in ferroelectric superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Misirlioglu, I. B., E-mail: burc@sabanciuniv.edu [Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla/Orhanli, 34956 Istanbul (Turkey); Kesim, M. T. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Alpay, S. P. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-10-27

    We theoretically examine the pyroelectric properties of ferroelectric-paraelectric superlattices as a function of layer thickness and configuration using non-linear thermodynamics coupled with electrostatic and electromechanical interactions between layers. We specifically study PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/SrTiO{sub 3} superlattices. The pyroelectric properties of such constructs consisting of relatively thin repeating units are shown to exceed the pyroelectric response of monolithic PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} films. This is related to periodic internal electric fields generated due to the polarization mismatch between layers that allows tailoring of the shift in the transition temperature. Our results indicate that higher and electric field sensitive pyroresponse can be achieved from layer-by-layer engineered ferroelectric heterostructures.

  20. Effective Pyroelectric Coefficient and Polarization Offset of Compositionally Step-like Graded Ferroelectric Structures

    Institute of Scientific and Technical Information of China (English)

    CAO Hai-Xia; WU Yin-Zhong; LI Zhen-Ya

    2005-01-01

    In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the co.mpositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradient in the compositionally step-like graded structure.

  1. Investigation of the durability of a pyroelectric neutron source and secondary electron suppression

    Energy Technology Data Exchange (ETDEWEB)

    Friske, Eduard; Deuter, Gerhard; Jochum, Josef [Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany)

    2015-04-15

    The performance of a pyroelectric neutron source depends on several factors, such as the achieved high voltage, deuterium gas pressure and the tip geometry. Here we present measurements to investigate the dependency of the neutron production on the high voltage specifically and discuss the interdependency with other factors. In addition we present results showing that a biased grid in front of the target, which is a common way to capture secondary electrons, does not have any significant effect on the amount of electrons streaming back to the pyroelectric crystal. This indicates that the bulk of these electrons does not originate from the target but from a different source. (orig.)

  2. Development of pyroelectric neutron source for calibration of neutrino and dark matter detectors

    Science.gov (United States)

    Chepurnov, A. S.; Ionidi, V. Y.; Gromov, M. B.; Kirsanov, M. A.; Klyuyev, A. S.; Kubankin, A. S.; Oleinik, A. N.; Shchagin, A. V.; Vokhmyanina, K. A.

    2017-01-01

    The laboratory experimental setup for development of pyroelectric neutron generator for calibration of neutrino and dark matter detectors for direct search of Weakly Interacting Massive Particles (WIMP) has been developed. The setup allows providing and controlling the neutrons generation process realized during d-d nuclear fusion. It is shown that the neutrons with energy 2.45 MeV can be generated starting from a level of electric potential generated by pyroelectric crystal about 30 kV, in contrast to the typical neutron tubes which need the applied outer high voltage level about 100 kV.

  3. Quantitative ultrasonic computed tomography using phase-insensitive pyroelectric detectors.

    Science.gov (United States)

    Zeqiri, Bajram; Baker, Christian; Alosa, Giuseppe; Wells, Peter N T; Liang, Hai-Dong

    2013-08-07

    The principle of using ultrasonic computed tomography (UCT) clinically for mapping tissue acoustic properties was suggested almost 40 years ago. Despite strong research activity, UCT been unable to rival its x-ray counterpart in terms of the ability to distinguish tissue pathologies. Conventional piezoelectric detectors deployed in UCT are termed phase-sensitive (PS) and it is well established that this property can lead to artefacts related to refraction and phase-cancellation that mask true tissue structure, particularly for reconstructions involving attenuation. Equally, it has long been known that phase-insensitive (PI) detectors are more immune to this effect, although sufficiently sensitive devices for clinical use have not been available. This paper explores the application of novel PI detectors to UCT. Their operating principle is based on exploiting the pyroelectric properties of the piezoelectric polymer polyvinylidene difluoride. An important detector performance characteristic which makes it particularly suited to UCT, is the lack of directionality of the PI response, relative to the PS detector mode of operation. The performance of the detectors is compared to conventional PS detection methods, for quantitatively assessing the attenuation distribution within various test objects, including a two-phase polyurethane phantom. UCT images are presented for a range of single detector apertures; tomographic reconstruction images being compared with the known structure of phantoms containing inserts as small as 3 mm, which were readily imaged. For larger diameter inserts (>10 mm), the transmitter-detector combination was able to establish the attenuation coefficient of the insert to within ±10% of values determined separately from plane-wave measurements on representative material plaques. The research has demonstrated that the new PI detectors are significantly less susceptible to refraction and phase-cancellation artefacts, generating realistic images in

  4. Human Movement Detection and Identification Using Pyroelectric Infrared Sensors

    Directory of Open Access Journals (Sweden)

    Jaeseok Yun

    2014-05-01

    Full Text Available Pyroelectric infrared (PIR sensors are widely used as a presence trigger, but the analog output of PIR sensors depends on several other aspects, including the distance of the body from the PIR sensor, the direction and speed of movement, the body shape and gait. In this paper, we present an empirical study of human movement detection and identification using a set of PIR sensors. We have developed a data collection module having two pairs of PIR sensors orthogonally aligned and modified Fresnel lenses. We have placed three PIR-based modules in a hallway for monitoring people; one module on the ceiling; two modules on opposite walls facing each other. We have collected a data set from eight subjects when walking in three different conditions: two directions (back and forth, three distance intervals (close to one wall sensor, in the middle, close to the other wall sensor and three speed levels (slow, moderate, fast. We have used two types of feature sets: a raw data set and a reduced feature set composed of amplitude and time to peaks; and passage duration extracted from each PIR sensor. We have performed classification analysis with well-known machine learning algorithms, including instance-based learning and support vector machine. Our findings show that with the raw data set captured from a single PIR sensor of each of the three modules, we could achieve more than 92% accuracy in classifying the direction and speed of movement, the distance interval and identifying subjects. We could also achieve more than 94% accuracy in classifying the direction, speed and distance and identifying subjects using the reduced feature set extracted from two pairs of PIR sensors of each of the three modules.

  5. Realization of an integrated VDF/TrFE copolymer-on-silicon pyroelectric sensor

    NARCIS (Netherlands)

    Setiadi, D.; Regtien, P.P.L.; Sarro, P.M.

    1995-01-01

    An integrated pyroelectric sensor based on a vinylidene fluoride trifluoroethylene (VDF/TrFE) copolymer is presented. A silicon substrate that contains FET readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling of the copolymer has been applied

  6. Effect of dielectrophoretic structuring on piezoelectric and pyroelectric properties of lead titanate-epoxy composites

    NARCIS (Netherlands)

    Khanbareh, H.; Zwaag, S. van der; Groen, W.A.

    2014-01-01

    Functional granular composites of lead titanate particles in an epoxy matrix prepared by dielectrophoresis show enhanced dielectric, piezoelectric and pyroelectric properties compared to 0-3 composites for different ceramic volume content from 10% to 50%. Two structuring parameters, the interparticl

  7. A 3 x 1 Integrated Pyroelectric Sensor Based on VDF/TrFE Copolymer

    NARCIS (Netherlands)

    Setiadi, D.; Sarro, P.M.; Regtien, P.P.L.

    1995-01-01

    This paper presents an integrated pyroelectric sensor based on a Vinylidene Fluoride TriFluoroEthylene (VDF/TrFE) copolymer. A silicon substrate that contains FET readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling of the copolymer has been a

  8. A 3x1 integrated pyroelectric sensor based on VDF/TrFE copolymer

    NARCIS (Netherlands)

    Setiadi, D.; Sarro, P.M.; Regtien, P.P.L.

    1996-01-01

    This paper presents an integrated pyroelectric sensor based on a vinylidene fluoride¿trifluoroethylene (VDF/TrFE) copolymer. A silicon substrate that contains field-effect transistor (FET) readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling o

  9. The Third Way of Thermal-Electric Conversion beyond Seebeck and Pyroelectric Effects

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-02-14

    Thermal-electric conversion is crucial for smart energy control and harvesting, such as thermal sensing and waste heat recovering. So far, people are aware of only two ways of direct thermal-electric conversion, Seebeck and pyroelectric effects, each with distinct working conditions and limitations. Here, we report the third way of thermal-electric conversion beyond Seebeck and pyroelectric effects. In contrast to Seebeck effect that requires spatial temperature difference, the-third-way converts the time-dependent ambient temperature fluctuation into electricity, similar to the behavior of pyroelectricity. However, the-third-way is also distinct from pyroelectric effect in the sense that it does not require polar materials but applies to general conducting systems. We demonstrate that the-third-way results from the temperature-fluctuation-induced dynamical charge redistribution. It is a consequence of the fundamental nonequilibrium thermodynamics and has a deep connection to the topological phase in quantum mechanics. Our findings expand our knowledge and provide new means of thermal-electric energy harvesting.

  10. Piezoelectric and pyroelectric properties of lead titanate-polyethylene oxide composites

    NARCIS (Netherlands)

    Khanbareh, H.; van der Zwaag, S.; Groen, W. A.

    2014-01-01

    Polymer-ceramic composites with pyroelectric sensitivity are presented as promising candidates for infrared detection. Selection of the appropriate ceramic filler and the polymer matrix is one of the key parameters in the development of optimized materials for specific applications. In this work lea

  11. Comparative Performance of PLZT and PVDF Pyroelectric Sensors Used to the Thermal Characterization of Liquid Samples

    Directory of Open Access Journals (Sweden)

    Gemima Lara Hernandez

    2013-01-01

    Full Text Available Among the photothermal methods, the photopyroelectric (PPE technique is a suitable method to determine thermal properties of different kinds of samples ranging from solids to liquids and gases. Polyvinylidene difluoride (PVDF is one of the most frequently used pyroelectric sensors in PPE technique but has the disadvantage that it can be easily deformed by the sample weight. This deformation could add a piezoelectric effect to the thermal parameters assessment; also PVDF has a narrow temperature operation range when compared with ceramic pyroelectric sensors. In order to minimize possible piezoelectric effects due to sensor deformation, a ceramic of lanthanum modified lead zirconate (PLZT was used as pyroelectric sensor in the PPE technique. Then, thermal diffusivity of some liquid samples was measured, by using the PPE configuration that denominated the thermal wave resonator cavity (TWRC, with a PLZT ceramic as pyroelectric detector. The performance obtained with the proposed ceramic in the TWRC configuration was compared with that obtained with PVDF by using the same configuration.

  12. First Principle Based Computation of Pyroelectricity in LiNbO3

    Science.gov (United States)

    Peng, Q.; Cohen, R. E.

    2010-03-01

    Pyroelectricity is of current interest since the discovery of particle acceleration of aqueous ions from changes in temperature at pyroelectric surfaces sufficient to generate hard X-rays[1] as well as neutrons via fusion[2]. We computed the pyroelectric coefficients in LiNbO3 from molecular dynamic simulation with DLPOLY using a shell model potential fitted to Density Functional Theory computations results. The potential was constructed by fitting energies and forces, as well as phonon frequencies and eigenvectors, Born effective charges, and dielectric constants computed from density functional perturbation theory using ABINT. The secondary pyroelectric effect is computed from density functional theory. The spontaneous polarizations were calculated using the Berry phase method. The coefficient of thermal expansivity, elastic moduli, elastic compliances, piezoelectric stress constants and piezoelectric strain constants are computed by linear response and lattice dynamics computations. [1] J. D. Brownridge and S. Raboy, Journal of Applied Physics 86, 640 (1999). [2] B. Naranjo, J. Gimzewski, and S. Putterman, Nature 434, 1115 (2005).

  13. Pyroelectricity Assisted Infrared-Laser Desorption Ionization (PAI-LDI) for Atmospheric Pressure Mass Spectrometry

    Science.gov (United States)

    Li, Yanyan; Ma, Xiaoxiao; Wei, Zhenwei; Gong, Xiaoyun; Yang, Chengdui; Zhang, Sichun; Zhang, Xinrong

    2015-08-01

    A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

  14. An infrared-driven flexible pyroelectric generator for non-contact energy harvester

    Science.gov (United States)

    Zhao, Tingting; Jiang, Weitao; Liu, Hongzhong; Niu, Dong; Li, Xin; Liu, Weihua; Li, Xuan; Chen, Bangdao; Shi, Yongsheng; Yin, Lei; Lu, Bingheng

    2016-04-01

    In recent years, energy harvesting technologies, which can scavenge many kinds of energies from our living environment to power micro/nanodevices, have attracted increasing attention. However, remote energy transmission, flexibility and electric waveform controllability remain the key challenges for wireless power supply by an energy harvester. In this paper, we design a new infrared-driven non-contact pyroelectric generator for harvesting heat energy, which avoids direct contact between the pyroelectric generator and heat source and realizes remote energy transfer exploiting the photothermal and penetrability of infrared light. The output voltage (under the input impedance of 100 MOhm) and short-circuit current of the pyroelectric generator consisting of a CNT/PVDF/CNT layer (20 mm × 5 mm × 100 μm) can be as large as 1.2 V and 9 nA, respectively, under a 1.45 W cm-2 near-infrared laser (808 nm). We also demonstrate the means by which the pyroelectric generator can modulate square waveforms with controllable periods through irradiation frequency, which is essential for signal sources and medical stimulators. The overshoot of square waveforms are in a range of 9.0%-13.1% with a rise time of 120 ms. The prepared pyroelectric generator can light a liquid crystal display (LCD) in a vacuum chamber from outside. This work paves the way for non-contact energy harvesting for some particular occasions where near-field energy control is not available.In recent years, energy harvesting technologies, which can scavenge many kinds of energies from our living environment to power micro/nanodevices, have attracted increasing attention. However, remote energy transmission, flexibility and electric waveform controllability remain the key challenges for wireless power supply by an energy harvester. In this paper, we design a new infrared-driven non-contact pyroelectric generator for harvesting heat energy, which avoids direct contact between the pyroelectric generator and heat

  15. Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses

    Energy Technology Data Exchange (ETDEWEB)

    Kesim, M. T.; Zhang, J.; Alpay, S. P. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Trolier-McKinstry, S. [Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, Pennsylvania 16802 (United States); Mantese, J. V. [United Technologies Research Center, East Hartford, Connecticut 06118 (United States); Whatmore, R. W. [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork City, County Cork (Ireland)

    2013-11-28

    Ferroelectric lead zirconate titanate [Pb(Zr{sub x}Ti{sub 1-x}O){sub 3}, (PZT x:1-x)] has received considerable interest for applications related to uncooled infrared devices due to its large pyroelectric figures of merit near room temperature, and the fact that such devices are inherently ac coupled, allowing for simplified image post processing. For ferroelectric films made by industry-standard deposition techniques, stresses develop in the PZT layer upon cooling from the processing/growth temperature due to thermal mismatch between the film and the substrate. In this study, we use a non-linear thermodynamic model to investigate the pyroelectric properties of polycrystalline PZT thin films for five different compositions (PZT 40:60, PZT 30:70, PZT 20:80, PZT 10:90, PZT 0:100) on silicon as a function of processing temperature (25–800 °C). It is shown that the in-plane thermal stresses in PZT thin films alter the out-of-plane polarization and the ferroelectric phase transformation temperature, with profound effect on the pyroelectric properties. PZT 30:70 is found to have the largest pyroelectric coefficient (0.042 μC cm{sup −2} °C{sup −1}, comparable to bulk values) at a growth temperature of 550 °C; typical to what is currently used for many deposition processes. Our results indicate that it is possible to optimize the pyroelectric response of PZT thin films by adjusting the Ti composition and the processing temperature, thereby, enabling the tailoring of material properties for optimization relative to a specific deposition process.

  16. Spectral responsivity calibrations of two types of pyroelectric radiometers using three different methods

    Science.gov (United States)

    Zeng, J.; Eppeldauer, G. P.; Hanssen, L. M.; Podobedov, V. B.

    2012-06-01

    Spectral responsivity calibrations of two different types of pyroelectric radiometers have been made in the infrared region up to 14 μm in power mode using three different calibration facilities at NIST. One pyroelectric radiometer is a temperature-controlled low noise-equivalent-power (NEP) single-element pyroelectric radiometer with an active area of 5 mm in diameter. The other radiometer is a prototype using the same type of pyroeletric detector with dome-input optics, which was designed to increase absorptance and to minimize spectral structures to obtain a constant spectral responsivity. Three calibration facilities at NIST were used to conduct direct and indirect responsivity calibrations tied to absolute scales in the infrared spectral regime. We report the calibration results for the single-element pyroelectric radiometer using a new Infrared Spectral Comparator Facility (IRSCF) for direct calibration. Also, a combined method using the Fourier Transform Infrared Spectrophotometry (FTIS) facility and single wavelength laser tie-points are described to calibrated standard detectors with an indirect approach. For the dome-input pyroelectric radiometer, the results obtained from another direct calibration method using a circular variable filter (CVF) spectrometer and the FTIS are also presented. The inter-comparison of different calibration methods enables us to improve the responsivity uncertainty performed by the different facilities. For both radiometers, consistent results of the spectral power responsivity have been obtained applying different methods from 1.5 μm to 14 μm with responsivity uncertainties between 1 % and 2 % (k = 2). Relevant characterization results, such as spatial uniformity, linearity, and angular dependence of responsivity, are shown. Validation of the spectral responsivity calibrations, uncertainty sources, and improvements for each method will also be discussed.

  17. Triboelectric-pyroelectric-piezoelectric hybrid cell for high-efficiency energy-harvesting and self-powered sensing.

    Science.gov (United States)

    Zi, Yunlong; Lin, Long; Wang, Jie; Wang, Sihong; Chen, Jun; Fan, Xing; Yang, Po-Kang; Yi, Fang; Wang, Zhong Lin

    2015-04-08

    A triboelectric-pyroelectric-piezoelectric hybrid cell, consisting of a triboelectric nanogenerator and a pyroelectric-piezoelectric nanogenerator, is developed for highly efficient mechanical energy harvesting through multiple mechanisms. The excellent performance of the hybrid cell enhances the energy-harvesting efficiency significantly (by 26.2% at 1 kΩ load resistance), and enables self-powered sensing, which will lead to a variety of advanced applications.

  18. Optimized Pyroelectric Vidicon Thermal Imager. Volume I. Thermal Imager. Volume 1a. Rain Camera. Volume 1b. Reticulation.

    Science.gov (United States)

    1979-06-01

    the pan mode. Reticulation of the TGS family of pyroelectric targets was demonstrated using standard ion-milling techniques. Reticula - tion of DTGFB...9 A technique for pedestal noise suppression (PNS) is being investigated as part of Contract DAAK70-77-C-0138 (Return Beam/Isocon Pyroelectric...reticulation studies under the basic contract because TGFB and DTGFB were not available in sufficient quantities during the early part of the program. The

  19. Minimization of pyroelectric effects in relaxor-PbTiO{sub 3} crystals for piezoelectric sensors

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yanxue, E-mail: yanxuetang@gmail.com [Key Laboratory of Optoelectronic Material and Device, Shanghai Normal University, Shanghai 200234 (China); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Shen, Zongyang [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403 (China); Zhang, Shujun; Jiang, Wenhua [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Luo, Jun [TRS Technologies Inc., 2820 E. College Ave., State College, PA 16801 (United States); Shrout, Thomas R. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

    2014-05-01

    To minimize pyroelectric effects while keeping high piezoelectric effects in relaxor-PbTiO{sub 3} single crystals, the crystallographic orientation dependence of the pyroelectric and piezoelectric coefficients were investigated for binary (1 − x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–xPbTiO{sub 3} (PMN–PT), ternary (1 − x − y)Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}–yPb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–xPbTiO{sub 3} (PIN–PMN–PT) and Mn-doped PIN–PMN–PT single crystals with the “4R” multidomain state. The secondary pyroelectric coefficients were calculated from the thermodynamic inter-relationship between the piezoelectric, elastic, and thermal expansion coefficients, being on the order of (1.16–1.23) × 10{sup −4} C m{sup −2} K{sup −1} for binary crystals and (0.97–2.03) × 10{sup −4} C m{sup −2} K{sup −1} for ternary ones. The primary pyroelectric coefficients were –(6.73–6.84) × 10{sup −4} C m{sup −2} K{sup −1} and −(5.44–6.43) × 10{sup −4} C m{sup −2} K{sup −1} for binary and ternary crystals, respectively. The pyroelectric coefficients could be reduced by matrix rotation, but at the cost of decreasing longitudinal piezoelectric coefficients d{sub 33}. Of particular interest is that the maximum piezoelectric coefficients d{sub 24}{sup ∗} at θ = ±55{sup o} and d{sub 34}{sup ∗} at θ = ±35{sup o} by a counterclockwise rotation of θ about the X axis (θ is the rotation angle about the coordinate axes), or d{sub 15}{sup ∗} at θ = ±55{sup o}, and d{sub 35}{sup ∗} at θ = ±35{sup o} by a counterclockwise rotation the Y axis, were found on the order of 3000 pC N{sup −1}. The corresponding pyroelectric coefficients could be reduced by ∼20%. The reduced pyroelectric coefficients that can contribute to decrease undesirable output signals, together with the high piezoelectric coefficients, enable relaxor-PT crystals as favorable candidates for high

  20. Pyroelectricity of Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} films grown by sol–gel process on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Moalla, R. [Institut des Nanotechnologies de Lyon, INL-CNRS UMR 5270, Ecole Centrale de Lyon, Bâtiment F7, 36 av. Guy de Collongue, 69134 Ecully Cedex (France); Le Rhun, G. [CEA, LETI, MINATEC Campus, 17 Rue des Martyrs, 38054 Grenoble (France); Defay, E. [CEA, LETI, MINATEC Campus, 17 Rue des Martyrs, 38054 Grenoble (France); Luxembourg Institute of Science and Technology (LIST), Materials Research & Technology Department (MRT), 41 Rue du Brill, L-4422 Belvaux (Luxembourg); Baboux, N. [Institut des Nanotechnologies de Lyon, INL-CNRS UMR 5270, INSA de Lyon, Bâtiment Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Sebald, G. [Laboratoire de Génie Electrique et Ferroélectricité, LGEF EA 682, INSA de Lyon, Bâtiment Gustave Ferrié, 8 rue de la Physique, 69621 Villeurbanne Cedex (France); Bachelet, R., E-mail: romain.bachelet@ec-lyon.fr [Institut des Nanotechnologies de Lyon, INL-CNRS UMR 5270, Ecole Centrale de Lyon, Bâtiment F7, 36 av. Guy de Collongue, 69134 Ecully Cedex (France)

    2016-02-29

    Pyroelectric Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} films have been grown by sol–gel process on Si(001). Intrinsic pyroelectric coefficient has been measured through ferroelectric loops recorded at different temperatures and is about − 300 μC/m{sup 2}K. Corresponding converted pyroelectric power density is estimated to be ~ 1 mW/cm{sup 3} for a temperature variation of 10 °C every 6 s. Pyroelectric response of these films has been confirmed by direct measurements of the pyroelectric current with temperature variations at zero electric field. These results are of high interest for integrated thermally-sensitive devices. - Highlights: • Functional oxide films are grown by low-cost sol–gel process and spin-coating. • Pyroelectric Pb(Zr,Ti)O{sub 3} films are integrated in planar capacitor structure on Si. • Bulk intrinsic pyroelectric coefficient is measured: ‐ 300 μC/m{sup 2}K. • Converted pyroelectric energy is estimated: 6 mJ/cm{sup 3} per 10 °C thermal cycle. • Direct measurements of pyroelectricity are done on integrated oxide thin films.

  1. Possible Explanation For Multiple Electron Emission From Pyroelectric Crystals In Dilute Gases

    Science.gov (United States)

    Shafroth, Stephen; Kaleko, David; Brownridge, James

    2009-05-01

    Pyroelectric crystals such as LiNbO3 when cut perpendicular to their z axes and when heated or cooled produce strong electric fields at their surfaces. If a 4 mm dia x 10 mm crystal is immersed in a dilute gas it acts as an accelerator of electrons when the surface is negative and positive ions when the surface is positive. In both cases a focused beam results but in the electron case multiple electron peaks are observed if they are detected through a pin hole with a surface barrier detector(1). In this poster we give evidence for an explanation of this effect. (1) Brownridge, J. D., Shafroth, S. M., Trott, D. W., Stoner, B. R., and Hooke, W. M., Observation of multiple nearly monoenergetic electron production by heated pyroelectric crystals in ambient gas, Appl. Phys. Lett., 78, 1158 (2001)

  2. The Control Method for Pyroelectric Chopper%热释电斩波器控制

    Institute of Scientific and Technical Information of China (English)

    王敏; 李晶; 朱洪洋; 刘愚; 郭小军; 陈如造; 罗凤旺; 秦伟; 朱光明

    2014-01-01

    斩波器是热释电型热像仪的重要组成部份,其平稳、匀速且按要求相位精确地运转,关系到整机成像质量的好坏。提出了一种对热释电斩波器进行闭环控制的方法,该方法的使用,解决了斩波器的控制问题。%Chopper is the important part of the pyroelectric thermal imager. The stable and uniform operation of chopper is related to the imaging quality. This paper presents a method about the closed-loop control for pyroelectric chopper, which solves the problem of the chopper control.

  3. Piezo- and pyroelectricity of a polymer-foam space-charge electret

    Science.gov (United States)

    Neugschwandtner, Gerhard S.; Schwödiauer, Reinhard; Bauer-Gogonea, Simona; Bauer, Siegfried; Paajanen, Mika; Lekkala, Jukka

    2001-04-01

    Charged closed-cell polypropylene polymer foams are highly sensitive and broadband piezoelectric materials with a quasistatic piezoelectric d33 coefficient about 250 pC/N and a dynamic d33 coefficient of 140 pC/N at 600 kHz. The piezoelectric coefficient is much larger than that of ferroelectric polymers, like polyvinylidene fluoride, and compares favorably with ferroelectric ceramics, such as lead zirconate titanate. The pyroelectric coefficient p3=0.25 μC/m2 K is small in comparison to ferroelectric polymers and ferroelectric ceramics. The low density, small pyroelectric coefficient and high piezoelectric sensitivity make charged polymer foams attractive for a wide range of sensor and transducer applications in acoustics, air-borne ultrasound, medical diagnostics, and nondestructive testing.

  4. Nanotubes, nanorods and nanowires having piezoelectric and/or pyroelectric properties and devices manufactured therefrom

    Science.gov (United States)

    Russell, Thomas P [Amherst, MA; Lutkenhaus, Jodie [Wethersfield, CT

    2012-05-15

    Disclosed herein is a device comprising a pair of electrodes; and a nanotube, a nanorod and/or a nanowire; the nanotube, nanorod and/or nanowire comprising a piezoelectric and/or pyroelectric polymeric composition; the pair of electrodes being in electrical communication with opposing surfaces of the nanotube, nanorod and/or a nanowire; the pair of electrodes being perpendicular to a longitudinal axis of the nanotube, nanorod and/or a nanowire.

  5. Real-time, continuous-wave terahertz imaging by a pyroelectric camera

    Institute of Scientific and Technical Information of China (English)

    Jun Yang; Shuangchen Ruan; Min Zhang

    2008-01-01

    Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.

  6. Pyroelectric generation of 2D spatial soliton sets in a bulk of lithium niobate crystal

    Science.gov (United States)

    Ryabchenok, V.; Shandarov, V.; Perin, A.

    2017-06-01

    The generation of two-dimensional bright spatial soliton sets in lithium niobate sample has been experimentally demonstrated at light wavelength of 532 nm, contribution of pyroelectric effect into nonlinear optical response of the crystal, and spatial modulation of one-dimensional beam along direction normal to the crystal optical axis. Diameters of soliton beams and channel waveguides formed within the crystal bulk by these solitons are near to 20 μm at light polarization corresponding to extraordinary wave of the crystal.

  7. The study of dielectric, pyroelectric and piezoelectric properties on hot pressed PZT-PMN systems

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Geetika; Umarji, A. M. [Materials Research Centre, Indian Institute of Science, Bangalore-560 012 (India); Maglione, Mario [ICMCB, Universite de Bordeaux,-CNRS, 87, Av Dr Schweitzer 33806 Pessac (France)

    2012-12-15

    Hot uniaxial pressing technique has been adopted for the densification of PZT-PMN system with an aim to yield dense ceramics and to lower the sintering temperature and time for achieving better and reproducible electronic properties. The ceramics having >97% theoretical density and micron size grains are investigated for their dielectric, pyroelectric and piezoelectric properties. The effect of Li and Mn addition has also been studied.

  8. The study of dielectric, pyroelectric and piezoelectric properties on hot pressed PZT-PMN systems

    Directory of Open Access Journals (Sweden)

    Geetika Srivastava

    2012-12-01

    Full Text Available Hot uniaxial pressing technique has been adopted for the densification of PZT-PMN system with an aim to yield dense ceramics and to lower the sintering temperature and time for achieving better and reproducible electronic properties. The ceramics having >97% theoretical density and micron size grains are investigated for their dielectric, pyroelectric and piezoelectric properties. The effect of Li and Mn addition has also been studied.

  9. Timing A Pulsed Thin Film Pyroelectric Generator For Maximum Power Denisty

    Science.gov (United States)

    Smith, A. N.; Hanrahan, B. M.; Neville, C. J.; Jankowski, N. R.

    2016-11-01

    Pyroelectric thermal-to-electric energy conversion is accomplished by a cyclic process of thermally-inducing polarization changes in the material under an applied electric field. The pyroelectric MEMS device investigated consisted of a thin film PZT capacitor with platinum bottom and iridium oxide top electrodes. Electric fields between 1-20 kV/cm with a 30% duty cycle and frequencies from 0.1 - 100 Hz were tested with a modulated continuous wave IR laser with a duty cycle of 20% creating temperature swings from 0.15 - 26 °C on the pyroelectric receiver. The net output power of the device was highly sensitive to the phase delay between the laser power and the applied electric field. A thermal model was developed to predict and explain the power loss associated with finite charge and discharge times. Excellent agreement was achieved between the theoretical model and the experiment results for the measured power density versus phase delay. Limitations on the charging and discharging rates result in reduced power and lower efficiency due to a reduced net work per cycle.

  10. Pyroelectric crystal D-D and D-T neutron generators

    Science.gov (United States)

    Danon, Y.

    2012-04-01

    Pyroelectric neutron generators are a recent development utilizing the pyroelectric effect to produce an accelerating electric field and thus enabling creation of small electron and ion accelerators without external high voltage power supply. The principle of operation includes a pyroelectric crystal (LiTaO3 for example) placed in vacuum and simple heating (or cooling) of the crystal to cause a change in polarization. The change in polarization creates free charges on the faces of the clyndrical z-cut crystal and due to its small capacitance this creates a high potential between one crystal face to the other which is placed at ground potential. To produce neutrons the crystal is placed in low pressure deuterium gas and when the crystal is heated or cooled it ionizes the gas and accelerates deuterium ions towards a deuterated or tritated target. A configuration with two crystals can double the acceleration potential and thus increase neutron production. When operating such a device x-rays with energy over 200 keV about 105 neutrons per heating cycle can be produced. Research is focused on improving the neutron yield, the emission reproducibility, and shortening the heating cycle. Neutron generators based on this technology can be made small portable and relatively cheap compared to sealed tube technology. Further development is needed in order to increase the neutron yield closer to the theoretical limit for a specific crystals size.

  11. DIELECTRIC AND PYROELECTRIC PROPERTIES OF THE COMPOSITES OF FERROELECTRIC CERAMIC AND POLY(VINYL CHLORIDE

    Directory of Open Access Journals (Sweden)

    M.Olszowy

    2003-01-01

    Full Text Available The dielectric and pyroelectric properties of lead zirconate titanate/poly(vinyl chloride [PZT/PVC] and barium titanate/poly(vinyl chloride [BaTiO3/ PVC] composites were studied. Flexible composites were fabricated in the thin films form (200-400 μm by hot-pressed method. Powders of PZT or BaTiO3 in the shape of ≤ 75 μm ceramics particles were dispersed in a PVC matrix, providing composites with 0-3} connectivity. Distribution of the ceramic particles in the polymer phase was examined by scanning electron microscopy. The analysis of the thermally stimulated currents (TSC have also been done. The changes of dielectric and pyroelectric data on composites with different contents of ceramics up to 40% volume were investigated. The dielectric constants were measured in the frequency range from 600 Hz to 6 MHz at room temperature. The pyroelectric coefficient for BaTiO3/PVC composite at 343 K is about 35 μC/m2K which is higher than that of β-PVDF (10 μC/m2 K.

  12. Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bloomfield, P. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering

    1992-03-27

    The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end.

  13. Correlation between intrinsic dipole moment and pyroelectric coefficient of Fe-Mg tourmaline

    Institute of Scientific and Technical Information of China (English)

    Chang-chun Zhao; Li-bing Liao; Jie Xing

    2014-01-01

    Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100ºC. The intrinsic dipole moments of polyhedra and the total intrinsic dipole moment of the unit cell were calculated. By comparing the intrinsic electric dipole moments of the X, Y, Z, T, and B site polyhedra, it is found that the T site polyhedron makes the greatest contribution to the total intrinsic dipole moment. The pyroelectric coefficients of four Fe-Mg tourmalines were experimentally determined, and the influence of intrinsic dipole moments on their pyroelectric properties was inves-tigated. The experimental results show that, compared with the case at room temperature, the intrinsic dipole moments change with the total Fe content at-100ºC in a completely different way. With the decrease of temperature, the total intrinsic dipole moments of tourmaline de-crease. Over the same temperature interval, the pyroelectric coefficients increase with the increase in intrinsic dipole moment.

  14. True differential pyroelectric infrared detector with improved D* test results with analysis

    Science.gov (United States)

    Doctor, Alan

    2016-10-01

    Pyroelectric infrared detectors are used in many commercial and industrial applications. Typically these devices have been "single ended" and thus any electronic perturbation from a non-detector related noise source such as line frequency interference or microprocessor clock and other sources of electronic noise can be coupled onto the detector's output signal. We have solved this problem by employing a rather unique connection which also provides an increase in the signal to noise of any pyroelectric detector by a factor of the square root of 2 or by about 1.41 times greater than devices not utilizing this connection. Many devices using this connection have been built, fully tested and the data analyzed which provide a true differential or double ended output and the increase in D* as predicted. This scheme will work with any pyroelectric material (LTO, DLATGS, PLZT, PVDF etc.) with current or voltage mode impedance conversion and configurations such as parallel or series with and without temperature fluctuation compensation and of course with standard single elements. This talk will present this data and conclusions regarding the approach.

  15. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

  16. Graphene Ink Laminate Structures on Poly(vinylidene difluoride) (PVDF) for Pyroelectric Thermal Energy Harvesting and Waste Heat Recovery.

    Science.gov (United States)

    Zabek, Daniel; Seunarine, Kris; Spacie, Chris; Bowen, Chris

    2017-03-15

    Thermal energy can be effectively converted into electricity using pyroelectrics, which act as small scale power generator and energy harvesters providing nanowatts to milliwatts of electrical power. In this paper, a novel pyroelectric harvester based on free-standing poly(vinylidene difluoride) (PVDF) was manufactured that exploits the high thermal radiation absorbance of a screen printed graphene ink electrode structure to facilitate the conversion of the available thermal radiation energy into electrical energy. The use of interconnected graphene nanoplatelets (GNPs) as an electrode enable high thermal radiation absorbance and high electrical conductivity along with the ease of deposition using a screen print technique. For the asymmetric structure, the pyroelectric open-circuit voltage and closed-circuit current were measured, and the harvested electrical energy was stored in an external capacitor. For the graphene ink/PVDF/aluminum system the closed circuit pyroelectric current improves by 7.5 times, the open circuit voltage by 3.4 times, and the harvested energy by 25 times compared to a standard aluminum/PVDF/aluminum system electrode design, with a peak energy density of 1.13 μJ/cm(3). For the pyroelectric device employed in this work, a complete manufacturing process and device characterization of these structures are reported along with the thermal conductivity of the graphene ink. The material combination presented here provides a new approach for delivering smart materials and structures, wireless technologies, and Internet of Things (IoT) devices.

  17. Evaluation of the solid state dipole moment and pyroelectric coefficient of phosphangulene by multipolar modeling of X-ray structure factors

    DEFF Research Database (Denmark)

    Madsen, G.K.H.; Krebs, Frederik C; Lebech, B.;

    2000-01-01

    The electron density distribution of the molecular pyroelectric material phosphangulene has been studied by multipolar modeling of X-ray diffraction data. The "in-crystal" molecular dipole moment has been evaluated to 4.7 D corresponding to a 42% dipole moment enhancement compared with the dipole...... pyroelectric coefficients has been introduced by combining the derived dipole moment with temperature-dependent measurements of the unit cell volume. The derived pyroelectric coefficient of 3.8(7)x 10(-6) Cm-2K-1 is in very good agreement with the measured pyroelectric coefficient of p = 3 +/- 1 x 10(-6) Cm-2...... K-1. This method for obtaining the pyroelectric coefficient uses information from the X-ray diffraction experiment alone and can be applied to much smaller crystals than traditional methods....

  18. Study of the growth and pyroelectric properties of TGS crystals doped with aniline-family dipolar molecules

    Science.gov (United States)

    Zhang, Kecong; Song, Jiancheng; Wang, Min; Fang, Changshui; Lu, Mengkai

    1987-04-01

    TGS crystals doped with aniline-family dipolar molecules (aniline, 2-aminobenzoic acid, 3-aminobenzoic acid, 3-aminobenzene-sulphonic acid, 4-aminobenzenesulphonic acid and 4-nitroraniline) have been grown by the slow-cooling solution method. The influence of these dopants on the growth habits, crystal morphology pyroelectric properties, and structure parameters of TGS crystals has been systematically investigated. The effects of the domain structure of the seed crystal on the pyroelectric properties of the doped crystals have been studied. It is found that the spontaneous polarization (P), pyroelectric coefficient (lambda), and internal bias field of the doped crystals are slightly higher than those of the pure TGS, and the larger the dipole moment of the dopant molecule, the higher the P and lambda of the doped TGS crystal.

  19. Dielectric and Pyroelectric Characteristics of the Infrared Sensitive(Pb_(1-x)Sr_x)TiO_3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    WANG Maoxiang; SHU Qing; MU Zhichun; JIAN Yuliang

    2009-01-01

    PST ferroelectric ceramics were fabricated successfully by a two-step method,i e first,PbTiO_3 and SrTiO_3 were sintered respectively,then mixed and sintered together.The process and characteristics of PST ferroelectric ceramics were introduced and researched.Their dielectric and pyroelectric characteristics are as follows dielectric constant 10~4 order,low dielectric loss(lower than 3.0%in the working frequency range of 1-1 000 kHz),saturation polarization intensity 10~(―1)C/m~2 order,and pyroelectric coefficient 10~(―3)C/m~2·K order.

  20. A selective pyroelectric detector of millimeter-wave radiation with an ultrathin resonant meta-absorber

    Science.gov (United States)

    Paulish, A. G.; Kuznetsov, S. A.

    2016-11-01

    The results of experimental investigations of spectral and amplitude-frequency characteristics for a discrete wavelength-selective pyroelectric detector operating in the millimetric band are presented. The high spectral selectivity is attained due to integrating the detector with a resonant meta-absorber designed for a close-to-unity absorptivity at 140 GHz. It is demonstrated that the use of this meta-absorber provides an opportunity to construct small-sized and inexpensive multispectral polarization-sensitive systems for radiation detection in the range of millimeter and submillimeter waves.

  1. Pyroelectric electron emissions and domain inversion of LiNbO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Wook [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of)]. E-mail: Peterkim@ucsd.edu; Bourim, E.M. [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Jeong, Soo-Hwan [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Yoo, In K. [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600, Korea (Korea)

    2004-10-30

    We investigated the electron emissions from a congruent LiNbO{sub 3} single crystal with variation in temperature. When there was a small gap between the crystal and detector (<2 mm), we observed abrupt drops in the emission current and polarization domain inversion of the crystal. The current burst was distributed in tree-like patterns that suggested plasma generation. A sufficient gap and a crystal with a high coercive field appear to be factors that allow reproducible electron emissions from pyroelectric materials.

  2. Electrical performances of pyroelectric bimetallic strip heat engines describing a Stirling cycle

    Science.gov (United States)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2015-12-01

    This paper deals with the analytical modeling of pyroelectric bimetallic strip heat engines. These devices are designed to exploit the snap-through of a thermo-mechanically bistable membrane to transform a part of the heat flowing through the membrane into mechanical energy and to convert it into electric energy by means of a piezoelectric layer deposited on the surface of the bistable membrane. In this paper, we describe the properties of these heat engines in the case when they complete a Stirling cycle, and we evaluate the performances (available energy, Carnot efficiency...) of these harvesters at the macro- and micro-scale.

  3. Study on the Interface Effects Based on Two-Dimensional Green's Functions for the Fluid and Pyroelectric Two-Phase Plane under a Line Heat Source

    Directory of Open Access Journals (Sweden)

    Peng-Fei Hou

    2014-11-01

    Full Text Available Two-dimensional Green's functions for a line heat source applied in the fluid and pyroelectric two-phase plane are presented in this paper. By virtue of the two-dimensional general solutions which are expressed in harmonic functions, six newly introduced harmonic functions with undetermined constants are constructed. Then, all the pyroelectric components in the fluid and pyroelectric two-phase plane can be derived by substituting these harmonic functions into the corresponding general solutions. And the undetermined constants can be obtained by the interface compatibility conditions and the mechanical, electric, and thermal equilibrium conditions. Numerical results are given graphically by contours.

  4. Dielectric and Pyroelectric Properties of La- and Pr-Modified Tungsten-Bronze Ferroelectrics

    Science.gov (United States)

    Parida, B. N.; Das, Piyush R.; Padhee, R.; Choudhary, R. N. P.

    2013-08-01

    The polycrystalline materials Li2Pb2R2W2Ti4Nb4O30 (R = La, Pr) of the tungsten-bronze structural family have been synthesized using a high- temperature mixed-oxide method. Room-temperature x-ray diffraction (XRD) analysis confirms the formation of single-phase compounds. Room-temperature scanning electron micrography of the pellet samples shows a uniform distribution of well-defined different sizes of grains on the surface of the samples, confirming the formation of single-phase compounds. Study of the frequency and temperature dependence of the dielectric constant and loss tangent suggests the existence of dielectric dispersion in the materials. The ferroelectric phase transition in the samples has been studied based on the variation of fitting parameters (calculated from a theoretical model) with temperature. Studies of pyroelectric properties [figure of merit (FOM) and coefficient] show that the materials have reasonably high FOM useful for pyroelectric detectors. The variation of alternating-current (AC) and direct-current (DC) conductivity with inverse absolute temperature (obtained from dielectric data) follows a typical Arrhenius relation. The low leakage current and negative temperature coefficient of resistance behavior of the samples have been verified from J- E plots.

  5. Demonstration of a non-contact x-ray source using an inductively heated pyroelectric accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Klopfer, Michael; Satchouk, Vladimir; Cao, Anh; Wolowiec, Thomas; Alivov, Yahya; Molloi, Sabee, E-mail: symolloi@uci.edu

    2015-04-11

    X-ray emission from pyroelectric sources can be produced through non-contact thermal cycling using induction heating. In this study, we demonstrated a proof of concept non-contact x-ray source powered via induction heating. An induction heater operating at 62.5 kHz provided a total of 6.5 W of delivered peak thermal power with 140 V DC of driving voltage. The heat was applied to a ferrous substrate mechanically coupled to a cubic 1 cm{sup 3} Lithium Niobate (LiNbO{sub 3}) pyroelectric crystal maintained in a 3–12 mTorr vacuum. The maximum temperature reached was 175 °C in 86 s of heating. The cooling cycle began immediately after heating and was provided by passive radiative cooling. The total combined cycle time was 250 s. x-ray photons were produced and analyzed in both heating and cooling phases. Maximum photon energies of 59 keV and 55 keV were observed during heating and cooling, respectively. Non-contact devices such as this, may find applications in cancer therapy (brachytherapy), non-destructive testing, medical imaging, and physics education fields.

  6. Investigation of pyroelectric electron emission from monodomain lithium niobate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bourim, El Mostafa [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of)]. E-mail: em.bourim@samsung.com; Moon, Chang-Wook [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Lee, Seung-Woon [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Kyeong Yoo, In [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of)

    2006-09-01

    The behaviors of thermally stimulated electron emission from pyroelectric monodomain lithium niobate single crystal (LiNbO{sub 3}) were investigated by utilizing a Si p-n junction photodiode as electron detector and a receptive electron beam resist (E-beam resist) as electron collector. In high vacuum (10{sup -6} Torr), the pyroelectric electron emission (PEE) was found to depend on the exposed emitting polar crystal surface (+Z face or -Z face) and was significantly influenced by the emitter-electron receiver gap distances. Thus, the PEE from +Z face was detected during heating and was activated, in small gaps (<2 mm), by field emission effect on which was superposed an intense field ionization effect that primed intermittent runway ionizations (plasma breakdown into a glow discharge). In large gaps (>2 mm) the emission was simply mastered by field emission effect. Whereas, The PEE from -Z face was detected during cooling and was solely due to the field ionization effect. Therewith, for small gaps (<2 mm) the emission was governed by intermittent runway ionization ignitions resulting from a high ionization degree leading to dense plasma formation, and for large gaps (>2 mm) PEE was governed by field ionization generating a soft and continuous plasma ambient atmosphere. Significant decrease of electron emission current was observed from +Z face after successive thermal cycles. A fast and fully emission recovery was established after a brief exposure of crystal to a poor air vacuum of 10{sup -1} Torr.

  7. Development of ruthenium dioxide electrodes for pyroelectric devices based on lithium tantalate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nougaret, Laurianne [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: laurianne.nougaret@univ-montp2.fr; Combette, Philippe [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: philippe.combette@univ-montp2.fr; Arinero, Richard [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: richard.arinero@univ-montp2.fr; Podlecki, Jean [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: jean.podlecki@univ-montp2.fr; Pascal-Delannoy, Frederique [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: Frederique.delannoy@univ-montp2.fr

    2007-02-26

    The aim of this paper is the study of ruthenium dioxide (RuO{sub 2}) films, grown on low-stress silicon nitride on silicon (SiN {sub x}/Si), in order to develop thermal micro-sensors based on pyroelectric effect. The active part of these micro-sensors is constituted by a new arrangement : lithium tantalate (LiTaO{sub 3})/RuO{sub 2}/SiN{sub x}/Si. Radio-frequency (RF) sputtering is employed to deposit RuO{sub 2} on SiN {sub x}/Si substrate. Morphology, crystallinity and resistivity of RuO{sub 2} are studied as function of growth parameters. Next, RF magnetron sputtering was used to deposit LiTaO{sub 3} on this electrode. Morphology studies, pyroelectric effect and dielectric parameters obtained, indicate that RuO{sub 2} material is a suitable candidate as back electrode for LiTaO{sub 3} thin films.

  8. Flexible Polymer-on-Polymer Architecture for Piezo/Pyroelectric Energy Harvesting.

    Science.gov (United States)

    Talemi, Pejman; Delaigue, Marine; Murphy, Peter; Fabretto, Manrico

    2015-04-29

    An all polymer piezo/pyroelectric device was fabricated using β phase poly(vinylidene fluoride) (PVDF) as the active material and vapor phase polymerized (VPP) poly(3,4-ethylenedioxythiphene) (PEDOT) as the flexible electrode overlay material. Inherent problems usually associated with coating polymeric electrodes onto the low surface energy PVDF were overcome by air plasma treating the film in conjunction with utilizing the VPP technique to simultaneously synthesize and in situ deposit the PEDOT electrode. Strain measurements up to the breaking-strain of PVDF (approximately 35%) indicated that the change in R/Ro was significantly smaller for the PEDOT based electrodes compared to the platinum electrode. Plasma treatment of the PVDF film increased the level of surface oxygenated carbon species that contributed to increased surface energy, as confirmed by confirmed by contact angle measurement. The enhanced adhesion between the two polymers layers contributed to a significant increase in the measured piezoelectric output voltage from 0.2 to 0.5 V for the same strain conditions. Pyroelectric voltage outputs were obtained by placing the film onto and off of a hotplate, for temperatures up to 50 °C above ambient. Finally, as a proof of concept, a simple energy harvesting device (plastic tube with slots for mounting multiple piezo/pyro films) was fabricated. The device was able to generate a usable level of peak output current (>3.5 μA) from human inhalation and exhalation "waste energy".

  9. Application of single-crystalline PMN-PT and PIN-PMN-PT in high-performance pyroelectric detectors.

    Science.gov (United States)

    Yu, Ping; Ji, Yadong; Neumann, Norbert; Lee, Sang-Goo; Luo, Hasou; Es-Souni, Mohammed

    2012-09-01

    The suitability for use in pyroelectric detectors of single-crystalline doped and undoped lead indium niobate-lead magnesium niobate-lead titanate was tested and compared with high-quality Mn-doped lead magnesium niobate-lead titanate and standard lithium tantalate. Pyroelectric and dielectric measurements confirmed an increased processing and operating temperature range because of the higher phase transitions of lead indium niobate-lead magnesium niobate-lead titanate. Pyroelectric coefficients of 705 to 770 μC/m(2)K were obtained with doped and undoped lead indium niobate-lead magnesium niobate-lead titanate, which are about 70% to 80% of the pyroelectric coefficient of lead magnesium niobate-lead titanate but 4 times higher than standard lithium tantalate. Manganese doping has been proved as a solution to decrease the dielectric loss of lead magnesium niobate-lead titanate and it also works well for lead indium niobate-lead magnesium niobate-lead titanate. An outstanding specific detectivity D* of about 1.1 · 10(9) cm·Hz(1/2)/W was achieved at a frequency of 2 Hz for Mn-doped lead magnesium niobate-based detectors.

  10. Preparation and Characterization of BaTiO3-PbZrTiO3 Coating for Pyroelectric Energy Harvesting

    Science.gov (United States)

    Raghavendra, R. M.; Praneeth, K. P. S. S.; Dutta, Soma

    2016-08-01

    Harvesting energy from waste heat is a promising field of research as there are significant energy recovery opportunities from various waste thermal energy sources. The present study reports pyroelectric energy harvesting using thick film prepared from a (x)BaTiO3-(1 - x)PbZr0.52Ti0.48O3 (BT-PZT) solid solution. The developed BT-PZT system is engineered to tune the ferro to paraelectric phase transition temperature of it in-between the phase transition temperature of BaTiO3 (393 K) and PbZrTiO3 (573 K) with higher pyroelectric figure-of-merit (FOM). The temperature-dependent dielectric behavior of the material has revealed the ferro- to paraelectric phase transition at 427 K with a maximum dielectric constant of 755. The room-temperature (298 K) pyroelectric coefficient (Pi) of the material was obtained as 738.63 μC/m2K which has yielded a significantly high FOM of 1745.8 J m-3 K-2. The enhancement in pyroelectric property is attributed to the morphotopic phase transition between tetragonal and rhombohedral PZT phases in the BT-PZT system. The developed BT-PZT system is capable of generating a power output of 1.3 mW/m2 near the Curie temperature with a constant rate (0.11 K/s) of heating. A signal conditioning circuit has been developed to rectify the time-varying current and voltage signals obtained from the harvester during heating cycles. The output voltage generated by the pyroelectric harvester has been stored in a capacitor for powering wearable electronics.

  11. Preparation and Characterization of BaTiO3-PbZrTiO3 Coating for Pyroelectric Energy Harvesting

    Science.gov (United States)

    Raghavendra, R. M.; Praneeth, K. P. S. S.; Dutta, Soma

    2017-01-01

    Harvesting energy from waste heat is a promising field of research as there are significant energy recovery opportunities from various waste thermal energy sources. The present study reports pyroelectric energy harvesting using thick film prepared from a (x)BaTiO3-(1 - x)PbZr0.52Ti0.48O3 (BT-PZT) solid solution. The developed BT-PZT system is engineered to tune the ferro to paraelectric phase transition temperature of it in-between the phase transition temperature of BaTiO3 (393 K) and PbZrTiO3 (573 K) with higher pyroelectric figure-of-merit (FOM). The temperature-dependent dielectric behavior of the material has revealed the ferro- to paraelectric phase transition at 427 K with a maximum dielectric constant of 755. The room-temperature (298 K) pyroelectric coefficient (Pi) of the material was obtained as 738.63 μC/m2K which has yielded a significantly high FOM of 1745.8 J m-3 K-2. The enhancement in pyroelectric property is attributed to the morphotopic phase transition between tetragonal and rhombohedral PZT phases in the BT-PZT system. The developed BT-PZT system is capable of generating a power output of 1.3 mW/m2 near the Curie temperature with a constant rate (0.11 K/s) of heating. A signal conditioning circuit has been developed to rectify the time-varying current and voltage signals obtained from the harvester during heating cycles. The output voltage generated by the pyroelectric harvester has been stored in a capacitor for powering wearable electronics.

  12. The development of potassium tantalate niobate thin films for satellite-based pyroelectric detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, Hilary B.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1997-05-01

    Potassium tantalate niobate (KTN) pyroelectric detectors are expected to provide detectivities, of 3.7 x 1011 cmHz 1/2W-1 for satellite-based infrared detection at 90 K. The background limited detectivity for a room-temperature thermal detector is 1.8 x 1010 cmHz1/2W-1 . KTN is a unique ferroelectric for this application because of the ability to tailor the temperature of its pyroelectric response by adjusting its ratio of tantalum to niobium. The ability to fabricate high quality KTN thin films on Si-based substrates is crucial to the development of KTN pyroelectric detectors. SixNymembranes created on the Si substrate will provide the weak thermal link necessary to reach background limited detectivities. The device dimensions obtainable by thin film processing are expected to increase the ferroelectric response by 20 times over bulk fabricated KTN detectors. In addition, microfabrication techniques allow for easier array development. This is the first reported attempt at growth of KTN films on Si-based substrates. Pure phase perovskite films were grown by pulsed laser deposition on SrRuO3/Pt/Ti/SixNy/Si and SrRuO3/SixNy/Si structures; room temperature dielectric permittivities for the KTN films were 290 and 2.5, respectively. The dielectric permittivity for bulk grown, single crystal KTN is ~380. In addition to depressed dielectric permittivities, no ferroelectric hysteresis was found between 80 and 300 K for either structure. RBS, AES, TEM and multi-frequency dielectric measurements were used to investigate the origin of this apparent lack of ferroelectricity. Other issues addressed by this dissertation include: the role of oxygen and target density during pulsed laser deposition of KTN thin films; the use of YBCO, LSC and Pt as direct contact bottom electrodes to the KTN films, and the adhesion of the bottom

  13. The development of potassium tantalate niobate thin films for satellite-based pyroelectric detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, H B.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1997-05-01

    Potassium tantalate niobate (KTN) pyroelectric detectors are expected to provide detectivities, of 3.7 x 10{sup 11} cmHz {sup {1/2}}W{sup {minus}1} for satellite-based infrared detection at 90 K. The background limited detectivity for a room-temperature thermal detector is 1.8 x 10{sup 10} cmHz{sup {1/2}}W{sup {minus}1}. KTN is a unique ferroelectric for this application because of the ability to tailor the temperature of its pyroelectric response by adjusting its ratio of tantalum to niobium. The ability to fabricate high quality KTN thin films on Si-based substrates is crucial to the development of KTN pyroelectric detectors. Si{sub x}N{sub y} membranes created on the Si substrate will provide the weak thermal link necessary to reach background limited detectivities. The device dimensions obtainable by thin film processing are expected to increase the ferroelectric response by 20 times over bulk fabricated KTN detectors. In addition, microfabrication techniques allow for easier array development. This is the first reported attempt at growth of KTN films on Si-based substrates. Pure phase perovskite films were grown by pulsed laser deposition on SrRuO{sub 3}/Pt/Ti/Si{sub x}N{sub y}/Si and SrRuO{sub 3}/Si{sub x}N{sub y}/Si structures; room temperature dielectric permittivities for the KTN films were 290 and 2.5, respectively. The dielectric permittivity for bulk grown, single crystal KTN is {approximately}380. In addition to depressed dielectric permittivities, no ferroelectric hysteresis was found between 80 and 300 K for either structure. RBS, AES, TEM and multi-frequency dielectric measurements were used to investigate the origin of this apparent lack of ferroelectricity. Other issues addressed by this dissertation include: the role of oxygen and target density during pulsed laser deposition of KTN thin films; the use of YBCO, LSC and Pt as direct contact bottom electrodes to the KTN films, and the adhesion of the bottom electrode layers to Si{sub x}N{sub y}/Si.

  14. Dynamic pyroelectric response of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and ferroelectric ceramics of barium lead zirconate titanate

    Energy Technology Data Exchange (ETDEWEB)

    Solnyshkin, A.V. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Morsakov, I.M.; Bogomolov, A.A. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); Belov, A.N.; Vorobiev, M.I.; Shevyakov, V.I.; Silibin, M.V. [National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Shvartsman, V.V. [University of Duisburg-Essen, Institute for Materials Science, Essen (Germany)

    2015-10-15

    In this work, pyroelectric properties of composite films on the basis of poly(vinylidene fluoride-trifluoroethylene) copolymer with a various level of ferroelectric ceramics inclusions of barium lead zirconate titanate solid solution were investigated by the dynamic method. The composite films were prepared by the solvent cast method. The unusual spike-like dynamic response with a quasi-stationary component was observed. It is supposed that composite films may be effectively used for pyroelectric applications. (orig.)

  15. EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals

    Directory of Open Access Journals (Sweden)

    Jiaduo Zhao

    2016-01-01

    Full Text Available In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector’s false alarms.

  16. Pyroelectric response of spray-deposited BaTiO3 thin film

    Science.gov (United States)

    Peale, Robert E.; Oladeji, Isaiah O.; Smith, Evan M.; Vasilyev, Vladimir; Alhasan, Sarmad Fawzi Hamza; Abouelkhair, Hussain; Todorovski, Dalibor; Kimani, Martin; Cleary, Justin W.

    2016-09-01

    Pyroelectric photoresponse of aqueous spray deposited thin films containing BaTiO3 nano-crystals is reported. X-ray diffraction data indicate the presence of hexagonal BaTiO3 nano-crystals with 20 nm crystalline domains in a matrix of some as yet unidentified nano-crystalline material. When the film is annealed at 600 C, the X-ray pattern changes significantly and indicates a conversion to one of the non-hexagonal phases of BaTiO3 as well as a complete change in the matrix. With suitable amplifier, the measured photoresponse was 40V/W. Ferroelectric hysteresis on a film with significant presence of hexagonal BaTiO3 shows saturated polarization which is about 5-times smaller than for the bulk tetragonal phase. A potential application is a patternable infrared detector for photonic and plasmonic devices, such as chip-scale spectral sensors.

  17. Optical properties of D-serine doped TGS crystals for pyroelectric sensors*

    Directory of Open Access Journals (Sweden)

    Kurlyak V.Yu.

    2015-12-01

    Full Text Available Refractive and birefringence indices in the range of transparency of 300 to 700 nm for triglycine sulphate crystals doped with D-serine molecules have been measured in the temperature range of 290 K to 340 K. The obtained optical properties are discussed together with characteristic electrical features of these materials used as pyroelectric sensors for measurement of temperature. The experimental results obtained in this study will be necessary as the reference data for comparison with the calculated refractive indices of TGS + D-serine on the basis of density functional theory. Determination of the proper position of D-serine, will reveal the features of TGS + D-serine crystal structure necessary to achieve stable unipolarity.

  18. Pyroelectric properties and conduction mechanism in solution grown glycine sodium nitrate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Sinha, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi 7 (India); Yadav, Harsh [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India)

    2015-04-01

    Nonlinear optical “glycine sodium nitrate” transparent single crystals were grown from aqueous solution by the solvent evaporation technique. The ferroelectric transition temperature was determined by dielectric measurement for GSN crystal. Temperature dependent pyroelectric coefficient and figure of merit were measured. The conduction mechanism of GSN crystal has been discussed. The ln σ−E{sup 1/2} characteristic in the high-field region supports dominating the Poole–Frenkel conduction while in the low field region; there are possibility of both Richardson–Schottky and Poole–Frenkel conduction mechanism. The activation energy of GSN crystal was found to be 0.58 eV. A low value of dielectric constant and good value of the figure of merit suggest the GSN crystal more promising for IR sensing applications. Hardness value shows the stability of GSN crystal.

  19. Tracking and Recognition of Multiple Human Targets Moving in a Wireless Pyroelectric Infrared Sensor Network

    Directory of Open Access Journals (Sweden)

    Ji Xiong

    2014-04-01

    Full Text Available With characteristics of low-cost and easy deployment, the distributed wireless pyroelectric infrared sensor network has attracted extensive interest, which aims to make it an alternate infrared video sensor in thermal biometric applications for tracking and identifying human targets. In these applications, effectively processing signals collected from sensors and extracting the features of different human targets has become crucial. This paper proposes the application of empirical mode decomposition and the Hilbert-Huang transform to extract features of moving human targets both in the time domain and the frequency domain. Moreover, the support vector machine is selected as the classifier. The experimental results demonstrate that by using this method the identification rates of multiple moving human targets are around 90%.

  20. Scanning thermal microscopy based on a modified atomic force microscope combined with pyroelectric detection

    Science.gov (United States)

    Antoniow, J.-S.; Chirtoc, M.; Trannoy, N.; Raphael, O.; Pelzl, J.

    2005-06-01

    We propose a novel approach in scanning thermal microscopy of layered samples. The thermal probe (ThP) (Wollaston wire) acts as a local a.c. heat source at the front of a sample layer deposited on a pyroelectric (PE) sensor. The PE signal is proportional to the heat wave transmitted through the sample. The ThP and PE signals can be used to generate complementary thermal conductivity maps and with some restrictions, thermal diffusivity maps of the sample. Additionally, the topography map is obtained in the usual way from the atomic force microscope. We give the theoretical background for the interpretation of PE signal obtained at low and at high frequency, and we demonstrate that it carries information on the thermal diffusivity of a test sample (12 μm thick PET polymer sheet). Finally, we discuss the contributions of heat transfer channels between ThP and sample, and the role of contact thermal resistance.

  1. EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals.

    Science.gov (United States)

    Zhao, Jiaduo; Gong, Weiguo; Tang, Yuzhen; Li, Weihong

    2016-01-20

    In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR) signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD)-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector's false alarms.

  2. PLZT ferroelectric ceramics on the morphotropic boundary phase. Study as possible pyroelectric sensors

    Energy Technology Data Exchange (ETDEWEB)

    Pelaiz Barranco, A.; Perez Martinez, O. [Univ. de La Habana (Cuba). Inst. de Materiales y Reactivos; Calderon Pinar, F. [Univ. de La Habana (Cuba). Inst. de Materiales y Reactivos; Centro de Investigaciones en Ciencia Aplicada y Tecnologia de Avanzada (CICATA), Altamira, Tamps (Mexico)

    2001-08-16

    PLZT compositions near the morphotropic boundary phase (Zr/Ti = 53/47) were studied changing the lanthanum fraction from 0.5 to 14 at%. The grain size and the porosity due to the lanthanum addition showed an important influence on the dielectric properties of the samples. Dielectric and pyroelectric studies show that the ceramics of lower lanthanum concentrations are suitable materials for practical applications. The ceramic's response subjected to light radiation was investigated. The radiation is absorbed near the material surface and its temperature rises leading to a change in the electrical polarization of the bulk material. This phenomenon is analyzed and correlated with the absorbed light on the surface of the material. (orig.)

  3. Piezoelectric and pyroelectric properties of Sr-doped PZT (PSZT) with minor manganese additions

    Science.gov (United States)

    Aleem, M. A.; Nawaz, H.; Shuaib, M.; Qaisar, S.; Akbar, M. S.

    2013-06-01

    A systematic study was performed to see the effect of Manganese addition and temperature gradient on the electrical properties of PSZT. Pb0.96 Sr0.04 (Zr0.52Ti0.48) O3 (PSZT) containing 0.3%, 0.5%, and 1% Mn was prepared by the sol gel method in order to ensure good stoichiometry and enhanced purity. The powders were calcined at 550 °C and sintered at 1200 °C to achieve 98% of the theoretical density. High field ac study was performed by (P-E) hysteresis measurements at different temperatures (RT, 60, 90, 120 and 150 °C) using an electric field up to 3 kV/mm. It was observed that for a lower Mn concentration P-E loops are pinched at the center while this constriction is found to decrease for greater concentrations. The optimized results were obtained for the 1 mol% of Mn content with 4 mol% of Sr. The values of Qm, k, d33 and tanδ were measured as 756, 0.38, 257 and 0.002 respectively. Higher temperatures coupled with a gradual increase of the electric field resulted in a shift of the hysteresis loops along electric field axis, indicating the presence of an internal bias field. Dependence of pyroelectric properties on applied electric field was also investigated. The value of pyroelectric coefficient was found maximum 6.25 × 10-4 (C/m2K) at 3 kV/mm.

  4. Graphene-based, mid-infrared, room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

    CERN Document Server

    Sassi, U; Nanot, S; Bruna, M; Borini, S; Milana, S; De Fazio, D; Zhuang, Z; Lidorikis, E; Koppens, F H L; Ferrari, A C; Colli, A

    2016-01-01

    Graphene is ideally suited for photonic and optoelectronic applications, with a variety of photodetectors (PDs) in the visible, near-infrared (NIR), and THz reported to date, as well as thermal detectors in the mid-infrared (MIR). Here, we present a room temperature-MIR-PD where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene, leading to a temperature coefficient of resistance up to 900%/K, two orders of magnitude higher than the state of the art, for a device area of 300x300um2. This is achieved by fabricating a floating metallic structure that concentrates the charge generated by the pyroelectric substrate on the top-gate capacitor of the graphene channel. This allows us to resolve temperature variations down to 15umK at 1 Hz, paving the way for a new generation of detectors for MIR imaging and spectroscopy

  5. Testing of InGaAs, microbolometer and pyroelectric detectors in support of the EarthCARE mission

    Science.gov (United States)

    Hopkinson, Gordon; Gomez Rojas, Luis; Skipper, Mark; Meynart, Roland

    2008-10-01

    A test programme for infrared detectors in support of the EarthCARE mission is discussed. Commercially available linear InGaAs arrays from XenICs, Belgium (cut-off wavelengths 1.7, 2.2 and 2.5 μm), 384 x 288 amorphous silicon microbolometer arrays from ULIS, France and un-windowed single element lithium tantalate pyroelectric detectors from Infratec, Germany have been studied in detail to assess their suitability for EarthCARE and to provide performance data to aid in the design of the flight instruments. Tests included radiation resistance (cobalt60 and 60 MeV protons plus a heavy ion latch-up test for the InGaAs and microbolometer arrays), dark signal, noise, output stability, linearity, crosstalk and spectral response. In addition, the pyroelectric detectors were tested for low microphony.

  6. Pyroelectric detectors with integrated operational amplifier for high modulation frequencies; Pyroelektrische Detektoren mit integriertem Operationsverstaerker fuer hohe Modulationsfrequenzen

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, N.; Saenze, H.; Heinze, M. [InfraTec GmbH Dresden (Germany)

    2006-02-01

    In order to use the advantages of the current mode operation a pyroelectric detector family with integrated transimpedance amplifier (TIA) was developed particularly for modulation frequencies up to the kHz range with a simplified external circuitry for new application fields, e.g. absorption spectroscopy using quantum-cascade-laser. The essential advantages of the TIA arise from the small electrical time constant {tau}{sub E} and the short-circuiting of the pyroelectric element. A flat amplitude response up to some kHz was aimed at for a sufficiently high response of 7500 V/W, appr., also at high modulation frequencies. This can be achieved through a electrical time constant of 1 ms or less and a wide bandwidth of the op amp. The article describes in detail how these demands were accomplished and which compromises had to be accepted. (orig.)

  7. Formation of the domain structure in CLN under the pyroelectric field induced by pulse infrared laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V. Ya.; Kosobokov, M. S.; Mingaliev, E. A.; Karpov, V. R. [Institute of Natural Sciences, Ural Federal University, Ekaterinburg, 620000 (Russian Federation)

    2015-10-15

    The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation in congruent lithium niobate crystal was studied by in situ optical observation. Several scenarios of domain kinetics represented covering of the irradiated zone by nets of the separated domain chains and rays have been revealed. The time dependence of the total domain length was analyzed in terms of modified Kolmogorov-Avrami theory. The domain structure evolution was attributed to the action of pyroelectric field appeared during cooling. The time dependence of the spatial distribution of the pyroelectric field during pulse laser heating and subsequent cooling was calculated by finite element method. The results of computer simulation allowed us to explain the experimental results and can be used for creation of tailored domain structures thus opening the new abilities of the submicron-scale domain engineering in ferroelectrics.

  8. Formation of the domain structure in CLN under the pyroelectric field induced by pulse infrared laser heating

    Directory of Open Access Journals (Sweden)

    V. Ya. Shur

    2015-10-01

    Full Text Available The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation in congruent lithium niobate crystal was studied by in situ optical observation. Several scenarios of domain kinetics represented covering of the irradiated zone by nets of the separated domain chains and rays have been revealed. The time dependence of the total domain length was analyzed in terms of modified Kolmogorov-Avrami theory. The domain structure evolution was attributed to the action of pyroelectric field appeared during cooling. The time dependence of the spatial distribution of the pyroelectric field during pulse laser heating and subsequent cooling was calculated by finite element method. The results of computer simulation allowed us to explain the experimental results and can be used for creation of tailored domain structures thus opening the new abilities of the submicron-scale domain engineering in ferroelectrics.

  9. A numerical investigation on exergy analyses of a pyroelectric tryglycine sulfate (TGS)-based solar energy harvesting system

    Science.gov (United States)

    Sharma, Manish; Vaish, Rahul; Singh Chauhan, Vishal

    2016-02-01

    This study is based on a numerical demonstration of energy and exergy analyses of a solar energy harvesting system based on the pyroelectric effect. The performance of a tryglycine sulfate (TGS) single crystal was investigated mathematically in the present study. The power output was optimized for different load resistances and load capacitances. The maximum power output was obtained as 0.95 μW across a load resistance of 40 MΩ and a 4.7 μF load capacitor. Further exergy analysis was performed for a pyroelectric energy harvesting system. Maximum values for electrical and thermal exergies obtained are 0.12 μW and 12 mW, respectively. Furthermore the maximum obtained electrical and thermal exergy efficiencies are 0.000 037% and 3.6%, respectively. The average thermal exergy efficiency is 2.15% for a cycle frequency of 0.014 Hz.

  10. Real-time continuous-wave imaging with a 1.63THz OPTL and a pyroelectric camera

    Institute of Scientific and Technical Information of China (English)

    YANG Jun; RUAN Shuang-chen; ZHANG Min; ZHANG Wei

    2008-01-01

    Real-time continuous-wave terahertz imaging is demonstrated with a 1.63 THz (184.31 μm) optically-pumped terahertz laser (OPTL) and a 124 × 124 element room-temperature pyroelectric camera. Transmission-mode THz imaging is presented for the samples hidden in various wrapping materials. These experimental results reveal the possibility to construct a simple real-time THz imaging system applied to nondestructive inspection.

  11. Pyroelectric and electrocaloric effect of <1 1 1>-oriented 0.9PMN-0.1PT single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Luo Laihui, E-mail: llhsic@126.com [Department of Physics, Ningbo University, Ningbo 315211 (China); Chen Hongbing [Institute of Materials Science and Engineering, Ningbo University, Ningbo 315211 (China); Zhu Yuejin; Li Weiping [Department of Physics, Ningbo University, Ningbo 315211 (China); Luo Haosu [Shanghai Institute of ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang Yuepin [Department of Physics, Ningbo University, Ningbo 315211 (China)

    2011-08-11

    Highlights: > Here, we use indirect method to measure pyroelectric and electrocaloric effect. > The largest temperature change achieves {approx}1 deg. C with a small field change. > The mechanism of electrocaloric effect of PMN-PT is explained. > The largest ({partial_derivative}P/{partial_derivative}T){sub E} value achieves -0.5 {mu}C/cm{sup 2} K. > PMN-PT has excellent pyroelectric effect. - Abstract: In this paper, the polarization vs. electric field hysteresis loops of <1 1 1>-oriented 0.9PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}-0.1PbTiO{sub 3} (0.9PMN-0.1PT) single crystal at different temperatures (20-110 deg. C) were measured. The adiabatic temperature change {Delta}T of <1 1 1>-oriented 0.9PMN-0.1PT single crystal due to the application or withdraw of electric field were calculated through the thermodynamic relation. The largest temperature change {Delta}T achieves {approx}1 K with only a change of 40 kV/cm electric field, the mechanism of the electrocaloric effect (ECE) is discussed for 0.9PMN-0.1PT crystal. The pyroelectric coefficient of 0.9PMN-0.1PT under bias field was calculated according to the data of hysteresis loop. The result shows that 0.9PMN-0.1PT have large pyroelectric coefficient under bias field, the largest ({partial_derivative}P/{partial_derivative}T){sub E} value achieves -0.5 {mu}C/cm{sup 2} K.

  12. Ionization Mechanism of the Ambient Pressure Pyroelectric Ion Source (APPIS) and Its Applications to Chemical Nerve Agent Detection

    OpenAIRE

    Neidholdt, Evan L.; Beauchamp, J. L.

    2009-01-01

    We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions su...

  13. Investigation of the effect of noise on the operation of the charge sensitive amplifier with compensated pyroelectric interference

    Directory of Open Access Journals (Sweden)

    Starcev V. I.

    2015-08-01

    Full Text Available The authors consider the problems that arise during the operation of the charge sensitive amplifier (CSA in critical conditions. Simplified schemes and mathematical models of the CSA are presented in order to study the effect of noise of operational amplifier and high-resistance resistor of negative feedback loop. The dependence of the CSA noise level on the pyroelectric interference compensation value is studied. Mathematical analysis data is confirmed by computer circuit simulation.

  14. 3D-Printing of inverted pyramid suspending architecture for pyroelectric infrared detectors with inhibited microphonic effect

    Science.gov (United States)

    Xu, Qing; Zhao, Xiangyong; Li, Xiaobing; Deng, Hao; Yan, Hong; Yang, Linrong; Di, Wenning; Luo, Haosu; Neumann, Norbert

    2016-05-01

    A sensitive chip with ultralow dielectric loss based on Mn doped PMNT (71/29) has been proposed for high-end pyroelectric devices. The dielectric loss at 1 kHz is 0.005%, one order lower than the minimum value reported so far. The detective figure of merit (Fd) is up to 92.6 × 10-5 Pa-1/2 at 1 kHz and 53.5 × 10-5 Pa-1/2 at 10 Hz, respectively. In addition, an inverted pyramid suspending architecture for supporting the sensitive chip has been designed and manufactured by 3D printing technology. The combination of this sensitive chip and the proposed suspending architecture largely enhances the performance of the pyroelectric detectors. The responsivity and specific detectivity are 669,811 V/W and 3.32 × 109 cm Hz1/2/W at 10 Hz, respectively, 1.9 times and 1.5 times higher than those of the highest values in literature. Furthermore, the microphonic effect can be largely inhibited according to the theoretical and experimental analysis. This architecture will have promising applications in high-end and stable pyroelectric infrared detectors.

  15. Characterisation and Modelling of Meshed Electrodes on Free Standing Polyvilylidene Difluoride (PVDF) Films for Enhanced Pyroelectric Energy Harvesting.

    Science.gov (United States)

    Zabek, Daniel; Taylor, John; Bowen, Chris

    2016-09-05

    Flexible pyroelectric energy generators provide unique features for harvesting temperature fluctuations which can be effectively enhanced using meshed electrodes that improve thermal conduction, convection and radiation into the pyroelectric. In this paper, thermal radiation energy is continuously harvested with pyroelectric free standing Polyvilylidene Difluoride (PVDF) films over a large number of heat heat cycles using a novel micro-sized symmetrical patterned meshed electrode. It is shown that, for the meshed electrode geometries considered in this work, the polarisation-field (P-E), current-field (I-E) characteristics and device capacitance are unaffected since the fringing fields were generally small; this is verified using numerical simulations and comparison with experimental measurements. The use of meshed electrodes has been shown to significantly improve both the open circuit voltage (16 V to 59 V) and closed-circuit current (9 nA to 32 nA). The pyroelectric alternating current (AC) is rectified for direct current (DC) storage and 30% reduction in capacitor charging time is achieved by using the optimum meshed electrodes. The use of meshed electrodes on ferroelectric materials provides an innovative route to improve their performance in applications such as wearable devices, novel flexible sensors and large scale pyroelectric energy harvesters.hese instructions give you guidelines for preparing papers for IEEE Transactions and Journals. Use this document as a template if you are using Microsoft Word 6.0 or later. Otherwise, use this document as an instruction set. The electronic file of your paper will be formatted further at IEEE. Paper titles should be written in uppercase and lowercase letters, not all uppercase. Avoid writing long formulas with subscripts in the title; short formulas that identify the elements are fine (e.g., "Nd-Fe-B"). Do not write "(Invited)" in the title. Full names of authors are preferred in the author field, but are not

  16. Sol-gel PZT and Mn-doped PZT thin films for pyroelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q. [Advanced Materials Group, School of Industrial and Manufactory Science, Cranfield University, Beds (United Kingdom)]. E-mail: q.zhang@cranfield.ac.uk; Whatmore, R.W. [Advanced Materials Group, School of Industrial and Manufactory Science, Cranfield University, Beds (United Kingdom)

    2001-08-07

    Thin films of ferroelectric lead zirconate titanate (PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} PZT30/70) and manganese-doped lead zirconate titanate ((Pb(Zr{sub 0.3}Ti{sub 0.7}){sub 1-x}Mn{sub x})O{sub 3}, where x=0.01, PM01ZT30/70; and x=0.03, PM03ZT30/70) have been prepared using sol-gel processing techniques. These materials can be used as the pyroelectric thin films in uncooled infrared detectors. The thin films were prepared via a sol-gel route based on a hybrid solvent of methanol and ethanol with acetic acid, ethanolamine and ethylene glycol as additives. The final solution is non-moisture sensitive and stable. Films deposited on Pt/Ti/SiO{sub 2}/Si substrates and annealed on a hot plate at 500-530{sup 0}C for a few minutes were seen to fully crystallize into the required perovskite phase and showed excellent ferroelectric behaviour, demonstrated by reproducible hysteresis loops (P{sub r}=33-37 {mu}C cm{sup -2}, Ec(+)=70-100 kV cm{sup -1}, Ec(-)=-170 to -140 kV cm{sup -1}). The pyroelectric coefficient (p) was measured using the Byer-Roundy method. At 20 deg. C, p was 2.11x10{sup -4} C m{sup -2} K{sup -1} for PZT30/70, 3.00x10{sup -4} C m{sup -2} K{sup -1} for PM01ZT30/70 and 2.40x10{sup -4} C m{sup -2} K{sup -1} for PM03ZT30/70 thin films. The detectivity figure-of-merit (F{sub D}) was 1.07x10{sup -5} Pa{sup -0.5} for PZT30/70, 3.07x10{sup -5} Pa{sup -0.5} for PM01ZT30/70 and 1.07x10{sup -5} Pa{sup -0.5} for PM03ZT30/70. These figures compare well with values reported previously. (author)

  17. Enhance the Pyroelectricity of Polyvinylidene Fluoride by Graphene-Oxide Doping

    Directory of Open Access Journals (Sweden)

    Yuh-Chung Hu

    2014-04-01

    Full Text Available The high quality properties and benefits of graphene-oxide have generated an active area of research where many investigations have shown potential applications in various technological fields. This paper proposes a methodology for enhancing the pyro-electricity of PVDF by graphene-oxide doping. The PVDF film with graphene-oxide is prepared by the sol-gel method. Firstly, PVDF and graphene-oxide powders are dispersed into dimethylformamide as solvent to form a sol solution. Secondly, the sol solution is deposited on a flexible ITO/PET substrate by spin-coating. Thirdly, the particles in the sol solution are polymerized through baking off the solvent to produce a gel in a state of a continuous network of PVDF and graphene-oxide. The final annealing process pyrolyzes the gel and form a β-phase PVDF film with graphene-oxide doping. A complete study on the process of the graphene oxide doping of PVDF is accomplished. Some key points about the process are addressed based on experiments. The solutions to some key issues are found in this work, such as the porosity of film, the annealing temperature limitation by the use of flexible PET substrate, and the concentrations of PVDF and graphene-oxide.

  18. A travelling photothermal technique employing pyroelectric detection to measure thermal diffusivity of films and coatings

    Science.gov (United States)

    Philip, J.; Manjusha, M. V.; Soumya, H.

    2011-10-01

    A travelling thermal wave technique employing optical excitation and pyroelectric detection of thermal waves propagating along a material film/coating on a substrate is described. The method enables direct measurement of thermal diffusivity. The technique involves measurement of the phase lag undergone by an optically excited thermal wave as it propagates along the coating. The set up has been automated for convenient and fast data acquisition and analysis. The technique has been adapted to measurement of thermal diffusivity of a commercial paint sample coated on glass and copper substrates. It is found that thermal diffusivity of the coating is independent of the thermal conductivity of the substrate. Dependence of thermal diffusivity on coating thickness shows exponential increase, with value reaching a constant at a characteristic high thickness. Measurements have been carried out on a few other samples with wide variations in thermal diffusivity, and the results compared with available reports or results obtained following other techniques. Analyses of the results show that the technique allows measurement of thermal diffusivity of coatings and films with uncertainties better than ±2.5%.

  19. Influence of Surface Transition Layers on Phase Transformation and Pyroelectric Properties of Ferroelectric Thin Film

    Institute of Scientific and Technical Information of China (English)

    SUN Pu-Nan; L(U) Tian-Quan; CHEN Hui; CAO Wen-Wu

    2008-01-01

    Taking into account surface transition layers (STLs), we study the phase transformation and pyroelectric properties of ferroelectric thin films by employing the transverse Ising model (TIM) in the framework of the mean field approximation. The distribution functions representing the intra-layer and inter-layer couplings between the two nearest neighbour pseudo-spins are introduced to characterize STLs. Compared with the results obtained by the traditional treatments for the thin films using only the single surface transition layer (SSL), it is shown that the STL model reflects a more realistic and comprehensive situation of films. The effects of various parameters on the phase transformation properties have shown that STL can make the Curie temperature of the film higher or lower than that of the corresponding bulk material, and the thickness of STL is a key factor influencing the film properties. For a film with definite thickness, there exists a critical STL thickness at which ferroelectricity will disappear when the intra-layer and inter-layer interactions are weak.

  20. Reversible Switching of Icing Properties on Pyroelectric Polyvenylidene Fluoride Thin Film Coatings

    Directory of Open Access Journals (Sweden)

    Dirk Spitzner

    2015-10-01

    Full Text Available In this work a new approach for ice repellent coatings is presented. It was shown that the coatings cause a decrease or increase in the freezing temperature of water depending on the alignment of an external electric field. For this coating the commonly used pyroelectric polymer polyvenylidene fluoride was deposited as a thin film on glass. The samples were dip-coated and subsequently thermally-treated at 140 °C for 1 h. All samples were found to cause a reduction of the icing temperature of water on their surface in comparison to uncoated glass. On several samples an external electric field was applied during this thermal treatment. The field application was found to cause a remarkable reduction of the icing temperature where a maximum lowering of the freezing temperature of 3 K compared to uncoated glass could be achieved. The actual achieved reduction of the icing temperature was observed to depend on the polarity of the field applied during the thermal treatment. Furthermore, a repetition of the thermal treatment under oppositely directed electric fields led to a switchable freezing behavior of water according to the direction of the applied field. With an increasing number of cycles of switching of the icing property a slight training effect towards lower freezing temperatures was observed.

  1. Enhancement of pyroelectric signal by continuous ultraviolet illumination of epitaxial Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Pintilie, L.; Iuga, A. [National Institute of Materials Physics, Atomistilor 105bis, Magurele, Ilfov 077125 (Romania); Botea, M. [National Institute of Materials Physics, Atomistilor 105bis, Magurele, Ilfov 077125 (Romania); Faculty of Physics, University of Bucharest, Magurele 077125 (Romania)

    2014-09-29

    The pyroelectric signal generated by an epitaxial Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} film can be enhanced by continuous illumination with ultraviolet (UV) light. The measured signal increases more than 2 times at low modulation frequencies of the incident infrared (IR) radiation (∼10 Hz) and at wavelengths where the short-circuit photocurrent presents the maximum value (∼280–300 nm). The tentative explanation is that the changes in polarization induced by the temperature variation under modulated IR illumination are generating a variable internal electric field, able to collect the photogenerated carriers produced under continuous UV illumination leading to an additional signal in phase with the pyroelectric one. This finding could be exploited for designing pyroelectric detectors with enhanced characteristics by combining both UV and IR responses.

  2. Optical damage in reduced Z-cut LiNbO{sub 3} crystals caused by longitudinal photovoltaic and pyroelectric effects

    Energy Technology Data Exchange (ETDEWEB)

    Kostritskii, S. M. [RPC Optolink, Sosnovaya al., d. 6 A, str.2, NPL-3-1, Zelenograd, Moscow, 124489 (Russian Federation); Aillerie, M. [LMOPS, University Paul Verlaine of Metz and Supelec, 2 rue E. Belin, 57070 Metz (France)

    2012-01-01

    The marked optical damage was observed in thin Z-cut plates of the deeply reduced nominally pure LiNbO{sub 3} crystals, when a 514.5-nm-laser beam with ordinary polarization was focused on the {+-}Z face. The longitudinal photovoltaic and pyroelectric effects are shown to be responsible for most of the important peculiarities of the optical damage dynamics. The anisotropy in the behavior between the +Z and -Z faces has been explained by interference of the different kinds of pyroelectric and photovoltaic effects to the space-charge field with an altering relative sign.

  3. Pyroelectric property of novel LiTa3O8 thin film prepared by sol-gel methods

    Science.gov (United States)

    Zhang, De-Yin

    2009-05-01

    A novel sol-gel derived LiTa3O8 film sample was prepared on the Pt/Ti/SiO2/Si(100) substrate using the lithium ethoxide and tantalum ethoxide as starting materials. The 0.2mol/L sol of LiTa3O8 was prepared by reacting lithium ethoxide with tantalum ethoxide in 2-methoxyethanol and acetic acid in argon atmosphere to prevent humidity. The sol of LiTa3O8 was firstly diluted to 0.1mol/L and then covered on the Pt/Ti/SiO2/Si(100) substrate to form wet film with the condition of the spin-coating speed of 3000~7000 r.p.m. for 30~60 second. Pyrolysis of the prepared wet film was carried out in oxygen atmosphere at temperature of 420~450ºC for 2~5 min to remove the residual organics. Annealing of the prepared film was performed at temperature of 750~900ºC for 2~4 min in the rapid thermal process furnace to crystallize the prepared film layer. More layers of LiTa3O8 film can be added by repeating the spin-coating and pyrolysis steps prior to the final firing. It was found that up to 18 layers of LiTa3O8 film sample can be deposited before the films begin to exhibit signs of cracking. The performance parameters such as orientation, surface morphology, grain size and thickness of the prepared LiTa3O8 film sample were studied by XRD and SEM. The structure of the LiTa3O8 film is similar to orthorhombic, different from LiTaO3 film based on XRD pattern. The SEM micrograph reveals that the prepared LiTa3O8 film sample is uniform, smooth and crack-free on the surface with a thickness of 1 µm after crystallized at 750ºC. The pyroelectric property of the LiTa3O8 film sample was measured by the home-made water-bath heating pyroelectric coefficient measurement system. The measurement result shows that the novel LiTa3O8 film sample has pyroelectric property and its pyroelectric coefficient is 14.07μC/m2K after the sample is subjected to the DC poling of 6V, 15min. The experimental results verify the pyroelectric coefficient of the novel LiTa3O8 film is smaller than that of

  4. Design of Pyroelectric Infrared Alarm System%热释电红外报警系统设计

    Institute of Scientific and Technical Information of China (English)

    尚小燕; 姜旭; 武继安

    2012-01-01

    Based on the working principle of pyroelectric infrared sensor,the passive pyroelectric infrared alarm system is designed for safety of residence house to detect whether outsiders enter or not.This system was made of pyroelectric infrared sensor,Fresnel lens and monitoring circuits.Infrared signal processor BISS0001 was chosen,amplifying and filtering circuits and infrared signal processing circuit were designed on basis of the concealment of infrared,then the voice chip was utilized to simulate alarm voice for warning thieves and burglars.After many experiments,it represented that the system has sensitive response,high anti-interference ability and safe and reliable performance.%基于热释电红外传感器的工作原理,设计了一种被动式热释电红外报警器。主要用于家居安全,探测有无外人闯入。该系统由热释电红外传感器、菲涅尔透镜和监控电路组成。系统把红外线的隐蔽性很好地应用于电路中,选用了新一代红外信号处理器BISS0001,设计了放大滤波电路,红外信号处理电路,并加入语音芯片,模拟警笛声音,达到防盗目的。经多次实验,该系统反应灵敏,抗干扰能力强,安全可靠。

  5. Thermoelectric-pyroelectric hybrid energy generation from thermopower waves in core-shell structured carbon nanotube-PZT nanocomposites

    Science.gov (United States)

    Yeo, Taehan; Hwang, Hayoung; Shin, Dongjoon; Seo, Byungseok; Choi, Wonjoon

    2017-02-01

    There is an urgent need to develop a suitable energy source owing to the rapid development of various innovative devices using micro-nanotechnology. The thermopower wave (TW), which produces a high specific power during the combustion of solid fuel inside micro-nanostructure materials, is a unique energy source for unusual platforms that cannot use conventional energy sources. Here, we report on the significant enhancement of hybrid energy generation of pyroelectrics and thermoelectrics from TWs in carbon nanotube (CNT)-PZT (lead zirconate titanate, P(Z0.5-T0.5)) composites for the first time. Conventional TWs use only charge carrier transport driven by the temperature gradient along the core materials to produce voltage. In this study, a core-shell structure of CNTs-PZTs was prepared to utilize both the temperature gradient along the core material (thermoelectrics) and the dynamic change in the temperature of the shell structure (pyroelectrics) induced by TWs. The dual mechanism of energy generation in CNT-PZT composites amplified the average peak and duration of the voltage up to 403 mV and 612 ms, respectively, by a factor of 2 and 60 times those for the composites without a PZT layer. Furthermore, dynamic voltage measurements and structural analysis in repetitive TWs confirmed that CNT-PZT composites maintain the original performance in multiple TWs, which improves the reusability of materials. The advanced TWs obtained by the application of a PZT layer as a pyroelectric material contributes to the extension of the usable energy portion as well as the development of TW-based operating devices.

  6. A One-Structure-Based Hybridized Nanogenerator for Scavenging Mechanical and Thermal Energies by Triboelectric-Piezoelectric-Pyroelectric Effects.

    Science.gov (United States)

    Wang, Shuhua; Wang, Zhong Lin; Yang, Ya

    2016-04-20

    A hybridized nanogenerator is demonstrated, which has the structure of PVDF nanowires-PDMS composite film/indium tin oxide (ITO) electrode/polarized PVDF film/ITO electrode, and which can individually/simultaneously scavenge mechanical and thermal energies using piezoelectric, triboelectric, and pyroelectric effects. As compared with the individual energy harvesting unit, the hybridized nanogenerator has a much better charging performance. This work may push forward a significant step toward multienergy harvesting technology. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Tunable liquid microlens array driven by pyroelectric effect: full interferometric characterization

    Science.gov (United States)

    Miccio, Lisa; Grilli, Simonetta; Vespini, Veronica; Ferraro, Pietro

    2008-09-01

    Liquid lenses with adjustable focal length are of great interest in the field of microfluidic devices. They are, usually, realized by electrowetting effect after electrodes patterning on a hydrofobic substrate. Applications are possible in many fields ranging from commercial products such as digital cameras to biological cell sorting. We realized an open array of liquid lenses with adjustable focal length without electrode patterning. We used a z-cut Lithium Niobate crystal (LN) as substrate and few microliters of an oily substance to obtain the droplets array. The spontaneous polarization of LN crystals is reversed by the electric field poling process, thus enabling the realization of periodically poled LN (PPLN) crystals. The substrate consists of a two-dimensional square array of reversed domains with a period around 200 μm. Each domain presents an hexagonal geometry due to the crystal structure. PPLN is first covered by a thin and homogeneous layer of the above mentioned liquid and therefore its temperature is changed by means of a digitally controlled hot plate. During heating and cooling process there is a rearrangement of the liquid layer until it reaches the final topography. Lenses formation is due to the superficial tension changing at the liquid-solid interface by means of the pyroelectric effect. Such effect allows to create a two-dimensional lens pattern of tunable focal length without electrodes. The temporal evolution of both shape and focal length lenses are quantitatively measured by Digital Holographic Microscopy. Array imaging properties and quantitative analysis of the lenses features and aberrations are presented.

  8. Enhancement in ferroelectric, pyroelectric and photoluminescence properties in dye doped TGS crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Nidhi [Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi-110007 (India); Goel, Neeti; Singh, B.K.; Gupta, M.K. [Crystal Lab, Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Kumar, Binay, E-mail: bkumar@physics.du.ac.in [Crystal Lab, Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2012-06-15

    Pure and dye doped (0.1 and 0.2 mol%) Triglycine Sulfate (TGS) single crystals were grown by slow evaporation technique. A pyramidal coloring pattern, along with XRD and FT-IR studies confirmed the dye doping. Decrease in dielectric constant and increase in Curie temperature (T{sub c}) were observed with increasing doping concentration. Low absorption cut off (231 nm) and high optical transparency (>90%) resulting in large band gap was observed in UV-VIS studies. In addition, strong hyper-luminescent emission bands at 350 and 375 nm were observed in which the relative intensity were found to be reversed as a result of doping. In P-E hysteresis loop studies, a higher curie temperature and an improved and more uniform figure of merit over a large region of the ferroelectric phase were observed. The improved dielectric, optical and ferroelectric/pyroelectric properties make the dye doped TGS crystals better candidate for various opto- and piezo-electronics applications. - Graphical abstract: Dye doping in TGS crystal resulted in hourglass morphology, increased hyper-luminescence intensity, improved T{sub c} and figure of merit. Highlights: Black-Right-Pointing-Pointer Amaranth dye doping in TGS crystals resulted in hourglass morphology. Black-Right-Pointing-Pointer Doping resulted in enhancement of Curie temperature from 49 to 53 Degree-Sign C. Black-Right-Pointing-Pointer Low cut off (230 nm) and wider transmittance window observed. Black-Right-Pointing-Pointer Strong hyper-luminescent emission bands at 350 and 375 nm were observed. Black-Right-Pointing-Pointer High and uniform figure of merit in ferroelectric phase was obtained.

  9. Graphene-based mid-infrared room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

    Science.gov (United States)

    Sassi, U.; Parret, R.; Nanot, S.; Bruna, M.; Borini, S.; De Fazio, D.; Zhao, Z.; Lidorikis, E.; Koppens, F.H.L.; Ferrari, A. C.; Colli, A.

    2017-01-01

    There is a growing number of applications demanding highly sensitive photodetectors in the mid-infrared. Thermal photodetectors, such as bolometers, have emerged as the technology of choice, because they do not need cooling. The performance of a bolometer is linked to its temperature coefficient of resistance (TCR, ∼2–4% K−1 for state-of-the-art materials). Graphene is ideally suited for optoelectronic applications, with a variety of reported photodetectors ranging from visible to THz frequencies. For the mid-infrared, graphene-based detectors with TCRs ∼4–11% K−1 have been demonstrated. Here we present an uncooled, mid-infrared photodetector, where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene. This is achieved by fabricating a floating metallic structure that concentrates the pyroelectric charge on the top-gate capacitor of the graphene channel, leading to TCRs up to 900% K−1, and the ability to resolve temperature variations down to 15 μK. PMID:28139766

  10. Light-Triggered Pyroelectric Nanogenerator Based on a pn-Junction for Self-Powered Near-Infrared Photosensing.

    Science.gov (United States)

    Wang, Xingfu; Dai, Yejing; Liu, Ruiyuan; He, Xu; Li, Shuti; Wang, Zhong Lin

    2017-08-22

    A nanogenerator, as a self-powered system, can operate without an external power supply for energy harvesting, signal processing, and active sensing. Here, near-infrared (NIR) photothermal triggered pyroelectric nanogenerators based on pn-junctions are demonstrated in a p-Si/n-ZnO nanowire (NW) heterostructure for self-powered NIR photosensing. The pyroelectric-polarization potential (pyro-potential) induced within wurtzite ZnO NWs couples with the built-in electric field of the pn-junction. At the moment of turning on or off the NIR illumination, external current flow is induced by the time-varying internal electric field of the pn-heterostructure, which enables a bias-free operation of the photodetectors (PDs). The NIR PD exhibits a high on/off photocurrent ratio up to 10(7) and a fast photoresponse component with a rise time of 15 μs and a fall time of 21 μs. This work provides an unconventional strategy to achieve active NIR sensing, which may find promising applications in biological imaging, optoelectronic communications, and optothermal detections.

  11. Dielectric and Pyroelectric Properties of (Pb0.50Sr0.50)TiO3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Yan-Ping; TANG Xin-Gui; LIU Qiu-Xiang; ZHOU Yi-Chun; CHANWONG Lai-Wa

    2008-01-01

    @@ Lead strontium titanate (Pb0.50Sr0.50)TiO3 (PST) ceramics are prepared by the traditional ceramic processing. The dielectric constants and dielectric loss have been investigated in a temperature range from 25℃ to 300℃. The maximum dielectric constants for unpoled and poled samples are 9924 and 9683, respectively. The temperatures of phase transition for unpoled and poled samples are observed at 153℃ and 157℃, respectively. The phase-transition temperatures for unpoled and poled samples are not equal, which results from the polarization state of the domains. The remnant polarization and the coercive electric field are 18 μC/cm2 and 6 k V/cm, respectively, from polarization-electric field (P- E) hysteresis loop. The temperature dependence of pyroelectric coefficients of the PST ceramics is measured by a dynamic technique. The dielectric constant and loss tan 5 of the poled PST ceramics are 813 and 0.010, respectively. The pyroelectric coefficients and figure of merit are 294 μC/cm2 K and 13.6 × 10-6 Pa-0.5, respectively, at room temperature 25℃ and frequency 100 Hz.

  12. Design of the Monocular Pyroelectric Infrared Detector%一种热释电红外探测器的单目设计

    Institute of Scientific and Technical Information of China (English)

    崔永俊; 贾磊; 王希鹏; 赵秀梅; 薛志勇; 杜文略

    2016-01-01

    To solve the problems of high false alarm rate, low sensitivity and unable to locate intrusion targets and other issues in ordinary pyroelectric infrared detection technology, the design based on compound eye structure is proposed for pyroelectric infrared detector. Combining the advantages of pyroelectric infrared detection, including good concealment, stable performance, environmental adaptability, large viewing angle of compound eye, small size and high sensitivity, the charge signal on pyroelectric material is converted into voltage signal, and output after filtering and amplifying. Experiments show that the monocular of the designed pyroelectric infrared detector can detect intrusion target within fifteen meters, and output pulse level as an alarm signal.%为解决普通热释电的红外探测技术误报率高、敏感度低且不能对入侵目标进行定位等问题,提出了一种基于热释电红外探测器的复眼结构的设计.结合热释电红外探测隐蔽性好、性能稳定、环境适应能力强、复眼视场角大、体积小且灵敏度高等优势,将热释材料上的电荷信号转换为电压信号,经滤波、放大后输出.通过实验表明,采用该热释电红外探测器的单目可以检测到15 m内的入侵目标,并输出脉冲电平作为报警信号.

  13. Progress in developing a thermal method for measuring the output power of medical ultrasound transducers that exploits the pyroelectric effect.

    Science.gov (United States)

    Zeqiri, Bajram; Zauhar, Gordana; Hodnett, Mark; Barrie, Jill

    2011-05-01

    Progress in developing a new measurement method for ultrasound output power is described. It is a thermal-based technique with the acoustic power generated by a transducer being absorbed within a specially developed polyurethane rubber material, whose high absorption coefficient ensures energy deposition within a few mm of the ultrasonic wave entering the material. The rate of change of temperature at the absorber surface is monitored using the pyroelectric voltage generated from electrodes disposed either side of a 60 mm diameter, 0.061 mm thick membrane of the piezoelectric polymer polyvinylidene fluoride (pvdf) bonded to the absorber. The change in the pyroelectric output voltage generated by the sensor when the transducer is switched ON and OFF is proportional to the delivered ultrasound power. The sensitivity of the device is defined as the magnitude of these switch voltages to a unit input stimulus of power (watt). Three important aspects of the performance of the pyroelectric sensor have been studied. Firstly, measurements have revealed that the temperature dependent sensitivity increases over the range from approximately 20°C to 30°C at a rate of +1.6% °C(-1). Studies point to the key role that the properties of both the absorbing backing layer and pvdf membrane play in controlling the sensor response. Secondly, the high sensitivity of the technique has been demonstrated using an NPL Pulsed Checksource, a 3.5 MHz focused transducer delivering a nominal acoustic power level of 4 mW. Finally, proof-of-concept of a new type of acoustic sensor responding to time-averaged intensity has been demonstrated, through fabrication of an absorber-backed hydrophone of nominal active element diameter 0.4 mm. A preliminary study using such a device to resolve the spatial distribution of acoustic intensity within plane-piston and focused 3.5 MHz acoustic fields has been completed. Derived beam profiles are compared to conventional techniques that depend on deriving

  14. The simulation curves of TSG and GTGS pyroelectric crystals by thermodynamics model%TGS和GTGS热释电晶体的热力学模型模拟曲线

    Institute of Scientific and Technical Information of China (English)

    胡文成; 杨传仁; 张万里; 廖希异

    2005-01-01

    Based on the thermodynamics theory of Devonshire, the polarization equation of pyroelectric crystal with the temperature was established under zero electric field. The equation of the pyroelectric coefficient with the temperature was established by the definition of pyroelectric coefficient and the derivation of polarization equation. The trend lines of spontaneous polarization and pyroelectric coefficient with the temperature and other coefficient are described. The simulation shows that our model and expression formula for pyroelectric crystals are in accordance with the experiment results of triglycine sulphate (TGS) and glycocyamine doped TGS (GTGS) pyroelectric crystals.%通过热力学推导,建立了零电场下热释电晶体的极化与温度的方程.由热释电系数的定义,对热释电晶体的极化方程对温度求导,得出由热力学模型建立的热释电方程.并对热释电晶体硫酸三甘氨酸(TGS)和掺胍TGS(GLTGS)的实验曲线进行了模拟,该理论基本符合.

  15. CH3NH3PbBr3 is not pyroelectric, excluding ferroelectric-enhanced photovoltaic performance

    Science.gov (United States)

    Rakita, Yevgeny; Meirzadeh, Elena; Bendikov, Tatyana; Kalchenko, Vyacheslav; Lubomirsky, Igor; Hodes, Gary; Ehre, David; Cahen, David

    2016-05-01

    To experimentally (dis)prove ferroelectric effects on the properties of lead-halide perovskites and of solar cells, based on them, we used second-harmonic-generation spectroscopy and the periodic temperature change (Chynoweth) technique to detect the polar nature of methylammonium lead bromide (MAPbBr3). We find that MAPbBr3 is probably centrosymmetric and definitely non-polar; thus, it cannot be ferroelectric. Whenever pyroelectric-like signals were detected, they could be shown to be due to trapped charges, likely at the interface between the metal electrode and the MAPbBr3 semiconductor. These results indicate that the ferroelectric effects do not affect steady-state performance of MAPbBr3 solar cells.

  16. CH3NH3PbBr3 is not pyroelectric, excluding ferroelectric-enhanced photovoltaic performance

    Directory of Open Access Journals (Sweden)

    Yevgeny Rakita

    2016-05-01

    Full Text Available To experimentally (disprove ferroelectric effects on the properties of lead-halide perovskites and of solar cells, based on them, we used second-harmonic-generation spectroscopy and the periodic temperature change (Chynoweth technique to detect the polar nature of methylammonium lead bromide (MAPbBr3. We find that MAPbBr3 is probably centrosymmetric and definitely non-polar; thus, it cannot be ferroelectric. Whenever pyroelectric-like signals were detected, they could be shown to be due to trapped charges, likely at the interface between the metal electrode and the MAPbBr3 semiconductor. These results indicate that the ferroelectric effects do not affect steady-state performance of MAPbBr3 solar cells.

  17. Large pyroelectric and thermal expansion coefficients in the [(CH3)2NH2]Mn (HCOO)3 metal-organic framework

    Science.gov (United States)

    Ma, Yinina; Cong, Junzhuang; Chai, Yisheng; Yan, Liqin; Shang, Dashan; Sun, Young

    2017-07-01

    The [(CH3)2NH2]Mn(HCOO)3 perovskite metal-organic framework exhibits a first-order ferroelectric phase transition with a high polarization at Tc ˜ 192 K, induced by the order-disorder transition of hydrogen bonds. Accompanying this sharp phase transition, a huge pyroelectric coefficient with a peak value of 5.16 × 10-2 C/m2 K is detected. In addition, there is a large lattice expansion along the [012] direction at Tc, resulting in a giant linear thermal expansion coefficient as high as 35 000 ppm/K. These striking results indicate that ferroelectric metal-organic frameworks combing both merits of inorganic and organic compounds hold a great potential in generating superior pyroelectric and thermal expansion properties.

  18. Pyroelectric characteristics of thin PbTiO3 and la-modified PbTiO3 films on platinum films for infrared sensors

    Science.gov (United States)

    Deb, K. K.; Tamagawa, T.; di, Y.; Gui, G.; Halpern, B. L.; Schmitt, J. J.

    2001-02-01

    In this work, we grew lead titanate (PbTiO3) and La-modified PbTiO3 thin films on platinized silicon (Si(100)) substrates under controlled substrate temperature and ambient by a modified jet-vapor deposition (JVD) process described in this paper. The x-ray diffraction patterns obtained from these films showed a single-phase perovskite structure. We examined locally homogeneity and thickness of these films through the comparative use of laser Raman spectroscopy. We also collected Raman and x-ray data on pure PbTiO3, as well as prepared lead zirconate titanate (PZT) (54/46), and PZT (50/50) films using the JVD process. This paper discusses the temperature variations of the pyroelectric and dielectric properties of three compositions of La-modified PbTiO3 films containing 5.2% to 15% of La, respectively, with a view toward studying the effect of La in place of Pb on these electrical properties. We detected significant pyroelectric currents on all three La-modified PbTiO3 films before performing poling treatments, and observed pyroelectric coefficeints as high as 84 nC/cm2·°C in the poled La-doped PbTiO3 films containing 5.2% La. The pyroelectric coefficient and dielectric constant varied significantly with La content. We compared the calculated figures of merit, which were based on the measured physical properties, with pure PbTiO3 as well as PZT and lead lanthanide zirconate titanate (PLZT) films. These properties just described illustrate that these films would be suitable for IR detectors.

  19. Pyroelectric-field driven defects diffusion along c-axis in ZnO nanobelts under high-energy electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yong, E-mail: yong.ding@mse.gatech.edu; Liu, Ying; Niu, Simiao; Wu, Wenzhuo; Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States)

    2014-10-21

    When ZnO nanobelts are exposed to a high-dose electron probe of several nanometers to hundred nanometers in diameter inside a transmission electron microscope, due to the radiolysis effect, part of oxygen atoms will be ejected into the vacuum and leaving a Zn-ion rich surface with a pit appearance at both the electron-entrance and electron-exit surfaces. At the same time, a temperature distribution is created around the electron probe due to local beam heating effect, which generates a unidirectional pyroelectric field. This pyroelectric field is strong enough to drive Zn ions moving along its positive c-axis direction as interstitial ions. In the first case, for the ZnO nanobelts with c-axis lie in their large surfaces, defects due to the aggregation of Zn interstitial ions will be formed at some distances of 30–50 nm approximately along the c-axis direction from the electron beam illuminated area. Alternatively, for the ZnO nanobelts with ±(0001) planes as their large surfaces, the incident electron beam is along its c-axis and the generated pyroelectric field will drive the interstitial Zn-ions to aggregate at the Zn terminated (0001) surface where the local electrical potential is the lowest. Such electron beam induced damage in ZnO nanostructures is suggested as a result of Zn ion diffusion driven by the temperature gradient induced pyroelectric field along c-axis. Our study shows a radiation damage caused by electron beam in transmission electron microscopy, especially when the electron energy is high.

  20. Pyroelectric and dielectric properties of lead-free ferroelectric Ba{sub 3}Nb{sub 2}O{sub 8} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Pati, Biswajit [Department of Physics, Institute of Technical Education and Research, Siksha O Anusandhan University, Bhubaneswar 751030 (India); Department of Physics, Government Junior College, Bhawanipatna, Kalahandi 766001 (India); Choudhary, R.N.P., E-mail: crnpfl@gmail.com [Department of Physics, Institute of Technical Education and Research, Siksha O Anusandhan University, Bhubaneswar 751030 (India); Das, Piyush R.; Parida, B.N.; Padhee, R. [Department of Physics, Institute of Technical Education and Research, Siksha O Anusandhan University, Bhubaneswar 751030 (India)

    2014-04-01

    Graphical abstract: - Highlights: • Barium orthoniobate (lead-free perovskite) crystallizes as palmierite with structural stability. • The material exhibits ferroelectric phase transition of diffuse-type suitable for devices. • The low values of ε{sub r} and tan δ at high frequencies makes it a potential candidate for microwave applications. • The material has very good pyroelectric properties for detector application. • The material exhibits smaller value of dc activation energy. - Abstract: The present study highlights ferroelectric phase transition, dielectric, pyroelectric properties and conduction mechanism of highly crystallized barium orthoniobate (Ba{sub 3}Nb{sub 2}O{sub 8}) ceramic, prepared by a solid-state reaction technique. X-ray diffraction studies show the formation of a single-phase compound in hexagonal crystal system. Detailed studies of dielectric parameters (ε{sub r} and tan δ) of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. An anomaly in ε{sub r} suggests the possible existence of a ferroelectric–paraelectric phase transition of diffuse-type in the material. The low dielectric loss and moderate relative permittivity make this material (with certain modification) a potential candidate for microwave applications. Studies of pyroelectric properties reveal that the materials have reasonably high figure of merit useful for fabrication of pyroelectric detectors. The low-leakage current and negative temperature coefficient of resistance (NTCR) behavior of the sample have been verified from J–E plots. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR behavior of the material.

  1. A novel pyroelectric generator utilising naturally driven temperature fluctuations from oscillating heat pipes for waste heat recovery and thermal energy harvesting

    Science.gov (United States)

    Zabek, D.; Taylor, J.; Ayel, V.; Bertin, Y.; Romestant, C.; Bowen, C. R.

    2016-07-01

    Low temperature thermal to electrical energy converters have the potential to provide a route for recovering waste energy. In this paper, we propose a new configuration of a thermal harvester that uses a naturally driven thermal oscillator free of mechanical motion and operates between a hot heat source and a cold heat sink. The system exploits a heat induced liquid-vapour transition of a working fluid as a primary driver for a pyroelectric generator. The two-phase instability of a fluid in a closed looped capillary channel of an oscillating heat pipe (OHP) creates pressure differences which lead to local high frequency temperature oscillations in the range of 0.1-5 K. Such temperature changes are suitable for pyroelectric thermal to electrical energy conversion, where the pyroelectric generator is attached to the adiabatic wall of the OHP, thereby absorbing thermal energy from the passing fluid. This new pyroelectric-oscillating heat pipe (POHP) assembly of a low temperature generator continuously operates across a spatial heat source temperature of 55 °C and a heat sink temperature of 25 °C, and enables waste heat recovery and thermal energy harvesting from small temperature gradients at low temperatures. Our electrical measurements with lead zirconate titanate (PZT) show an open circuit voltage of 0.4 V (AC) and with lead magnesium niobate-lead titanate (PMN-PT) an open circuit voltage of 0.8 V (AC) at a frequency of 0.45 Hz, with an energy density of 95 pJ cm-3 for PMN-PT. Our novel POHP device therefore has the capability to convert small quantities of thermal energy into more desirable electricity in the nW to mW range and provides an alternative to currently used batteries or centralised energy generation.

  2. Investigation on crystalline perfection, optical transmittance, birefringence, temperature-dependent refractive index, laser damage threshold and pyroelectric characteristics of inversely soluble lithium sulfate monohydrate single crystals

    Science.gov (United States)

    Silambarasan, A.; Rajesh, P.; Bhatt, Rajeev; Bhaumik, Indranil; Karnal, A. K.; Ramasamy, P.; Gupta, P. K.

    2016-08-01

    Bulk prismatic lithium sulfate monohydrate (LSMH) single crystals were grown by seed rotation with slow heating method from aqueous solution. Small FWHM obtained from high-resolution X-ray diffraction spectrum shows that the crystals grown by this method have less defects and absence of low-angle grain boundaries. The high transmittance and low reflectance nature of the grown crystal was observed using UV-Vis-NIR spectrometer. The principal refractive indices of a LSMH crystal have been measured by a prism coupling method for the wavelengths of 0.407, 0.532, 0.828, 1.064 and 1.551 µm at room temperature, and Sellmeier equations are determined from the fitting of the data point. The refractive index data confirm that LSMH crystal is negative biaxial and the optic axis lies in YZ plane with an angle (2 V y ) of 51.74° with respect to y axis at 532 nm wavelength. The thermo-optic coefficients were determined from the temperature-dependent refractive indices measured in the range of 30-125 °C for the wavelengths of 532 and 1064 nm. The surface laser damage threshold studies reveal the higher optical radiation stability against 532-nm laser. The pyroelectric coefficients and pyroelectric figure of merit were determined from the pyroelectric current measurement by the Byer and Roundy method.

  3. Flexible Pb(Zr0.52Ti0.48)O3 Films for a Hybrid Piezoelectric-Pyroelectric Nanogenerator under Harsh Environments.

    Science.gov (United States)

    Ko, Young Joon; Kim, Dong Yeong; Won, Sung Sik; Ahn, Chang Won; Kim, Ill Won; Kingon, Angus I; Kim, Seung-Hyun; Ko, Jae-Hyeon; Jung, Jong Hoon

    2016-03-01

    In spite of extremely high piezoelectric and pyroelectric coefficients, there are few reports on flexible ferroelectric perovskite film based nanogenerators (NGs). Here, we report the successful growth of a flexible Pb(Zr0.52Ti0.48)O3 (PZT) film and its application to hybrid piezoelectric-pyroelectric NG. A highly flexible Ni-Cr metal foil substrate with a conductive LaNiO3 bottom electrode enables the growth of flexible PZT film having high piezoelectric (140 pC/N) and pyroelectric (50 nC/cm(2)K) coefficients at room temperature. The flexible PZT-based NG effectively scavenges mechanical vibration and thermal fluctuation from sources ranging from the human body to the surroundings such as wind. Furthermore, it stably generates electric current even at elevated temperatures of 100 °C, relative humidity of 70%, and pH of 13 by virtue of its high Curie temperature and strong resistance for water and base. As proof of power generation under harsh environments, we demonstrate the generation of extremely high current at the exhaust pipe of a car, where hot CO and CO2 gases are rapidly expelled to air. This work expands the application of flexible PZT film-based NG for the scavenging mechanical vibration and thermal fluctuation energies even at extreme conditions.

  4. 大电流宽频带热释电红外探测器优化设计%Optimization Design of Large current broadband pyroelectric infrared detector

    Institute of Scientific and Technical Information of China (English)

    王芳; 杨桂勇; 宋艳; 颜延志; 马春旺

    2011-01-01

    本文提出了一种大电流宽频带的热释电红外探测器的优化设计方法.在分析热释电输出电压响应的基础上,结合热辐射探测的特点,提出了新的仿真模型,实际电路与仿真数据基本吻合.通过采用双极型结型场效应管(BJFET)和改变热释电时间常数等方法解决了热释电前置放大器输出信号弱和通频带窄的关键问题.%This paper presents a large current broadband pyroelectric infrared detector optimal design method. The analysis of the pyroelectric response of the output voltage based on the combination of the characteristics of thermal radiation detection, put forword a new simulation model, and the actual circuit is basically consistent with simulation data. Through using bipolar JFET (BJFET) and changing the time constant and so on, we will improve the low - output and narrow bands which were the key issues of pyroelectric preamplifier.

  5. Effect of Misfit Strain on Pyroelectric Properties of (111) Oriented Pb(Zr1-x Ti x ) O3 Thin Films

    Science.gov (United States)

    Qiu, Jian-Hua; Chen, Zhi-Hui; Wang, Xiu-Qin; Yuan, Ning-Yi; Ding, Jian-Ning

    2016-10-01

    Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1-xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1-xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1-xTix) O3 thin films can be adjusted by choosing the suitable substrates. Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, the research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology, Major Projects of Natural Science Research in Jiangsu Province under Grant Nos. 15KJA43002, 16KJD430006, and also sponsored by Qing Lan Project of Education Department of Jiangsu Province

  6. Pyroelectric properties of the monoclinic rare earth nitrates A{sub 2}Ln(NO{sub 3}){sub 5}.4H{sub 2}O (A = NH{sub 4}, Rb; Ln = La, Ce)

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Matthias; Andersen, Lionel; Becker, Petra; Bohaty Ladislav [Koeln Univ. (Germany). Inst. fuer Kristallographie

    2015-07-01

    The pyroelectric effect of four isomorphic monoclinic (space group Cc), non-ferroelectric rare earth nitrates A{sub 2}Ln(NO{sub 3}){sub 5}.4H{sub 2}O (A = NH{sub 4}, Rb; Ln = La, Ce) was investigated in the temperature range between 100 K and 300 K, using a home-made continuous-flow cryostat for measurements of pyroelectric currents. The symmetry-allowed temperature-dependent change of orientation of the pyroelectric vector p within the mirror plane is unusually large, showing a rotation of p of 148 , 129 , 36 and 40 for (NH{sub 4}){sub 2}La(NO{sub 3}){sub 5}.4H{sub 2}O, (NH{sub 4}){sub 2}Ce(NO{sub 3}){sub 5}.4H{sub 2}O, Rb{sub 2}La(NO{sub 3}){sub 5}.4H{sub 2}O and Rb{sub 2}Ce(NO{sub 3}){sub 5}.4H{sub 2}O, respectively, while changing the temperature from 100 K to 300 K in each case. The pyroelectric coefficients are up to ten times larger than p{sub 3} of tourmaline. In addition, new data of the pyroelectric coefficients of Li{sub 2}SO{sub 4}.H{sub 2}O and BiB{sub 3}O{sub 6} and their temperature dependence are given.

  7. Electrical and Pyroelectric Properties of Sol-Gel Derived (Pb, Ca)TiO3 Thin Films with Various Orientations

    Institute of Scientific and Technical Information of China (English)

    唐新桂; 丁爱丽; 王丽华

    2003-01-01

    (Pb0.76Ca0.24)TiO3(PCT)thin films with various orientations were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process and by controlling the temperature of heat-treatment.The PCT thin films with(100)and random orientation showed well-saturated hysteresis loops at an applied field of 800kV/cm,with remanent polarization and coercive electric field of 23.6 μC/cm2 and 225 k V/cm,17.8 μC/cm2 and 195 k V/cm,respectively.For highly(100)-and random-oriented PCT films,the dielectric constant and dielectric loss values of these films are 121 and 0.016,121 and 0.024 at 1 kHz,respectively.The pyroelectric coefficients p of the PCT thin films are measured by a dynamic technique.At room temperature,the p values and figures of merits of the highly(100)-and random-oriented PCT films are 185μC/m2K and 1.79 × 10-5Pa-0.5,176μC/m2K and 1.39 × 10-5Pa-0.5,respectively.

  8. Thermoelastic and Pyroelectric Couplings Effects on Dynamics and Active Control of Smart Piezolaminated Beam Modeled by Finite Element Method

    Directory of Open Access Journals (Sweden)

    M. Sanbi

    2014-01-01

    Full Text Available Smart structures with integrated sensors, actuators, and control electronics are of importance to the next generation high-performance structural systems. In this study, thermopiezoelastic characteristics of piezoelectric beam continua are studied and applications of the theory to active structures in sensing and optimal control are discussed. Using linear thermopiezoelastic theory and Timoshenko assumptions, a generic thermopiezoelastic theory for piezolaminated composite beam is derived. Finite element equations for the thermopiezoelastic media are obtained by using the linear constitutive equations in Hamilton's principle together with the finite element approximations. The structure consists of a modeling of cantilevered piezolaminated Timoshenko beam with integrated thermopiezoelectric elements between two aluminium layers. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG accompanied by the Kalman filter is applied. The effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. We show that the control procedure cannot be perturbed by applying a thermal gradient and the control can be applied at any time during the period of vibration of the beam.

  9. Pyroelectric and piezoelectric responses of thin AlN films epitaxy-grown on a SiC/Si substrate

    Science.gov (United States)

    Kukushkin, S. A.; Osipov, A. V.; Sergeeva, O. N.; Kiselev, D. A.; Bogomolov, A. A.; Solnyshkin, A. V.; Kaptelov, E. Yu.; Senkevich, S. V.; Pronin, I. P.

    2016-05-01

    This paper presents the results of pyroelectric and piezoelectric studies of AlN films formed by chloride-hydride epitaxy (CHE) and molecular beam epitaxy (MBE) on epitaxial SiC nanolayers grown on Si by the atom substitution method. The surface topography and piezoelectric and pyroelecrtric responses of AlN films have been analyzed. The results of the study have shown that the vertical component of the piezoresponse in CHE-grown AlN films is more homogeneous over the film area than that in MBE-grown AlN films. However, the signal from the MBE-synthesized AlN films proved to be stronger. The inversion of the polar axis (polarization vector) on passage from MBE-grown AlN films to CHE-grown AlN films has been found experimentally. It has been shown that the polar axis in MBE-grown films is directed from the free surface of the film toward the Si substrate while, in CHE-grown films, the polarization vector is directed toward the free surface.

  10. Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection.

    Science.gov (United States)

    Neidholdt, Evan L; Beauchamp, J L

    2009-11-01

    We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions such as protonated water clusters or clusters of hydroxide and water. Reactant ions can be observed directly in the mass spectrometer. These go on to react with trace neutrals via proton transfer reactions to produce the ions observed in mass spectra, which are usually singly protonated or deprotonated species. Further implicating gas-phase ionization, observed product distributions are highly dependent on the composition of ambient gases, especially the concentration of water vapor and oxygen surrounding the source. For example, basic species such as triethylamine are observed as singly protonated cations at a water partial pressure of 10 torr. At a water pressure of 4 torr, reactive oxygen species are formed and lead to observation of protonated amine oxides. The ability of the APPIS source to detect basic molecules with high proton affinities makes it highly suited for the detection of chemical nerve agents. We demonstrate this application using simulants corresponding to VX and GA (Tabun). With the present source configuration pyridine is detected readily at a concentration of 4 ppm, indicating ultimate sensitivity in the high ppb range.

  11. Improved ferroelectric and pyroelectric properties of Pb-doped SrBi{sub 4}Ti{sub 4}O{sub 15} ceramics for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Venkata Ramana, E., E-mail: venkataramanaesk@rediffmail.com [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro 3810 193 (Portugal); Graça, M.P.F.; Valente, M.A. [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro 3810 193 (Portugal); Bhima Sankaram, T. [Materials Research Laboratory, Department of Physics, Osmania University, Hyderabad 500 007 (India)

    2014-01-15

    Highlights: • Sr{sub 1−x}Pb{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} (SPBT, x = 0 − 0.4) ceramics were synthesized by soft chemical method. • X-ray diffraction analysis confirmed the formation of bismuth layered structure. • SEM images showed plate like grain morphology with random orientation of plate faces. • Pb-doping resulted in improved ferroelectricity of SrBi{sub 4}Ti{sub 4}O{sub 15} ceramics. • Pb-doped SrBi{sub 4}Ti{sub 4}O{sub 15} exhibited improved pyroelectric properties with high T{sub C}. -- Abstract: Ferroelectric properties of Pb-modified strontium bismuth titanate ceramics with chemical formula Sr{sub 1−x}Pb{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} (x = 0–0.4) were investigated. Polycrystalline ceramics were synthesized by soft chemical method to study the effect of Pb-doping on its physical properties. X-ray diffraction analysis revealed a bismuth layered structure for all the compounds. The doping resulted in an increased tetragonal strain and improved ferroelectric properties. Scanning electron microscope images showed plate like grain morphology with random orientation of platelets. The ferroelectric transition temperature of the ceramics increased systematically from 525 °C to 560 °C with the increase of doping concentration. The piezoelectric coefficient (d{sub 33}) of the ceramics was enhanced significantly with Pb doping, exhibiting a maximum value of 21.8 pC/N for 40 mol.% Pb-doped SBT. Pyroelectric studies carried out using the Byer–Roundy method indicated that the modified SBT ceramics are promising candidates for high temperature pyroelectric applications.

  12. Studies on the pyroelectric properties of ferroelectric bilayer film%铁电薄膜热释电性质的研究

    Institute of Scientific and Technical Information of China (English)

    张芹; 董亚男; 陈红

    2013-01-01

    Using Ginzburg-Landau-Devonshire theory, a ferroelectric bilayer film consisting of two different ferroelectric constituent films with the transition layer within each constituent film is considered. Introduced a parameter,which described the differences of physical properties between two constituent films, to investigate the temperature dependence of the pyroelectric coefficient of the bilayer film. It is shown that one or two peaks can be obtained in the pyroelectric curve by the adjustment of parameter Q. The modification of ferroelectric interfacial coupling cofficient,parameter a and surficial transition layer parameter leads to the peaks of the pyroelectric curve shifting to the higher or lower temperature region.%利用Ginzburg-Landau-Devonshire (GLD)热力学唯象理论,对由2种不同铁电材料构成的含有表面过渡层的铁电双层膜体系进行了探讨.通过引入一个描述2种铁电材料物理性能差异大小的物理参量α,并考虑2种铁电材料物理性能的差异,研究了铁电双层膜的热释电性质.结果表明:通过控制参量α的大小,热释电曲线上会呈现1个或2个峰;改变铁电界面耦合系数、参量α以及表面过渡层参量的大小,热释电曲线的峰位向高温区或低温区移动.

  13. PMNT热释电陶瓷材料的制备及性能研究%Preparation and Properties Study of PMNT Pyroelectric Ceramic Materaials

    Institute of Scientific and Technical Information of China (English)

    王实现; 张约品; 王冲; 章践立

    2011-01-01

    The PMNT ceramics with complex perovskite structure were prepared by the soft chemistry method. X-ray diffraction was used to detect the perovskite phase evolution and the presence of the pyrochlore phase in PMNT ceramics. The grain morphology was observed by scanning electron microscopy (SEM). The pyroelectric and piezoelectric properties of the ceramics were studied. The results show that the PMNT ceramics posses high densities and good pyroelectric properties. The pyroelectric coefficient of 0.67PMN-0.33PT ceramics is 5.5×10^-4C·m^-2.K^-1, Fd is 3.9× 10^-5 Pa^-1/2.%用软化学法合成了驰豫型复合钙钛矿结构铁电PMNT粉体,并将制备好的粉体压制成圆片状后放入硅碳棒炉中,于1150℃下烧结成致密热释电陶瓷材料.然后用x射线粉末衍射对合成材料进行物相分析,并用扫描电镜观察了晶粒形貌特征.结果表明:烧结后的陶瓷具有很好的致密性和热释电性,其中,0.67PMN.0.33PT组分热释电陶瓷的热释电系数为4.5×10^-4C·m^-2.K^-1,探测优值Fd为3.9×10^-5Pa^-1/2。

  14. Pyroelectric Arrays with Relax-based Ferroelectric Single Crystals%基于弛豫铁电单晶的热释电焦平面研究

    Institute of Scientific and Technical Information of China (English)

    邵秀梅; 马学亮; 于月华; 方家熊

    2011-01-01

    PMN-PT是一种综合性能优异的新型热释电材料.本文以PMN-PT单晶作为热释电探测器材料,开展了8×1线列探测器的芯片结构设计及器件关键工艺研究,获得了8元热释电探测器芯片,电压响应率约280N/W.同时,实现了8元热释电光敏芯片与8元读出电路的耦合互连,得到了8元热释电焦平面原型器件,并进行了性能测试.由于读出电路对可见光存在响应,影响了焦平面模块的热释电信号提取,电路设计有待改进.本丈的研究为基于新型弛豫铁电单晶的大规模非制冷焦平面的研制奠定了一定的基础.%PMN-PT single crystal is a novel pyroelectric material with superior performances. An 8x I linear array was designed, and research on the key processes of device fabrication was carried out based on PMN-PT crystal. The responsivity of the 8xl chip was about 280 V/W. At the same time, the 8xl pyroelectric chip was coupled with an 8xl read-out circuit. The performance of the 8× 1 FPA was studied. The pyroelectric signal of the FPA device can't be measured because the read-out circuits respond to visible light. The design of read-out circuits needs to be improved. The results of the paper lay a foundation for the development of large-scale uncooled pyroelectric FPA based on novel ferroeleetric single crystals.

  15. High-Quality Continuous-Wave Imaging with a 2.53 THz Optical Pumped Terahertz Laser and a Pyroelectric Detector

    Institute of Scientific and Technical Information of China (English)

    BING Pi-Bin; YAO Jian-Quan; XU De-Gang; XU Xiao-Yan; LI Zhong-Yang

    2010-01-01

    @@ A CW terahertz(THz)transmission imaging system is demonstrated and a high-quality THz image can be obtained using a pyroelectric detector.The factors that affect the imaging quality,such as the THz wavelength,spot size on the sample surface,step length of the motor,and frequency of the chopper,are theoretically and experimentally investigated.The experimental results show that the maximum resolution of the THz image can reach 0.4mm with the THz wavelength of 118.8μm.the spot size of 1.8 mm and the step length of 0.25mm.

  16. Systematic evaluation of a secondary method for measuring diagnostic-level medical ultrasound transducer output power based on a large-area pyroelectric sensor

    Science.gov (United States)

    Zeqiri, B.; Žauhar, G.; Rajagopal, S.; Pounder, A.

    2012-06-01

    A systematic study of the application of a novel pyroelectric technique to the measurement of diagnostic-level medical ultrasound output power is described. The method exploits the pyroelectric properties of a 0.028 mm thick membrane of polyvinylidene fluoride (PVDF), backed by an acoustic absorber whose ultrasonic absorption coefficient approaches 1000 dB cm-1 at 3 MHz. When exposed to an ultrasonic field, absorption of ultrasound adjacent to the PVDF-absorber interface results in heating and the generation of a pyroelectric output voltage across gold electrodes deposited on the membrane. For a sensor large enough to intercept the whole of the acoustic beam, the output voltage can be calibrated for the measurement of acoustic output power. A number of key performance properties of the method have been investigated. The technique is very sensitive, with a power to voltage conversion factor of typically 0.23 V W-1. The frequency response of a particular embodiment of the sensor in which acoustic power reflected at the absorber-PVDF interface is subsequently returned to the pyroelectric membrane to be absorbed, has been evaluated over the frequency range 1.5 MHz to 10 MHz. This has shown the frequency response to be flat to within ±4%, above 2.5 MHz. Below this frequency, the sensitivity falls by 20% at 1.5 MHz. Linearity of the technique has been demonstrated to within ±1.6% for applied acoustic power levels from 1 mW up to 120 mW. A number of other studies targeted at assessing the achievable measurement uncertainties are presented. These involve: the effects of soaking, the influence of the angle of incidence of the acoustic beam, measurement repeatability and sensitivity to transducer positioning. Additionally, over the range 20 °C to 30 °C, the rate of change in sensitivity with ambient temperature has been shown to be +0.5% °C-1. Implications of the work for the development of a sensitive, traceable, portable, secondary method of ultrasound output power

  17. 热释电红外探测器PZT晶片粘接质量控制%Quality Control of the PZT Wafer Bonding in Pyroelectric Infrared Detector

    Institute of Scientific and Technical Information of China (English)

    黄江平; 冯江敏; 王羽; 苏玉辉; 信思树; 李玉英

    2013-01-01

    热释电红外探测器芯片研制中,晶片粘接是芯片研制中的关键工艺之一。本文详细论述了粘接胶的选择依据及晶片粘接质量控制。确定了适合器件研制的粘接胶和粘胶工艺流程。对粘接中出现的问题及解决办法进行了讨论。研制出了完全能满足器件工艺要求的热释电探测器PZT晶片。%The wafer bonding is one of the key technologies in pyroelectric infrared detector chip development. This paper discusses the selection basis of bonding glue and quality control of wafer bonding in details, also determines the adhesive glue and the technology suitable for detector development, and analyzes the problems and the resolution method in the course of wafer bonding. The PZT wafer that can fully meet the technology requirements of pyroelectric detector is provided.

  18. Pyroelectric Study on Dipolar Alignment in 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liang; SHEN Ming-Rong; CAO Wen-Wu

    2012-01-01

    Pyroelectric measurements are conducted during zero-Geld heating in [001], [110] and [111] poled 0.69Pb(Mg1/3 Nb2/3)O3-0.31PbTiO3 single crystals. Compared to the room-temperature-poled samples, the crystals poled by using the Rield cooling method show broad but well recognizable pyroelectric current peaks near 190℃, which is much higher than the Curie point (126℃) of the crystal. We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.%Pyroelectric measurements are conducted during zero-field heating in [001],[110] and [111] poled 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 single crystals.Compared to the room-temperature-poled samples,the crystals poled by using the field cooling method show broad but well recognizable pyroelectric current peaks near 190℃,which is much higher than the Curie point (126℃) of the crystal.We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.

  19. Pyroelectric IRFPA mosaic image acquisition system with multi channels%多通道热释电 IRFPA 图像拼接采集系统

    Institute of Scientific and Technical Information of China (English)

    程瑶

    2014-01-01

    为了实现分辨率高的大规模热释电IRFPA 探测器,设计了多路通道并行输出的读出电路。针对多路输出的热释电IRFPA探测器,依据热释电探测的时序要求,设计了图像拼接采集系统。利用外部驱动信号控制采集卡的触发及采样时钟,由斩波器同步信号判断热释电探测器的亮场及暗场信号。构造PC-DA Q虚拟仪器系统对多通道输出的热释电型IRFPA进行多路并行图像采集,并对每路图像信号进行亮、暗场判断后进行差分处理,通过软件拼接处理成一副完整的图像,最终在软件平台上显示。对实验室研制的160列×120行双通道读出及320列×120行四通道读出的热释电读出电路进行了图像采集实验,对于同样阵列大小的单通道读出探测器,双通道结构读出速度提高了1倍,四通道结构读出速度提高了3倍。通过采集成像实验验证了系统的可行性。%In order to achieve large-scale pyroelectric infrared focal plane array (IRFPA ) detec-tor with high resolution ,the readout circuit with multi-channel parallel output was designed . Based on the pyroelectric IRFPA detector of multiple-output and the pyroelectric detecting tim-ing requirements ,the system of mosaic imaging acquisition was designed .The external driving signals were used to control the trigger and sampling clock of acquisition card ,and a chopper synchronizing signal was used to judge the bright field and dark field signal of the pyroelectric detector .The system was constructed with PC-DAQ virtual instrument system to acquire multi-channel parallel image ,judge the bright and dark field for differential processing on each channel ,and display a whole image after mosaic processing on software platform .The experi-mental image acquisition of the pyroelectric readout circuit with 160 × 120 two-channels read-out and 320 × 120 four-channels readout were taken and the output signal waveform and image were

  20. 基于弛豫铁电单晶的红外热释电探测器研究%Pyroelectric infrared detector with relax-based ferroelectric single crystals

    Institute of Scientific and Technical Information of China (English)

    马学亮; 邵秀梅; 于月华; 李言谨

    2012-01-01

    研究了新型热释电材料驰豫铁电单晶(1-x)Pb(Mg1/3Nbz/a)O3-xPbTiO3(PMNT)的低损伤减薄工艺、电极成型和耦合封装等关键技术,研制了基于PMNT的单元热释电探测器。对减薄后约30um晶片材料性能的测试分析表明,部分样品的热释电系数约为9.0×10^-4C/m^2K,无明显衰减。采用低噪声电路提取单元探测器的微弱热释电电流,对所研制的单元探测器性能进行了测试分析。%PMNT single crystal is a novel pyroelectric material with superior pyroelectric performance. The fabrication of pyroelectirc infrared detectors based on PMNT single crystal, including lapping and polishing of the crystal, metallization and assembly,is carried out. The pyroelectric coefficient of PMNT chip with thickness of 30 um is measured and the results indicate that the pyroelectric coefficients of some chips are 9.0 × 10^-4 C/m2K, similar to that of the PMNT single crystal with thickness of 500 um. Weak pyroelectric current is extracted by a low-noise circuit, and the performance of the fabricated detector is tested and analyzed.

  1. 手性化合物S811的强热释效应及反铁电特性%Large Pyroelectric Effect and Anti-ferroelectric Properties of Chiral Compound S811

    Institute of Scientific and Technical Information of China (English)

    牛小玲; 刘卫国; 刘鹏

    2011-01-01

    用热释电流谱、介电温谱、电滞回线谱、差示扫描量热仪(DSC)、热台偏光显微镜(PLM)对手性化合物S811的电学性能及相变行为进行了研究.热释电流谱、介电温谱显示S811在相变附近具有强热释电电流,其最大热释电系数达到384nC/(cm2·K),介电常数在相变过程也发生了突变.电滞回线谱显示,在冷却过程依次出现了反铁电体-铁电体转变的双电滞回线和单电滞回线,揭示了S811作为热释电探测材料的应用潜力,拓展了其应用范围.%The electrical properties and phase transition behaviors of chiral compound S811 have been investigated by pyroelectric, dielectric, polarization spectroscopy, DSC and PLM at different temperatures. It is found that S811 appeared a large pyroelectric current peak and a sharp growth of dielectric constants near the phase transition temperature The maximum value of the pyroelectric coefficient p obtained is 384nC/(cm2 · K). In the cooling process, the sample presented the transition of anti-ferroelectric to ferroelectric phase. The outstanding pyroelectric performances of S811 make it possible as a novel pyroelectric detectors.

  2. Study on Pyroelectric Property of BST Ceramics with DC Field%BST陶瓷场致热释电性能的研究

    Institute of Scientific and Technical Information of China (English)

    张光祖; 姜胜林; 张洋洋; 张清风; 张先云

    2009-01-01

    采用改进的电子陶瓷工艺,制备了高密度Ba0.6Sr0.4TiO3热释电陶瓷样品.研究发现,在1 340 ℃下烧结的样品,其密度可达到理论密度的98.3%.室温下测得样品的介电损耗为0.2%.外加直流偏场对材料的介电和热释电性能影响显著.样品的场致热释电系数为3.4×10-8 C/cm2·℃,探测率优值为10.0×10-5 Pa-1/2.%The Ba0.6Sr0.4TiO3 ceramics were prepared by improved electronic ceramics preparing process. The sample was obtained under the optimalized sintering temperature 1 340 ℃.The density could reach 98.3% of the theoretical density. At room temperature, the dielectric loss of the sample was 0.2%. The effects of DC field on the material's dielectric and pyroelectric property was obvious. The pyroelectric coefficient of the sample was 3.4×10-8 C/cm2·℃, the figure of merit of the sample was 10.0×10-5 Pa-1/2.

  3. 热释电探测器PZT晶片制备工艺研究%Study on Fabrication of Pyroelectric Detector PZT Wafer

    Institute of Scientific and Technical Information of China (English)

    黄江平; 王羽; 袁俊; 王学森; 郭雨航; 余瑞云

    2013-01-01

      This paper introduces the study of pyroelectric detector PZT wafer and the theory basis of choice of lead zirconate titanate(PZT)as sensitive element material. It also describes polishing and grinding theory. Factors affecting the polishing quality are analyzed in detail. The crystal surfaces polished by several different polishing liquid are analyzed by SEM, and SEM photos, surface roughness analysis and crystal surface morphology were gained. The best polishing material was determined. Through the combination of theory and practice, the pyroelectric detector wafer which could meet the technological requirements was got.%  介绍了热释电探测器PZT晶片制备工艺及选择锆钛酸铅(PZT)陶瓷材料制作敏感元的理论依据,阐述了晶片磨抛理论,对磨抛质量影响因素进行了细致分析。对比了几种抛光液对晶片表面的抛光效果,并进行了扫描电镜和表面粗糙度分析,得到了抛光后晶片表面的扫描电子显微镜(SEM)照片和晶片表面形态,确定了最佳抛光材料。通过理论和实践的结合,研制出了完全能满足器件工艺要求的热释电探测器晶片。

  4. Research on Spatial Uniformity Calibration of Pyroelectric Laser Energy Meter%热释电型激光能量计空间均匀性校准技术研究

    Institute of Scientific and Technical Information of China (English)

    易瑔; 罗天峰; 杨建昌

    2016-01-01

    热释电探测器由于其灵敏度高、响应速度快、体积小、损伤阈值高等特点,作为激光能量计的传感器在激光能量检测方面使用广泛。由于制作工艺的限制,热释电型激光能量计的热敏面灵敏度系数存在空间非均匀性问题,导致当激光照射到探测器不同位置时,激光能量测量结果不准确。针对这一问题,设计一种热释电型激光能量计空间均匀性校准方法,通过对热释电探头光路的控制,消除空间均匀性对测量结果的影响,并通过实例验证了方法的可行性。%For good features such as high sensitivity, fast response speed, small volume and high damage threshold, the pyroelectric detector as the sensor of the laser energy meter is widely used in laser energy detection. Limited by the manufacture process, the thermal surface sensitivity coefficients of the pyroelectric laser energy me⁃ter has spatial non-uniformity problem. When the laser irradiates the different positions of the detector, the results of the laser energy measurement is different. To solve this problem, a pyroelectric laser energy meter spatial uniformity calibration method is designed. Through controlling the light path of the pyroelectric detector, the influence on mea⁃sured results from spatial uniformity is removed. And the feasibility of the method is verified by the experiments.

  5. Pyroelectric Coefficient Testing System with Single Serial Port of Computer Feedback Control%计算机反馈控制型单串口热释电系数测试系统

    Institute of Scientific and Technical Information of China (English)

    杨俊; 曾亦可; 陈朝晖; 罗旖旎

    2011-01-01

    An improvement of pyroelectric coefficient testing system was studied. A single serial-port replaced the multi-serial port,which reduced complexity of the system and increased stability. A computer feedhack conLrol heatingrate was designed for the heater constniction,which eliminated the measurementerror caused by the temperature lag of the heater construction. It improved the linearity of line heating curve , and the linearity reached 0. 37% . Therehy it enhanced the accuracy of the measurement system.Several kind of pyroelectric materials were used to prove the superiority of the new system, and theexperimental results showed that the pyroelectric coefficient of pyroelectric materials measured by the new system were in accord with the theoretical values. Therefore,this system can accurately measure the pyroelecrric coefficient of the materials.%对热释电系数测试系统进行了研究,用单串口取代多串口,降低了系统连线的复杂度,提高了系统运行的稳定性;加入计算机控温机制,实现了计算机反馈控制加热炉升温速率,极大地提高了升温曲线的线性度,其线性度达到0.37%,从而消除了加热炉升温滞后性带来的测量误差,提高了测量的准确性.用几种热释电材料对现有系统进行了验证,实验表明新热释电系数测试系统的测试结果与理论数据相符,该系统已经可以较准确测量热释电材料的热释电系数.

  6. Fabrication and Properties of the Multi-layer Pyroelectric Thin Film Infrared Detectors%复合热释电薄膜红外探测器的制备和性能测试

    Institute of Scientific and Technical Information of China (English)

    王三红; 吴小清; 姚熹

    2001-01-01

    为解决热释电薄膜红外探测器中的热损失问题,引入了复合热释电薄膜的概念.它利用多孔二氧化硅具有的低热导率特点,有效地减少了热量从热释电层向衬底的热扩散.利用溶胶-凝胶和金属有机物热分解等工艺制备的复合热释电薄膜红外探测器,在温度为420K、频率为10Hz时,电压响应率约为1400V/W,探测器的星探测率D(420,10,2)为9.3×107cm.Hz1/2/W.%In order to reduce the thermal dissipation from the pyroelectric film to the substrate and meet the needs of integration with silicon, the multi-layer pyroelectric thin film (MPTF) was introduced. It is mainly composed of pyroelectric sensitive layer-lead titanate, thermal isolating layer-porous silicon dioxide film, and the buffer layer-dense silicon dioxide film. A pyroelectric measuring system was built to measure the infrared response of the detector. The voltage response and the specific detectivity of the detector were also given.

  7. Diagnosis of high-repetition-rate pulse laser with pyroelectric detector%基于热释电探测器的重频脉冲激光诊断

    Institute of Scientific and Technical Information of China (English)

    张磊; 邵碧波; 杨鹏翎; 王振宝; 闫燕

    2011-01-01

    Based on the working principles of a pyroelectric detector, the transient response of the detector to the pulse laser is researched. The model of pyroelectric detector is built, and the response in practical application is simulated according to the parameters of materials and structures. Signal process circuits which are suitable for a high-repetition-rate pulse laser are designed. Finally', a number of the repetition frequency laser radiation experiments on the pyroelectric detector are carried out. The experiments on frequency response and pulse width of the detector are completed, and the feasibility of applying the pyroelectric detector to the energy measurement of the high-repetition-rate and narrow pulse laser is verified.%摘以热释电探测器的工作原理为基础,研究了热释电探测器对重频脉冲激光的瞬态响应特性,建立了热释电探测器对单脉冲激光辐照响应的工作模型,分析了影响探测器频率特性的主要因素。根据材料和结构参数模拟计算了实际应用中的响应模型。设计了信号检测电路并对其进行计算仿事。完成了探测器的频率响应、脉宽响应等实验测量,验证了热释电探测器用于高重频、窄脉冲激光能量测量的可行性。

  8. Study on pyroelectric characteristic of piezoelectric ceramic excited by periodic thermal excitation%周期性热激励下压电陶瓷的热释电特性研究

    Institute of Scientific and Technical Information of China (English)

    吴仲武; 董卫; 姚丽; 张庆; 乔正辉

    2012-01-01

    设计了一套研究压电陶瓷热电特性的实验系统,并基于热释电效应研究了压电陶瓷在周期性热激励下的热电特性,拟合出了周期性热激励下压电陶瓷中产生的电压与电流的表达式.模拟和实验结果表明,当采用周期性的聚焦光线照射在压电陶瓷表面时,压电陶瓷表面的温度和正负极之间的电压也会周期性的变化,且变化的频率与调频装置的频率一致.%An experimental system was designed to study the pyroelectric characteristic of the piezoelectric ceramic. Based on pyroelectric effect,the pyroelectric characteristic of the piezoelectric ceramic under a condition of periodic thermal excitation was studied,and the formulas of voltage and current of the piezoelectric ceramic were also concluded. Results of the simulation and experiments show that the voltage of the piezoelectric ceramic changes periodically when the piezoelectric ceramic is illuminated by a periodic focused light. The frequency of the voltage is consistent with the frequency of the frequency converter.

  9. Composition and temperature dependence of ferroelectric and pyroelectric properties of (1 − x)[PMN–PT(65/35)]–xPZ (0 ≤ x ≤ 0.10) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Tong; Li, Qiang [Department of Chemistry, Tsinghua University, Beijing 10084 (China); Yan, Qingfeng, E-mail: yanqf@mail.tsinghua.edu.cn [Department of Chemistry, Tsinghua University, Beijing 10084 (China); Luo, Nengneng [Department of Chemistry, Tsinghua University, Beijing 10084 (China); Zhang, Yiling; Chu, Xiangcheng [State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China)

    2014-11-15

    Highlights: • PMN–PT–PZ ceramics with PZ content smaller than 0.10 mol% were synthesized. • T{sub rt} of the PMN–PT–PZ ceramics increased linearly with the increase of PZ constant. • A mutation of the ferroelectric and pyroelectric properties was observed near T{sub rt}. - Abstract: (1 − x)[Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3} (65/35)]–xPbZrO{sub 3} (PMN–PT–PZ) ceramics near morphotropic phase boundary with 0 ≤ x ≤ 0.10 were synthesized via the conventional solid-state reaction method. X-ray diffraction and variable temperature dielectric property characterization indicated that the rhombohedral to tetragonal phase transition temperature (T{sub rt}) increased linearly with the increase of PZ constant. The composition and temperature dependence of their ferroelectric and pyroelectric properties were also investigated. The results showed that there appeared mutation for remnant polarization, coercive field, as well as pyroelectric coefficient at the temperate range near T{sub rt}, which was ascribed to the reorientation of dipoles caused by the rhombohedral–tetragonal phase transition.

  10. Ferroelectric, piezoelectric, pyroelectric and Raman spectroscopy studies on BaTi{sub 0.9}(Fe{sub 1/2}Nb{sub 1/2}){sub 0.1}O{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkafi, Z.; Abdelmoula, N. [Laboratoire des Materiaux Ferroelectriques, Faculte des Sciences de Sfax, BP 802, 3018 Sfax (Tunisia); Simon, A.; Maglione, M. [ICMCB CNRS-Universite Bordeaux 1, Pessac (France); Khemakhem, H.

    2008-12-15

    The hysteresis, piezoelectric and pyroelectric properties were measured in the temperature range near the ferroelectric-paraelectric phase transition. The BaTi{sub 0.9}(Fe{sub 1/2}Nb{sub 1/2}){sub 0.1}O{sub 3} ceramic exhibits typical ferroelectric P -E hysteresis behavior with a remanant polarization, P{sub r}, of about 7.52 {mu}C/cm{sup 2} detected at 155 K. The electromechanical properties of this composition were measured using the resonance method. The ceramic provides high piezoelectric performance at the temperature of transition (T{sub max}=216 K): the piezoelectric constant is d{sub 31}=140 pC/N and the electromechanical coupling factor was k{sub P}=22%. The pyroelectric study confirms the dielectric and ferroelectric measurements. The pyroelectric coefficient is about 125 nC/cm{sup 2} K at T{sub max}. Raman spectra of BaTi{sub 0.9}(Fe{sub 1/2}Nb{sub 1/2}){sub 0.1}O{sub 3} ceramic were taken at various temperatures and measured over the wave number range from 150 to 1300 cm{sup -1}. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Effects of Ca-dopant on the pyroelectric, piezoelectric and dielectric properties of (Sr 0.6Ba 0.4) 4Na 2Nb 10O 30 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-12-01

    Calcium-doped sodium strontium barium niobate (SBNN, (Sr 0.6Ba 0.4) 4-xCa xNa 2Nb 10O 30, 0 ≤ x ≤ 0.5) ceramics were prepared by a conventional solid-state reaction method. SBNN showed \\'filled\\' tetragonal tungsten-bronze structure with fully occupied A-sites. The tetragonal structure, as revealed by X-ray diffraction (XRD) and Raman spectroscopy, was not affected by the Ca-dopant. Effects of Ca-doping concentration on the phase transitions as well as ferroelectric, piezoelectric and pyroelectric properties of the SBNN ceramics were investigated. From the dielectric studies, two anomalies were observed, namely, a sharp normal ferroelectric transition at 260 °C and a broad maximum at round -110 °C. The later was affected by the Ca-doping concentration and its origin was discussed. At x = 0.3, the sample exhibited the highest pyroelectric coefficient of 168 μC/m 2 K and the largest piezoelectric coefficient (d 33) of 63 pC/N at room temperature. On the basis of our results, the pyroelectric properties of the SBNN were improved by Ca-doping. © 2012 Elsevier B.V. All rights reserved.

  12. 热释电红外传感器及其在人员计数系统中的应用%Pyroelectric infrared sensor and its application in people counting system

    Institute of Scientific and Technical Information of China (English)

    易金桥; 黄勇; 廖红华; 谭建军; 姜胜林

    2015-01-01

    People-counting systems for image acquisition are usually complicated and expensive. In this paper, with detailed analysis of the pyroelectric effect and infrared sensor, BISS0001 integrated signal processing chip were chosen to design an amplifier circuit for the RE200B pyroelectric infrared sensor, in order to study its output waveforms under various human movement states. A people-counting system was designed, with double pyroelectric infrared sensors as the signal acquisition unit and a Cortex-M3 microcontroller as the control core, and its main algorithms were researched. The experimental results demonstrate that different body movement states can be accurately characterized using the output waveforms of the RE200B pyroelectric infrared sensor and the movement directions can be precisely distinguished by the people-counting system based on double pyroelectric infrared sensors designed in this paper. Furthermore, the system realizes real-time counting, and can be applied to a wide range of areas including human body detection and counting.%针对图像采集人员计数系统复杂、价格昂贵等缺点,在分析热释电效应以及红外传感的基础上,采用BISS0001型信号处理专用集成芯片设计了基于RE200B热释电红外传感器的放大电路,研究其在不同人体运动状态下的输出波形;设计了以双热释电红外传感器为信号采集单元,以Cortex-M3单片机为控制核心的人员计数系统,并研究其主要算法。实验结果表明,RE200B型热释电红外传感器的输出波形能够准确表征人体的不同运动状态,基于双热释电红外传感器的人员计数系统能准确分辨人体的运动方向,并实时计数,可广泛应用于人体探测和人员计数等领域。

  13. 人工复合铁电多层膜热释电性质的理论研究%Theoretical Investigation on Pyroelectric Properties of Artificial Composite Ferroelectric Thin Films

    Institute of Scientific and Technical Information of China (English)

    陈辉; 成泰民; 陈思群

    2011-01-01

    A theoretical model of ferroelectric thin film composite by three ferroelectric materials with different phase-transition temperatures has been built, in which the three components composite perpendicular to the polarization. Using ginzburg-landau-devonshire(GLD) theory, a local distribution function has been introduced to describe the properties of the transition layers, and the pyroelectric properties of the composite ferroelectric thin films have been mainly investigated. Polarization distributions, transition temperatures and pyroelectric coefficients were calculated with different composite methods. It was shown that the composite methods had importance influence on polarization and pyroelectric properties; two pyroelectric peaks appeared with the change of the film temperature. The composite ferroelectric thin film under new model presented many new properties, especially provide a reference on the improvement of pyroelectric devices. This composite film may be a new choice of multi-layer films in applications.%建立3种具有不同相变温度的铁电材料垂直于极化方向复合而成的铁电薄膜的理论模型,在ginzburg-landau-devonshire (GLD)唯象理论的框架下展开研究,同时引入局域分布函数来描述不同材料间过渡层的性质,主要研究了复合铁电薄膜的热释电性质.通过改变3种不同铁电材料的复合方式,计算了铁电多层膜内部的极化强度分布、相变温度及热释电系数.研究表明,具有不同相变温度的铁电材料间的复合方式对铁电薄膜的极化和热释电性质有着重要的影响,3种不同材料复合而成的铁电薄膜随着温度的变化出现了2个热释电峰.新模型下的复合铁电薄膜表现很多新的特性,尤其对于铁电热释电器件性能的改良提出了一种参考,该种复合薄膜也许能够成为通常使用的多层膜的一种选择.

  14. Study on Inter-Diffusion Barrier Layer between PZT Pyroelectric Thick Film and Si Substrate%PZT厚膜与Si衬底互扩散阻挡层研究

    Institute of Scientific and Technical Information of China (English)

    陈冲; 吴传贵; 彭强祥; 罗文博; 张万里; 王书安

    2013-01-01

    在Pt/Ti/SiO2/Si基片上,利用电泳沉积制备PZT热释电厚膜材料.为防止Pb和Si互扩散,在Pt底电极与SiO2/Si衬底间通过直流磁控溅射制备了TiOx薄膜阻挡层.对具有0、300 nm和500 nm TiOx阻挡层的PZT厚膜材料用SEM和能量色散谱仪(EDS)表征了Pb和Si互扩散情况,用动态热释电系数测量仪测试了热释电系数.结果表明,当TiOx阻挡层为500 nm时,可阻挡Pb和Si互扩散,热释电性能最好.热释电系数p=1.5×10-8 C·cm-2·K-1,相对介电常数εr=170,损耗角正切tanδ=0.02,探测度优值因子Fd=1.05×10-5pa-0.5.%PZT thick film as pyroelectric material has been prepared on the Pt/Ti/SiCK/Si substrate by using the electrophoresis deposition (EPD) method. In order to prevent the inter-diffusion between Pb and Si,a TiOx film barrier layer between Pt bottom electrode and SiO2/Si substrate has been prepared by using the DC magnetron sputtering method. The inter-diffusion between Pb and Si in PZT thick film material with TiO, barrier layer thickness of 0, 300 nm and 500 nm respectively have been characterized by SEM and EDS. The pyroelectric coefficient has been measured by the dynamic pyroelectric coefficient instrument. The results show that the inter-diffusion between Pb and Si can be blocked when the thickness of TiOx barrier layer is 500 nm and have the best pyroelectric properties. The pyroelectric coefficient, relative dielectric constant,dielectric loss and detectivity figure of merit are p=1. 5 × 10-8C · cm-2k-1 ,εr = 170,tan 8=0. 02 and Fd = 1. 05 × 10-5 Pa-0.5 respectively.

  15. Contactless Temperature Measurement System Based on Pyroelectric Sensor%热释电传感器的非接触式测控系统设计

    Institute of Scientific and Technical Information of China (English)

    叶健成

    2013-01-01

    Basic principles of using pyroelectric infrared sensor for non-contact measurement,infrared temperature measurement system structure and composition of signal processing circuit are introduced in this paper.On this basis,the paper designs and implements a set of non-contact infrared temperature measurement device,it uses the device to measure movement target surface temperature.When it simulates the application of actual scene,it can realize the accurate measurement of the distant pedestrian body temperature,also it increases the high temperature alarm circuit and bluetooth wireless communication module,and expands the using function.%介绍了利用热释电红外传感器进行非接触式测温的基本原理、红外测温系统结构和信号处理电路的组成.以此为基础,设计了一套非接触式红外测温装置,用该装置测定了移动目标表面温度.在模拟实际场景应用时,实现了对较远距离的运动行人体温的准确测量;装置还增加了高温报警电路和蓝牙无线通信模块,丰富了使用功能.

  16. 动态下红外热释电传感器的目标定位方法%New target location method based on dynamic pyroelectric infrared sensor

    Institute of Scientific and Technical Information of China (English)

    孙乔; 杨卫; 于海洋; 刘俊

    2012-01-01

    In order to improve detection sensitivity of the pyroelectric sensor and broaden the scope of traditional use of the sensor, a new applied method based on dynamic pyroelectric infrared sensor was presented in this paper, which can find the body target and coordinates. This method greatly expanded the detection range of pyroelectric infrared sensor, which could accurately determine the direction of the target according to the waveform, deduce the distance from experience. A pyroelectric infrared sensor was used as a detector in this system, innovatively use of infrared lens to replace the traditional Fresnel lenses. MCU recorded the original infrared waveform of the measurement area(if the environment keeped changeless in a long time the waveform would have a certain basic rules); once the body target walked into the measurement area, it would lead to changes of the original law, and the microcontroller would obtain direction, distance and other results according to the use of inter-frame difference method. With the traditional use of pyroelectric sensor, the method had some new feathures such as fast response, detection sensitivity, wide detection range, direction measure and distance measure. It significantly broadens the use scope of the pyroelectric sensor, and further strengthens its application in security and smart home system.%为了提高热释电传感器的探测灵敏度,拓宽其传统使用范围,提出了一种动态下热释电传感器发现人体目标并测向测距的新型使用方法.该方法大大扩展了热释电传感器的探测范围,根据波形能准确判定目标的方向,利用经验值推断出人体的目标距离.该系统采用热释电红外传感器作为探测器,创新运用红外透镜代替传统用法中的菲涅耳透镜,在步进电机的匀速带动下,单片机记录测量区域的原始红外波形(在环境基本不变且没有目标进入的情况下,波形具有一定规律且基本保持不变);目标进入测

  17. 热释电红外传感器在新型弹药引信中的应用%Application of Pyroelectric Infrared Sensor in New Ammunition Fuze

    Institute of Scientific and Technical Information of China (English)

    平子鹏; 赵洋

    2016-01-01

    The target detection and recognition of the fuze is an important part of the new intelligent ammunition .Com‐bined with the current target detection and recognition technology ,a method of target detection and identification is presented based on the pyroelectric infrared sensor .On the basis of the working principle of pyroelectric infrared sensor ,the infrared characteristics of the human body are analyzed and the experimental simulation is carried out .The results show that the tar‐get detection and recognition based on pyroelectric infrared sensor is feasible ,which has a key role in improving the opera‐tional effectiveness of weapon system ,enhancing the conventional deterrence and combat capability .%引信的目标探测与识别是新型智能弹药系统的重要组成部分,结合当今目标探测识别技术,给出了一种基于热释电红外传感器的引信探测与识别方法。文章在阐述热释电红外传感器工作原理的基础上,分析人体目标的红外特性并进行实验仿真。结果表明,基于热释电红外传感器的引信目标探测与识别是可行的,对提高武器系统作战效能,增强常规威慑和实战能力具有关键作用。

  18. Multi-Object Tracking Scheme with Pyroelectric Infrared Sensor and Video Camera Coordination%融合热释电红外传感器与视频监控器的多目标跟踪算法

    Institute of Scientific and Technical Information of China (English)

    李方敏; 姜娜; 熊迹; 张景源

    2014-01-01

    现有基于热释电红外传感器的多目标跟踪系统在目标之间距离较近或者轨迹相交的情况下存在着误差较大的缺点。针对此缺点,提出了一种新型的基于热释电红外传感器与视频监测器协同工作的多目标跟踪方案。该方案可以充分利用两种传感器的优势,弥补在目标跟踪中的不足。算法采用最小二乘法利用热释电信息进行定位,并通过从图像或热释电传感器信号的幅频特性中提取特征信息来校正联合概率数据关联算法的关联矩阵,有效避免了错误关联。实验表明,该方案在多目标交叉情况下跟踪误差仅为其它算法的八分之一到四分之一。%The error tends to be significant in many existing pyroelectric infrared sensor based multi-object tracking systems when the measured objects get close to each other or their trajectories have intersections .To solve this problem ,we proposed a mul-ti-object tracking scheme by having pyroelectric infrared sensors and video cameras work cooperatively .This scheme takes the ad-vantages of both kinds of sensors ,which help to improve the performance compared to those using any kind of such sensors .In the proposed scheme ,we first achieve coarse positioning using least square method with data collected by pyroelectric infrared sensors , and then we correct the incidence matrix in joint probabilistic data association with features extracted from the images or the fre -quency responses of pyroelectric sensors .The coarse positioning is further filtered by joint probabilistic data association algorithm to obtain the final fine result .Such a method prevents false association effectively .Experimental results show that the tracking error of the proposed scheme in multi-object crossover scenario reduces to a quarter ,even to one eighth of the errors that exist in the com-pared schemes .

  19. 基于热释电传感器的能量采集系统设计%The design of thermal energy harvesting system based on pyroelectric sensor

    Institute of Scientific and Technical Information of China (English)

    王芳; 李焕焕; 韩文超; 彭玉峰

    2012-01-01

    This paper designed an embedded integrated rechargeable battery system which could achieve a variety of energy collection. The battery system can be used in the multiple micro - sensor nodes of monitoring and warning system , which can make use of environment temperature and heating signal to charge directly. The system is made of a pyroelectric element, rectifier circuit, the DC/DC voltage boost circuit and a switch control circuit module. The article analysised the influence of the electrical parameters of the pyroelectric unit in the thermal cycle on the charge of the capacitor charge; besides, gave the key part of the circuit design of the pyroelectric charge battery and made study of design of improved CMOS rectifier circuit, booster circuit and switch control circuit. The study does not only improve the efficiency of the output,but also achieve a high degree of integration. The simulation and experiment results show that making use of the pyroelectricity to collect and store the energy is effective and feasible.%本文设计一种可实现多种能量收集的嵌入式集成微充电电池系统,该电池系统可用在监测预警系统中的多个微传感器节点上,直接利用环境中的温度和热信号进行充电.该系统包含热释电单元、整流电路、DC/DC升压电路等模块.理论分析了热释电单元的电参数在热循环周期内对充电电容上电荷的影响,给出了热释电充电电池的关键部分电路设计,对改进CMOS整流电路、升压电路进行了研究,不仅提高了输出效率,同时实现了高集成度.仿真和实验结果表明利用热释电进行能量收集和储存是有效可行的.

  20. Design and Research on Amplifier Circuit for Pyroelectric Infrared Sensor%热释电红外传感器前置放大电路设计与研究

    Institute of Scientific and Technical Information of China (English)

    滕飞扬; 陈连坤

    2012-01-01

    介绍热释电红外传感器的工作原理和性能,分析热释电红外传感器的信号输出特性,设计基于此类传感器的前置滤波放大电路.并使用单片机进行经过电路放大后的脉冲信号的分析,完成对人体运动的检测。使用Alfium Designer6.9对前置滤波放大电路进行软件仿真,以验证该放大电路的有效性和可靠性。%Introduces the working principle and performance of pyroelectric infrared sensor, and analyses the characteristics of pyroelectric infrared sensor signal output, then designs an preamplifier based on this type of sensor, and uses the microcontroller for analysis of the amplified signal to finish the detection of human motion. Uses Ahium Designer 6.9 to simulate the preamplifier, verifies the validities and reliability of the preamplifier.

  1. Pyroelectricity and Spontaneous Polarization in [111] Oriented 0.955 Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    SHEN Ming-Rong; YAO Dong-Lai; CAO Wen-Wu

    2005-01-01

    @@ We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0. 955 Pb(Zn1/3Nb2/3)O3-0.045 PbTiO3 (PZN-4.5%PT) single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30℃ increases abruptly from 14μC/cm2 for a poling field of 0.06kV/cm to 29.5μC/cm2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm2 for poling fields beyond 0.55 kV/cm.

  2. Study on Low Temperature Pyroelectric and Elastic Properties of Li0.06Na0.94NbO3 Ceramics%低温下铌酸锂钠陶瓷的热释电性与弹性研究

    Institute of Scientific and Technical Information of China (English)

    艾树涛; 王春雷; 张沛霖; 赵明磊; 杜爱军

    2001-01-01

    Pyroelectric and elastic properties of Li0.06Na0.94NbO3 ceramics have been investigated in the temperature range from 120~320 K.Its pyroelectric and elastic properties behave anomalously in certain low temperature intervals.This shows there is a low temperature ferroelectric phase transition in Li0.06Na0.94NbO3 ceramics.The inversion of its pyroelectric coefficient in polarized direction to the opposite sign and the change of the polarity of pyroelectric charge with time during phase transtion have been observed.The evolution of elastic properties is connected with the secondary piezoelectric effect.%在120~320 K的温度范围内研究了锂酸锂钠陶瓷的热释电性与弹性。其热释电行为与弹性行为在低温区域内显著反常,表明该陶瓷存在低温铁电-铁电相变。观测到极化方向的热释电系数改变符号及热释电电荷随时间改变极性的现象。弹性变化与次级压电效应是相关的。

  3. 制备工艺对Fe掺杂PZN-PZT热释电陶瓷性能的影响%The effects of synthesis route on the electricalproperties of Fe-doped PZN-PZT pyroelectric ceramics

    Institute of Scientific and Technical Information of China (English)

    韦慧; 陈拥军; 郭栋

    2016-01-01

    采用传统氧化物反应法(一步法)和前驱体法(两步法)合成铁掺杂改性的0.075Pb(Zn1/3 Nb2/3)O3-0.925Pb(Zr0.95 Ti0.05)O3(PZN-PZT)热释电陶瓷,研究制备方法对PZN-PZT热释电陶瓷的微观形貌、相结构及电学性能的影响。XRD结果表明,采用一步法制备的陶瓷不如两步法,前者存在钙钛矿相和少量焦绿石相,后者能有效抑制焦绿石相的生成,陶瓷为纯菱方钙钛矿相。SEM分析进一步证实了两步法能够制备出晶粒分布均匀、晶型饱满的致密陶瓷。结合介电、铁电及热释电性能分析可知,单一钙钛矿结构和均匀紧凑的晶粒结构对陶瓷材料电学性能的增强起着重要的作用。%Fe-doped 0.075 Pb(Zn1/3 Nb2/3 )O3-0.925Pb(Zr0.95 Ti0.05 )O3 (PZN-PZT)pyroelectric ceramics were pre-pared by a conventional oxide-mixed one-step method and precursor two-step method,respectively.The phase structure and electrical properties of the prepared ceramics were systematically investigated.X-ray diffraction results indicated that the ceramics fabricated by the one-step method possess a mixture of perovskite phase and pyrochlore phase,while the ceramics prepared from the two-step method have a single perovskite phase struc-ture.Scanning electron microscopy observation suggests that the ceramics prepared by the two-step method have a dense microstructure with uniform grains.The dielectric,ferroelectric and pyroelectric properties were measured,which revealed that the ceramics with single phase and dense microstructure have enhanced ferroelec-tric and pyroelectric properties.

  4. Study on the pyroelectric properties of lithium niobate wafer prepared by wafer bonding and thinning%铌酸锂晶片的键合减薄及热释电性能研究

    Institute of Scientific and Technical Information of China (English)

    杨绪军; 陈箫; 刘岗; 牛坤旺; 张文栋

    2011-01-01

    铌酸锂(LN)作为一种热释电材料,可以被用于制作光电探测器敏感单元的敏感层,但通常LN晶片厚度为0.5 mm,远大于光电敏感单元厚度的要求,所以需要用键合减薄及抛光技术对LN晶片进行加工处理.本研究所用键合减薄技术主要包含:RZJ-304光刻胶键合、铣磨、抛光、剥离液剥离和丙酮清洗RZJ-304胶.利用该技术加工得到了面积为10 mm×10 mm,厚度为50 μm,表面比较光滑,表面粗糙度为1.63 nm的LN晶片.LN晶片的热释电信号峰峰值在减薄抛光后为176 mV,是未经处理时的4倍,满足了热释电探测器敏感层的要求.%Pyroelectric material lithium niobate (LN) can be used for the preparation of sensitive layer in the sensitive element of photoelectric detector. However, as the thickness of normal LN wafer, which is 0.5 mm, is much larger than the thickness of sensitive element, LN wafer need to be processed using the thinning and polishing techniques. A novel wafer bonding and thinning technique was introduced in this study, and it mainly included: wafer bonding with RZJ-304 photoresist, grinding, polishing, separating wafers with stripper and removing photoresist with acetone. LN wafer (10mm in square) with a thickness of 50 um is prepared using this technique, and the surface of prepared LN wafer is very smooth with the surface roughness being 1.63 nm. The peak value of the pyroelectric signal of the processed LN wafer is 176 mV, which is four times that of the unprocessed wafer, fulfilling the requirements of the sensitive layer of pyroelectric detector.

  5. LHI878热释电红外传感器的体温检测系统设计%Design of temperature detection system base on LH878 pyroelectric infrared sensor

    Institute of Scientific and Technical Information of China (English)

    赵春华; 许云涛; 宁春玉

    2013-01-01

      设计一种以ATmage32单片机为核心的热释电红外体温测量系统.利用热释电红外传感器,设计一个非接触式的语音播报体温测量系统.采用热释电红外传感器来提取人体温度信号,同时由DS18B20测量环境温度信号,进行温度补偿减少测量误差.将提取的温度信号经过模拟处理后由AVR单片机控制实现对人体温度值的转换及处理,将得到的温度值送入LCD显示及语音播报.同时还加入了时钟功能和超温报警功能,使设计更具实用性.该体温测量系统测量范围为35~42益,测量时间小于1 s.该温度检测系统具有使用方便、灵活性好、可靠性高等优点,具有一定的推广应用价值.%A kind of pyroelectric infrared temperature measurement system was designed, which core was the ATmage32 SCM. It was a non-contact and voice prompt temperature measurement system by using pyroelectric infrared sensor. It used the pyroelectric infrared sensor to extrat the temperature of the human body and the DS18B20 to measure the environmental temperature, which could achieve the temperature compensation to reduce the measurement error. It could be controlled to realize the temperature convertion and processing, and sent the temperature value to the LCD to display and the voice prompt by the AVR SCM. Simultaneously, it was added the clock function and overtemperature alarm function to make the design more practical. The temperature measurement range was from 35-42℃. The measurement time was less than 1s. The temperature measurement system had the advantages of handy use, good flexibility, high reliability, and had a promotional value.

  6. Influence of Boundary Conditions on Pyroelectric Properties of Temperature-graded Ferroelectric Films%边界条件对温度梯度铁电薄膜热释电性质的影响

    Institute of Scientific and Technical Information of China (English)

    陈辉; 冮铁臣; 成泰民; 陈思群; 李青云

    2013-01-01

    In the framework of the mean field approximation, a transverse Ising model was adopted to investigate the influence of different boundary conditions (clamped boundary condition and free boundary condition) on the pyroelectric properties of temperature-graded ferroelectric thin films. A function was introduced to characterize the distribution of the interaction couplings between two pseudo-spins under different boundary conditions. It is shown that the distribution of temperature gradient and boundary conditions have great influence on polarization distribution and pyroelectric coefficients. There are two pyroelectric peaks in curves for temperature-graded ferroelectric thin films. The second peak under free boundary condition is much higher than the peaks of non-graded film and peaks under clamped boundary condition.%在平均场近似的理论框架下,采用横场伊辛模型研究了不同边界条件(固定边界条件和自由边界条件)对温度梯度铁电薄膜热释电性质的影响.引入一个分布函数来描述不同边界条件下赝自旋相互作用系数的变化.研究表明,薄膜内部的温度梯度分布和薄膜所处的边界条件对其极化分布和热释电系数都有很大的影响.温度梯度铁电薄膜的热释电曲线中出现了2个热释电峰,其中自由边界条件下的薄膜所对应的第2个热释电峰比无温度梯度的铁电薄膜和固定边界条件下的温度梯度铁电薄膜的热释电峰都要高出许多.

  7. 基于单片机热释电红外安防报警器的设计%Design of Pyroelectric Infrared Security Alarm Based Single-Chip Microcomputer

    Institute of Scientific and Technical Information of China (English)

    赵巧妮

    2016-01-01

    热释电红外防盗报警器是利用红外传感器技术来自动探测发生在布防监测区域内的异常人员的入侵行为,并及时产生声光报警信号,提示主人及时处理异常情况,避免危险情况发生,维护社会和家庭人员、财产的安全。%Pyroelectric infrared burglar alarm, by using infrared sensor technology, can automatically detect abnormalities by armed persons in the event of intrusion monitoring area, and timely produce sound and light alarms to notify the owner to respond to avoid theft, snatches, or sabotage, in order to maintain security of social and family members, and of property.

  8. Ferroelectric, piezoelectric, pyroelectric studies on BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Boujelben, F; Bouzid, H; Bahri, F; Maalej, A; Khemakhem, H; Simon, A; Maglione, M, E-mail: faizaboujelben@yahoo.fr

    2010-11-15

    The main objective of this paper is to study dielectric, ferroelectric, pyroelectric and piezoelectric proprieties of BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3}. From dielectric experiments, a single ferroelectric transition temperature of about 300K was found. The ferroelectric hysteresis loops were recorded versus temperature evidencing a saturation polarisation of about 4{mu}C/cm{sup 2} and a coercive field of 0.97kV/cm at the lowest temperature. The most promising result for BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3} is its effective piezoelectric coefficient d{sub 31}which reaches 55pCN{sup -1} at room temperature.

  9. Pyroelectric effect in PbZr0.3Ti0.7O3/PbTiO3 superlattices%PbZr0.3Ti0.7O3/PbTiO3超晶格的热释电性研究

    Institute of Scientific and Technical Information of China (English)

    陈加文; 戴大鹏; 曹海霞

    2011-01-01

    Based on the Landau-Ginzburg- Devonshire theory, the pyroelectric effect of ferroelectric superlattices PbZro.3Ti0.7O3/PbTiO3 has been investigated , in which the misfit strain between the two slabs is taken into account. The impact of interfacial coupling strength, composition concentration proportion of Pb2r0.3Ti0.7O3 slab in one period on the pyroelectric coefficient has been calculated. It is found that the ferroelectric superlattice displays pronounced pyroelectric effect. Essentially, the ferroelectric superlattices provide an effective means to acquire good pyroelectric effect by adjusting the interfacial coupling strength , as well as compositional thickness concentration.%基于朗道-金兹堡格-德文希尔(Landau-Ginzburg-Devonshire)热力学理论,我们研究了由PbZr0.3Ti0.7O3(PZT)与PbTiO3(PT)两种组份组成的超晶格的热释电性,并且考虑了两组份之间的失配应变的影响.我们探讨了界面耦合强度、组分厚度比例以及失配应变等对超晶格的极化强度和热释电性的影响.计算结果表明,这种铁电超晶格材料具有巨大的热释电系数.因此,我们可以通过调节界面耦合强度、组份比例等方法达到调控热释电性的目的,为实验和应用研究提供一个可靠而有效的方法.

  10. Growth and pyroelectric properties of high Curie temperature relaxor-based ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ternary single crystal

    Science.gov (United States)

    Yu, Ping; Wang, Feifei; Zhou, Dan; Ge, Wenwei; Zhao, Xiangyong; Luo, Haosu; Sun, Jinglan; Meng, Xiangjian; Chu, Junhao

    2008-06-01

    To enhance the service temperature of relaxor-PbTiO3 pyroelectric single crystals, high quality ternary perovskite single crystal was grown by a modified Bridgman technique. Analyzed by x-ray fluorescence, the as-grown crystal is 0.41Pb(In1/2Nb1/2)O3-0.17Pb(Mg1/3Nb2/3)O3-0.42PbTiO3 [PIMNT(41/17/42)], which appears to be a tetragonal ferroelectric phase with relatively high Curie temperature of 253°C. It exhibits the relative permittivity of 487 and low dielectric loss of 0.3% at 50Hz and room temperature. The pyroelectric properties with a pyroelectric coefficient of 5.7×10-4C /m2K and a detectivity of 6.34×10-5Pa-1/2 would satisfy the needs of operation as a high Curie temperature material. The results show that PIMNT crystal with better temperature stability, compared with the pure PMNT single crystals, is a good candidate as an infrared detector material.

  11. 新型热释电材料及其在红外探测器中的应用%Novel pyroelectric materials and their applications in high performance infrared devices

    Institute of Scientific and Technical Information of China (English)

    刘林华; 罗豪甦; 吴啸; 赵祥永; 方家熊; 李言瑾; 邵秀梅; 景为平

    2011-01-01

    以(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3{PMNT[(1-x)/x}为代表的大尺寸、高质量弛豫铁电单晶具有非常高的热释电系数、探测优值和较低的热扩散系数,其综合热释电性能远优于传统的热释电材料.概述了PMNT[(1-x)/x]单晶、掺锰PMNT(74/26)单晶和0.42Pb(In1/2Nb1/2)O3-0.3Pb(Mg1/3NB2/3)O3-0.28PbTiO3[PIMNT(42/30/28)]单晶的介电性能、铁电性能和热释电性能.掺杂后PMNT(74/26)单晶的介电损耗降低到0.0005,探测优值提高到40.2×10-5Pa-1/2,是目前所有三方四方相变温度(TRT)高于90℃的本征热释电材料中最高的.高居里温度PIMNT(42/30/28)单晶的TRT达到152℃,且具有较高的探测优值(10.2×10-5Pa-1/2),将在更宽温度范围内得到广泛的应用.制作了基于掺锰PMNT(74/26)单晶的单元探头,其比探测率D*达到1.07×109cmHz1/2W-1,是目前商用LiTaO3探测器的两倍,器件性能满足实用要求.%The large-size, high-quality relaxor-based ferroelectric single crystals represented by(1-x)Pb (Mg1/3Nb2/3) O3-xPbTiO3 {PMNT [(1-x)/x] } perform very high pyroelectric coefficient, detectivity figures of merit and relatively low thermal diffusivity, which makes its comprehensive pyroelectric properties far superior to the traditional pyroelectric materials. The dielectric, ferroelectric and pyroelectric properties of the PMNT [(1-x)/x], Mn-doped PMNT (74/26) and 0.42Pb(In1/2Nb1/2)O3-0.3Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 [PIMNT(42/30/28)] single crystals were overviewed. The dielectric loss of Mn-doped PMNT(74/26) crystals was declined to 0.0005, and the detectivity figures of merit was enhanced to 40.2×10-5 Pa-1/2, which was the highest value so far reported among intrinsic pyroelectric materials with TRr higher than 90 ℃. HighCurie-temperature PIMNT (42/30/28) crystals with TRT of 152 ℃, employed relatively high detectivity figures of merit (10.2×l0-5 Pa-1/2), would be widely used in a wider temperature range. The specific detectivity of infrared detector based

  12. 宽温区热释电陶瓷的复合烧结法与性能研究%The Study on Mixed Sintering Method and Properties of Pyroelectric Ceramics with Wide Temperature Range

    Institute of Scientific and Technical Information of China (English)

    赵强; 曾亦可; 姜胜林; 张光祖; 张洋洋

    2012-01-01

    There is a famous Frl-Frh phase transition giving high pyroelectric coefficient with very little change in the dielectric constant and loss occurred near room temperature in Zr-rich PZT ceramics. However,the temperature range of this phase transition is very narrow and the transition temperature could be changed by the variation of the Zr/Ti ratio. In this paper, two kinds of Mn-doped starting materials, those Zr/Ti ratio were 95/5 and 93, 5/6. 5 respectively, were mixed sintered in order to broaden the phase transition temperature. It was found that, the temperature range was successfully extended when the two starting materials were pre-treated at 1100 C before mixed by the mass ratio of 1 : 1. The pyroelectric coefficient p was higher than 6. 3×10-8 C/(cm2·℃ and the figured merit FD was higher than 7. 7× 1013 Pa-1/2 in the temperature range 19 ℃ to 43 ℃. The effects of mixed sintering on their pyroelectric,dielectric and ferroelectric properties have been comprehensively studied, and it was found that the dielectric and ferroelectric properties were also improved.%富锆型PZT陶瓷在室温附近发生低温铁电三方相到高温铁电三方相的相变(FRL-FRH)相变并产生很大的热释电系数,相变过程中介电常数和损耗变化很小,相变温区很窄,相变温度随锆钛比的不同而不同.该文选取锆钛比为95/5和93.5/6.5的Mn掺杂PZT材料进行复合烧结,以期展宽相变温区.实验结果表明,两种初始原料1 100℃预处理后按照质量比1∶1进行复合烧结,相变温区得到了有效的展宽,在19~43℃内热释电系数p大于6.3×10-8 C/(cm2·C),探测率优值FD大于7.7×10-5 Pa1/2.通过对热释电、介电和铁电性能的综合研究,发现复合烧结在优化PZT陶瓷热释电性能的同时优化了其介电和铁电性能.

  13. 辽西北票二道沟金矿的成矿特点和黄铁矿热电性特征%Ore-forming Characteristics and Pyroelectricity of Pyrite of the Erdaogou Gold Deposit, Beipiao, Western Liaoning

    Institute of Scientific and Technical Information of China (English)

    王鹏; 董国臣; 李志国; 聂飞; 陈友长; 孙凡; 王霞; 董美玲

    2013-01-01

    通过对辽西北票二道沟金矿Ⅲ号脉的不同中段的矿石组构、金的分布特点和主要载金矿物立方体、五角十二面体及它形黄铁矿的热电性研究,讨论了成矿特征,计算了成矿温度和矿体剥蚀率并对深部找矿远景进行了预测.研究表明:二道沟金矿金的分布特点存在不均匀性;黄铁矿热电性以P型为主且变化范围宽,只有少量的N型,表明矿体的剥蚀率较低.二道沟金矿可能存在多期次的热液活动,且每一期次相互叠加改造;成矿热液来自南东方向,成矿热液早期温度较高,金属元素大量沉淀温度为150 ~300℃,属中低温,且不同中段的成矿温度有一定的变化规律.不同晶形的黄铁矿热电性研究表明,不同晶形载金能力不同,黄铁矿热电性P型频率不同,形成的温度不同,但计算的矿体剥蚀率相差不大.%According to the ore texture, gold occurrence, shape and pyroelectricity of pyrites of vein Ⅲ in the Erdaogou gold deposit in Western Liaoning, the authors discussed the ore-forming temperatures, denudation rates and evaluated the ore deep prospects. The studies prove that the gold occurrence in the ores was unhomo-geneous. The pyrite was mainly P-type and varied widely, with a few N-type, in terms of pyroelectricity, which indicated that a few part of the orebody was removed by uplift and erosion. Possibly, there were several hydro-thermal activities superposed each other in the Erdaogou gold deposit. The metallogenic hydrothermal solution came from southeast direction. Though the initial hydrothermal temperature was high, most metal minerals precipitated when the temperature ranged from 150 to 300 ℃ , indicating that the Erdaogou gold deposit belonged low-medium hydrothermal type. The pyroelectricity measurements of pyrite indicated that denudation rate was similar, even though the pyrites were different in frequency of P-type, forming temperature and gold content.

  14. Synthesis of 0.64Pb(Mg1/3Nb2/3O3–0.36PbTiO3 ceramic near morphotropic phase boundary for high performance piezoelectric, ferroelectric and pyroelectric applications

    Directory of Open Access Journals (Sweden)

    Abid Hussain

    2016-09-01

    Full Text Available A near MPB composition of 0.64PMN–0.36PT ceramic has been synthesized by solid-state reaction technique using columbite precursor. Sintering at 1030 °C resulted in a single perovskite phase with tetragonal structure having uniform and dense microstructure as revealed by powder XRD, Raman spectroscopy and FESEM analyses. An excellent dielectric response was obtained with room temperature dielectric permittivity value of 142 and high-phase transition temperature (Tm of 210 °C at 1 kHz. A huge value of piezoelectric charge coefficient (490 pC/N was obtained, which shows potential of PMN–PT for piezoelectric device applications. Well-shaped and fatigue-free P–E hysteresis loops over a wide temperature range of 30–230 °C were traced. A very large value of pyroelectric coefficient (p ∼ 2739.2 μC m−2 °C−1 was obtained.

  15. 固相法制备钇掺杂的钛酸钡锶钙陶瓷的介电和热释电性能%Dielectric and Pyroelectric Properties of Y-doped Ba0.6Sr0.3Ca0.1TiO3 Ceramics by Solid-state Reaction Technique

    Institute of Scientific and Technical Information of China (English)

    曹盛; 毛朝梁; 姚春华; 曹菲; 王根水; 董显林

    2013-01-01

    (Ba0.6Sr0.3Ca0.1)1-xYxTi0.999Mn0.001O3(0≤x≤0.007) ceramics were prepared by the solid-state reaction technique.The effects of Y doping on the microstructure,dielectric properties and pyroelectric properties were investigated.The average grain size decreases with the increase of Y concentration.The dielectric and pyroelectric properties measurement results show that the dielectric constant,dielectric loss,Tc and pyroelectric coefficient all initially increase and then decrease with Y concentration.And the pyroelectric figure of merit Fd can be improved by the Y doping.The specimen doped with 0.7mol%Y shows a higher maximum Fd value of 8.22×10-5 Pa-1/2 under 700 V/mm near 30℃ with the smallest average grain size of 3.1 μm,indicating its promising application in infrared thermal imaging arrays devices.%采用固相反应法制备了Y掺杂(Ba0.6Sr0.3Ca0.1) 1-xYxTi0.999Mn0.001O3(0≤x≤0.007)陶瓷,重点研究了Y含量对BSCT基陶瓷的显微结构、介电性能和热释电性能的影响.结果表明:随着Y含量的增加,BSCYxTM陶瓷的平均晶粒尺寸逐渐减小,介电常数、介电损耗、居里温度和热释电系数均呈现先增加后减小的趋势.当Y掺杂量为0.7mol%时,BSCYxTM陶瓷的平均晶粒尺寸最小为3.1 μm,且探测优值Fd较大,最大值可达8.22×10-5 pa-1/2(700 V/mm,30℃),高于采用溶胶-凝胶法制备的同组分陶瓷的探测优值5.91×10-5 pa-1/2.

  16. Unattended safety control system based on pyroelectric infrared sensor%基于热释红外传感器无人值守的安全控制系统

    Institute of Scientific and Technical Information of China (English)

    王良升; 郭杰荣; 黄民; 肖利平; 王瑞成

    2015-01-01

    This system scanning the workplace environment uses the pyroelectric infrared module to determine whether there are persons in the presence. And then send information to the CPU through the plurality of wireless modules nRF24L01, and the central processor executes corresponding control through the corresponding electric appliances or control switch. The system adopts the wireless receiving and sending, the infrared sensor technology, wireless communication technology, combined with single-chip microcomputer technology and computer application technology, work closely with each other to achieve the unattended environment management, which has good market application value.%采用热释电人体红外感应模块对工作场所环境扫描检测以判断有无人员在场,然后通过多个无线模块nRF24L01发送信息给中央处理器,中央处理器再对相应的用电器或者开关等进行相应的控制。系统采用无线接收与发送来实现匹配,并且将红外传感技术、无线通信技术、单片机技术与计算机应用技术结合实现对无人值守环境的管理,具有较好的市场应用价值。

  17. Design of Readout Circuit for Pyroelectric Detector Based on Relaxor Ferroelectric Single Crystals%弛豫铁电单晶热释电探测器读出电路的设计

    Institute of Scientific and Technical Information of China (English)

    王将; 景为平

    2011-01-01

    Relaxor-based ferroelectric single crystals, such as (1- x)Pb(Mg1/3Nb2/3 )O3-xPbTiO3 (PMN-xPT, or PMNT) single crystals, exhibit large pyroelectric response, Iow thermal diffusivity and high temperature stability.To fabricate high performance infrared detectors with relaxor-based single crystals, the related readout circuit is investigated to increase signal-to-noise ratio, and 8 × 1 CMOS readout circuit is fabricated to gain very weak current.%以(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-xPT或PMNT)(PMN-xPT,或PMN-PT)为代表的弛豫铁电单晶具有非常高的热释电系数、比较低的热扩散系数、比较稳定的化学性能,是一种综合性能优异的热释电材料.利用弛豫铁电单晶可以制备出高性能的红外光传感器,针对用这种新型热释电材料制成的红外光传感器,研究了相关的读出电路,探索了抑制读出电路噪声的方法,研制出了8通道的微弱电流读取电路.

  18. 热释电红外传感器在生物特征识别领域中的研究进展%Pyroelectric infrared(PIR) sensor in the field of biometric identification applications

    Institute of Scientific and Technical Information of China (English)

    冯莉; 明东; 徐瑞; 邱爽; 许敏鹏; 綦宏志; 万柏坤; 王威杰

    2011-01-01

    Biometrics makes use of the physiological or behavioral characteristics of people to validate their identities. Gait recognition is an emerging field of biometrics technologies, whose aim is to identify the individuals based on their walking style. Therefore, this technique has a bright prospect and gains more and more attention from the field of biomedical information detection. When a human walks, the motion of various components of the body produce a characteristic signature, and can be detected by PIR sensor. The features of human motion can be extracted by analyzing the output signals of PIR sensor, then the recognition of different persons or different motion styles can be realized. In this paper, the improvements of this topic in the last several years are discussed in detail from three parts: the sensor detection principle, the applications in the field of gait recognition, and the feature extraction and classification methods of the pyroelectric information. At the end of the survey, some vital problems of this research are presented and analyzed.%步态识别作为生物特征识别技术的一个新兴子领域,旨在根据人的行走姿势实现对个体身份的识别.人行走过程中身体各部分的红外热辐射信号具有某种个体特征,该特征信息能够被热释电红外传感器有效检测.通过分析传感器的输出信号,就可以提取出人体运动的特征性数据,实现对不同人、不同运动状态的识别.本文对热释电红外传感器应用于生物特征识别领域的研究进展进行论述,从传感器的探测原理、在步态识别中的应用以及热释电信息的特征提取与分类算法进行总结,并对当前该研究方向上亟待解决的问题作简要的分析.

  19. Pyroelectric infrared alarm system based on human gait recognition%基于人体步态识别的热释电红外传感报警系统

    Institute of Scientific and Technical Information of China (English)

    张涛; 钟舜聪

    2011-01-01

    In order to solve the problem of difficult detecting the motionless human body using pyroelectric infrared (PIR) sensor, a passive PIR alarm system based on human gait recognition was investigated to enhance the intelligence of the system and to reduce the false alarm rate. As the detector, PIR sensor was employed in the system for non-contact monitoring the human body within a certain distance. The PIR signal was filtered, amplified, and then converted to a digital signal by an analog-to-digital converter. Consequently, the digital signal was sent to a microcomputer ( MCU ) for processing. The human body movement characteristics were analyzed to achieve accurate security alarm purpose. The experimental results demonstrate the stable performance, high sensitivity and low false alarm rate of the developed PIR alarm system, therefore, it can be recommended for the applications in security system of home, shopping center, and warehouse.%针对热释电红外传感器对运动后静止的人体无法感应的缺点,设计了一种基于人体步态识别的热释电红外报警系统,大大提高了系统感知智能度,减少了报警的误报率.该系统利用热释电红外传感器(PIR)作为探头,将感测到人体的红外信息转换成电压信号,通过滤波、放大等信号调理以及经过数据采集后,将信号传递给单片机处理,结合人体运动特征进行步态识别,从而实现智能报警,达到安全防护的目的.研究结果表明,基于人体步态识别的热释电红外报警系统具有性能稳定、灵敏度高、误报率低等优点,适合各种安全报警的场合,具有广泛的应用前景.

  20. PbTiO3微晶玻璃陶瓷的结构和热释电性能研究%Structure and Pyroelectric Properties of PbTiO3 Glass-Ceramics by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    翟继卫; 姚熹; 张良莹

    2001-01-01

    采用溶胶-凝胶方法在Pb-Ti-B-Si-O凝胶玻璃体系中,析出了PbTiO3微晶. DTA和X-ray衍射分析表明,随玻璃含量的增加,析晶温度升高. 热释电测试结果说明,随着玻璃含量的增加,热释电系数增大;随烧结温度的升高,PbTiO3微晶玻璃陶瓷的热释电系数也随之增大. 介电温谱的测量则显示,PbTiO3陶瓷与PbTiO3微晶玻璃陶瓷具有明显的差异.%PbTiO3-SiO2-B2O3 glass-ceramics were prepared by the sol-gel process. DTA and X-ray diffraction analysis show that the crystallization temperature of PbTiO3 glass-ceramics is higher than that of PbTiO3 ceramics. As the glass content increasing, their pyroelectric coefficients are increased, and the pyroelectric coefficients are increased with the increase of sintering temperatures. The temperature dependence of the dielectric constant of PbTiO3 ceramics and PbTiO3 glass-ceramics is different obviously.

  1. Nanoscale Studies of Pyroelectric and Thermoelectric Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Gruverman, Alexei [Univ. of Nebraska, Lincoln, NE (United States); Ducharme, Stephen [Univ. of Nebraska, Lincoln, NE (United States)

    2014-07-31

    This research project is focused on (1) development of novel scanning probe microscopy techniques for investigation of the thermally and electrically induced changes in the physical properties of organic polymer ferroelectrics; (2) fabrication of ferroelectric nanostructures and investigation of their functional behavior; (3) fabrication and testing of the organic photovoltaic devices with enhanced energy conversion efficiency. Research activities throughout this project resulted in novel effects and exciting physics reported in 10 papers published in high-profile journals, including Nature Materials, Nano Letters, Advanced Materials, Energy and Environmental Science and Applied Physics Letters. These findings have been presented at a number of domestic and international conferences such as MRS Spring and Fall meetings, International Symposium on Integrated Functionalities, International Symposium on Applications of Ferroelectrics (in total 9 presentations). Below we summarize the most important findings of this project.

  2. Medical Thermography with a Pyroelectric Vidicon Camera.

    Science.gov (United States)

    1981-03-01

    thermal picture. The scab at the centre of the ulcer has no blood flow to it and is cooler than its surroundings. The good sign of the positive...temperature gradient towards the ulcer is evident. Again however, a better medical judgement may be made from more quantified data. The contouring unit was...were again set to 0.50, From the numbers below the pictures the temgerature difference between the scene edges and the edge of the ulcer is 4 C. This

  3. Tuning of dielectric, pyroelectric and ferroelectric properties of 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ceramic by internal clamping

    Directory of Open Access Journals (Sweden)

    Satyanarayan Patel

    2015-08-01

    Full Text Available This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Lead-free 0.715Bi0.5Na0.5TiO3−0.065BaTiO3−0.22SrTiO3 (BNT-BT-ST bulk ferroelectric ceramic was selected for the course of investigation. 3BaO − 3TiO2 − B2O3 (BTBO glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight. Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density ∼174 kJ/m3 to ∼203 kJ/m3 and pyroelectric coefficient 5.7x10−4 Cm−2K−1 to 6.8x10−4 Cm−2K−1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs for high voltage responsivity (Fv high detectivity (Fd and energy harvesting (Fe from 0.018 to 0.037 m2C−1, 5.89 to 8.85 μPa−1/2 and 28.71 to 61.55 Jm−3K−2, respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements.

  4. Systematic Study of Pyroelectricity. Generalized Molecular Field Theory of Ferroelectricity and Pyroelectricity

    Science.gov (United States)

    1975-10-01

    8217. AUTHOR’aJ Vih . kell «A Pl4./^accah I 9. PERFORMING ORGANIZATION NApTE AND ADDRESS Yeshiva University, ’BeIfer Graduate School of Science...approximation, the results are rather peculiar and unphysical. It can be shown with the aid of Eq. (20) that for t. < 0 and t2 = 0, we have p - -5/3t, as t...values of N^. Finally, it is interesting to note that the scale factor in Eq. (ho) can be writt.en, with the aid of Eq, (6), as T Thus the

  5. Effect of Polarization Fatigue on Harvesting Energy Using Pyroelectric Materials

    Directory of Open Access Journals (Sweden)

    Saber Mohammadi

    2014-01-01

    Full Text Available The phenomenon of polarization fatigue in ferroelectric materials is defined and the effect of this phenomenon on harvested energy using these materials has been studied. In order to illustrate this effect, the harvested energy using PZN-4.5PT single crystal was compared in two cases of fatigued and nonfatigued samples. The results have been calculated between two temperatures of 100 and 130°C using Ericsson thermodynamic cycle.

  6. Characterization of a Polymer-Based MEMS Pyroelectric Infrared Detector

    Science.gov (United States)

    2007-03-01

    engineered protein in hydrogels tailors stimuli-responsive characteristics.” Nature, vol 4, pp 298 – 302, Apr 2005. [8] Brott, Lawrence L...CR Detector Pre- amp Φe (t) 38 three regimes can be seen in Figure 14, which represents the voltage reponsivity...detector needs amplification, using one of the two circuits shown in Figure 19 or 20. In lieu of this circuit, a voltage pre- amp was used

  7. Heavy electrons: Electron droplets generated by photogalvanic and pyroelectric effects

    CERN Document Server

    Krasnoholovets, V; Kukhtareva, T

    2009-01-01

    Electron clusters, X-rays and nanosecond radio-frequency pulses are produced by 100 mW continuous-wave laser illuminating ferroelectric crystal of LiNbO_3. A long-living stable electron droplet with the size of about 100 mcm has freely moved with the velocity 0.5 cm/s in the air near the surface of the crystal experiencing the Earth gravitational field. The microscopic model of cluster stability, which is based on submicroscopic mechanics developed in the real physical space, is suggested. The role of a restraining force plays the inerton field, a substructure of the particles' matter waves, which a solitary one can elastically withstand the Coulomb repulsion of electrons. It is shown that electrons in the droplet are heavy electrons whose mass at least 1 million of times exceeds the rest mass of free electron. Application for X-ray imaging and lithography is discussed.

  8. Demonstration of a Pyroelectric Conversion Power Cycle with a Polymer.

    Science.gov (United States)

    1985-03-01

    OLSEN CHRONOS RESEARCH LABORATORIES, INC. AD-A158 964 3025 VIA DE CABALLO OLIVENHAIN, CALIFORNIA 92024 MARCH 1985 FINAL REPORT FOR PERIOD OCTOBER 1983...City. State and ZIP Code) 30 ’ Via De Caballo , Olivenhai,i, CA 92024 Wright-Patterson AFB, OH 45433 Sa. NAME OF FUNDING/SPONSORING Ib. OFFICE SYMBOL 9...Rahilly R.B. Olsen AFWAL/POOC-2 Chronos Research Laboratories, Bldg. 18 Rm A201 Inc. " Wright-Patterson AFB, 3025 Via De Caballo * Ohio 45433 Olivenhain

  9. Photothermal method using a pyroelectric sensor for thermophysical characterization of agricultural and biological samples

    Science.gov (United States)

    Frandas, A.; Dadarlat, Dorin; Chirtoc, Mihai; Jalink, Henk; Bicanic, Dane D.; Paris, D.; Antoniow, Jean S.; Egee, Michel; Ungureanu, Costica

    1998-07-01

    The photopyroelectric method in different experimental configurations was used for thermophysical characterization of agricultural and biological samples. The study appears important due to the relation of thermal parameters to the quality of foodstuffs (connected to their preservation, storage and adulteration), migration profiles in biodegradable packages, and the mechanism of desiccation tolerance of seeds. Results are presented on the thermal parameters measurement and their dependence on temperature and water content for samples such as: honey, starch, seeds.

  10. Pyroelectric Infrared Detectors Designed%热释电红外报警器的设计

    Institute of Scientific and Technical Information of China (English)

    吕璠

    2009-01-01

    以热释电红外元件作为传感器组成的电子防盗系统,正在得到越来越广泛的应用.本文就热释电红外报警器的工作原理、安装要求和应用中存在的优缺点进行了筒述.

  11. Pyroelectric Adaptive Nanodispenser (PYRANA) microrobot for liquid delivery on a target.

    Science.gov (United States)

    Vespini, Veronica; Coppola, Sara; Grilli, Simonetta; Paturzo, Melania; Ferraro, Pietro

    2011-09-21

    Manipulation of micro-sized objects in lab-on-a-chip and microfluidic environments is essential for different experiments and procedures ranging from chemical to biological applications and for experimental biotechnologies. For example polymeric particles, useful as targets for encapsulating or for being covered by drug vaccines, can be manipulated and controlled with the aim of releasing them to specific sites. Here we show a novel ElectroHydroDynamic tool able to control and manipulate dielectric micro-targets by a touch-less approach. This approach allows one to manipulate liquids and nano-particles simultaneously for specific delivery applications (i.e. decoration and coating). Thus a sort of EHD micro-robot is proposed. This flexible tool provides a new and powerful way to operate various tasks as demonstrated by the experiments reported here. This journal is © The Royal Society of Chemistry 2011

  12. Dielectric, piezoelectric, and pyroelectric anisotropy in KCL- modified grain-oriented bismuth vanadate ceramics

    OpenAIRE

    Shantha, K; Varma, KBR

    1999-01-01

    The effect of the additive KCl, on the structural, microstructural, and polar properties of bismuth vanadate (BiV) ceramics is investigated. The scanning electron microscopic (SEM) studies reveal a remarkable modification in the microstructure and the occurrence of high grain-orientation (75%) on KCl addition. The energy dispersive x ray (EDX) analyses indicate the presence of chemically inhomogeneous distribution of KCl, with core-shell-like grain structure. The KCl-modified BiV samples exhi...

  13. A Study of the Nature and Origins of Pyroelectricity and Piezoelectricity in Polyvinylidenefluoride and Its Co-Polymers.

    Science.gov (United States)

    1980-01-01

    IDb, UCIHL, bangor). A micromesh control in PV72 are enhanced by polin & with high electric gric. was introduced between the sample and the corora...This 0 2 4 0 has the advantage that a satisfactory polin may be Original d31 (PC/N completed in PVFi bN corona charging at ambient temperaturt in a veo...electric coefficient was obtained from the data provided by ferent temperatures. the third cyclic operation for each polin ; temperature. In Fig. 6, curve

  14. Investigation of the Character of the Phase Transitions in Nb Doped Zr-rich PZT by Pyroelectric and Dielectric Measurements

    NARCIS (Netherlands)

    Cereceda, N.; Noheda, B.; Gonzalo, J.A.

    1999-01-01

    We present a study of the character of the phase transitions of the solid solution PbZr1-xTixO3. Using the spontaneous polarization curves we determined the mean-field parameters. These parameters show the first order character of the phase transitions for the richer Zr content and its evolution wit

  15. PZ-PT-PMN热释电陶瓷的制备研究%Preparation of PZ-PT-PMN Pyroelectric Ceramics

    Institute of Scientific and Technical Information of China (English)

    鄢国强; 来旭春; 顾箐; 周海丽

    2001-01-01

    用经典的电子陶瓷工艺过程制得了PZ-PT-PMN热释电陶瓷.通过分析晶体构型、原子半径等,设计了几个典型的配方,并制得了相应的陶瓷材料,实验还对影响陶瓷热释电及机械性能的烧结温度、烧结时间、模压压力等工艺参数进行了优化.本制备方法简单,工艺成熟,制得的陶瓷适合应用于红外探测领域.

  16. PbSc0.5Ta0.5O3 pyroelectric materials and their application in pyroelectric detector arrays%PbSc0.5Ta0.5O3热释电材料及其红外探测器列阵

    Institute of Scientific and Technical Information of China (English)

    于光龙; 肖定全; 朱建国; 余萍; 袁小武

    2003-01-01

    热释电红外探测器具有探测波长范围广、室温工作、无需致冷等优点.近年来,工作于介电方式下的PbSc0.5Ta0.5O3 (PST)热释电材料由于具有热释电系数大,热释电探测优值高等特点,成为热释电应用研究的热点之一.本文综述了目前PST热释电陶瓷材料的介电,热释电性能及其探测器列阵的发展.由于小型化的要求,PST薄膜亦倍受关注,因此本文还对目前PST热释电薄膜的制备方法,薄膜的热释电、介电性能及薄膜型探测器结构和发展进行了概述.

  17. Charge-sensitive amplifier

    Directory of Open Access Journals (Sweden)

    Startsev V. I.

    2008-02-01

    Full Text Available The authors consider design and circuit design techniques of reduction of the influence of the pyroelectric effect on operation of the charge sensitive amplifiers. The presented experimental results confirm the validity of the measures taken to reduce the impact of pyroelectric currents. Pyroelectric currents are caused by the influence of the temperature gradient on the piezoelectric sensor and on the output voltage of charge sensitive amplifiers.

  18. 热释电传感器在井下人员安全监护系统中的应用%Application of Pyroelectric Sensor in Underground Staff Safety Monitoring System

    Institute of Scientific and Technical Information of China (English)

    吴天祥

    2010-01-01

    @@ 本系统是为井下恶劣工作环境所设汁的安全保护系统,目的是杜绝或减少井下生产过程所存在的大型机械(破碎机、装载机等)伤人事故,是一种人员安全探测系统.

  19. Polarization characterization of PZT disks and of embedded PZT plates by thermal wave methods

    Energy Technology Data Exchange (ETDEWEB)

    Eydam, Agnes, E-mail: Agnes.Eydam@tu-dresden.de; Suchaneck, Gunnar, E-mail: Agnes.Eydam@tu-dresden.de; Gerlach, Gerald [Technische Universität Dresden, Solid State Electronics Laboratory, Helmholtzstraße 18, 01062 Dresden (Germany); Esslinger, Sophia; Schönecker, Andreas; Neumeister, Peter [Fraunhofer Institute for Ceramic Technologies and Systems, Winterbergstraße 28, 01277 Dresden (Germany)

    2014-11-05

    In this work, the thermal wave method was applied to characterize PZT disks and embedded PZT plates with regard to the polarization magnitude and spatial homogeneity. The samples were exposed to periodic heating by means of a laser beam and the pyroelectric response was determined. Thermal relaxation times (single time constants or distributions of time constants) describe the heat losses of the PZT samples to the environment. The resulting pyroelectric current spectrum was fitted to the superposition of thermal relaxation processes. The pyroelectric coefficient gives insight in the polarization distribution. For PZT disks, the polarization distribution in the surface region showed a characteristic decrease towards the electrodes.

  20. Infrared Sensor with Liquid Crystal Chopper

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An infrared sensor using the liquid crystal chopper is presented. The infrared sensor is designed to detect infrared rays with a pyroelectric element used as a liquid crystal chopper in such an infrared sensor or the like.

  1. Low temperature fiber optic pyrometer for fast time resolved temperature measurements

    Science.gov (United States)

    Willsch, M.; Bosselmann, T.; Gaenshirt, D.; Kaiser, J.; Villnow, M.; Banda, M.

    2016-05-01

    Low temperature Pyrometry at temperatures beyond 150°C is limited in the measurement speed due to slow pyroelectric detectors. To detect the circumferential temperature distribution of fast rotating machines a novel Fiber Optical Pyrometer Type is presented here.

  2. Measurement of complicated temperature-dependent polarization of multiferroic RMn2O5

    Science.gov (United States)

    Fukunaga, Mamoru; Noda, Yukio

    2011-09-01

    We have measured the temperature-dependent electric polarization P(T) of multiferroic rare-earth (R) manganese oxides RMn2O5 using both typical pyroelectric measurements and hysteresis loops with the double-wave method (DWM), and revealed the complicated behavior of the P(T). RMn2O5 single crystal samples often exhibit a tendency to macroscopically polarize without applying an external electric field. We have found that the tendency appeared in P(T) by the pyroelectric measurement can be measured by the DWM loops. The tendency to polarize is equivalent to asymmetric non-hystersis loops obtained by the DWM. We clarify the relationship between P(T) by pyroelectric measurement and that by the DWM loops, which can warrant the measured P(T).

  3. Origin and structure of polar domains in doped molecular crystals

    Science.gov (United States)

    Meirzadeh, E.; Azuri, I.; Qi, Y.; Ehre, D.; Rappe, A. M.; Lahav, M.; Kronik, L.; Lubomirsky, I.

    2016-11-01

    Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). The approach comprises crystal engineering and pyroelectric measurements, together with dispersion-corrected density functional theory and classical molecular dynamics calculations of the doped crystals, using neutron diffraction data of the host at different temperatures. This approach is illustrated using centrosymmetric α-glycine crystals doped with minute amounts of different L-amino acids. The experimentally determined pyroelectric coefficients are explained by the structure and polarization calculations, thus providing strong support for the local and global understanding of how different dopants influence the properties of molecular crystals.

  4. Phase transition in tungsten-bronze Li2Pb2Nd2W2Ti4Nb4O30 ferroelectric

    Science.gov (United States)

    Parida, B. N.; Das, Piyush R.; Padhee, R.; Choudhary, R. N. P.

    2013-08-01

    The polycrystalline sample of Li2Pb2Nd2W2Ti4Nb4O30 was prepared by a solid-state reaction technique. Room temperature X-ray structural analysis confirms the formation of a single-phase compound. The morphology of the sintered sample recorded by scanning electron microscope exhibits a uniform grain distribution. Detailed studies of the nature of variation of dielectric constant, tangent loss, and polarization with temperature and frequency confirmed the existence of ferroelectricity in the material at room temperature. The temperature and frequency dependence of impedance parameters (impedance, modulus, etc.) of the material exhibits a strong correlation of its microstructure (i.e., bulk, grain boundary, etc.). Furthermore, the temperature dependence of DC conductivity shows a typical Arrhenius behavior of the material. The nature of variation of pyroelectric coefficient and current with temperature suggests that material has good pyroelectric properties useful for pyroelectric detector.

  5. Enhanced P3HT/ZnO Nanowire Array Solar Cells by Pyro-phototronic Effect.

    Science.gov (United States)

    Zhang, Kewei; Wang, Zhong Lin; Yang, Ya

    2016-11-22

    The pyro-phototronic effect is based on the coupling among photoexcitation, pyroelectricity, and semiconductor charge transport in pyroelectric materials, which can be utilized to modulate photoexcited carriers to enhance the output performance of solar cells. Herein, we have demonstrated the largely enhanced output performance of a P3HT/ZnO nanowire array photovoltaic cell (PVC) by using the pyro-phototronic effect under weak light illuminations. By applying an external cooling temperature variation, the output current and voltage of the PVC can be dramatically enhanced by 18% and 152% under indoor light illumination, respectively. This study realizes the performance enhancement of pyroelectric semiconductor materials-based solar cells via a temperature-variation-induced pyro-phototronic effect, which may have potential applications in solar energy scavenging and self-powered sensor systems.

  6. Static Charge Development on Explosives .

    Directory of Open Access Journals (Sweden)

    K. Raha

    1991-01-01

    Full Text Available Static charge development character of some of the important explosive crystals have been predicted on the basis of their crystal class and symmetry. Among the important mechanism of charge development, the piezoelectric and pyroelectric characters have been considered. Ammonium trinitrate, ammonium nitrate, m-dinitro-benzene, trinitro-toluene, styphnic acid, beeta-lead styphnate, 4,4'dinitro-dipheny1, a-hexamethylenetetranitramine, nitroguanidine, picric acid, dimethylnitramine, a-lead azide and beeta-lead azide are pyroelectric in nature, whereas pentaerythritol tetranitrate, picryliodide, hexamethylenetranitramine, tetranitromethane and trinitroethane are piezoelectric in nature.

  7. Gate-Induced Thermally Stimulated Current on the Ferroelectric-like Dielectric Properties of (BEDT-TTF(TCNQ Crystalline Field Effect Transistor

    Directory of Open Access Journals (Sweden)

    Kazuhiro Kudo

    2012-06-01

    Full Text Available A gate-induced thermally stimulated current (TSC on β′-(BEDT-TTF(TCNQ crystalline FET were conducted to elucidate the previously observed ferroelectric-like behaviors. TSC which is symmetric for the polarization of an applied VPG and has a peak at around 285 K was assigned as a pyroelectric current. By integrating the pyroelectric current, temperature dependence of the remnant polarization charge was obtained and the existence of the ferroelectric phase transition at 285 K was clearly demonstrated. We have tentatively concluded that the phase transition between dimer Mott insulator and charge ordered phase occurred at around the interface of organic crystal and substrate.

  8. Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation.

    Science.gov (United States)

    Rong, Lu; Latychevskaia, Tatiana; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

    2014-07-14

    We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO(2) pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hindwing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 μm width cross veins.

  9. Piezoelectric and Electrostrictive Materials for Transducer Applications.

    Science.gov (United States)

    1986-07-01

    epoxy is as follows: 10 gm vinylcyclohexene dioxide 4 gmn diglycidyl ether of polypropylene glycol 26 gm nonenyl succinic anhydride 0.4 gm...Pb substitution and four different levels of Pyroelectric measurements were made to obtain spon- Nb substitution. The nomenclature CPNT-y-x will be

  10. Characterization of Perovskite Films Grown by a Novel Low-Temperature Process for Uncooled IR Detector Applications

    Science.gov (United States)

    2008-12-01

    and semiconductor thin- films (Schwenzer et al., 2006; Kisailus et al, 2006; Brutchey and Morse, 2006). The resulting pyroelectric, perovskite -based...1 CHARACTERIZATION OF PEROVSKITE FILMS GROWN BY A NOVEL LOW- TEMPERATURE PROCESS FOR UNCOOLED IR DETECTOR APPLICATIONS W.L. Sarney* and J.W...multimetallic perovskite nanoparticle deposition, direct-write digitally-scripted laser phase conversion, and MEMS fabrication and optimization

  11. Second harmonic generation microscopy reveals hidden polar organization in fluoride doped MIL-53(Fe)

    NARCIS (Netherlands)

    Markey, K.; Putzeys, T.; Horcajada, P.; Devic, T.; Guillou, N.; Wübbenhorst, M.; Van Cleuvenbergen, S.; Verbiest, T.; De Vos, D.E.; Van der Veen, M.A.

    2016-01-01

    Polar metal–organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(III) terephthalate MOF MIL-53(Fe) induces a polar or

  12. Zero-power receiver

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert W.

    2016-10-04

    An unpowered signal receiver and a method for signal reception detects and responds to very weak signals using pyroelectric devices as impedance transformers and/or demodulators. In some embodiments, surface acoustic wave devices (SAW) are also used. Illustrative embodiments include satellite and long distance terrestrial communications applications.

  13. In-flight calibration system for the INTEGRAL x-ray monitor

    DEFF Research Database (Denmark)

    Costa, E.; Feroci, M.; Barbanera, L.;

    1996-01-01

    of Amptek Cool-X15 X-ray generators. The latter is a novel product, based on a pyroelectric crystal used to generate energetic electrons that produce fluorescence lines by hitting a metallic target. We plan to use the four low intensity radioactive sources for monitoring the four independent anode chains...

  14. 柔性PZT复合材料的热释电性质研究%INVESTIGATION OF THE PYROELECTRIE PROPERTIES OF THE FLEXIBLE PZT COMPOSITE

    Institute of Scientific and Technical Information of China (English)

    王国欣

    2001-01-01

    The pyroelectric properties of a flexble composite composed ofNb-doped PZT grains and silica gel are reported.Compared with compact piezoelectric its pyroelectric coefficient is 0.2×10-8~0.28×10-8 C/(cm2·℃),while that of pyroelectric PZT ceramic is 4.9×10-8C/(cm2·℃);the pyroeletric response of the flexible composite is about 5 times greater,than that of the compact ceramic.A method of calculating the pyroelectric coefficient and response of these materials is also described.%研究了由掺铌的钛锆酸铅颗粒与硅橡胶混合物的热释电性质;与一般的致密压电陶瓷相比较,其热释电系数为0.6×10-8~2.0×10-8C/(cm2·℃),而致密PZT陶瓷的热释电系数为4.9×10-8C/(cm2·℃),柔性复合物的热释电响应大约比致密陶瓷大5倍;描述了一种计算这些材料热释电系数和热释电响应的方法.

  15. FRL–FRH phase transition behavior in the stacked Pb(Zr1-xTix)O3 perovskite ceramics

    NARCIS (Netherlands)

    Duan, Ning; Sun, Dazi; Dong, Xianlin; Lin, Shenwei; Wang, Yongling

    1999-01-01

    Zirconium rich Pb(Zr1-xTix)O3 (PZT in abbreviation) reveals a pronounced nonlinear pyroelectric effect at the temperature induced FRL–FRH phase transition. This characteristic makes it a competitive candidate for the applications of the direct thermal-electric energy conversion and infrared detectin

  16. COMPARATIVE ANALYSIS OF THE TECHNOLOGY OF ROLLS CASTING LS-57 EXECUTION

    Directory of Open Access Journals (Sweden)

    J. S. Maymur

    2013-01-01

    Full Text Available It is shown that the use of complex modifier is not accompanied by gas evolution and the pyroelectric effect, which increases the sustainability of the process. When using modifier simplifies complex technology of the modified roller melt and reduced the duration of melting due to lower discharge temperature of the melt from the melting unit.

  17. Crystal structure and magnetic properties of the Ba3TeCo3P2O14, Pb3TeCo3P2O14, and Pb3TeCo3V2O14 langasites

    DEFF Research Database (Denmark)

    Krizan, J.W.; de la Cruz, C.; Andersen, Niels Hessel;

    2013-01-01

    of the three compounds studied along with the zinc analog Pb3TeZn3P2O14, also characterized here, suggests that the distortion is driven by Pb2+ lone pairs; as such, the Pb compounds crystallize in a pyroelectric space group, P2. Magnetic susceptibility, magnetization, and heat capacity measurements were...

  18. Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Chitharanjan, E-mail: raichitharanjan@gmail.co [Department of Physics, Mangalore University, Mangalagangotri 574 199 (India); Kalpataru First Grade Science College, Tiptur 572 202 (India); Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Dharmaprakash, S.M., E-mail: smdharma@yahoo.co [Department of Physics, Mangalore University, Mangalagangotri 574 199 (India)

    2009-11-15

    Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 deg. C/min. An increase in the Curie temperature T{sub c}=51 deg. C (for pure TGS, T{sub c}=48.5 deg. C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

  19. Self-Powered Ultrabroadband Photodetector Monolithically Integrated on a PMN-PT Ferroelectric Single Crystal.

    Science.gov (United States)

    Fang, Huajing; Xu, Chao; Ding, Jie; Li, Qiang; Sun, Jia-Lin; Dai, Ji-Yan; Ren, Tian-Ling; Yan, Qingfeng

    2016-12-07

    Photodetectors capable of detecting two or more bands simultaneously with a single system have attracted extensive attentions because of their critical applications in image sensing, communication, and so on. Here, we demonstrate a self-powered ultrabroadband photodetector monolithically integrated on a 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) single crystal. By combining the optothermal and pyroelectric effect, the multifunctional PMN-28PT single crystal can response to a wide wavelength range from UV to terahertz (THz). At room temperature, the photodetector could generate a pyroelectric current under the intermittent illumination of incident light in absence of external bias. A systematic study of the photoresponse was investigated. The pyroelectric current shows an almost linear relationship to illumination intensity. Benefiting from the excellent pyroelectric property of PMN-28PT single crystal and the optimized device architecture, the device exhibited a dramatic improvement in operation frequency up to 3 kHz without any obvious degradation in sensitivity. Such a self-powered photodetector with ultrabroadband response may open a window for the novel application of ferroelectric materials in optoelectronics.

  20. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    NARCIS (Netherlands)

    Ding, M. S.; Weits, H. H.; Oepts, D.

    1997-01-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 x 10 mm(2) pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 mu m to 10 mm) without st

  1. Electronic, magnetic, and optical materials

    CERN Document Server

    Fulay, Pradeep

    2013-01-01

    Technological aspects of ferroelectric, piezoelectric and pyroelectric materials are discussed in detail, in a way that should allow the reader to select an optimal material for a particular application. The basics of magnetostatics are described clearly, as are a wide range of magnetic properties of materials … .-Tony Harker, Department of Physics and Astronomy, University College London

  2. Uniform, large surface-area polarization by modifying corona-electrodes geometry.

    Science.gov (United States)

    Tansel, T; Ener Rusen, S; Rusen, A

    2013-01-01

    We report on the uniform, large scale polarization of ferroelectric materials by a newly designed corona charging technique developing nonconventional electrodes geometry. The results of pyroelectric measurements represented the spatial homogeneity of the polarization attained through a surface area of ~25 cm(2).

  3. Using a CO2 laser for PIR-detector spoofing

    NARCIS (Netherlands)

    Schleijpen, R.; Putten, F.J.M. van

    2016-01-01

    This paper presents experimental work on the use of a CO2 laser for triggering of PIR sensors. Pyro-electric InfraRed sensors are often used as motion detectors for detection of moving persons or objects that are warmer than their environment. Apart from uses in the civilian domain, also

  4. Ferroelectric polarization in nanocrystalline hydroxyapatite thin films on silicon.

    Science.gov (United States)

    Lang, S B; Tofail, S A M; Kholkin, A L; Wojtaś, M; Gregor, M; Gandhi, A A; Wang, Y; Bauer, S; Krause, M; Plecenik, A

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone--a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

  5. Short range ferromagnetic, magneto-electric, and magneto-dielectric effect in ceramic Co{sub 3}TeO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harishchandra, E-mail: singh85harish@gmail.com, E-mail: singh85harish@rrcat.gov.in; Ghosh, Haranath [Homi Bhabha National Institute, Raja Ramanna Center for Advanced Technology, Indore 452013 (India); Indus Synchrotrons Utilization Division, Raja Ramanna Center for Advanced Technology, Indore 452013 (India); Chandrasekhar Rao, T. V. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sharma, G.; Saha, J.; Patnaik, S. [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2016-01-28

    We report observation of magneto-electric and magneto-dielectric couplings along with short range ferromagnetic order in ceramic Cobalt Tellurate (Co{sub 3}TeO{sub 6}, CTO) using magnetic, structural, dielectric, pyroelectric, and polarization studies. DC magnetization along with dielectric constant measurements indicate a coupling between magnetic order and electrical polarization. A strong anomaly in the dielectric constant at ∼17.4 K in zero magnetic field indicates spontaneous electric polarization, consistent with a recent neutron diffraction study. Observation of weak short range ferromagnetic order at lower temperatures is attributed to the Griffiths-like ferromagnetism. Furthermore, magnetic field dependence of the ferroelectric transition follows earlier theoretical predictions, applicable to single crystal CTO. Finally, combined dielectric, pyroelectric, and polarization measurements suggest that the ground state of CTO may possess spontaneous symmetry breaking in the absence of magnetic field.

  6. Características estruturais, microestruturais, dielétricas e piroelétricas de cerâmicas de SrxBa1-XNb2O6 forjadas a quente

    Directory of Open Access Journals (Sweden)

    Venet Michel

    2003-01-01

    Full Text Available The texturing process and the characterization of textured Sr xBa1-xNb2O6 (x = 0.5; x = 0.6 ferroelectric ceramics were investigated. The ceramic bodies were fabricated through two stage sintering. The first and second stage consisted in conventional firing and hot forging of the ceramic bodies, respectively, both at oxygen atmosphere. The forged ceramics achieved high densification level although showing abnormal grain growth. X-ray diffraction, dielectric and pyroelectric analysis showed that is possible to obtain preferential orientation of the [00l] crystallographic planes due to grain arrangement during hot forging. Consequently, the investigated properties for this textured material were strongly dependent on the measurement direction. On the other hand, high room temperature pyroelectric coefficients, of the same order of that obtained for single crystals of same composition, were observed.

  7. Milking liquid nano-droplets by an IR laser: a new modality for the visualization of electric field lines

    Science.gov (United States)

    Vespini, Veronica; Coppola, Sara; Grilli, Simonetta; Paturzo, Melania; Ferraro, Pietro

    2013-04-01

    Liquid handling at micron- and nano-scale is of paramount importance in many fields of application such as biotechnology and biochemistry. In fact, the microfluidics technologies play an important role in lab-on-a-chip devices and, in particular, the dispensing of liquid droplets is a required functionality. Different approaches have been developed for manipulating, dispensing and controlling nano-droplets under a wide variety of configurations. Here we demonstrate that nano-droplets can be drawn from liquid drop or film reservoirs through a sort of milking effect achieved by the absorption of IR laser radiation into a pyroelectric crystal. The generation of the pyroelectric field induced by the IR laser is calculated numerically and a specific experiment has been designed to visualize the electric field stream lines that are responsible for the liquid milking effect. The experiments performed are expected to open a new route for the visualization, measure and characterization procedures in the case of electrohydrodynamic applications.

  8. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-07-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

  9. A Prospecting Mineralogy Study:Arsenopyrite In Endogenetic Gold Deposits

    Institute of Scientific and Technical Information of China (English)

    LI Xiaomin; ZHANG Hongzhi

    2001-01-01

    Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphism, composition typomorphism, pyroelectricity typomorphism and so on, were established. The crystal form of arsenopyrite is simple, and the form symbols mainly are {101}, {120}, {210}, {140}, {230}, {012}, etc. The smaller groin and poor crystal form arsenopyrite indicates the better auriferous characteristics. The major elements (Fe, As and S) of gold- bearing arsenopyrite usually show Fe/As + S > 0.5, As/S< 1 which deviates from its theoretical value. The most important trace element is Au and next is Ag in arsenopyrite, and they often show the positive correlation. The pyroelectricity of arsenopyrite can reflect the mineralization epoch, and it also is related to the crystal form and granudarity.

  10. Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation

    CERN Document Server

    Rong, Lu; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

    2014-01-01

    We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hind wing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 {\\mu}m width cross veins.

  11. Short range ferromagnetic, magneto-electric, and magneto-dielectric effect in ceramic Co3TeO6

    Science.gov (United States)

    Singh, Harishchandra; Ghosh, Haranath; Chandrasekhar Rao, T. V.; Sharma, G.; Saha, J.; Patnaik, S.

    2016-01-01

    We report observation of magneto-electric and magneto-dielectric couplings along with short range ferromagnetic order in ceramic Cobalt Tellurate (Co3TeO6, CTO) using magnetic, structural, dielectric, pyroelectric, and polarization studies. DC magnetization along with dielectric constant measurements indicate a coupling between magnetic order and electrical polarization. A strong anomaly in the dielectric constant at ˜17.4 K in zero magnetic field indicates spontaneous electric polarization, consistent with a recent neutron diffraction study. Observation of weak short range ferromagnetic order at lower temperatures is attributed to the Griffiths-like ferromagnetism. Furthermore, magnetic field dependence of the ferroelectric transition follows earlier theoretical predictions, applicable to single crystal CTO. Finally, combined dielectric, pyroelectric, and polarization measurements suggest that the ground state of CTO may possess spontaneous symmetry breaking in the absence of magnetic field.

  12. Effect of the out-of-plane stress on the properties of epitaxial SrTiO{sub 3} films with nano-pillar array on Si-substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Gang, E-mail: baigang@njupt.edu.cn [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Xie, Qiyun [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Liu, Zhiguo [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wu, Dongmei [School of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China)

    2015-08-21

    A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO{sub 3} films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO{sub 3} films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO{sub 3} films similar to PZT and other lead-based ferroelectrics can be expected.

  13. Effect of the out-of-plane stress on the properties of epitaxial SrTiO3 films with nano-pillar array on Si-substrate

    Science.gov (United States)

    Bai, Gang; Xie, Qiyun; Liu, Zhiguo; Wu, Dongmei

    2015-08-01

    A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO3 films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO3 films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO3 films similar to PZT and other lead-based ferroelectrics can be expected.

  14. Ferroelectric materials and their applications

    CERN Document Server

    Xu, Y

    2013-01-01

    This book presents the basic physical properties, structure, fabrication methods and applications of ferroelectric materials. These are widely used in various devices, such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage, display devices, etc. The ferroelectric materials described in this book include a relatively complete list of practical and promising ferroelectric single crystals, bulk ceramics and thin films. Included are perovskite-type, lithium niobate, tungsten-bronze-type, water-soluable

  15. Contribution of an extrinsic mechanism for the electrical polarization in BiMn{sub 2}O{sub 5} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Fier, I.; Chinaglia, D. L.; Walmsley, L. [Departamento de Fisica, Instituto de Geociencias e Ciencias Exatas, Universidade Estadual Paulista (UNESP) Caixa Postal 178, CEP 13500-970, Rio Claro, Sao Paulo (Brazil); Pereira, E. C.; Rabelo, A. C.; Freitas, R. G. [Departamento de Quimica, Universidade Federal de Sao Carlos, C.P. 676, CEP13560-970, Sao Carlos, SP (Brazil)

    2012-12-15

    DC conductivity, frequency dependent dielectric constant and pyroelectric coefficients, obtained from thermal stimulated depolarization current curves, in BiMn{sub 2}O{sub 5} ceramics in the range of temperatures from 10 K to 320 K are reported. The data could be explained if it is assumed that a dipole defect is formed due to an oxygen vacancy and two manganese ions which have their valence changed to accept an electron.

  16. Synthesis and Characterization of Sol-Gel-Derived (Pb1-xLax)Ti1-x/4O3 Thin Films

    Science.gov (United States)

    Chopra, Sonalee; Sharma, Seema; Goel, Tara Chand; Mendiratta, Raj Gopal

    2004-09-01

    Ferroelectric lead lanthanum titanate (Pb1-xLaxTi1-x/4O3) (PLTx) thin films (x=0.04, 0.08 and 0.12) have been prepared by sol-gel spin-coating process on ITO- coated 7059 Corning glass substrates. Investigations have been made on the crystal structure, surface morphology, dielectric and ferroelectric properties of the thin films. Characterization of these films by X-ray diffraction shows that the films annealed at 650°C exhibit tetragonal structure with perovskite phase. Replacement of lanthanum in lead titanate results in reduction of the tetragonal ratio (c/a), thereby resulting in better mechanical stability. Microstructural analyses of the films are carried out by obtaining atomic force microscope (AFM) images. AFM images are characterized by slight surface roughness with a uniform crack-free, densely packed structure. Dielectric, pyroelectric and ferroelectric studies carried out on these films have been reported. The dielectric constant increases with La concentration. The Curie temperature is found to decrease with the addition of lanthanum. The pyroelectric coefficient increases from 17 nC/cm2K to 31 nC/cm2K as La content increases from 4 to 12%. The pyroelectric figures of merit of the films have been calculated from these studies. These studies indicate that 8% lanthanum is the material best suited for infrared detectors owing to its high pyroelectric coefficient (˜29 nC/cm2K), high voltage responsivity (˜420 Vcm2/J), high detectivity (˜1.04× 10-5 Pa-1/2) and low variation of pyrocoefficient with temperature.

  17. Analysis and development of an aqueous tape casting ceramic process

    OpenAIRE

    Mortara, L.

    2005-01-01

    The laboratory scale process developed by Navarro [Navarro, 2001 ] for the production of pyroelectric ceramics was used as a case study for the design of a high-level methodology for the scale-up of ceramic processes. A twofold approach was adopted as the basis of the methodology to perform the process scale-up. A "process focussed" approach was used that considered the sequence of processing operations, their feasibility on a larger scale and the potential problems foreseeable for a scale...

  18. Contribution of an extrinsic mechanism for the electrical polarization in BiMn2O5 ceramics

    Directory of Open Access Journals (Sweden)

    I. Fier

    2012-12-01

    Full Text Available DC conductivity, frequency dependent dielectric constant and pyroelectric coefficients, obtained from thermal stimulated depolarization current curves, in BiMn2O5 ceramics in the range of temperatures from 10 K to 320 K are reported. The data could be explained if it is assumed that a dipole defect is formed due to an oxygen vacancy and two manganese ions which have their valence changed to accept an electron.

  19. 机械偶合

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    DYNAMICS OF MECHANICALLY AND ELECTROSTATICALLY COUPLED MICROCANTILEVERS;Effect of adiabatic heating in some processes of plastic deformation;Evaluation of kerfless linear arrays; MECHANICALLY CORNER-COUPLED SQUARE MICRORESONATOR ARRAY FOR REDUCED SERIES MOTIONAL RESISTANCE;Finite element modeling of the thermo-electro-mechanical coupling in pyroelectric infrared sensor arrays; Medical ultrasonic transducer using composite materials for acoustic matching layers-computer simulations of transducer arrays;

  20. EXPERIMENTAL SETUP FOR THE STUDY OF INFRARED SIGNALS OF DIFFERENT SOIL MOISTURE

    Directory of Open Access Journals (Sweden)

    A. N. Popov

    2013-01-01

    Full Text Available The article presents: structural scheme of the installation for measuring the infrared radiation of the soil in the range of 6-14 um; technical characteristics device ИКВП-01. The opportunities of use of pyroelectric sensors type MLX90614ESF were researched. Dependence of the temperature of soil from its humidity and dependence of the signal IR instrument of soil temperature and humidity are presented.

  1. Electric field dependence of crystallinity in poly(vinylidene fluoride)

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, R.G.; Anderson, R.A.; Lagasse, R.R.

    1982-05-03

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  2. Electric Field Dependence of Crystallinity in Poly(Vinylidene Fluoride)

    Science.gov (United States)

    Kepler, R. G.; Anderson, R. A.; Lagasse, R. R.

    1982-05-01

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  3. Powering Future Naval Forces

    Science.gov (United States)

    2010-11-01

    Ground Renewable Expeditionary Energy System Bulk Heterojunction Solar Cell 9  Long endurance fuel cell power (26hr flight Nov 2009)  Low noise...Near Mid Long EMRG Solid State Lights for Submarines Power Node Switching Center Perovskite - based Pyroelectrics 3 Power & Energy Technologies...Fuel Power Generation Energy Storage Distribution& Control Power Loads Fuels Chemistry Alternative Fuels Gas Turbine Generators Fuel Cells Aircraft

  4. Ferroelectricity of Europium Manganese Oxide EuMn2O5 with Helimagnetic Ordering

    OpenAIRE

    Nakamura, H.; Ishikawa, M; Kohn, K.

    1997-01-01

    From the measurements of pyroelectricity, dielectric constant, magnetic susceptibility and specific heat, we conclude that EuMn2O5 is ferroelectric below the Curie temperature TC of 38.6 K. This temperature coincides with the Néel temperature of the helimagnetic ordering of Mn3+ and Mn4+ moments within the accuracy of the measurements. The spontaneous polarization is along the b-direction.

  5. Progress In Materials Synthesis And Processing Of Barium Titanium Oxide (BaTiO3) and Barium Strontium Titanium Oxide (BaTiSrO3) Films For Uncooled Infrared (IR) Detector Applications

    Science.gov (United States)

    2011-12-01

    This wavelength is ideal for enhancing the near IR photoresponse of solar cells , and we are transitioning this technology to our quantum dot solar ...nanoparticles was also achieved using polyvinylpyrrolidone (PVP), which was found to facilitate the formation of stable colloids of BaTiO3 and thereby...processing parameters with the (pyro)electrical properties and IR responsiveness of the perovskite test structures. Based on the existing and preferred ARL

  6. Raman spectral analysis of high efficiency PVDF: nanocomposite films doped with MWCNT

    Science.gov (United States)

    Guggilla, Padmaja; Kassu, Aschalew; Powell, Rachel

    2016-09-01

    Nanocomposite films are of great interest in the development of infrared detectors and other technology. Polyvinylidenefluoride (PVDF) with excellent pyroelectric and piezoelectric properties such as fast, dynamic response has great potential for use in touch/tactile sensors, infrared detectors and thermal vidicon/imaging devices. PVDF:LiNbO3, PVDF:LiTaO3, and PVDF:BaTiO3 nanocomposites are fabricated with optimal characteristics using the solution casting technique. All these nanocomposite films are doped with multi-walled carbon nanotubes (MWCNT) with various weight percentages. The objective of this research was to characterize the low-frequency dielectric constant, dielectric loss and the pyroelectric properties of these composite films and thus the materials figures of merit for their use in space applications. Nanocomposites are also characterized using Raman Spectroscopy to get the finger print of these materials and their existence in the composite film. Dielectric constant and dielectric loss results are presented as a function of temperature and frequency, and pyroelectric coefficient as a function of temperature. Raman Spectrum of the nanocomposite materials is presented using 785nm laser. Obtained Raman spectrum matches with the literature available. Authors also observed that both microscopic structure and environmental conditions contributed to observed properties. Dielectric loss resulted from electromagnetic energy loss as manifested through phase differences between low-frequency input signal to the films and time varying polarization. In addition, both the dielectric constant and dielectric loss were observed to be highest for MWCNT doped nanocomposite materials compared to pure PVDF and pure PVDF:LiNbO3, PVDF:LiTaO3, and PVDF:BaTiO3. Among all the MWCNT doped nanocomposite materials PVDF:LiTaO3 showed the highest Pyroelectric coefficient which would make the best material to be used in space applications compared to the other materials at test.

  7. Developing an Ear Prosthesis Fabricated in Polyvinylidene Fluoride by a 3D Printer with Sensory Intrinsic Properties of Pressure and Temperature

    OpenAIRE

    Ernesto Suaste-Gómez; Grissel Rodríguez-Roldán; Héctor Reyes-Cruz; Omar Terán-Jiménez

    2016-01-01

    An ear prosthesis was designed in 3D computer graphics software and fabricated using a 3D printing process of polyvinylidene fluoride (PVDF) for use as a hearing aid. In addition, the prosthesis response to pressure and temperature was observed. Pyroelectric and piezoelectric properties of this ear prosthesis were investigated using an astable multivibrator circuit, as changes in PVDF permittivity were observed according to variations of pressure and temperature. The results show that this pr...

  8. Waste energy harvesting mechanical and thermal energies

    CERN Document Server

    Ling Bing, Kong; Hng, Huey Hoon; Boey, Freddy; Zhang, Tianshu

    2014-01-01

    Waste Energy Harvesting overviews the latest progress in waste energy harvesting technologies, with specific focusing on waste thermal mechanical energies. Thermal energy harvesting technologies include thermoelectric effect, storage through phase change materials and pyroelectric effect. Waste mechanical energy harvesting technologies include piezoelectric (ferroelectric) effect with ferroelectric materials and nanogenerators. The book aims to strengthen the syllabus in energy, materials and physics and is well suitable for students and professionals in the fields.

  9. Materials Research of Perovskite Thin Films for Uncooled Infrared (IR) Detectors

    Science.gov (United States)

    2011-07-01

    a. spinning a liquid photoresist onto the wafer b. baking the wafer for about an hour, exposing the wafer (the mask could have several arrays on...a wafer will go through the photolithographic steps (a-c) several times (~50 times). Figure 17 shows a film grown by conventional MBE with pixels...shows a similar process using laser-induced pyroelectric activation and bump bonding to a Si fan-out. This procedure will be used to prove proof-of

  10. Optimisation and thermal control of a multi-layered structure for space electronic devices and thermal shielding of re-entry vehicles

    Science.gov (United States)

    Monti, Riccardo; Barboni, Renato; Gasbarri, Paolo; Chiwiacowsky, Leonardo D.

    2012-06-01

    All electronic devices, due to Joule effect, present heat dissipation, when they are electrically fed. The heat overstocking produces efficiency and performances reduction. On account of this the thermal control is mandatory. On small electronic equipments, the difficulty or impossibility of using a cooling fluid for the free or forced convection heat dissipation imposes the presence of cooling systems based on another kind of functioning principle such as the conduction. In this paper the thermal control, via pyroelectric materials, is presented. Furthermore, an optimisation of geometric, thermal and mechanical parameters, influencing the thermal dissipation, is studied and presented. Pyroelectric materials are able to convert heat into electrical charge spontaneously and, due to this capability, such materials could represent a suitable choice to increase the heat dissipation. The obtained electric charge or voltage could be used to charge a battery or to feed other equipments. In particular, a sequence of different materials such as Kovar®, molybdenum or copper-tungsten, used in a multi-layer pyroelectric wafer, together with their thicknesses, are design features to be optimised in order to have the optimal thermal dissipation. The optimisation process is performed by a hybrid approach where a genetic algorithm (GA) is used coupled with a local search procedure, in order to provide an appropriate balance between exploration and exploitation of the search space, which helps in the search for the optimal or quasi-optimal solution. Since the design variables used in the optimisation procedure are defined in different domains, discrete (e.g. the number of layers in the pyroelectric wafer) and continuous (e.g. the layers thickness) domains, the genetic representation for the solution should take it into account. The chromosome used in the genetic algorithm will mix both integer and real values, what will also be reflected in the genetic operators used in the

  11. Study on data acquisition system for living environmental information for biofication of living spaces

    Science.gov (United States)

    Shimoyama, Norihisa; Mita, Akira

    2008-03-01

    In Japan's rapidly aging society, the number of elderly people living alone increases every year. Theses elderly people require more and more to maintain as independent a life as possible in their own homes. It is necessary to make living spaces that assist in providing safe and comfortable lives. "Biofication of Living Spaces" is proposed with the concept of creating save and pleasant living environments. It implies learning from biological systems, and applying to living spaces features such as high adaptability and excellent tolerance to environmental changes. As a first step towards realizing "Biofied Spaces", a system for acquisition and storing information must be developed. This system is similar to the five human senses. The information acquired includes environmental information such as temperature, human behavior, psychological state and location of furniture. This study addresses human behavior as it is the most important factor in design of a living space. In the present study, pyroelectric infrared sensors were chosen for human behavior recognition. The pyroelectric infrared sensor is advantageous in that it has no limitation on the number of sensors put in a single space because sensors do not interfere with each other. Wavelet analysis was applied to the output time histories of the pyroelectric infrared sensors. The system successfully classified walking patterns with 99.5% accuracy of walking direction (from right or left) and 85.7% accuracy of distance for 440 patterns pre-learned and an accuracy of over 80% accuracy of walking direction for 720 non-learned patterns.

  12. Section 1: Interfacial reactions and grain growth in ferroelectric SrBi{sub 2}Ta{sub 2}O (SBT) thin films on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, B.D.; Zhang, X.; Desu, S.B. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)] [and others

    1997-04-01

    Much of the cost of traditional infrared cameras based on narrow-bandgap photoelectric semiconductors comes from the cryogenic cooling systems required to achieve high detectivity. Detectivity is inversely proportional to noise. Generation-recombination noise in photoelectric detectors increases roughly exponentially with temperature, but thermal noise in photoelectric detectors increases only linearly with temperature. Therefore `thermal detectors perform far better at room temperature than 8-14 {mu}m photon detectors.` Although potentially more affordable, uncooled pyroelectric cameras are less sensitive than cryogenic photoelectric cameras. One way to improve the sensitivity to cost ratio is to deposit ferroelectric pixels with good electrical properties directly on mass-produced, image-processing chips. `Good` properties include a strong temperature dependence of the remanent polarization, P{sub r}, or the relative dielectric constant, {epsilon}{sub r}, for sensitive operation in pyroelectric or dielectric mode, respectively, below or above the Curie temperature, which is 320 C for SBT. When incident infrared radiation is chopped, small oscillations in pixel temperature produce pyroelectric or dielectric alternating currents. The sensitivity of ferroelectric thermal detectors depends strongly on pixel microstructure, since P{sub r} and {epsilon}{sub r} increase with grain size during annealing. To manufacture SBT pixels on Si chips, acceptable SBT grain growth must be achieved at the lowest possible oxygen annealing temperature, to avoid damaging the Si chip below. Therefore current technical progress describes how grain size, reaction layer thickness, and electrical properties develop during the annealing of SBT pixels deposited on Si.

  13. Phase transitions and electrical characterizations of (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics with 'unfilled' and 'filled' tetragonal tungsten-bronze (TTB) crystal structure

    KAUST Repository

    Yao, Yingbang

    2012-12-01

    Alkali-doped strontium barium niobate (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics has been prepared by a conventional solid-state reaction method. The alkali-dopant concentration x has been varied from 0.24 to 1.15 so that the crystal structure was transformed from \\'unfilled\\' to \\'filled\\' tetragonal tungsten-bronze (TTB) structure. Apart from the change in the structural properties, the effects of the alkali-dopants on the phase transition as well as ferroelectric, piezoelectric and pyroelectric properties have also been investigated. Phase transitions have been studied in the temperature range of -200°C to 350°C. The origins of these phase transitions are discussed. The addition of the alkali-dopants enhances the ferroelectric, piezoelectric and pyroelectric properties of the KNSBN ceramics. Alkali-doping also favors abnormal grain growth and thus results in a porous microstructure, which might contribute to the enhancement of the pyroelectric performance. © 2012 Elsevier Ltd.

  14. Effects of oxygen ion irradiation on PMN-PT ferroelectric materials for space applications

    Science.gov (United States)

    Guggilla, Padmaja; Batra, A. K.; Powell, Rachel

    2016-09-01

    Lead magnesium niobate-lead titanate (PMN-PT) is an important and high performance piezoelectric and pyroelectric relaxor material having wide range of applications in infrared sensor devices. Present work studies the fabrication and dielectric characteristics of PMN-PT in the bulk form. The PMN-PT bulk material was prepared in sol-gel method and subsequently irradiated with heavy ion oxygen. The materials were analyzed and determined that the relaxorferroelectric material indicated changes in its dielectric constant and pyroelectric coefficient after irradiation. Due to the radiation fluent of 1×1016 ions/cm2, the dielectric constant of the material increased uniformly, while its pyroelectric coefficient showed a sharp increased to the value of 5×10-9 μC/cm2 °C with increase in temperature. Its dielectric constants showed increase in values of 527 μC/cm2 °C at 50°C, 635 μC/cm2 °C at 60°C and 748 μC/cm2 °C at 70°C. Properties such as the material impedance, admittance and modulus were investigated for changes in properties which became evident after irradiation.

  15. Thermoelectric studies of charge density wave dynamics.

    Science.gov (United States)

    McDonald, Ross; Harrison, Neil; Singleton, John

    2008-03-01

    The conventional pyroelectric effect is intimately connected to the symmetry, or rather lack of center of symmetry, of the material. Although the experiments we discuss involve studies of low symmetry materials, the pyroelectric currents observed are of an entirely new origin. Systems with broken-translational-symmetry phases that incorporate orbital quantization can exhibit significant departures from thermodynamic equilibrium due to a change in magnetic induction. For charge density wave systems, this metastable state consists of a balance between the density-wave pinning force and the Lorentz force on the extended currents due to the drift of cyclotron orbits. In this way the density wave pinning potential plays a similar role to the edge potential in a two-dimensional electron gas, leading to a large Hall angle and quantization of the Hall resistance. A thermal perturbation that reduces the pinning potential returns the system towards thermal equilibrium, via a phason avalanche orthogonal to the sample surface. The observation of this new form of pyroelectric effect in the high magnetic field phase (B > 30 T) of the organic charge transfer salt α-(BEDT-TTF)2KHg(SCN)4, thus provides a measure of the phason thermopower.

  16. Production and structural characterization of nanolayers of LiNbO{sub 3} by wet chemical synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Eger, Doreen; Gutmann, Emanuel; Stoecker, Hartmut; Mehner, Erik; Meyer, Dirk-Carl [TU Bergakademie Freiberg, Inst. fuer Experimentelle Physik (Germany)

    2012-07-01

    There are many known applications of pyroelectrics. Some new ideas, e.g. disinfecting and biocatalytic surfaces, require thin pyroelectric layers on a substrate. A substance with high pyroelectric coefficient is lithium niobate. There, basic investigations of a new method for manufacturing thin layers of lithium niobate are presented. The thin layers are produced by dip coating of fused silica in a solvent of lithium niobate. Samples with different drawing speed and reaction temperature are manufactured. The resulting layers are characterized by reflected light microscopy (RLM), atomic force microscopy (AFM) and X-ray diffraction (XRD). It is proven by XRD that the layers consist of lithium niobate. AFM and RLM show that samples with low drawing speed become so thick that clefts are formed. Therefore, the manufacturing of nanolayers of lithium niobate with dip coating is possible and reasonable. For an optimization of process parameters for deposition of a defined layer thickness more improvement of the method is necessary, e.g. adding a wetting agent or a conditioning step of the substrate.

  17. Thermoelectric studies of the non-thermal equilibrium dynamics in chiral metals

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, R.D. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS-E536, Los Alamos, NM 87545 (United States)], E-mail: rmcd@lanl.gov; Harrison, N.; Singleton, J. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS-E536, Los Alamos, NM 87545 (United States)

    2008-04-01

    The conventional pyroelectric effect is intimately connected to the symmetry, or rather lack of center of symmetry, of the material. Although the experiments we discuss involve studies of low symmetry materials, the pyroelectric currents observed are of an entirely new origin. Systems with broken-translational-symmetry phases that incorporate orbital quantization can exhibit significant departures from thermodynamic equilibrium due to a change in magnetic induction. For example, orbitally quantized field-induced spin- or charge density wave systems, in which the competition between the elastic forces of the density wave and pinning leads to a critical state analogous to the vortex phase of type II superconductors. This metastable state consists of a balance between the density-wave pinning force and the Lorentz force on the extended currents due to the drift of cyclotron orbits. This results in the establishment of a three-dimensional chiral metal that can extend deep into the bulk of the crystal. In this way the density wave pinning potential plays a similar role to the edge potential in a two-dimensional electron gas, leading to a large Hall angle and quantization of the Hall resistance. A thermal perturbation that reduces the pinning potential returns the system toward thermal equilibrium, which can only be achieved by current flow orthogonal to the surface. The observation of this new form of pyroelectric effect in the high magnetic field phase (B>30 T) of the organic charge transfer salt {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} is conclusive proof of the existence of a three-dimensional chiral metal.

  18. Thermoelectric studies of the non-thermal equilibrium dynamics in chiral metals

    Science.gov (United States)

    McDonald, R. D.; Harrison, N.; Singleton, J.

    2008-04-01

    The conventional pyroelectric effect is intimately connected to the symmetry, or rather lack of center of symmetry, of the material. Although the experiments we discuss involve studies of low symmetry materials, the pyroelectric currents observed are of an entirely new origin. Systems with broken-translational-symmetry phases that incorporate orbital quantization can exhibit significant departures from thermodynamic equilibrium due to a change in magnetic induction. For example, orbitally quantized field-induced spin- or charge density wave systems, in which the competition between the elastic forces of the density wave and pinning leads to a critical state analogous to the vortex phase of type II superconductors. This metastable state consists of a balance between the density-wave pinning force and the Lorentz force on the extended currents due to the drift of cyclotron orbits. This results in the establishment of a three-dimensional chiral metal that can extend deep into the bulk of the crystal. In this way the density wave pinning potential plays a similar role to the edge potential in a two-dimensional electron gas, leading to a large Hall angle and quantization of the Hall resistance. A thermal perturbation that reduces the pinning potential returns the system toward thermal equilibrium, which can only be achieved by current flow orthogonal to the surface. The observation of this new form of pyroelectric effect in the high magnetic field phase (B>30 T) of the organic charge transfer salt α- (BEDT-TTF)2KHg(SCN)4 is conclusive proof of the existence of a three-dimensional chiral metal.

  19. Strain engineering on structures and properties in ferroelectric thin films with perovskite structures

    Directory of Open Access Journals (Sweden)

    TANG Yanxue

    2015-08-01

    Full Text Available Ferroelectric thin films possess ferroelectric,piezoelectric,pyroelectric and photovoltaic properties,which have bright prospect for transducers,actuators,sensors,energy harvesting and solar cells.The properties of ferroelectric films are closely related to their strain due to films constrained by substrates.Therefore,the key to improve the properties of ferroelectric films is how to use substrates to regulate and control their strain,and then regulate their polarized state.This paper review the research progress of regulating the properties of ferroelectric films with perovskite structure by strain engineering and the problems needed to be resolved.

  20. Terahertz Transmission Imaging with 2.52 THz Continuous Wave

    Institute of Scientific and Technical Information of China (English)

    Xiao-Tong Guan; De-Wei Zheng; Min Hu; Wen-Jie Fu; Yu-Meng Cui; Xiang Fan; Liang Zhang; Ye Yuan; Jing-Yuan Xu; Yuan Li

    2013-01-01

    In this article, two terahertz transmission imaging systems are built with a 2.52 THz continuous wave laser and two types of sensors. One is array scanning system using a 124×124 pyro-electric array camera as the detector; the other is a point-wise scanning system utilizing a Golay cell as the detector. The imaging speed and quality is briefly analyzed. Terahertz (THz) imaging results demonstrate that the array scanning system has higher imaging speed with lower resolution. The point-wise scanning system has higher imaging quality with lower speed.

  1. Characterisation of ferroelectric bulk materials and thin films

    CERN Document Server

    Cain, Markys G

    2014-01-01

    This book presents a comprehensive review of the most important methods used in the characterisation of piezoelectric, ferroelectric and pyroelectric materials. It covers techniques for the analysis of bulk materials and thick and thin film materials and devices. There is a growing demand by industry to adapt and integrate piezoelectric materials into ever smaller devices and structures. Such applications development requires the joint development of reliable, robust, accurate and - most importantly - relevant and applicable measurement and characterisation methods and models. In the past f

  2. Science of materials. Progress report, January 1-December 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    The research program includes studies of the microchemistry, microstructure, deformation, corrosion and fracture of metals, ceramics and alloy materials, of the hydrogen embrittlement of metals, the mechanism of heat transfer across interfacts, catalytic properties of surfaces, and erosion of surfaces by fluid suspended particles. The structure of liquids, polymers and disordered solids is under investigation with emphasis on molecular interactions and bonding, on ionic conduction, phase transitions and radiation damage. Ferro- and pyro-electric materials with potential for solar energy applications are under development. The study of optical properties includes the mechanism of luminescence, the design of molecular photoreceptors, and new semiconductor materials for photovoltaic devices.

  3. An integrating sphere radiometer as a solution for high power calibrations in fibre optics

    Science.gov (United States)

    Carrasco-Sanz, Ana; Rodríguez-Barrios, Félix; Corredera, Pedro; Martín-López, Sonia; González-Herráez, Miguel; Hernanz, María Luisa

    2006-04-01

    This paper describes the design, characterization and calibration of a high power transfer standard for optical power measurements in optical fibres based on an integrating sphere radiometer. This radiometer, based on two detectors (Si and InGaAs), can measure powers between 100 nW and 10 W within the wavelength range of (400-1700) nm. The radiometer has been calibrated over the total spectral range of use against an electrically calibrated pyroelectric radiometer and different fibre laser diodes and ion lasers. The total uncertainty obtained is lower than ±1.5% for these wavelengths and power ranges (excluding the water absorption region).

  4. Recent developments in materials and detectors for the infrared; Proceedings of the Meeting, Cannes, France, November 25, 26, 1985

    Science.gov (United States)

    Morten, F. D. (Editor); Seeley, John S. (Editor)

    1986-01-01

    The present conference on advancements in IR-sensitive materials and detector technologies employing them gives attention to thermal detectors, focal plane array processing detectors, novel detector designs, general properties of IR optics materials, and preparation methods for such materials. Specific topics encompass the fabrication of InSb MIS structures prepared by photochemical vapor deposition, IR heterodyne detectors employing cadmium mercury telluride, low microphony pyroelectric arrays, IR detection based on minority carrier extrusion, longwave reststrahl in IR crystals, and molecular beam techniques for optical thin film fabrication.

  5. Hot-pressed transparent PLZT ceramics from low cost chemical processing

    Directory of Open Access Journals (Sweden)

    I.A. Santos

    2001-10-01

    Full Text Available Lanthanum-modified lead zirconate titanate (PLZT ceramics were obtained with high transmittance in the visible range by a combination of an inexpensive chemical processing and hot pressing. Optical, microstructural, pyroelectric, ferroelectric and dielectric properties characterized in this study attested the applicability of the employed method in the production of PLZT transparent ferroelectric ceramics. In fact, the corresponding analyzed physical parameters are in very good agreement with those obtained in samples traditionally prepared by other methods. Furthermore, due to high sample quality, a phenomenological analysis of the PLZT 10/65/35 relaxor features was performed in these ceramics.

  6. Spin-driven multiferroics in BaYFeO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Cong, Jun-Zhuang; Shen, Shi-Peng; Chai, Yi-Sheng; Yan, Li-Qin; Shang, Da-Shan; Wang, Shou-Guo; Sun, Young, E-mail: youngsun@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-05-07

    We report on the spin-driven multiferroic property and magnetoelectric effect in the lately synthesized compound BaYFeO{sub 4}. Due to its peculiar crystal structure, the system exhibits complex magnetic phases with multiple transitions. The dielectric and pyroelectric measurements evidence a spin-driven multiferroic state raised by the cycloidal spin structure below T{sub 1} = 36 K. Strong magnetoelectric effect has also been observed in the multiferroic state. The origin of noncollinear cycloidal spin structure in BaYFeO{sub 4} is believed to arise from the interactions between low-dimensional magnetic columns.

  7. Physical properties of ferroelectric superlattice A3/B3 system in electric field

    Institute of Scientific and Technical Information of China (English)

    Jiang Wei; Lo Veng-Cheong; Bai Bao-Dong

    2005-01-01

    Based on the differential operator technique, a transverse Ising model (TIM) in the effective-field theory is developed to study the physical properties of a ferroelectric superlattice A3/B3 system. The effects of an external electric field on the polarization, susceptibility and pyroelectric coefficient of the ferroelectric superlattice A3/B3 system are discussed in detail. The susceptibility of the ferroelectric superlattice A3/B3 system decreases with the increase of the electric field, implying that the polarization is weak.

  8. Release of charges under external fields of PbLa(Zr,Sn,Ti)O3 ceramic

    Institute of Scientific and Technical Information of China (English)

    Zhang Chong-Hui; Xu Zhuo; Gao Jun-Jie; Yao Xi

    2011-01-01

    This paper investigates the pyroelectric of poled antiferroelectric (AFE) ceramic Pb0.97La0.02 (Zr0.69Sn0.196 Ti0.114)O3 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.

  9. Polarization Switching in Ferroelectric Thin Films Undergoing First-Order Phase Transitions

    Directory of Open Access Journals (Sweden)

    L. A. Bakaleinikov

    2010-01-01

    Full Text Available The main switching properties in ferroelectrics undergoing first-order phase transitions are simulated within the framework of the extended Ishibashi dipole-lattice model including the dipole-dipole interaction in a two-dimensional case for ferroelectric nanoscale objects. The peculiarities of the temperature dependence of the switching rate and the pyroelectric coefficient are discussed in the range of coexistence of the metastable states. The used coefficients of the long-range and short-range interactions between the dipoles are taken from the dielectric and structure measurements in BaTiO3.

  10. A thermal insulation method for a piezoelectric transducer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study deals with the sources of signal distortion of a piezoelectric transducer heated by measured gas flow. These signal distortions originate from both unloading of preload on a piezocrystal because of expansion of a diaphragm in the test apparatus and the pyroelectric effect of a heated piezoelectric crystal. A plastic film on the diaphragm of the transducer can effectively insulate the diaphragm and the piezocrystal within transducer from heating by gas flow, eliminating the sources of distortion. A method for evaluating the thickness of the film is proposed.

  11. Evaluation of polarization of embedded piezoelectrics by the thermal wave method.

    Science.gov (United States)

    Suchaneck, Gunnar; Eydam, Agnes; Hu, Wenguo; Kranz, Burkhart; Drossel, Welf-Guntram; Gerlach, Gerald

    2012-09-01

    This work demonstrates the benefit of the thermal wave method for the evaluation of the polarization state of embedded piezoelectrics. Two types of samples were investigated: A low-temperature co-fired ceramics (LTCC)/lead zirconate titanate (PZT) sensor-actuator and a macro-fiber composite (MFC) actuator. At modulation frequencies below 10 Hz, the pyroelectric response was governed by thermal losses to the embedding layers. Here, the sample behavior was described by a harmonically heated piezoelectric plate exhibiting heat losses to the environment characterized by a single thermal relaxation time.

  12. In-flight calibration system for the INTEGRAL x-ray monitor

    DEFF Research Database (Denmark)

    Costa, E.; Feroci, M.; Barbanera, L.

    1996-01-01

    of Amptek Cool-X15 X-ray generators. The latter is a novel product, based on a pyroelectric crystal used to generate energetic electrons that produce fluorescence lines by hitting a metallic target. We plan to use the four low intensity radioactive sources for monitoring the four independent anode chains......JEM-X is the x-ray monitor serving the two gamma-ray experiments imager and spectrometer onboard the ESA's INTEGRAL satellite. Due to the intrinsic weakness of the celestial sources in the gamma energy range they will need very long integration times. During these long pointings JEM-X will be able...

  13. One-step fabrication of free-standing flexible membranes reinforced with self-assembled arrays of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Grilli, S.; Coppola, S.; Vespini, V.; Pagliarulo, V.; Ferraro, P. [Istituto Nazionale di Ottica (CNR) Via Campi Flegrei, 34 Pozzuoli, Napoli (Italy); Nasti, G. [Department of Chemical Materials and Production Engineering, University of Naples Federico II, PiazzaleTecchio 80 (Naples) (Italy); Institute for Polymers Composites and Biomaterials, National Council of Research of Italy, Via Campi Flegrei 34, 80078 Pozzuoli (Italy); Carfagna, C. [Department of Chemical Materials and Production Engineering, University of Naples Federico II, PiazzaleTecchio 80 (Naples) (Italy)

    2014-10-13

    Here, we report on a single step approach for fabricating free-standing polymer membranes reinforced with arrayed self-assembled carbon nanotubes (CNTs). The CNTs are self-assembled spontaneously by electrode-free DC dielectrophoresis based on surface charge templates. The electrical charge template is generated through the pyroelectric effect onto periodically poled lithium niobate ferroelectric crystals. A thermal stimulus enables simultaneously the self-assembly of the CNTs and the cross-linking of the host polymer. Examples of thin polydimethylsiloxane membranes reinforced with CNT patterns are shown.

  14. Multiferroic and magnetoelectric nature of GaFeO3, AlFeO3 and related oxides

    OpenAIRE

    Saha, Rana; Shireen, Ajmala; Shirodkar, Sharmila N.; Waghmare, Umesh V.; Sundaresan, A.; Rao, C. N. R.

    2011-01-01

    GaFeO3, AlFeO3 and related oxides are ferrimagnetic exhibiting magnetodielectric effect. There has been no evidence to date for ferroelectricity and hence multiferroicity in these oxides. We have investigated these oxides as well as oxides of the composition Al1-x-yGaxFe1+yO3 (x = 0.2, y = 0.2) for possible ferroelectricity by carrying out pyroelectric measurements. These measurements establish the occurrence of ferroelectricity at low temperatures below the N\\`eel temperature in these oxides...

  15. Nanostructures of zinc oxide

    Directory of Open Access Journals (Sweden)

    Zhong Lin Wang

    2004-06-01

    Full Text Available Zinc oxide (ZnO is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric multiple properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobows, nanobelts, nanowires, and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO is probably the richest family of nanostructures among all materials, both in structures and properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers, and biomedical science because it is bio-safe.

  16. Voltage generation of piezoelectric cantilevers by laser heating.

    Science.gov (United States)

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-15

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

  17. Synthesis, Structure and Properties of Various Molecules Based on the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene System With an Evaluation of the Effect Differing Molecular Substitution Patterns Has on the Space Group Symmetry

    DEFF Research Database (Denmark)

    Faldt, André; Krebs, Frederik C; Thorup, Niels

    1997-01-01

    determined, The crystal structure of4,8,12-trioxa-12c-oxophospha-4,8,12,12c-tetrahydrodibenzo[cd,mn] pyrene (13) has also been determined for comparison, Compounds 3 and 11 crystallise in non-centrosymmetric space groups, Compound 12 also crystallises in a centrosymmetric :space group but molecules...... of opposite chirality are present within the unit cell, Finally compound 13 crystallises in a centrosymmetric space group. The room temperature pyroelectric coefficient of 3 has been determined, The spatial extent of the trioxatriangulene ground system has been perturbed by chemical substitution...

  18. Investigation of defect properties of Li in ZnO - A first-principles study of vibrational frequencies, transition rates and diffusion profiles of Li and Li-complexes in ZnO

    OpenAIRE

    Wold, Roger

    2013-01-01

    ZnO is a promising material for modern technological applications. Due to its large direct bandgap (3.4 eV) and large exciton binding energy (60 meV), the compound is suggested as a material for optoelectronic devices, such as light emitting diodes, lasers etc. Moreover, the piezoelectric and pyroelectric properties make ZnO a promising candidate for sensors, actuators and energy generators. ZnO is also suggested for spintronics, and in other application areas in science like biotechnology an...

  19. Solid State Cooling with Advanced Oxide Materials

    Science.gov (United States)

    2014-06-03

    SECURITY CLASSIFICATION OF: 17 . LIMITATION OF a. REPORT b. ABSTRACT c. THIS PAGE ABSTRACT u u u uu 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON...Jan. 2013, Ames, IA ) 14. B. Bhatia, J. Karthik, T. Trong, D. G. Cahill, L. W. Martin, W. P. King, Pyroelectric Measurements on PbZr0.2Ti0.8O3...Physique de la Matière Condensée Colloquium, Université de Genève (March 2012, Geneva, Switzerland) [Invited] 17 . L. W. Martin, Engineering Thermal

  20. Bio-assembled nanocomposites in conch shells exhibit giant electret hysteresis

    KAUST Repository

    Yao, Yingbang

    2012-10-23

    Giant electric polarization (2000-4000 μC cm-2) is observed in natural conch shells. The nanolaminas and biopolymer layers of their unique hierarchical microstructures exhibit ferroelectret behavior and account for the observed polarization. Such huge polarization leads to extremely high pyroelectric coefficients, 2-3 orders of magnitude larger than those of conventional ferroelectric materials. The possibility of tailoring the giant polarization for various applications is considered. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Thermal energy harvesting for application at MEMS scale

    CERN Document Server

    Percy, Steven; McGarry, Scott; Post, Alex; Moore, Tim; Cavanagh, Kate

    2014-01-01

    This book discusses the history of thermal heat generators and focuses on the potential for these processes using micro-electrical mechanical systems (MEMS) technology for this application. The main focus is on the capture of waste thermal energy for example from industrial processes, transport systems or the human body to generate useable electrical power.  A wide range of technologies is discussed, including external combustion heat cycles at MEMS ( Brayton, Stirling and Rankine), Thermoacoustic, Shape Memory Alloys (SMAs), Multiferroics, Thermionics, Pyroelectric, Seebeck, Alkali Metal Thermal, Hydride Heat Engine, Johnson Thermo Electrochemical Converters, and the Johnson Electric Heat Pipe.

  2. A poling study of lead zirconate titanate/polyurethane 0-3 composites

    Science.gov (United States)

    Lau, S. T.; Kwok, K. W.; Shin, F. G.; Kopf, S.

    2007-08-01

    0-3 composites of lead zirconate titanate particles dispersed in a thermoplastic elastomer polyurethane matrix were fabricated. The dielectric permittivity and loss of the composite film were measured and compared to the theoretical values. The composites were polarized by the ac fields at different frequencies. With the application of the Sawyer-Tower circuit, the D-E hysteresis loops of the composites can be measured during the poling process. By decreasing the poling frequency, the composite sample shows a larger "remanent" polarization at the same poling field. To evaluate the poling effectiveness, the pyroelectric coefficients of the poled composite samples were measured by a dynamic method.

  3. Квазистатическая задача термоупругости для анизотропного слоя с учетом пьезо-и пироэлектрических эффектов Quasi-static problem of thermoelasticity for anisotropic layer with piezo- and pyroelectric effects

    Directory of Open Access Journals (Sweden)

    Космодамианский А. С.

    1975-12-01

    Full Text Available В настоящей работе дается решение квазистатической задачи термоупругости для анизотропного слоя с учетом пьезо- и пироэлектрических эффектов.

  4. Electroactive polymers for healthcare and biomedical applications

    Science.gov (United States)

    Bauer, Siegfried

    2017-04-01

    Electroactivity was noticed early in biological substances, including proteins, polynucleotides and enzymes, even piezoand pyroelectricity were found in wool, hair, wood, bone and tendon. Recently, ferroelectricity has been identified in a surprisingly large number of biologically relevant materials, including hydroxyapatite, aortic walls and elastin. Inspired by the variety of natural electroactive materials, a wealth of new elastomers and polymers were designed recently, including an all organic elastomer electret and self-healing dielectric elastomers. Let's further draw inspiration from nature and widen the utilization of electroactive polymers towards (mobile) healthcare and biomedical applications. Ferroelectrets, internally charged polymer foams with a strong piezoelectric thickness coefficient are employed in biomedical sensing, for example as blood pressure and pulse sensor, as vital signs monitor or for the detection of tonicclonic seizures. Piezo- and pyroelectric polymers are booming in printed electronics research. They provide electronic skin the ability to "feel" pressure and temperature changes, or to generate electrical energy from vibrations and motions, even from contractile and relaxation motions of the heart and lung. Dielectric elastomers are pioneered by StretchSense as wearable motion capture sensors, monitoring pressure, stretch, bend and shear, quantifying comfort in sports and healthcare. On the cellular level, electroactive polymer arrays are used to study mechanotransduction of individual cells. Ionic electroactive polymers show potential to be used in implantable electroactive biomedical devices. Already with the currently available science and technology, we are at the verge of witnessing the demonstration of truly complex bionic systems.

  5. Growth and characterization of crystals for room temperature I.R. detectors and second harmonic generation devices

    Science.gov (United States)

    Lal, R. B.

    1995-01-01

    One of the major objectives of this program was to modify the triglycine sulfate (TGS) crystals with suitable dopants and variants to achieve better pyroelectric properties and improved infrared detectivities (D(sup *)), and higher Curie transition temperature compared to undoped TGS crystals. Towards these objectives, many promising dopants, both inorganic and organic, were investigated in the last few years. These dopants gave significant improvement in the D(sup *) value of the infrared detectors fabricated from the grown crystals with no significant increase in the Curie temperature (49 C). The IR detectors were fabricated at EDO/Barnes Engineering Division, Shelton, CT. In the last one year many TGS crystals doped with urea were grown using the low temperature solution crystal growth facility. It is found that doping with urea, the normalized growth yield increased significantly compared to pure TGS crystals and there is an improvement in the pyroelectric and dielectric constant values of doped crystals. This gave a significant increase in the materials figure of merits. The Vicker's hardness of 10 wt percent urea doped crystals is found to be about three times higher in the (010) direction compared to undoped crystals. This report describes in detail the results of urea doped TGS crystals.

  6. DYNAMIC BIMORPH THERMO-PIEZOELECTRIC BENDERS WITH ARBITRARY SUPPORT LOCATION. PART I: APPLICATION TO ENERGY HARVESTING-ANALYTICAL DERIVATIONS

    Directory of Open Access Journals (Sweden)

    Bagdasaryan G. Y.

    2016-03-01

    Full Text Available A comprehensive theoretical analysis of a dynamic thermo-ferro-electric pre-stressed bimorph energy harvester is performed. The analysis also takes into account pyroelectric and thermal expansion effects. The most general analytical expression for the energy conversation coefficients are presented for bi-layer. These coefficients we derive for more general situation when mechanical, electrical, thermal fields are present. We derive coefficients (transformation coefficients for sensing, actuating, and energy harvesting. As a particular case, we derive an analytical expression for the energy harvesting coefficient due to pyroelectric and thermal expansion effects in a rater general situation. This is a function of material properties, location of boundary conditions, vibration frequency, and in plane compressive/tensile follower force. Numerical simulations of the analytical results are presented. Effects of volume fraction, material properties, applied mechanical loads, and boundary conditions on the harvesting coefficients are introduced in the figures. The results for a cantilever and a simply-supported plate-layer are obtained as particular cases. The result for a low frequency (static system is obtained as a particular case by approaching the vibration frequency to zero. It is shown that volume fraction, material properties, plain compressive/tensile follower force, the location of the boundary conditions, and the vibrational frequency of the bimorph strongly influence the strain distribution, and this in effect influences the charge coefficient and the generation of energy. The proposed model can be extended to thermal energy harvesters of piezoelectric-shape memory alloy (SMA composites.

  7. Evidence of large magneto-dielectric effect coupled to a metamagnetic transition in Yb{sub 2}CoMnO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Blasco, J., E-mail: jbc@unizar.es; García, J.; Stankiewicz, J.; Subías, G. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); García-Muñoz, J. L. [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus Univ. de Bellaterra, E-08193 Bellaterra (Spain); Ritter, C. [Institute Laue Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Rodríguez-Velamazán, J. A. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Institute Laue Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2015-07-06

    The double perovskite Yb{sub 2}CoMnO{sub 6} has been synthesized with an almost perfect checkerboard arrangement of Co{sup 2+} and Mn{sup 4+} cations in the B-sublattice of the perovskite cell. It presents an anomaly in the electric capacitance and a strong magneto-dielectric effect at about 40 K whose interplay with the microscopic magnetic behavior has been investigated by means of neutron diffraction, magnetization, pyroelectric, and relative dielectric permittivity measurements. We show that the onset of an E-type antiferromagnetic ordering of Co{sup 2+} and Mn{sup 4+} moments monitored by neutron diffraction provokes the noticeable jump of the relative dielectric permittivity (∼9%) at about 40 K. It is also shown that this jump can be totally suppressed by application of a magnetic field of μ{sub 0}H = 5 T. Neutron experiments and magnetic measurements confirm that such a suppression leading to a significant magneto-dielectric effect is driven by a metamagnetic phase transition from the peculiar E-type ordering of 3d moments into a collinear ferromagnetic order. Pyroelectric current measurements do not show any spontaneous electric polarization, so the large dielectric anomaly at zero field cannot be ascribed to a ferroelectric ordering.

  8. Picosecond Bunch length and Energy-z correlation measurements at SLAC's A-Line and End Station A

    Energy Technology Data Exchange (ETDEWEB)

    Molloy, Stephen; Emma, P.; Frisch, J.C.; Iverson, R.H.; Ross, M.; McCormick, D.J.; /SLAC; Ross, Marc C.; /Fermilab /SLAC; Walston, S.; /LLNL, Livermore; Blackmore, V.; /Oxford U.

    2007-06-27

    We report on measurements of picosecond bunch lengths and the energy-z correlation of the bunch with a high energy electron test beam to the A-line and End Station A (ESA) facilities at SLAC. The bunch length and the energy-z correlation of the bunch are measured at the end of the linac using a synchrotron light monitor diagnostic at a high dispersion point in the A-line and a transverse RF deflecting cavity at the end of the linac. Measurements of the bunch length in ESA were made using high frequency diodes (up to 100 GHz) and pyroelectric detectors at a ceramic gap in the beamline. Modeling of the beam's longitudinal phase space through the linac and A-line to ESA is done using the 2-dimensional tracking program LiTrack, and LiTrack simulation results are compared with data. High frequency diode and pyroelectric detectors are planned to be used as part of a bunch length feedback system for the LCLS FEL at SLAC. The LCLS also plans precise bunch length and energy-z correlation measurements using transverse RF deflecting cavities.

  9. Detection and spectral measurements of coherent synchrotron radiation at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Christopher

    2010-02-15

    The operation of high-gain free-electron laser (FEL) underlies tremendous demands on high quality electron beams with high peak currents. At the Free-Electron-Laser in Hamburg (FLASH), two magnetic bunch compressors are used to compress the electron bunches longitudinally. In the bunch compressor magnets, these short electron bunches generate coherent synchrotron radiation (CSR). This CSR contains information on the longitudinal bunch profile, which is relevant for driving an FEL. In order to investigate coherent synchrotron radiation at the second bunch compressor BC3 at FLASH, a new setup behind the last dipole was installed. For the detection of coherent synchrotron radiation, which is emitted in the infrared regime, pyroelectric detectors were used. These pyroelectric detectors have been calibrated at the free-electron laser FELIX in the wavelength range from 5 {mu}m to 110 {mu}m. For characterisation of the emitted radiation, a transverse scanning device was used to measure the transverse intensity distribution. Various transmission filters were used to obtain additional information about the spectral content. In order to get spectral information with high resolution over a wide wavelength range, a rotating mirror spectrometer using reflective blazed gratings was installed. Using this spectrometer, the first spectral measurements of coherent synchrotron radiation at FLASH in a wavelength range from 10 {mu}m to 160 {mu}m were done. (orig.)

  10. Influence of ionic radius of rare-earths on the structural and electrical properties of Ba5RTi3Nb7O30 (R=rare-earth) ferroelectric ceramics

    Institute of Scientific and Technical Information of China (English)

    Prasun Ganguly

    2015-01-01

    In the present report, Ba5RTi3Nb7O30 (R=La, Nd, Sm, Eu, Dy) compounds were synthesized by solid-state reaction method in order to know the effect of ionic radius of rare-earths on their structural, dielectric, ferroelectric, pyroelectric, piezoelectric and con-ductive properties. X-ray diffraction analysis revealed the formation of the compounds having orthorhombic structure. Scanning elec-tron micrographs showed the formation of fine granular microstructure in all the compounds with a decrease in the average grain size with increasing ionic radius of the substituted rare-earths. Detailed dielectric studies showed that the dielectric constant (ε'r) increased while Curie temperature (Tc) decreased as the ionic radius of the rare-earths increased. With the decrease in the ionic radius of the rare-earths, remanent polarization (2Pr), piezoelectric (d33) and pyroelectric coefficients were observed to increase in Ba5RTi3Nb7O30 compounds. The temperature variation of dc conductivity suggested that the compounds had negative temperature coefficient of re-sistance (NTCR) behaviour.

  11. Hot Plate Annealing at a Low Temperature of a Thin Ferroelectric P(VDF-TrFE Film with an Improved Crystalline Structure for Sensors and Actuators

    Directory of Open Access Journals (Sweden)

    Rahman Ismael Mahdi

    2014-10-01

    Full Text Available Ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE thin films are measured as a function of different annealing temperatures (80 to 140 °C. It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  12. Bus Passenger Flow Counter Design%客车客流量计数器的设计

    Institute of Scientific and Technical Information of China (English)

    姚锦江

    2013-01-01

      本文介绍一种基于单片机与热释电红外传感技术,统计客车客流量的自动计数器系统的设计过程。本系统通过安装在客车车门上方的双探头热释电传感器,自动扫描进入感应区域的乘客并判断其是否上下车,再通过单片机的数据处理,最后输出到液晶显示屏上显示。本系统实时统计车上的乘客数量,方便大客车司机根据车上人数判断是否满载。%This paper introduces a method based on MCU and pyroelectric infrared sensor technology, statistics of bus passenger flow of the automatic counter system design process. The system through the double probe pyroelectric sensor which installed at the top of the passenger door, automatic scanning into the sensing region and judge whether the passengers get on and off, through the MCU data processing, than output to a liquid crystal display.

  13. An Investigation on the Thermal Effusivity of Nanofluids Containing Al2O3 and CuO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zaidan Abd Wahab

    2012-08-01

    Full Text Available The thermal effusivity of Al2O3 and CuO nanofluids in different base fluids, i.e., deionized water, ethylene glycol and olive oil were investigated. The nanofluids, nanoparticles dispersed in base fluids; were prepared by mixing Al2O3, CuO nanopowder and the base fluids using sonication with high-powered pulses to ensure a good uniform dispersion of nanoparticles in the base fluids. The morphology of the particles in the base fluids was investigated by transmission electron microscopy (TEM. In this study, a phase frequency scan of the front pyroelectric configuration technique, with a thermally thick PVDF pyroelectric sensor and sample, was used to measure the thermal effusivity of the prepared nanofluids. The experimental results of the thermal effusivity of the studied solvents (deionized water, ethylene glycol and olive oil showed good agreement with literature values, and were reduced in the presence of nanoparticles. The thermal effusivity of the nanofluid was found to be particularly sensitive to its base fluid and the type of nanoparticles.

  14. The Design of Outdoor Passive Infrared Detector Alarm%户外被动红外探测器的设计

    Institute of Scientific and Technical Information of China (English)

    谢白玉

    2013-01-01

    This paper introduced the structure theory and application circuit of a passive-type pyroelectric infrared de-tector. This circuit has certain practical application value. The core part of this type control circuit is pyroelectric infrared sensor,which mainly uses its infrared radiation and infrared detection characteristic. This circuit applicants the hidden nature of infrared to the warning systems. Thus,it realizes the function of burglar alarm and achieves the purpose of se-curity protection.%本文主要介绍了一种被动式红外探测器的结构原理及其应用电路,此电路具有一定的实际应用价值。该类型控制电路的核心器件为热释电红外传感器,并且主要利用了它的红外辐射和红外探测的特性。这种电路把红外线的隐蔽性很好地应用于报警系统之中,从而实现了防盗报警功能,达到了安全防护之目的。

  15. STUDIES ON STRESS STATE OF SOLIDS MADE OF FUNCTIONAL STRUCTURALLY INHOMOGENEOUS MATERIALS: A REVIEW OF PUBLICATIONS TILL 2010

    Directory of Open Access Journals (Sweden)

    Pasternak Ia.M.

    2015-12-01

    Full Text Available The paper presents a review on the recent advances in the theoretical and experimental studies of functional (smart materials and structures. Particular attention is paid to piezoelectric and magnetoelectroelastic materials, which internally couple mechanical, electric and magnetic fields and can operate as sensors or actuators. Modern smart magnetoelectroelastic materials consisting of piezoelectric and piezomagnetic phases are widely used due to the effect of electromagnetic coupling, which is hundred or even thousand times larger than that of a single crystal magnetoelectroelastic materials. The highest electromagnetic coupling due to the regular arrangement of phases is possessed by ferrite-piezoelectric nanostructures, in particular self-assembled nanocomposite thin films. Ferroelectric materials are widely used in modern technologies, especially precise devices, due to the highest values of electro-mechanical coupling among other piezoelectric materials. In turn, all ferroelectric materials are pyroelectric ones, thus, polarize when heated or cooled. The presence of different defects (e.g. cracks or inclusions can additionally cause high stress and electric displacement intensity under the applied thermal load, especially, when the pyroelectric material is not homogeneous, or consists of homogeneous parts bonded together. The paper presents a comprehensive review on the methods, especially numeric and analytic ones, used to study the influence of different fields on stress concentration at defects and fibers. The questions on fracture of defective solids with thin inclusions are also examined.

  16. Research on Spectral Response of an Infrared Detector%红外探测器光谱响应测量研究

    Institute of Scientific and Technical Information of China (English)

    陈亚卓; 秦玉伟

    2013-01-01

    A spectral response system for infrared detector is designed.The principle of the system is also analyzed.The spectral response experiment of the pyroelectricity detector is performed with different temperature and frequency The experiment result shows that the response of the pyroelectricity detector to infrared radiation is different,but the change trend curve of the voltage is similar.The theory of the infrared detector is thereby verified.The system has high measurement accuracy and stability,which can suppress the disturbance signal effectively and improve the signal-to-noise ratio of the system.%设计了一个红外探测器的光谱响应测试系统,并对系统原理进行了分析.对不同温度和频率情况下的热释电探测器进行光谱响应实验.实验结果表明,热释电探测器对红外辐射信号的响应不同,但电压变化曲线的趋势基本一致,从而验证了红外探测器光谱响应理论.该设计能有效抑制系统的干扰信号,提高信噪比,具有测量精度高、稳定性好的优点.

  17. Evidence for multiferroic characteristics in NdCrTiO{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Saha, J.; Sharma, G.; Patnaik, S., E-mail: spatnaikjnu@gmail.com

    2014-06-01

    We report NdCrTiO{sub 5} to be an unusual multiferroic material with large magnetic field dependent electric polarization. While magneto-electric coupling in this two magnetic sub-lattice oxide is well established, the purpose of this study is to look for spontaneous symmetry breaking at the magnetic transition. The conclusions are based on extensive magnetization, dielectric and polarization measurements around its antiferromagnetic ordering temperature of 18 K. Room temperature X-ray diffraction pattern of NdCrTiO{sub 5} reveals that the sample is single phase with an orthorhombic crystal structure that allows linear magneto-electric coupling. DC magnetization measurement shows magnetization downturn at 11 K together with a small kink corresponding to the Cr{sup +3} sub-lattice ordering at ∼18 K. An anomaly in dielectric constant is observed around the magnetic ordering temperature that increases substantially with increasing magnetic field. Through detailed pyroelectric current measurements at zero magnetic field, particularly as a function of thermal cycling, we establish that NdCrTiO{sub 5} is a genuine multiferroic material that is possibly driven by collinear magneto-striction. - Highlights: • We provide evidence for multiferroicity in NdCrTiO{sub 5}. • Large magnetic field dependent electric polarization is confirmed. • Sign reversal of pyroelectric current upon thermal cycling proves genuine ferroelectricity. • A model based on collinear magneto-striction is proposed. • A new class of multiferroic materials with large ME coupling is established.

  18. The Design of Outdoor Passive Infrared Detector%户外被动红外探测器的设计

    Institute of Scientific and Technical Information of China (English)

    谢白玉

    2013-01-01

    This paper introduced the structure theory and application circuit of a passive-type pyroelectric infrared detector. This circuit possesses certain practical application value. The core part of this type control circuit is pyroelectric infrared sensor,which mainly uses its infrared radiation and infrared detection characteristic. This circuit uses the hidden nature of infrared to the warning systems. Thus,it realizes the function of burglar alarm and achieves the purpose of security protection.%本文主要介绍了一种被动式红外探测器的结构原理及其应用电路,此电路具有一定的实际应用价值。该类型控制电路的核心器件为热释电红外传感器,并且主要利用了它的红外辐射和红外探测的特性。这种电路把红外线的隐蔽性很好地应用于报警系统之中,从而实现了防盗报警功能,达到了安全防护之目的。

  19. 紫外光谱响应度测量系统设计%Design of Ultraviolet Spectrum Response Measurement System

    Institute of Scientific and Technical Information of China (English)

    肖光平; 许晓君; 许建坪

    2012-01-01

    Because of the big errors in the ultraviolet radiation calibration measurement, this paper uses pyroelectric detector as the base probe to benchmark detector (GaN) for calibration, puts forward the design principles of spectral response measurement system and designs high stability Ultraviolet light source system, pyroelectric electrical calibration system, signal detection circuit, analysis the functions of computer control and software processing system. Finally , it uses monochromator wavelength calibration to prove that the accuracy of the system.%由于目前的紫外辐射的定标测量存在测量误差大的缺点,采用热释电探测器作为基准探测器给被测探测器(GaN)进行定标,给出光谱响应度测量系统的设计原理,对高稳定度紫外光源系统、热释电电学定标系统、信号检测电路进行了详细的设计,分析计算机控制和软件处理系统部分功能构成,最后进行了单色仪的波长标定来证明系统的准确性.

  20. Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

    Science.gov (United States)

    Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

    2014-10-14

    Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  1. Mechanical confinement for tuning ferroelectric response in PMN-PT single crystal

    Science.gov (United States)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2015-02-01

    Ferroelectrics form an important class of materials and are employed for a variety of applications. However, specific applications dictate the need of tailored ferroelectric response. This creates a requirement to obtain ferroelectric materials with tunable properties. Generally, chemical modifications or domain engineering are employed to this effect. This study attempts to shed light on the use of compressive pre-stresses for tuning and enhancing the ferroelectric properties. For the purpose, polarization versus electric field hysteresis data for 68Pb(Mn1/3Nb2/3)O3-32PbTiO3 (PMN-PT) single crystals were obtained as a function of uniaxial compressive stresses and operating temperatures. These data were utilized to investigate the effects of mechanical confinement for four individual case studies of electrocaloric effect, electrical energy storage, pyroelectric, and piezoelectric effect. A significant improvement was obtained for all case studies. The adiabatic temperature change was improved by ≈80% (28 MPa, 353 K); energy storage density increased by a factor of five (28 MPa, 353 K); pyroelectric figure of merits improved by an order of magnitude (21 MPa) and the piezoelectric coefficient was tailored (variable stress). The results offer promising insight into the use of directional confinement for improving application specific ferroelectric properties in PMN-PT single crystal.

  2. Crystal growth and dielectric characterization of crystals derived from the solid-solution Ba{sub (1-x)}Na{sub x}Ti{sub (1-x)}Nb{sub x}O{sub 3} (BTNN)

    Energy Technology Data Exchange (ETDEWEB)

    Gacem, Lakhdar [ICMCB-CNRS, Universite de Bordeaux, 87 av. Schweitzer, 33608 Pessac (France); Departement de physique, Universite Mohamed Khider de Biskra, Biskra 07000 (Algeria); Ouadjaout, Djamel [UDTS, 2 Bd. Frantz Fanon, BP. 140 Alger-7 Merveilles, 16200 Alger (Algeria); Chaminade, Jean-Pierre, E-mail: chamin@icmcb-bordeaux.cnrs.fr [ICMCB-CNRS, Universite de Bordeaux, 87 av. Schweitzer, 33608 Pessac (France); Maglione, Mario; Von der Muehll, Regnault; Pechev, Stanislas [ICMCB-CNRS, Universite de Bordeaux, 87 av. Schweitzer, 33608 Pessac (France)

    2009-12-15

    Single crystals of (1 - x)BaTiO{sub 3} + xNaNbO{sub 3} (BTNN) for x = 0.84 were obtained by high temperature solution growth using Na{sub 2}B{sub 4}O{sub 7} as solvent. The room temperature crystal structure of BTNN 16/84-phase was determined from X-ray single crystal diffraction data, in the tetragonal system with space group P4bm. The refinement from 246 independent reflections led to the following parameters: a = b = 5.5845(3) A, c = 3.9453(2) A, V = 123.041(11) A{sup 3}, Z = 2, with final cR{sub wp} = 0.150 and R{sub B} = 0.041. The structure of BTNN 16/84-phase can be described as a three-dimensional framework built up from (Nb-Ti)O{sub 6} octahedra with Na and Ba in the dodecahedral site of perovskite-like type. Some mm{sup 3}-sized crystals have been selected and various dielectric measurements (ferroelectric, pyroelectric, and piezoelectric) have been performed. Transition from paraelectric to ferroelectric state at around 460 K has been observed to be in good agreement with ceramics of closer composition. Dielectric, piezoelectric and pyroelectric measurements on crystal confirm the ferroelectric behaviour of BTNN 16/84.

  3. A novel device for determining ultrasonic power

    Science.gov (United States)

    Zeqiri, B.; Shaw, A.; Gélat, P. N.; Bell, D.; Sutton, Y. C.

    2004-01-01

    A novel concept for an ultrasonic power meter is presented which utilises the pyro-electric effect of a thin membrane of the piezo-electric polymer, pvdf. One side of the membrane is in intimate contact with a polyurethane-based acoustical absorber. The attenuation coefficient of this material is very high, ensuring that the majority of the ultrasonic energy passing through the pvdf membrane is absorbed within a thin layer of the interface, resulting in a rapid increase in temperature. Through the pyro-electric effect, this temperature increase results in a voltage across the electrodes of the membrane. Under specific conditions, the generated voltage is proportional to the rate of temperature rise and, immediately after switch on of ultrasound, the rate of temperature rise is proportional to the delivered ultrasonic power. This paper describes details of the concept, and includes theoretical calculations of the expected behaviour. Proof-of-concept is demonstrated through careful studies of several low-megahertz NPL reference therapy-level transducers, covering an applied power range of 250 mW to 8 W. Results are encouraging, suggesting that this novel solid-state power meter concept holds considerable promise for a rapid, simple, relatively low cost, power measurement method, appropriate for use at the physiotherapist level.

  4. DYNAMIC BIMORPH THERMO-PIEZOELECTRIC BENDERS WITH ARBITRARY SUPPORT LOCATION. PART II: APPLICATION TO ENERGY HARVESTING-NUMERICAL RESULTS AND DISCUSSIONS

    Directory of Open Access Journals (Sweden)

    Bagdasaryan, Gevorg Y.

    2016-06-01

    Full Text Available A comprehensive theoretical analysis of a dynamic thermo-ferro-electric pre-stressed bimorph energy harvester is performed. The analysis also takes into account pyroelectric and thermal expansion effects. The most general analytical expression for the energy conversation coefficients are presented for bi-layer. These coefficients we derive for more general situation when mechanical, electrical, thermal fields are present. We derive coefficients (transformation coefficients for sensing, actuating, and energy harvesting. As a particular case, we derive an analytical expression for the energy harvesting coefficient due to pyroelectric and thermal expansion effects in a rater general situation. This is a function of material properties, location of boundary conditions, vibration frequency, and in plane compressive/tensile follower force. Numerical simulations of the analytical results are presented. Effects of volume fraction, material properties, applied mechanical loads, and boundary conditions on the harvesting coefficients are introduced in the figures. The results for a cantilever and a simply-supported plate-layer are obtained as particular cases. The result for a low frequency (static system is obtained as a particular case by approaching the vibration frequency to zero. It is shown that volume fraction, material properties, plain compressive/tensile follower force, the location of the boundary conditions, and the vibrational frequency of the bimorph strongly influence the strain distribution, and this in effect influences the charge coefficient and the generation of energy. The proposed model can be extended to thermal energy harvesters of piezoelectric-shape memory alloy (SMA composites.

  5. An investigation on the thermal effusivity of nanofluids Containing Al(2)O(3) and CuO nanoparticles.

    Science.gov (United States)

    Noroozi, Monir; Zakaria, Azmi; Moksin, Mohd Maarof; Wahab, Zaidan Abd

    2012-01-01

    The thermal effusivity of Al(2)O(3) and CuO nanofluids in different base fluids, i.e., deionized water, ethylene glycol and olive oil were investigated. The nanofluids, nanoparticles dispersed in base fluids; were prepared by mixing Al(2)O(3), CuO nanopowder and the base fluids using sonication with high-powered pulses to ensure a good uniform dispersion of nanoparticles in the base fluids. The morphology of the particles in the base fluids was investigated by transmission electron microscopy (TEM). In this study, a phase frequency scan of the front pyroelectric configuration technique, with a thermally thick PVDF pyroelectric sensor and sample, was used to measure the thermal effusivity of the prepared nanofluids. The experimental results of the thermal effusivity of the studied solvents (deionized water, ethylene glycol and olive oil) showed good agreement with literature values, and were reduced in the presence of nanoparticles. The thermal effusivity of the nanofluid was found to be particularly sensitive to its base fluid and the type of nanoparticles.

  6. Improper ferroelectrics as high-efficiency energy conversion materials

    Energy Technology Data Exchange (ETDEWEB)

    Wakamatsu, Toru; Tanabe, Kenji; Terasaki, Ichiro; Taniguchi, Hiroki [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2017-05-15

    An improper ferroelectric is a certain type of ferroelectrics whose primary order parameter is not polarization but another physical quantity such as magnetization. In contrast to a conventional proper ferroelectrics as represented by Pb(Zr,Ti)O{sub 3} and BaTiO{sub 3}, the improper ferroelectrics has been inconceivable for practical applications thus far. Herein, we illustrate the great potential of improper ferroelectrics for efficient conversion of temperature fluctuation to electric energy, as demonstrated with (Ca{sub 0.84}Sr{sub 0.16}){sub 8}[AlO{sub 2}]{sub 12}(MoO{sub 4}){sub 2} (CSAM-16). The present study has experimentally proven that CSAM-16 achieves an excellent electrothermal coupling factor and high electric field sensitivity for pyroelectric energy conversion that approach a practical level for application to self-powered autonomous electronic devices for rapidly spreading wireless sensor networks. The present results provide a novel approach to developing innovative pyroelectric energy harvesting devices using improper ferroelectrics. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Large electric polarization in high pressure synthesized orthorhombic manganites RMnO3 (R=Ho,Tm,Yb and Lu) by using the double-wave PE loop measurements

    Science.gov (United States)

    Chai, Y. S.; Oh, Y. S.; Manivannan, N.; Yang, Y. S.; Kim, Kee Hoon; Feng, S. M.; Wang, L. J.; Jin, C. Q.

    2009-03-01

    The magnitude of electric polarization via the conventional pyroelectric current and/or PE loop measurements often is ambiguous due to resistive components of the sample. To avoid this, a new technique called the double-wave method has been recently developed [1], in which only hysteretic PE components can be measured. Using this technique, we have measured the ferroelectric polarization of the orthorhombic RMnO3 (R=Ho, Tm, Yb, and Lu) synthesized under high pressure. Large remnant polarization Pr up to 920 μC/m^2 is observed at 10 K for LuMnO3. Furthermore, the Pr vs. temperature data from the PE loop has shown consistency with that measured through the pyroelectric current measurements, supporting a theoretical prediction of large polarization in the E-type spin structure in this system [2]. We also discuss the influence of thermal histories on the ferroelectric domain dynamics and possible internal bias field effects originating from oxygen vacancies in RMnO3. [1] M. Fukunaga, et al. J. Phys. Soc. Jpn. 77, 064706 (2008). [2] I. A. Sergienko, et al. Phys. Rev. Lett., 97, 227204 (2006)

  8. Relaxor ferroelectric properties of the (1-2 x)BiScO3 · xPbTiO3 · xPbMg1/3Nb2/3O3 (0.30 ≤ x ≤ 0.46) system

    Science.gov (United States)

    Bush, A. A.; Kamentsev, K. E.; Bekhtin, M. A.; Segalla, A. G.

    2017-01-01

    X-ray diffraction, dielectric, piezoelectric, and pyroelectric studies have been performed on ceramic samples of (1-2 x)BiScO3 · xPbTiO3 · xPbMg1/3Nb2/3O3 (0.30 ≤ x ≤ 0.46) perovskite-like solid solutions. The solid solution symmetry was found to vary from the rhombohedral ( x ≤ 0.38) to tetragonal ( x ≥ 0.42) as x increases. The samples with 0.30 < x ≤ 0.42 have properties characteristic of relaxor ferroelectrics, namely the existence of a wide peak in the temperature dependence of the dielectric permittivity at T mɛ = 390-440 K that shifts to higher temperatures as the frequency increases, narrow unsaturated dielectric hysteresis loops, and an electric field-induced transition to the ferroelectric state at 318 K. The observed features of the dielectric, piezo-, and pyroelectric properties of these solid solutions are explained by the fact that they are relaxor ferroelectrics.

  9. Novel solar-blind photodetector using AlGaN in combination with a PVDF film%结合AlGaN和 PVDF的新型日盲紫外探测器的研究

    Institute of Scientific and Technical Information of China (English)

    刘秀娟; 李超; 王建禄; 张燕; 孙璟兰; 李向阳

    2013-01-01

    制作了一种新型的结合了AlGaN材料结构和Poly(vinylidene fluoride)(PVDF)热释电材料的日盲紫外探测器。当紫外光从AlGaN一侧背照射至器件上时,测量PVDF两端的热释电响应光谱,测得峰值响应在入射光波长为260 nm处,响应电压高达129.6 mV(此时辐射功率为39.8 nW)。器件响应机理为:紫外光被i-Al0.35Ga0.65层吸收,产生光生载流子并复合生热,热量通过AlGaN材料传导给PVDF结构的电极,温度升高,PVDF对温度变化产生响应。为了进一步验证,制作了对比器件,即在AlGaN结构和PVDF结构之间加了一层多孔SiO2隔热层,测得的响应光谱中有两个峰值,一个在260 nm,另外一个在300 nm。与参考器件相比,在260 nm处的响应电压大大减小,说明了利用热效应探测的可行性。另外,测量了不同频率下的器件响应并对其进行理论拟合,深入研究300 nm处的响应机理。%A novel solar-blind detector which combined a AlGaN-based structure and a Poly (vinylidene fluoride) (PVDF) -based pyroelectric detector structure in one chip was fabricated. The pyroelectric response spectra of the PVDF-based pyroelectric structure was measured when the UV light illuminated from the side of the AlGaN-based structure. The peak response voltage was measured as high as 129.6 mV when the light’s wavelength was 260 nm and the radiation power was 39.8 nW. The response mechanism was assumed as followed: the light at 260 nm was absorbed by i-Al0.35Ga0.65N layer and the heat energy was generated through the direct recombination of photoexcited-carriers, then the heat transferred to the PVDF layer and a response voltage was got through the pyroelectric effect of the PVDF. To confirm this assumption, another sample which added a porous SiO2 layer between the AlGaN-based structure and the PVDF-based structure was fabricated. Its response spectra showed two peaks, one was at 260 nm and the other was at 300 nm

  10. Polar hexagonal tungsten bronze-type oxides: KNbW2O9, RbNbW2O9, and KTaW2O9.

    Science.gov (United States)

    Chang, H Y; Sivakumar, T; Ok, K M; Halasyamani, P Shiv

    2008-10-06

    The synthesis, crystal structures, second-harmonic generation (SHG), piezoelectric, pyroelectric, and ferroelectric properties of three polar noncentrosymmetric (NCS) hexagonal tungsten bronze-type oxides are reported. The materials KNbW 2O 9, RbNbW 2O 9, and KTaW 2O 9 were synthesized by standard solid-state techniques and structurally characterized by laboratory powder X-ray diffraction. The compounds are isostructural, crystallizing in the polar NCS space group Cmm2. The materials exhibit a corner-shared MO 6 (M = Nb (5+)/W (6+) or Ta (5+)/W (6+)) octahedral framework, with K (+) or Rb (+) occupying the "hexagonal" tunnels. The d (0) transition metals, Nb (5+), Ta (5+), and W (6+), are displaced from the center of their oxide octahedra attributable to second-order Jahn-Teller effects. SHG measurements using 1064 nm radiation revealed frequency-doubling efficiencies ranging from 180 to 220 x alpha-SiO 2. Converse piezoelectric measurements resulted in d 33 values ranging from 10 to 41 pm V (-1). The total pyroelectric coefficient, p, at 50 degrees C ranged from -6.5 to -34.5 muC K (-1) m (-2). The reported materials are also ferroelectric, as demonstrated by hysteresis loops (polarization vs electric field). Spontaneous polarization values, P s, ranging from 2.1 to 8.4 muC cm (-2) were measured. The magnitudes of the SHG efficiency, piezoelectric response, pyroelectric coefficient, and ferroelectric polarization are strongly dependent on the out-of-center distortion of the d (0) transition metals. Structure-property relationships are discussed and explored. Crystal data: KNbW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 21.9554(2) A, b = 12.60725(15) A, c = 3.87748(3) A, V = 1073.273(13) A (3), and Z = 6; RbNbW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 22.00985(12) A, b = 12.66916(7) A, c = 3.8989(2) A, V = 1086.182(10) A (3), and Z = 6; KTaW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 22.0025(2) A, b = 12.68532(14) A, c = 3.84456(4) A, V

  11. Laser-induced breakdown and damage generation by nonlinear frequency conversion in ferroelectric crystals: Experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi [Center for Advanced Photonics, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hatano, Hideki; Kitamura, Kenji [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2013-11-28

    Using our experimental data for ns pulsed second harmonic generation (SHG) by periodically poled stoichiometric LiTaO{sub 3} (PPSLT) crystals, we consider in detail the mechanism underlying laser-induced damage in ferroelectric crystals. This mechanism involves generation and heating of free electrons, providing an effective kinetic pathway for electric breakdown and crystal damage in ns pulsed operation via combined two-photon absorption (TPA) and induced pyroelectric field. In particular, a temperature increase in the lattice of ≈1 K induced initially by ns SHG and TPA at the rear of operating PPSLT crystal is found to induce a gradient of spontaneous polarization generating a pyroelectric field of ≈10 kV/cm, accelerating free electrons generated by TPA to an energy of ≈10 eV, followed by impact ionization and crystal damage. Under the damage threshold for ns operation, the impact ionization does not lead to the avalanche-like increase of free electron density, in contrast to the case of shorter ps and fs pulses. However, the total number of collisions by free electrons, ≈10{sup 18} cm{sup −3} (generated during the pulse and accelerated to the energy of ≈10 eV), can produce widespread structural defects, which by entrapping electrons dramatically increase linear absorption for both harmonics in subsequent pulses, creating a positive feedback for crystal lattice heating, pyroelectric field and crystal damage. Under pulse repetition, defect generation starting from the rear of the crystal can propagate towards its center and front side producing damage tracks along the laser beam and stopping SHG. Theoretical analysis leads to numerical estimates and analytical approximation for the threshold laser fluence for onset of this damage mechanism, which agree well with our (i) experiments for the input 1064 nm radiation in 6.8 kHz pulsed SHG by PPSLT crystal, (ii) pulsed low frequency 532 nm radiation transmission experiments, and also (iii) with the data

  12. An improved single crystal adsorption calorimeter for determining gas adsorption and reaction energies on complex model catalysts

    Science.gov (United States)

    Fischer-Wolfarth, Jan-Henrik; Hartmann, Jens; Farmer, Jason A.; Flores-Camacho, J. Manuel; Campbell, Charles T.; Schauermann, Swetlana; Freund, Hans-Joachim

    2011-02-01

    A new ultrahigh vacuum microcalorimeter for measuring heats of adsorption and adsorption-induced surface reactions on complex single crystal-based model surfaces is described. It has been specifically designed to study the interaction of gaseous molecules with well-defined model catalysts consisting of metal nanoparticles supported on single crystal surfaces or epitaxial thin oxide films grown on single crystals. The detection principle is based on the previously described measurement of the temperature rise upon adsorption of gaseous molecules by use of a pyroelectric polymer ribbon, which is brought into mechanical/thermal contact with the back side of the thin single crystal. The instrument includes (i) a preparation chamber providing the required equipment to prepare supported model catalysts involving well-defined nanoparticles on clean single crystal surfaces and to characterize them using surface analysis techniques and in situ reflectivity measurements and (ii) the adsorption/reaction chamber containing a molecular beam, a pyroelectric heat detector, and calibration tools for determining the absolute reactant fluxes and adsorption heats. The molecular beam is produced by a differentially pumped source based on a multichannel array capable of providing variable fluxes of both high and low vapor pressure gaseous molecules in the range of 0.005-1.5 × 1015 molecules cm-2 s-1 and is modulated by means of the computer-controlled chopper with the shortest pulse length of 150 ms. The calorimetric measurements of adsorption and reaction heats can be performed in a broad temperature range from 100 to 300 K. A novel vibrational isolation method for the pyroelectric detector is introduced for the reduction of acoustic noise. The detector shows a pulse-to-pulse standard deviation ≤15 nJ when heat pulses in the range of 190-3600 nJ are applied to the sample surface with a chopped laser. Particularly for CO adsorption on Pt(111), the energy input of 15 nJ (or 120 nJ cm

  13. Measurements of energy loss in the scrape-off layer of C-2U

    Science.gov (United States)

    Griswold, M. E.; Korepanov, S.; Thompson, M. C.; the TAE Team Team

    2016-10-01

    We report on measurements of energy transport in the scrape-off layer (SOL) plasma that surrounds the advanced beam-driven field reversed configuration (FRC) of the C-2U experiment at Tri Alpha Energy. The SOL plasma is trapped on mirror-like open field lines outside of the FRC separatrix that connect to material surfaces at both ends of the vacuum vessel. Heat transport in this region is expected to be convective, like in mirror machines, and can be characterized by the amount of energy lost per electron-ion pair. We measured this value with an end loss analyzer system that consists of gridded ion energy analyzers that measure ion current density and pyroelectric crystal bolometers that measure total particle power flux.

  14. Evaluation of PTCa/PEKK composite sensors for acoustic emission detection

    CERN Document Server

    Marin-Franch, P

    2002-01-01

    This thesis reports for the first time the fabrication and characterisation of novel electroactive ceramic/polymer composite films of calcium modified lead titanate (PTCa) and poly (ether ketone ketone). Composite sensors with different concentrations of ceramic were fabricated using a hot pressing technique. The PTCa ceramic was treated using titanate coupling agent in order to improve sample quality. Dielectric measurements have been performed to study sample characteristics. Piezoelectric and pyroelectric properties of the composites have been measured and the mixed connectivity cube model used to determine the relative amounts of 0-3 and 1-3 connectivity. The advantages and limitations of the model have been discussed. Additionally, some mechanical properties of the composites have been assessed to study their potential ability to detect acoustic emission (AE) in carbon fibre reinforced composites (CFRC). The composite sensors were placed on and inserted into different panels in order to compare their abi...

  15. Effect of Ba addition on the structural, dielectric and ferroelectric properties of Na0.5Bi0.5TiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Suchanicz J.

    2015-06-01

    Full Text Available Lead-free (Na0.5Bi0.51-xBaxTiO3 (x = 0, 0.04 and 0.06 ceramics were fabricated by conventional solid phase sintering process. X-ray diffraction analysis shows that obtained specimens possess the perovskite structure. The microstructure study shows a dense structure, in good agreement with the relative density determined by the Archimedes method (above 95 %. Electric permittivity anomaly is shifted to low temperature after Ba doping of NBT. The pyroelectric and hysteresis loops measurements show that polarization and coercive field increases and decreases, respectively, after Ba doping of NBT. The obtained results are discussed in terms of ions/lattice imperfections, which create local electromechanical fields. The investigated ceramics are considered to be promising candidates for lead-free electronic materials.

  16. Next-generation PIR security sensors: concept testing and evaluation

    Science.gov (United States)

    Liddiard, Kevin C.

    2009-05-01

    In previous presentations to this SPIE forum a new technology was outlined aimed at replacing pyroelectric sensors with resistance microbolometer MOEMS-based sensors capable of vastly superior performance. The technology can be implemented as either a PCB replacement to current sensors, giving extended detection range and ability to sense slow temperature change, or a 'smart' sensor with further performance enhancements and imaging capability. This paper reports the results of new laboratory and field tests of a laboratory prototype sensor and extrapolates these results to performance of production sensors. In particular, results are presented for NETD, detection range for human targets and detection of simulated electrical faults and developing fires. Previous results were reported for FPA operated without evacuation and using a low cost plastic Fresnel lens. However with wafer level packaging now becoming widely available in MEMS and CMOS foundries, much high performance can be achieved, opening up many additional applications. Performance of new FPAs designed for vacuum packaging is highlighted.

  17. Thermophysical analysis of II-VI semiconductors by PPE calorimetry and lock-in thermography

    Energy Technology Data Exchange (ETDEWEB)

    Streza, M.; Dadarlat, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Strzałkowski, K. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 (Poland)

    2013-11-13

    An accurate determination of thermophysical properties such as thermal diffusivity, thermal effusivity and thermal conductivity is extremely important for characterization and quality assurance of semiconductors. Thermal diffusivity and effusivity of some binary semiconductors have been investigated. Two experimental techniques were used: a contact technique (PPE calorimetry) and a non contact technique (lock-in thermography). When working with PPE, in the back (BPPE) configuration and in the thermally thick regim of the pyroelectric sensor, we can get the thermal diffusivity of the sample by performing a scanning of the excitation frequency of radiation. Thermal effusivity is obtained in front configuration (sensor directly irradiated and sample in back position) by performing a thickness scan of a coupling fluid. By using the lock-in thermography technique, the thermal diffusivity of the sample is obtained from the phase image. The results obtained by the two techniques are in good agreement. Nevertheless, for the determination of thermal diffusivity, lock-in thermography is preferred.

  18. Experimental research on spectrum and imaging of continuous-wave terahertz radiation based on interferometry

    Science.gov (United States)

    Lu, Tie-Lin; Yuan, Hui; Kong, Ling-Qin; Zhao, Yue-Jin; Zhang, Liang-Liang; Zhang, Cun-Lin

    2016-08-01

    A system for measuring terahertz spectrum is proposed based on optical interferometer theory, and is experimentally demonstrated by using a backward-wave oscillator as the terahertz source. A high-resolution, high-precision interferometer is constructed by using a pyroelectric detector and a chopper. The results show that the spectral resolution is better than 1 GHz and the relative error of frequency is less than 3%. The terahertz energy density distribution is calculated by an inverse Fourier transform and tested to verify the feasibility of the interferometric approach. Two kinds of carbon-fiber composites are imaged. The results confirm that the interferometer is useful for transmission imaging of materials with different thickness values. Project supported by the National Natural Science Foundation of China (Grant Nos. 61377109 and 11374007).

  19. Photovoltaic spectral responsivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  20. Application of mobile computers in a measuring system supporting examination of posture diseases

    Science.gov (United States)

    Piekarski, Jacek; Klimiec, Ewa; Zaraska, Wiesław

    2013-07-01

    Measuring system designed and manufactured by the authors and based on mobile computers (smartphones and tablets) working as data recorders has been invented to support diagnosis of orthopedic, especially feet, diseases. The basic idea is to examine a patient in his natural environment, during the usual activities (such as walking or running). The paper describes the proposed system with sensors manufactured from piezoelectric film (PVDF film) and placed in the shoe insole. The mechanical reliability of PVDF film is excellent, though elimination of the pyroelectric effect is required. A possible solution of the problem and the test results are presented in the paper. Data recording is based on wireless transmission to a mobile device used as a data logger.

  1. Hypothetical planar and nanotubular crystalline structures with five interatomic bonds of Kepler nets type

    Directory of Open Access Journals (Sweden)

    Aleksey I. Kochaev

    2017-02-01

    Full Text Available The possibility of metastable existence of planar and non-chiral nanotubular crystalline lattices in the form of Kepler nets of 34324, 3342, and 346 types (the notations are given in Schläfly symbols, using ab initio calculations, has researched. Atoms of P, As, Sb, Bi from 15th group and atoms of S, Se, Te from 16th group of the periodic table were taken into consideration. The lengths of interatomic bonds corresponding to the steadiest states for such were determined. We found that among these new composed structures crystals encountered strong elastic properties. Besides, some of them can possess pyroelectric and piezoelectric properties. Our results can be used for nanoelectronics and nanoelectromechanical devices designing.

  2. Physically Functional Materials

    DEFF Research Database (Denmark)

    2002-01-01

    acids or peptides having azobenzenes or other physicially functional groups, e.g., photoresponsive groups, as side chains. These compounds may be synthesized using solid phase peptide synthesis techniques. Materials, e.g., thin films, comprising such compounds may be used for optical storage...... of information (holographic data storage), nonlinear optics (NLO), as photoconductors, photonic band-gap materials, electrically conducting materials, electroluminescent materials, piezo-electric materials, pyroelectric materials, magnetic materials, ferromagnetic materials, ferroelectric materials......, photorefractive materials, or materials in which light-induced conformational changes can be produced. Optical anisotropy may reversibly be generated with polarized laser light whereby a hologram is formed. First order diffraction efficiencies of up to around 80% have been obtained....

  3. Polymorphism Control of Poly(vinylidene fluoride)

    Science.gov (United States)

    Zheng, Jianfen; He, Aihua; Li, Junxing; Han, Charles C.

    2008-03-01

    Poly(vinylidene fluoride) (PVDF) is well-known for its polymorphism, and can exhibit five different polymorphs depending on its processing conditions. The α-phase is the most common and stable polymorph and the β-phase is the most important one due to its piezoelectric and pyroelectric properties. Polymorphism control of PVDF has been realized through electrospinning. PVDF fibrous membranes with fiber diameter in the range of 100 nm to several micrometers were produced by electrospinning and the crystal phase of electrospun PVDF fibers can be adjusted at the same time. Through the control of electrospinning parameters such as the solvent and electrospinning temperature, PVDF fibrous membranes containing mainly α- or β- or γ-phase could be fabricated successfully.

  4. Polymorphism Behaviors of Electrospun Poly(vinylidene fluoride) Nanofibers

    Science.gov (United States)

    Zhong, Zhenxin; Reneker, Darrell

    2009-03-01

    Poly(vinylidene fluoride) (PVDF) and its copolymers have drawn great attention in recent years due to their attractive electrical properties such as ferro-, piezo- and pyro-electricity. Depending on its processing, PVDF can exhibit five different polymorphs. Among them, the beta phase has the highest piezo-, pyro- and ferroelectric activities. Electrospinning was used to produce thin polymer fibers. The polymorphic behavior of electrospun PVDF fibers was observed. Long cylindrical PVDF specimens with cross-sections in the range of 10 nm to 1 micron was obtained by varying the electrospinning conditions. Almost pure beta phase was obtained in electrospun PVDF nanofibers. The morphology and internal structure of single PVDF electrospun nanofibers were studied by transmission electron microscopy.

  5. Novel multiferroic state and ME enhancement by breaking the AFM frustration in LuMn1-xO3.

    Science.gov (United States)

    Figueiras, F G; Karpinsky, D; Tavares, P B; Gonçalves, J N; Yañez-Vilar, S; Moreira Dos Santos, A F; Franz, A; Tovar, M; Agostinho Moreira, J; Amaral, V S

    2017-01-04

    This study provides a comprehensive insight into the effects of controlled off-stoichiometry on the structural and multiferroic properties of the hexagonal manganite LuMn1-xO3+δ (x = 0.02; δ ∼ 0), supported by neutron powder diffraction measurements confirming single phase P63cm symmetry and evidencing a relevant ferromagnetic component, below TN ∼ 90 K, which breaks the archetypal geometrically frustrated antiferromagnetic state typically ascribed to LuMnO3. The perturbations in the triangular disposition of spins prompt an additional electric polarization contribution and a clear enhancement of the magnetoelectric coupling which are in good agreement with the results of first principles calculations. In addition, Raman spectroscopy, dielectric permittivity, pyroelectric current and magnetic measurements as a function of temperature point out the precursor effects of the magnetic phase transitions involving a strong coupling between spins, lattice and electric order, even above the Néel temperature.

  6. Application of Terahertz Field Enhancement Effect in Metal Microstructures

    Science.gov (United States)

    Nakajima, M.; Kurihara, T.; Tadokoro, Y.; Kang, B.; Takano, K.; Yamaguchi, K.; Watanabe, H.; Oto, K.; Suemoto, T.; Hangyo, M.

    2016-12-01

    Applications of high-field terahertz pulses are attractive in physics and terahertz technology. In this study, two applications related to high-intensity terahertz pulses are demonstrated. The field enhancement effect by subwavelength metallic microstructures is utilized for terahertz excitation measurement. The spin precession dynamics in magnetic materials was induced by a terahertz magnetic field. Spin precession was amplified by one order of magnitude in amplitude by the enhanced magnetic terahertz field in orthoferrite ErFeO3 with metal microstructures. The induced spin dynamics was analyzed and explained by LLG-LCR model. Moreover, a detection method for terahertz pulses was developed using a cholesteric liquid crystal at room temperature without any electronic devices. The beam profile of terahertz pulses was visualized and compared to other methods such as the knife edge method using pyroelectric detector and micro-bolometer array. The liquid crystal terahertz imager is very simple and has good applicability as a portable terahertz-sensing card.

  7. Simultaneously Harvesting Thermal and Mechanical Energies based on Flexible Hybrid Nanogenerator for Self-Powered Cathodic Protection.

    Science.gov (United States)

    Zhang, Hulin; Zhang, Shangjie; Yao, Guang; Huang, Zhenlong; Xie, Yuhang; Su, Yuanjie; Yang, Weiqing; Zheng, Chunhua; Lin, Yuan

    2015-12-30

    Metal corrosion occurs anytime and anywhere in nature and the corrosion prevention has a great significance everywhere in national economic development and daily life. Here, we demonstrate a flexible hybrid nanogenerator (NG) that is capable of simultaneously or individually harvesting ambient thermal and mechanical energies and used for a self-powered cathodic protection (CP) system without using an external power source. Because of its double peculiarities of both pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based NG was constructed to scavenge both thermal and mechanical energies. As a supplementary, a triboelectric NG was constructed below the pyro/piezoelectric NG to grab ambient mechanical energy. The output power of the fabricated hybrid NG can be directly used to protect the metal surface from the chemical corrosion. Our results not only verify the feasibility of self-powered CP-based NGs, but also expand potential self-powered applications.

  8. Splendid one-dimensional nanostructures of zinc oxide: a new nanomaterial family for nanotechnology.

    Science.gov (United States)

    Wang, Zhong Lin

    2008-10-28

    Zinc oxide is a unique material that exhibits exceptional semiconducting, piezoelectric, and pyroelectric properties. Nanostructures of ZnO are equally as important as carbon nanotubes and silicon nanowires for nanotechnology and have great potential applications in nanoelectronics, optoelectronics, sensors, field emission, light-emitting diodes, photocatalysis, nanogenerators, and nanopiezotronics. Fundamental understanding about the growth of ZnO nanowires is of critical importance for controlling their size, composition, structure, and corresponding physical and chemical properties. The papers by She et al. and Ito et al. in this issue describe the controlled growth and field-emission properties of individual nanostructures, respectively. These studies provide new approaches and insight into the controlled growth and electrical properties of ZnO nanostructures.

  9. Diffusion theory of slow responses

    Institute of Scientific and Technical Information of China (English)

    李景德; 陈敏; 郑凤; 周镇宏

    1997-01-01

    When an action is applied to a macroscopic substance, there is a particular sort of slow response he sides the well-known fast response. Using diffusion theory, the characteristics of slow response in dielectric, elastic, piezoelectric, and pyroelectric relaxation may he explained A time domain spectroscopy method suitable for slow and fast responses in linear and nonlinear effects is given. Every relaxation mechanism contributes a peak in differential spectroscopy, and its position, height, and line shape show the dynamical properties of the mechanism The method of frequency domain spectroscopy is suitable only for linear fast response. Time domain spectroscopy is another nonequiv-alent powerful method. The theory is confirmed by a lot of experimental data

  10. Preparation of room temperature terahertz detector with lithium tantalate crystal and thin film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun, E-mail: ueoewj@gmail.com; Gou, Jun; Li, Weizhi [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2014-02-15

    Research on room temperature terahertz (THz) detector is essential for promoting the application of THz science and technology. Both lithium tantalate crystal (LiTaO{sub 3}) and lithium tantalate thin film were used to fabricate the THz detector in this paper. Polishing process were used to reduce the thickness of LiTaO{sub 3} crystal slice by chemical mechanical polishing techniques and an improved sol-gel process was used to obtain high concentration LiTaO{sub 3} precursor solution to fabricate LiTaO{sub 3} thin film. Three dimension models of two THz detectors were set up and the temperature increasing map of two devices were simulated using finite element method. The lowest noise equivalent power value for terahertz detector using pyroelectric material reaches 6.8 × 10{sup −9} W at 30 Hz operating frequency, which is suitable for THz imaging application.

  11. Preparation of room temperature terahertz detector with lithium tantalate crystal and thin film

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2014-02-01

    Full Text Available Research on room temperature terahertz (THz detector is essential for promoting the application of THz science and technology. Both lithium tantalate crystal (LiTaO3 and lithium tantalate thin film were used to fabricate the THz detector in this paper. Polishing process were used to reduce the thickness of LiTaO3 crystal slice by chemical mechanical polishing techniques and an improved sol-gel process was used to obtain high concentration LiTaO3 precursor solution to fabricate LiTaO3 thin film. Three dimension models of two THz detectors were set up and the temperature increasing map of two devices were simulated using finite element method. The lowest noise equivalent power value for terahertz detector using pyroelectric material reaches 6.8 × 10−9 W at 30 Hz operating frequency, which is suitable for THz imaging application.

  12. 光学塑料、光学陶瓷

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    TQ74.758.23 2001010632兼有热释电性及内光电效应的压电陶瓷的探索=Aninvestigation into pyroelectricity and internalphotoeffect of piezoelectric ceramics[刊,中]/李全禄(陕西师范大学陕西物理研究所.陕西,西安(710062))∥物理.-2000,29(5).-293-296讨论了热释电效应与热电效应、外光电效应与内光电效应的基本概念,对兼有热释电性及内光电效应的压电陶瓷进行了研究。图3参4(李瑞琴)

  13. Ten years' venturing in ZnO nanostructures: from discovery to scientific understanding and to technology applications

    Institute of Scientific and Technical Information of China (English)

    Zhong Lin WANG

    2009-01-01

    Zinc oxide is a unique material that exhibits semiconducting,piezoelectric and pyroelectric multiple properties.Nanostructures of ZnO are equally important as carbon nanotubes and silicon nanowires (NWs) for nanotechnology,and have great potential applications in nano-electronics,optoelectronics,sensors,field emission,light emitting diodes,photocatalysis,nanogenerators,and nanopiezotronics.Ever since the discovery of nanobelts (NBs) in 2001 by my group,a world wide research in ZnO has been kicked off.This review introduces my group's experience in venturing the discovery,understanding and applications of ZnO NWs and NBs.The aim is to introduce the progress made in my research in the last 10 years in accompany to the huge social advances and economic development taking place in China in the last 10 years.

  14. 320×240单片式热释电红外焦平面读出电路设计

    Institute of Scientific and Technical Information of China (English)

    胡滨; 李平; 白丕绩; 杨邦朝

    2005-01-01

    本文介绍了一种采用源随前置输入(SFD)的320x240单片式热释电IRFPACMOS读出电路设计,该电路基于LAMPAR(Low-noise Arrays of MOSFETs for Pyroelectric Array Readout)设计,具有单片集成,结构紧凑,噪声低,功耗低,较高的多路传输效率,易于扩充阵列规模的优点。本文分析了电路结构,给出了仿真结果,完成了版图设计。

  15. Orbital Hybridization of the Ferroelectric Rb2Cd2 (SO4)3: Origin of Domain Walls

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi-Feng; YI Lin

    2005-01-01

    @@ We perform first-principle calculations for the study of the orthorhombic Rb2Cd2 (SO4)3 structure. Electronic energy bands, total and partial densities of states are reported and analysed. It is found that oxygen atomic 2p electrons strongly hybridize with Rb/or Cd 4d and S 2p states, resulting in two-type ionic groups with weak couplings. It is shown that macroscopic domain walls originate from such weak-coupling ionic groups, arising at the cell boundaries. The asymmetric cation bonds (Rb-O and Cd-O) and the subsequent rotations of the SO4tetrahedra can lead to the driving force of the ferroelectric behaviour. The predicted pyroelectric current effects are observed experimentally in the ferroelectric phase.

  16. Quantum state specific reactant preparation in a molecular beam by rapid adiabatic passage

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, Helen, E-mail: helen.chadwick@epfl.ch; Hundt, P. Morten; Reijzen, Maarten E. van; Yoder, Bruce L.; Beck, Rainer D. [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)

    2014-01-21

    Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved in a molecular beam using tunable infrared (IR) radiation from a single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing of the IR radiation, molecules in the molecular beam crossing the fixed frequency IR field experience a Doppler tuning that can be adjusted to achieve complete population inversion of a two-level system by rapid adiabatic passage (RAP). A room temperature pyroelectric detector is used to monitor the excited fraction in the molecular beam and the population inversion is detected and quantified using IR bleaching by a second IR-OPO. The second OPO is also used for complete population transfer to an overtone or combination vibration via double resonance excitation using two spatially separated RAP processes.

  17. 洛河市区段河道监控系统的优化与设计%Optimization and Design of a Riverway Monitoring System in the Cantonal Area of Luohe River

    Institute of Scientific and Technical Information of China (English)

    时永鹏

    2012-01-01

    针对洛河市区段现有的河道监控系统提出了一种优化方法,提出了将热释电红外探测器应用到河道监控中,结合语音报警系统,构建了一种新的河道监控系统设计方案,该方案电路结构简单,可靠性强。%An optimization method for the existed riverway monitoring system in the cantonal area of Luohe river is presented. It is proposed that the pyroelectric infrared detector be applied to the riverway monitoring. Combined with the voice alarm system, a new riverway monitoring system with simple circuit structure and strong reliability is designed.

  18. A Novel Multiple Component Gas Infrared Ray Sensor

    Institute of Scientific and Technical Information of China (English)

    张永怀; 周金林; 林继鹏; 刘君华

    2003-01-01

    In this paper, The principle, structure and practical application of a novel multiple component gas infrared ray sensor are discussed. The optical gas sensor, which has infrared radiation impulses input and electric single output, is composed of narrow band light filter, optical taper and pyroelectric detector array. An infrared gas analyzer with multiple component gas tested synchronously consists of the sensor, single middle infrared source, single gas cell and computer data acquire system. As compared with sensor in other infrared gas analyzer, it has many merits such as novel structure, strong anti-oscillate performance and low cost. Different gas in different measurement area can be analyzed quantitatively by replacing optical filter module easily.

  19. End loss analyzer system for measurements of plasma flux at the C-2U divertor electrode

    Science.gov (United States)

    Griswold, M. E.; Korepanov, S.; Thompson, M. C.

    2016-11-01

    An end loss analyzer system consisting of electrostatic, gridded retarding-potential analyzers and pyroelectric crystal bolometers was developed to characterize the plasma loss along open field lines to the divertors of C-2U. The system measures the current and energy distribution of escaping ions as well as the total power flux to enable calculation of the energy lost per escaping electron/ion pair. Special care was taken in the construction of the analyzer elements so that they can be directly mounted to the divertor electrode. An attenuation plate at the entrance to the gridded retarding-potential analyzer reduces plasma density by a factor of 60 to prevent space charge limitations inside the device, without sacrificing its angular acceptance of ions. In addition, all of the electronics for the measurement are isolated from ground so that they can float to the bias potential of the electrode, 2 kV below ground.

  20. An ultraviolet/infrared matrix-assisted laser desorption ionization sample stage integrating scanning knife-edge and slit devices for laser beam analysis.

    Science.gov (United States)

    Soltwisch, Jens; Dreisewerd, Klaus

    2011-05-15

    A sample stage is described that allows the on-line analysis of laser intensity profiles and spot sizes directly in the ion source of a matrix-assisted laser desorption ionization (MALDI) mass spectrometer. The detector uses either a scanning knife-edge or a narrow slit in combination with diffusing disks for scattering of photons and a pyroelectric sensor for recording the light pulses. The setup was integrated into the sample holder of a oMALDI2(TM) ion source (AB Sciex) and allows parallel analysis of UV- and IR-laser beams at typical UV-/IR-MALDI laser fluences. The concept could be especially useful for a precise control of the laser spot size in MALDI imaging applications. Copyright © 2011 John Wiley & Sons, Ltd.

  1. Gravity and the cells of gravity receptors in mammals

    Science.gov (United States)

    Ross, M. D.

    1983-01-01

    A model of the mammalian gravity receptor system is presented, with attention given to the effects of weightlessness. Two receptors are on each side of the head, with end organs in the saccule and utricle of the vestibular membranous labyrinth of the inner ear, embedded in the temporal bone. Each end organ has a macula, containing hair cells and supporting cells, and an otoconial complex, an otoconial membrane and mineral masses called otoconia. X ray powder diffraction examinations have revealed that the otoconia can behave like crystals, i.e., with piezoelectric properties, due to the mineral deposits. Bending of the hair cells because of acceleration can put pressure on the otoconial mineral, producing an electrical signal in the absence of a gravitational field. The possibility that pyroelectricity, as well as piezoelectricity, is present in the otoconial complexes, is discussed.

  2. Design and implementation of green intelligent lights based on the ZigBee

    Science.gov (United States)

    Gan, Yong; Jia, Chunli; Zou, Dongyao; Yang, Jiajia; Guo, Qianqian

    2013-03-01

    By analysis of the low degree of intelligence of the traditional lighting control methods, the paper uses the singlechip microcomputer for the control core, and uses a pyroelectric infrared technology to detect the existence of the human body, light sensors to sense the light intensity; the interface uses infrared sensor module, photosensitive sensor module, relay module to transmit the signal, which based on ZigBee wireless network. The main function of the design is to realize that the lighting can intelligently adjust the brightness according to the indoor light intensity when people in door, and it can turn off the light when people left. The circuit and program design of this system is flexible, and the system achieves the effect of intelligent energy saving control.

  3. Photostrictive actuators for photonic control of shallow spherical shells

    Science.gov (United States)

    Shih, Hui-Ru; Tzou, Horn-Sen

    2007-10-01

    Photostrictive materials, exhibiting light-induced strain, are of interest for the future generation of wireless remote control photo-actuators. Photostrictive actuators are expected to be used as the driving component in optically controlled flexible structures. In this paper, the photonic control of flexible spherical shells using discrete photostrictive actuators is investigated. This paper presents a coupled opto-piezothermoelastic shell theory that incorporates photovoltaic, pyroelectric and piezoelectric effects, and has the capability to predict the response of a spherical shell driven by the photostrictive actuators. In this study, the effects of actuator location as well as membrane and bending components on the control action have been analyzed. The results obtained indicate that the control forces are mode and location dependent. Analysis also shows that the membrane control action is much more significant than the bending control action.

  4. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    Science.gov (United States)

    Ding, Meisong; Weits, H. H.; Oepts, D.

    1997-02-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 × 10 mm 2 pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 μm to 10 mm) without strong variation in efficiency. An evacuated 15 m long overmoded waveguide is used to transport the transition radiation to the experimental area. The intensity of the transition radiation was measured and compared with our calculation. The phase-retrieval technique applied to the measured spectrum provides details of the electron bunch. The bunch shapes have been studied at different buncher phase settings. Measurements of coherent transition radiation and coherent undulator radiation are compared.

  5. Electrical characterization of a buckling thermal energy harvester

    Science.gov (United States)

    Trioux, E.; Rufer, L.; Monfray, S.; Skotnicki, T.; Muralt, P.; Basrour, S.

    2015-12-01

    This paper presents the electrical characterizations of a novel concept for thermal energy harvesting at micro scale. The devices presented here are based on a two-step transduction combining thermo-mechanical and piezoelectric conversion. The piezoelectric layer is directly integrated into a buckling bilayer plate made of aluminium and aluminium nitride. For the first time, we have characterized the structures electrically and we have investigated their output power during the buckling. Firstly, we have used an insulating tip to make the plate buckle in order to have an estimation of the output power due to piezoelectric contribution only, and to eliminate any pyroelectric contribution that might be present during the thermal actuation. Then, we heated up the structure and we collected the output signal with an instrumentation amplifier in order to measure the voltage generated during the buckling. The output power during the mechanical and the thermal buckling is compared in the paper.

  6. Coupled improvement between thermoelectric and piezoelectric materials

    Science.gov (United States)

    Montgomery, David; Hewitt, Corey; Dun, Chaochao; Carroll, David

    A novel coupling effect in a thermoelectric and piezoelectric meta-structure is discussed. Thermo-piezoelectric generators (TPEGs) exhibit a synergistic effect that amplifies output voltage, and has been observed to increase piezoelectric voltages over 500% of initial values a time dependent thermoelectric/pyroelectric effect. The resulting improvement in voltage has been observed in carbon nanotubes as well as inorganics such as two-dimensional Bismuth Selenide platelets and Telluride nanorods thin-film thermoelectrics. TPEGs are built by integrating insulating layers of polyvinylidene fluoride (PVDF) piezoelectric films between flexible thin film p-type and n-type thermoelectrics. The physical phenomena arising in the interaction between thermoelectric and piezoelectrics is discussed and a model is presented to quantify the expected coupling voltage as a function of stress, thermal gradient, and different thermoelectric materials. TPEG are ideal to capture waste heat and vibrational energy while creating larger voltages and minimizing space when compared with similar thermoelectric or piezoelectric generators.

  7. Direct conversion technology

    Energy Technology Data Exchange (ETDEWEB)

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  8. Direct conversion technology. Annual summary report CY 1991, January 1, 1991--December 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  9. Resting heart rate estimation using PIR sensors

    Science.gov (United States)

    Kapu, Hemanth; Saraswat, Kavisha; Ozturk, Yusuf; Cetin, A. Enis

    2017-09-01

    In this paper, we describe a non-invasive and non-contact system of estimating resting heart rate (RHR) using a pyroelectric infrared (PIR) sensor. This infrared system monitors and records the chest motion of a subject using the analog output signal of the PIR sensor. The analog output signal represents the composite motion due to inhale-exhale process with magnitude much larger than the minute vibrations of heartbeat. Since the acceleration of the heart activity is much faster than breathing the second derivative of the PIR sensor signal monitoring the chest of the subject is used to estimate the resting heart rate. Experimental results indicate that this ambient sensor can measure resting heart rate with a chi-square significance level of α = 0.05 compared to an industry standard PPG sensor. This new system provides a low cost and an effective way to estimate the resting heart rate, which is an important biological marker.

  10. Thermomechanic micro-generators for energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Huesgen, Till

    2010-07-01

    the engine chamber's kinetic energy. Due to the low thermomechanic conversion efficiency and the insufficient electromagnetic coupling the average electric output power remains in the nW range. The second approach is based on a direct thermal to electric conversion. Here, an integrated pyroelectric material generates an electric output power upon temporal temperature changes induced by the engine chamber motion. A simple demonstrator, with a pyroelectric PZT ceramic plate attached to the heat sink, provides an electric output power of 3.6 {mu}W at 80 K temperature difference. This generator could be improved by integrating single crystalline PMN-PT ceramics in the engine chamber. Such a hypothetic engine would provide 6 mW, due to the enhanced pyroelectric properties of the material and the higher temperature amplitudes in the engine chamber. The respective efficiency is 0.4%. In an application scenario with passive cooling of the heat sink, this thermomechanic heat engine with optimized pyroelectric generator would provide twice the output power of an commercially available thermoelectric micro generator. (orig.)

  11. Thermoacoustic and thermoreflectance imaging of biased integrated circuits: Voltage and temperature maps

    Science.gov (United States)

    Hernández-Rosales, E.; Cedeño, E.; Hernandez-Wong, J.; Rojas-Trigos, J. B.; Marin, E.; Gandra, F. C. G.; Mansanares, A. M.

    2016-07-01

    In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam is focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit.

  12. Correct Implementation of Polarization Constants in Wurtzite Materials and Impact on III-Nitrides

    Science.gov (United States)

    Dreyer, Cyrus E.; Janotti, Anderson; Van de Walle, Chris G.; Vanderbilt, David

    2016-04-01

    Accurate values for polarization discontinuities between pyroelectric materials are critical for understanding and designing the electronic properties of heterostructures. For wurtzite materials, the zincblende structure has been used in the literature as a reference to determine the effective spontaneous polarization constants. We show that, because the zincblende structure has a nonzero formal polarization, this method results in a spurious contribution to the spontaneous polarization differences between materials. In addition, we address the correct choice of "improper" versus "proper" piezoelectric constants. For the technologically important III-nitride materials GaN, AlN, and InN, we determine polarization discontinuities using a consistent reference based on the layered hexagonal structure and the correct choice of piezoelectric constants, and discuss the results in light of available experimental data.

  13. Technology for low-cost PIR security sensors

    Science.gov (United States)

    Liddiard, Kevin C.

    2008-03-01

    Current passive infrared (PIR) security sensors employing pyroelectric detectors are simple, cheap and reliable, but have several deficiencies. These sensors, developed two decades ago, are essentially short-range moving-target hotspot detectors. They cannot detect slow temperature changes, and thus are unable to respond to radiation stimuli indicating potential danger such as overheating electrical appliances and developing fires. They have a poor optical resolution and limited ability to recognize detected targets. Modern uncooled thermal infrared technology has vastly superior performance but as yet is too costly to challenge the PIR security sensor market. In this paper microbolometer technology will be discussed which can provide enhanced performance at acceptable cost. In addition to security sensing the technology has numerous applications in the military, industrial and domestic markets where target range is short and low cost is paramount.

  14. Power balance and characterization of impurities in the Maryland Spheromak

    Energy Technology Data Exchange (ETDEWEB)

    Cote, C.

    1993-12-31

    The Maryland Spheromak is a medium size magnetically confined plasma of toroidal shape. Low T{sub e} and higher n{sub e} than expected contribute to produce a radiation dominated short-lived spheromak configuration. A pyroelectric radiation detector and a VUV spectrometer have been used for space and time-resolved measurements of radiated power and impurity line emission. Results from the bolometry and VUV spectroscopy diagnostics have been combined to give the absolute concentrations of the major impurity species together with the electron temperature. The large amount of oxygen and nitrogen ions in the plasma very early in the discharge is seen to be directly responsible for the abnormally high electron density. The dominant power loss mechanisms are found to be radiation (from impurity line emission) and electron convection to the end walls during the formation phase of the spheromak configuration, and radiation only during the decay phase.

  15. Dispensing nano-pico droplets and liquid patterning by pyroelectrodynamic shooting.

    Science.gov (United States)

    Ferraro, P; Coppola, S; Grilli, S; Paturzo, M; Vespini, V

    2010-06-01

    Manipulating and dispensing liquids on the micrometre- and nanoscale is important in biotechnology and combinatorial chemistry, and also for patterning inorganic, organic and biological inks. Several methods for dispensing liquids exist, but many require complicated electrodes and high-voltage circuits. Here, we show a simple way to draw attolitre liquid droplets from one or multiple sessile drops or liquid film reservoirs using a pyroelectrohydrodynamic dispenser. Local pyroelectric forces, which are activated by scanning a hot tip or an infrared laser beam over a lithium niobate substrate, draw liquid droplets from the reservoir below the substrate, and deposit them on the underside of the lithium niobate substrate. The shooting direction is altered by moving the hot tip or laser to form various patterns at different angles and locations. Our system does not require electrodes, nozzles or circuits, and is expected to have many applications in biochemical assays and various transport and mixing processes.

  16. PyzoFlex: a printed piezoelectric pressure sensing foil for human machine interfaces

    Science.gov (United States)

    Zirkl, M.; Scheipl, G.; Stadlober, B.; Rendl, C.; Greindl, P.; Haller, M.; Hartmann, P.

    2013-09-01

    Ferroelectric material supports both pyro- and piezoelectric effects that can be used for sensing pressures on large, bended surfaces. We present PyzoFlex, a pressure-sensing input device that is based on a ferroelectric material (PVDF:TrFE). It is constructed by a sandwich structure of four layers that can easily be printed on any substrate. The PyzoFlex foil is sensitive to pressure- and temperature changes, bendable, energy-efficient, and it can easily be produced by a screen-printing routine. Even a hovering input-mode is feasible due to its pyroelectric effect. In this paper, we introduce this novel, fully printed input technology and discuss its benefits and limitations.

  17. Flexible hybrid energy cell for simultaneously harvesting thermal, mechanical, and solar energies.

    Science.gov (United States)

    Yang, Ya; Zhang, Hulin; Zhu, Guang; Lee, Sangmin; Lin, Zong-Hong; Wang, Zhong Lin

    2013-01-22

    We report the first flexible hybrid energy cell that is capable of simultaneously or individually harvesting thermal, mechanical, and solar energies to power some electronic devices. For having both the pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based nanogenerator (NG) was used to harvest thermal and mechanical energies. Using aligned ZnO nanowire arrays grown on the flexible polyester (PET) substrate, a ZnO-poly(3-hexylthiophene) (P3HT) heterojunction solar cell was designed for harvesting solar energy. By integrating the NGs and the solar cells, a hybrid energy cell was fabricated to simultaneously harvest three different types of energies. With the use of a Li-ion battery as the energy storage, the harvested energy can drive four red light-emitting diodes (LEDs).

  18. A Bluetooth-Based Device Management Platform for Smart Sensor Environment

    Science.gov (United States)

    Lim, Ivan Boon-Kiat; Yow, Kin Choong

    In this paper, we propose the use of Bluetooth as the device management platform for the various embedded sensors and actuators in an ambient intelligent environment. We demonstrate the ease of adding Bluetooth capability to common sensor circuits (e.g. motion sensor circuit based on a pyroelectric infrared (PIR) sensor). A central logic application is proposed which controls the operation of controller devices, based on values returned by sensors via Bluetooth. The operation of devices depends on rules that are learnt from user behavior using an Elman recurrent neural network. Overall, Bluetooth has shown its potential in being used as a device management platform in an ambient intelligent environment, which allows sensors and controllers to be deployed even in locations where power sources are not readily available, by using battery power.

  19. The longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX

    Directory of Open Access Journals (Sweden)

    Florent Pessina

    2017-02-01

    Full Text Available Research efforts for realizing safer and higher performance energetic materials are continuing unabated all over the globe. While the thermites – pyrotechnic compositions of an oxide and a metal – have been finely tailored thanks to progress in other sectors, organic high explosives are still stagnating. The most symptomatic example is the longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX. Recent advances in crystallization processes and milling technology mark the beginning of a new area which will hopefully lead the pyroelectric industry to finally embrace nanotechnology. This work reviews the previous and current techniques used to crystallize RDX at a submicrometer scale or smaller. Several key points are highlighted then discussed, such as the smallest particle size and its morphology, and the scale-up capacity and the versatility of the process.

  20. The longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

    Science.gov (United States)

    Spitzer, Denis

    2017-01-01

    Research efforts for realizing safer and higher performance energetic materials are continuing unabated all over the globe. While the thermites – pyrotechnic compositions of an oxide and a metal – have been finely tailored thanks to progress in other sectors, organic high explosives are still stagnating. The most symptomatic example is the longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). Recent advances in crystallization processes and milling technology mark the beginning of a new area which will hopefully lead the pyroelectric industry to finally embrace nanotechnology. This work reviews the previous and current techniques used to crystallize RDX at a submicrometer scale or smaller. Several key points are highlighted then discussed, such as the smallest particle size and its morphology, and the scale-up capacity and the versatility of the process. PMID:28326236

  1. THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing

    Directory of Open Access Journals (Sweden)

    Paolo De Natale

    2013-03-01

    Full Text Available We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range.

  2. Beam profile analyzer for CO2 lasers

    Directory of Open Access Journals (Sweden)

    Rubén López

    2015-12-01

    Full Text Available The development of an optoelectronic system to analyze the beam intensity profile of CO2 lasers is presented herein. The device collects the beam profile with a LiTaO3 pyroelectric detector and uses a sampling technique based on the acquisition of horizontal sections at different levels. The digital signal processing includes subroutines that drop down two dimensional and three dimensional beam profile displays to determine the laser beam parameters of optical power, peak pixel location, centroid location and width of the laser beam, with algorithms based on the ISO 11146 standard. With the systematic calibration of the analyzer was obtained in the measurement of power an error under 5%, for a 20–200 W range and an error under 1.6% for spatial measurements of a TEM00 laser. By design, the analyzer can be used during the laser process.

  3. Nanogenerators: An emerging technology towards nanoenergy

    Science.gov (United States)

    Zi, Yunlong; Wang, Zhong Lin

    2017-07-01

    Nanoenergy is a field of studying the small-scale, highly efficient energy harvesting, storage, and applications by using nanomaterials and nanodevices. Nanogenerators are developed to harvest these small-scale energies in the ambient environment, which were first invented in our group in 2006. In the past decade, we have developed nanogenerators based on piezoelectric and triboelectric effects for mechanical energy harvesting, and those based on pyroelectric and thermoelectric effects for thermal energy harvesting. We also explored other novel nanogenerators such as that based on ion streams. The proposed nanogenerators will facilitate the development of self-powered systems, which enables efficient energy utilization and sustainable operations of mobile devices for "smart" wearable technology, health monitoring, biomedical sensing, environmental protection, and even security.

  4. Thermoacoustic and thermoreflectance imaging of biased integrated circuits: Voltage and temperature maps

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Rosales, E.; Cedeño, E. [Gleb Wataghin Physics Institute, University of Campinas - Unicamp, 13083-859 Campinas, SP (Brazil); Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); Hernandez-Wong, J. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); CONACYT, México, DF, México (Mexico); Rojas-Trigos, J. B.; Marin, E. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); Gandra, F. C. G.; Mansanares, A. M., E-mail: manoel@ifi.unicamp.br [Gleb Wataghin Physics Institute, University of Campinas - Unicamp, 13083-859 Campinas, SP (Brazil)

    2016-07-25

    In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam is focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit.

  5. Minimizing Fabrication Time Of Calcium Modified Pbti03 Nanoceramics By HEBM Technique

    Directory of Open Access Journals (Sweden)

    Sona Kumari

    2015-08-01

    Full Text Available Lead titanate is one of the family member of ABO3 structure perovskite having piezoelectric as well as pyroelectric properties in nature. It shows highl ferroelectric property as ceramic materials. Ca modified lead titanate termed as P1-xCXT synthesized by HEBM at 270 C of room temperature. The stoichiometric ratio was taken as Pb1-xCaxTi03 where Ca0 was taken in various ratio . Structural and electrical properties were studied by taking measurement with standard instruments LCR metre. Analysis of XRD gives that doping of calcium produce a decrease in tetragonal size and hence the volume . As a result on A-site substitution observed. Graph of electrical parameters shows that impedence decreases exponentially with frequency.

  6. Generation of efficient THz radiation by optical rectification in DAST crystal using tunable femtosecond laser pulses

    Science.gov (United States)

    Venkatesh, Mottamchetty; Thirupugalmani, K.; Rao, K. S.; Brahadeeswaran, S.; Chaudhary, A. K.

    2017-03-01

    We report the efficient THz generation by optical rectification from an indigenously grown organic DAST crystal using the 140 fs oscillator laser pulses tunable in between 780 and 850 nm. The generated THz pulse profile and powers have been measured using the photoconductive (PC) antennas and pyroelectric detector, respectively. The highest THz peak amplitude and power is obtained at 825 nm central wavelength. We have theoretically explained the enhancement of THz radiation based on the matching of average optical group refractive index and average THz refractive index of the DAST crystal at 825 nm. In addition, the dependence of THz peak amplitude and THz power on laser power have been carried out. The measured quantum conversion efficiency (QCE) of 0.5 and 1.5 THz bands are of the order 3.7 × 10-3, 1.4 × 10-3, respectively. Finally, an attempt has been made to study the effect of polarizations on generated THz signal.

  7. Longitudinal bunch profile diagnostics in the 50fs range using coherent Smith-Purcell radiation

    CERN Document Server

    Delerue, Nicolas; Maclean, Ewen; Reichold, Armin

    2009-01-01

    We have considered the possibility of using coherent Smith-Purcell radiation for the single-shot determination of the longitudinal profile of 50 fs (FWHM) long electron bunches. This length is typical for the bunches currently produced by Laser Wakefield Acceleration and is at the limit of what is achievable by alternative techniques, such as Electro-Optic sampling. It is concluded that there are no obstacles, either theoretical or experimental, in the implementation of this technique. A set of three gratings, with periods of 15, 85 and 500 micrometres, will produce detectable energy in the wavelength region 10-1000 micrometres, which should be adequate for the reconstruction of the bunch shape by the Kramers-Kronig technique. For bunch charges of 109 electrons, or more, the radiated energy can be detected by room temperature pyroelectric detectors. The limits of possible extension of the technique to even shorter lengths are also considered.

  8. An improved sensor for electrochemical microcalorimetry, based on lithiumtantalate

    Science.gov (United States)

    Frittmann, Stefan; Halka, Vadym; Jaramillo, Carlos; Schuster, Rolf

    2015-06-01

    We have developed a pyroelectric sensor for electrochemical microcalorimetry, based on LiTaO3, which provides unprecedented sensitivity for the detection of electrochemically induced heat effects. Deterioration of the heat signal by electrostriction effects on the electrode surface is suppressed by a multilayered construction, where an intermediate sapphire sheet dampens mechanical deformations. Thus, well textured thin metal films become viable candidates as electrodes. We demonstrate the sensor performance for Cu underpotential deposition on (111)-textured Au films on sapphire. The sensor signal compares well with a purely thermal signal induced by heating with laser pulses. The high sensitivity of the sensor is demonstrated by measuring heat effects upon double layer charging in perchloric acid, i.e., in the absence of electrochemical charge- or ion-transfer reactions.

  9. Clouds of short-circuited thermionic nanobatteries and promising prospects for development of nanobattery-based aerosol fusion reactors. The preliminary report

    CERN Document Server

    Meshcheryakov, Oleg

    2012-01-01

    The physical mechanisms of periodic separation and relaxation of electric charges within aerosol particles possessing the properties the short-circuited batteries can be extremely diverse. With use of appropriate materials and dispersing methods, the electrochemical, thermoelectric, thermionic, pyroelectric, photoelectric, photo electronic emission, or even radionuclide-based emission micro and nano-batteries can be synthesized and be dispersed in the air as clouds self-assembed of the short-circuited aerosol batteries due to the inter-particle electromagnetic dipole-dipole attraction. Intense thermionic emission from ionized hot spots migrating on the relatively cold surface of charged explosive particles, can convert these particles into short-circuited thermionic batteries, turning an aerosol cloud consisting of such unipolar charged, gradually decomposing explosive particles into ball lightning. The slow exothermic decomposition of the highly sensitive explosive aerosol particles, catalyzed by excess ions...

  10. Ionic thermoelectric gating organic transistors

    Science.gov (United States)

    Zhao, Dan; Fabiano, Simone; Berggren, Magnus; Crispin, Xavier

    2017-01-01

    Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is limited by their low Seebeck coefficient (∼100 μV K−1). Here we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (∼10,000 μV K−1) to introduce the concept of ionic thermoelectric gating a low-voltage organic transistor. The temperature sensing amplification of such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles. This suggests that ionic thermoelectric sensors offer a way to go beyond the limitations of traditional thermopiles and pyroelectric detectors. These findings pave the way for new infrared-gated electronic circuits with potential applications in photonics, thermography and electronic-skins. PMID:28139738

  11. Electropyroelectric technique for measurement of the thermal effusivity of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, R; Moreno, I; Araujo, C [Facultad de Fisica, Universidad Autonoma de Zacatecas, Calz. Solidaridad Esquina Paseo de la Bufa s/n, C. P. 98060, Zacatecas, Zac. (Mexico); Marin, E, E-mail: emarin63@yahoo.e, E-mail: emarinm@ipn.m [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada, Instituto Politecnico Nacional, LegarIa 694, Colonia Irrigacion, C. P. 11500, Mexico D. F. (Mexico)

    2010-06-09

    The photopyroelectric method has been recognized as a reliable and useful tool for the measurement of the thermal properties of condensed matter samples. Usually the photothermal signal is generated using intensity modulated light beams, whose amplitudes are difficult to maintain stable. In this paper we describe a variant of this technique that uses amplitude modulated electrical current as excitation source, via Joule heating of the metal contact on one side of the pyroelectric sensor. The possibilities of this method, called by us the electropyroelectric technique, for thermal effusivity measurements of liquid samples are shown using test samples of distilled water, ethanol and glycerine. The results obtained for this parameter agree well with the values reported in the literature. Our measurement uncertainties are about 3%, a fact that opens several possible applications.

  12. Ionic thermoelectric gating organic transistors

    Science.gov (United States)

    Zhao, Dan; Fabiano, Simone; Berggren, Magnus; Crispin, Xavier

    2017-01-01

    Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is limited by their low Seebeck coefficient (~100 μV K-1). Here we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (~10,000 μV K-1) to introduce the concept of ionic thermoelectric gating a low-voltage organic transistor. The temperature sensing amplification of such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles. This suggests that ionic thermoelectric sensors offer a way to go beyond the limitations of traditional thermopiles and pyroelectric detectors. These findings pave the way for new infrared-gated electronic circuits with potential applications in photonics, thermography and electronic-skins.

  13. Review of ferroelectric hydroxyapatite and its application to biomedicine

    Science.gov (United States)

    Lang, Sidney B.

    2016-08-01

    Hydroxyapatite (HA) is a major component of bone in humans and animals. Until about 10 years ago, it was considered to have a centrosymmetric crystal structure and could not contribute to the well-known piezoelectric effect in bone. This review describes the theoretical and experimental studies that showed that HA does have a non-centrosymmetric structure. Recent experiments have shown that HA exhibits piezoelectricity, pyroelectricity, and ferroelectricity. It has been made in the form of thick films and as space-charge electrets. It has an important biomedical application as an implant for bone cell attachment and growth. This paper is contributed in honor of the 80th birthday of my long-time friend and colleague, Bozena Hilczer.

  14. A Cryogenic Radiometry Based Spectral Responsivity Scale at the National Metrology Centre

    Science.gov (United States)

    Xu, Gan; Huang, Xuebo

    This paper describes the spectral responsivity scale established at the National Metrology Centre (NMC) based on cryogenic radiometry. A primary standard - a mechanically pumped cryogenic radiometer together with a set of intensity-stabilised lasers provides traceability for optical power measurement with an uncertainty in the order of 10-4 at 14 discrete wavelengths in the spectral range from 350 nm to 800 nm. A silicon trap detector, with its absolute responsivity calibrated against the cryogenic radiometer is used as a transfer standard for the calibration of other detectors using a specially built spectral comparator. The relative spectral responsivity of a detector at other wavelengths can be determined through the use of a cavity pyroelectric detector and the extrapolation technique. With this scale, NMC is capable to calibrate the spectral responsivity of different type of photo detectors from 250 nm to 1640 nm with an uncertainty range from 3.7% to 0.3%.

  15. Proceedings of the 9th IEEE International Symposium on Applications of Ferroelectrics

    Science.gov (United States)

    Pandey, R. K.; Liu, Michael; Safari, Ahmad

    1994-08-01

    The Ninth International Symposium on the Applications of Ferroelectrics (ISAF '94) was held at the Penn State Scanticon Conference Center, the Pennsylvania State University, University Park, Pennsylvania, during August 7-10, 1994. The Symposium program contained 377 scientific papers on various aspects of ferroelectrics and their applications. There were 116 oral (42 invited) and 261 poster papers presented in three parallel oral sessions and in the poster sessions each day over the three days of the meeting. The meeting covered major advances in the areas of piezoelectrics, dielectrics, thin film ferroelectrics, actuators, smart materials, pyroelectrics, nonlinear optical ferroelectrics, photorefractive materials, and their applications. The conference was attended by international scientists representing 21 countries. The geographical distribution of the papers, international and national, is represented in the accompanying table and graphs.

  16. Pulsed ultra-violet inactivation spectrum of Escherichia coli.

    Science.gov (United States)

    Wang, T; Macgregor, S J; Anderson, J G; Woolsey, G A

    2005-08-01

    Inactivation of Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30 micros). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of E. coli to inactivation by the pulsed UV light. Using 8 nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270 nm and no inactivation is observed above 300 nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for E. coli population reduction of 0.43 log per mJ/cm(2) is measured at 270 nm. The results are compared with the published data available for continuous UV light sources.

  17. Electrodynamics of a Cosmic Dark Fluid

    CERN Document Server

    Balakin, Alexander B

    2016-01-01

    Cosmic Dark Fluid is considered as a non-stationary medium, in which electromagnetic waves propagate, and magneto-electric field structures emerge and evolve. A medium - type representation of the Dark Fluid allows us to involve into analysis the concepts and mathematical formalism elaborated in the framework of classical covariant electrodynamics of continua, and to distinguish dark analogs of well-known medium-effects, such as optical activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a Dark Matter (a pseudoscalar axionic constituent) and Dark Energy (a scalar element); respectively, we distinguish electrodynamic effects induced by these two constituents of the Dark Fluid. The review contains discussions of ten models, which describe electrodynamic effects induced by Dark Matter and/or Dark Energy. The models are accompanied by examples of exact solutions to the master equations, correspondingly extende...

  18. Science of materials. Progress report, July 1, 1977--June 30, 1978

    Energy Technology Data Exchange (ETDEWEB)

    1978-04-01

    Progress is reported in research which includes studies of the deformation, stress corrosion and fracture of alloys and geologic materials with emphasis on hydrogen embrittlement of metals; the mechanism of heat transfer across interfaces; catalytic properties of surfaces; and erosion of surfaces by fluid suspended particles. The structure of liquids, polymers and disordered solids is under investigation with emphasis on ionic conduction, phase transitions and radiation damage. Ferro- and pyroelectric materials with potential for solar energy applications are under development. The study of optical properties includes the mechanism of luminescence and new semiconductor materials for photovoltaic devices. The electronic properties of crystals are the subject of a continued effort to resolve current problems of magnetic behavior and photon-solid interactions. Specific quantum properties of matter are explored with emphasis on superconductivity, diffusion of hydrogen in metals and the properties of solid helium.

  19. PLZT Microfibers Technology Optimization

    Directory of Open Access Journals (Sweden)

    Kozielski L.

    2016-09-01

    Full Text Available Electrocaloric (EC structures for a new generation of cooling or heating elements utilize the temperature dependence of spontaneous polarization in some ferroelectric materials to convert waste heat into electricity and vice versa. A (Pb0.93La0.07 (Zr0.65Ti0.35O3 material, have the largest recorded pyroelectric coefficient. An effective predicted form for such applications is fiber, due to small heat capacitance and quick response time, even for nano second laser excitation. Consequently, the presented work provides a description of the optimization of structural, ferroelectric and piezoelectric properties of obtained fibers, finally concluding on necessity of sintering temperature reduction in 100°C in contrast to bulk form to effectively prevent its destruction.

  20. Electrodynamic phenomena induced by a dark fluid: Analogs of pyromagnetic, piezoelectric, and striction effects

    CERN Document Server

    Balakin, Alexander B

    2014-01-01

    We establish a new model of coupling between a cosmic dark fluid and electrodynamic systems, based on an analogy with effects of electric and magnetic striction, piezo-electricity and piezo-magnetism, pyro-electricity and pyro-magnetism, which appear in classical electrodynamics of continuous media. Extended master equations for electromagnetic and gravitational fields are derived using Lagrange formalism. A cosmological application of the model is considered, and it is shown that a striction-type interaction between the dark energy (the main constituent of the dark fluid) and electrodynamic system provides the universe history to include the so-called unlighted epochs, during which electromagnetic waves can not propagate and thus can not scan the universe interior.

  1. Smart material-based radiation sources

    Science.gov (United States)

    Kovaleski, Scott

    2014-10-01

    From sensors to power harvesters, the unique properties of smart materials have been exploited in numerous ways to enable new applications and reduce the size of many useful devices. Smart materials are defined as materials whose properties can be changed in a controlled and often reversible fashion by use of external stimuli, such as electric and magnetic fields, temperature, or humidity. Smart materials have been used to make acceleration sensors that are ubiquitous in mobile phones, to make highly accurate frequency standards, to make unprecedentedly small actuators and motors, to seal and reduce friction of rotating shafts, and to generate power by conversion of either kinetic or thermal energy to electrical energy. The number of useful devices enabled by smart materials is large and continues to grow. Smart materials can also be used to generate plasmas and accelerate particles at small scales. The materials discussed in this talk are from non-centrosymmetric crystalline classes including piezoelectric, pyroelectric, and ferroelectric materials, which produce large electric fields in response to external stimuli such as applied electric fields or thermal energy. First, the use of ferroelectric, pyroelectric and piezoelectric materials for plasma generation and particle acceleration will be reviewed. The talk will then focus on the use of piezoelectric materials at the University of Missouri to construct plasma sources and electrostatic accelerators for applications including space propulsion, x-ray imaging, and neutron production. The basic concepts of piezoelectric transformers, which are analogous to conventional magnetic transformers, will be discussed, along with results from experiments over the last decade to produce micro-thrusters for space propulsion and particle accelerators for x-ray and neutron production. Support from ONR, AFOSR, and LANL.

  2. Monitoring millimeter wave stray radiation during ECRH operation at ASDEX Upgrade

    Directory of Open Access Journals (Sweden)

    Wagner D.

    2012-09-01

    Full Text Available Due to imperfection of the single path absorption, ECRH at ASDEX Upgrade (AUG is always accompanied by stray radiation in the vacuum vessel. New ECRH scenarios with O2 and X3 heating schemes extend the operational space, but they have also the potential to increase the level of stray radiation. There are hazards for invessel components. Damage on electric cables has already been encountered. It is therefore necessary to monitor and control the ECRH with respect to the stray radiation level. At AUG a system of Sniffer antennas equipped with microwave detection diodes is installed. The system is part of the ECRH interlock circuit. We notice, however, that during plasma operation the variations of the Sniffer antenna signal are very large. In laboratory measurements we see variations of up to 20 dB in the directional sensitivity and we conclude that an interference pattern is formed inside the copper sphere of the antenna. When ECRH is in plasma operation at AUG, the plasma is acting as a phase and mode mixer for the millimeter waves and thus the interference pattern inside the sphere changes with the characteristic time of the plasma dynamics. In order to overcome the difficulty of a calibrated measurement of the average stray radiation level, we installed bolometer and pyroelectric detectors, which intrinsically average over interference structures due to their large active area. The bolometer provides a robust calibration but with moderate temporal resolution. The pyroelectric detector provides high sensitivity and a good temporal resolution, but it raises issues of possible signal drifts in long pulses.

  3. From electrode charges on dielectric elastomers to trapped charges and electric dipoles in electrets and ferroelectrets: fundamental and applications-relevant aspects of diversity in electroactive polymers

    Science.gov (United States)

    Gerhard, Reimund

    2016-04-01

    Some recent developments in the areas of soft and basically incompressible electro-electrets (dielectric elastomers) with large strains, of anisotropic polymer ferro- or piezo-electrets with quasi-ferroelectric behavior, of moleculardipole electrets with significant ferro-, pyro- and piezo-electricity, and of space-charge polymer electrets with locally stabilised charges are described. Such materials may be applied, e.g., in soft actuators, energy harvesters and flexible and stretchable sensors for devices such as artificial muscles, electrically controllable refractive and diffractive optics, flexible pyroelectric detectors, motion and displacement sensors, earphones and microphones, ultrasonic transducers, air filters, radiation dosimeters, etc. The performance of dielectric elastomers for actuator, energy-harvester and sensor applications relies on a high relative permittivity and a low elastic modulus. High densities of electric charges in the electrodes are required in order to provide large Maxwell stresses or high energy densities. Significant amounts of localised or trapped charges, as well as electric dipoles from pairs of charges, lead to useful electro-mechanical and mechano-electrical effects (or inverse and direct piezoelectricity, respectively) if they are properly arranged in dielectric materials with extremely low conductivities. Space-charge electret films and ferroelectret systems should exhibit thermal and long-term stability of the trapped charges within the respective materials. Ferroelectric polymers and other polar polymers show useful piezo- and pyroelectric properties if their polymer-chain conformations allow for parallel packing of the molecular dipoles. Space-charge and molecular-dipole electrets are widely applied, e.g. in microphones, air filters, radiation dosimeters, ultrasonic transducers, etc. Basically, the performance of all electro-active polymers relies on the attraction (and repulsion) of electric charges and thus directly on

  4. Determinación del coeficiente piroeléctrico del sistema ferroeléctrico cerámico de Pb0.88Ln0.08Ti0.98Mn0.02O3 (Ln=La, Sm, Eu y su aplicación en detectores de infrarrojo

    Directory of Open Access Journals (Sweden)

    Suaste-Gómez, E.

    2004-12-01

    Full Text Available In this work the dielectric and pyroelectric characteristics of the ferroelectric ceramic system of Pb0.88(Ln0.08Ti0.98Mn0.02O3 (Ln = La, Sm, Eu are studied in order to determine its usefulness as infrared dectectors. Dielectric constant and pyroelectric coefficient of the ceramics were determined. This material with perovskite structure presented a phase transition from tetragonal to cubic on the heating process, besides of presenting high values of dielectric constant. Values of figure of merit for infrared detection Rv=pi/εr were calculated. The results were compared with other materials used as infrared detectors.En este trabajo se estudian las características dieléctricas y piroeléctricas del sistema ferroléctrico cerámico de Pb0.88(Ln0.08Ti0.98 Mn0.02O3 (Ln = La, Sm, Eu para determinar su utilidad como detectores de infrarrojo. Se determinó la constante dieléctrica y el coeficiente piroeléctrico de las cerámicas. Este material con estructura de perovskita presentó una transición de fase tetragonal a cúbica en el proceso de calentamiento, además de presentar altos valores de la constante dieléctrica. Se obtuvieron valores de la figura de mérito para detección infrarroja Rv=pi/εr Los resultados se compararon con otros materiales usados como detectores de infrarrojo.

  5. Evaluation of Pyro-optic Materials for Infrared Imaging

    Science.gov (United States)

    Pandey, R. K.; Kotru, Sushma; Song, Xiuyu; Donnelly, David

    2004-03-01

    Infrared detectors are needed for a wide range of applications. IR detectors operate either on the principles of photon detection or pyroelectric detection. Both these systems have their respective advantages and disadvantages. However, both of them inherently have difficulties in management of noise to signal ratio and in read-out circuitory. One of the most serious handicaps of photon detectors is requirement of cryogenic cooling for satisfactory operation. In this respect uncooled pyroelectric detectors operating at above room temperature have an advantage. An alternative to these approaches can be pyro-optic based detectors. Only a handful of materials have been found with some satisfactory level of pyro-optic coefficients appropriate for imaginig devices. Some of them are: antimony-sulfo-iodide (SbSI), molybdenum sulfide (MoS2), bismuth vanadate (BiVO4) and Pb-based titanates. Pyrooptic coefficients of these materials have been reported using presumably bulk single crystals. However, no such data are available for their thin films which would be very important for light weight integrated structured devices.In this paper we will describe the parameters and optimization protocol for the growh of thin films of these materials on thermally insulating substrates. We will also discuss their structural, electrical and optical properties. Our investigations suggest that SbSI, BiVO4 and PNZT films are attractive options for advancing the IR detecting technology by utilizing the pyro-optic effect. Integrated thin film structures might lead to the fabrication of light weight, low cost, noise immune and efficient imaging devices based on pyro-optic properties. This research is sponsored by the DEPSCoR program of the U.S. Army Research Office.

  6. 基于STM32的智能家居无线激光报警系统%Intelligent indoor wireless laser alarm system based on STM32

    Institute of Scientific and Technical Information of China (English)

    李娜; 牛晓飞; 许海峰; 汪材印; 唐永刚

    2013-01-01

    This thesis has designed an intelligent indoor wireless laser alarm system which takes Micro controller Unit STM 32F103 as the core .The system consists of Micro controller Unit ,GSM wireless transceiver ,matrix keyboard ,sound and light alarm and pyroelectric laser sensors .Pyroelectric laser sensor receives infrared signal which would be analysed by STM 32F103 .Alarm signal would be send out by the sound and light alarm module .In the meantime GSM would transmit short message to the mobile of user through mobile network to reflect the circumstances of the alarm location .Because of the wide mobile network , the system is unnecessary to set up special network and maintain it .Therefore ,it has unique advantages compared with the traditional monitor systems .%以STM32为核心,设计了智能家居无线激光报警系统。该系统由单片机控制模块、GSM无线发送接收模块、矩阵键盘模块、声光报警模块、热释电激光传感器模块组成。通过热释电激光传感器采集相关信号,单片机STM32经过处理后控制声光报警模块发出报警信号,并将报警信号通过GSM短信模块发送至用户手机上,实时反馈报警地点的情况。该系统利用广泛的移动网络,不需要组建专用网络和维护网络,较传统的监控系统有着独特的优势。

  7. 智能照明控制器的设计

    Institute of Scientific and Technical Information of China (English)

    贾正松

    2012-01-01

    The design of Lighting control circuit system aims at reducing the phenomena of wasting electricity in public places. It adopts the combination of pyroelectric infrared sensor and lighting detection and takes Single Chip microcomputer AT89C52 as its core. The pyroelectric infrared sensor detects the signals of human bodies' movement and the intensity of light which will be transmitted to the Single Chip Micyoco immediately. Then the system can cut off or switch on the lighting device according to the signals. It has been proved that the circuit system is simple and feasible, sensitive and manageable with low costs, which makes it possible to achieve energy saving and scientific management and control the lighting indoor effectively.%为降低公共场所用电浪费现象,设计出一种室内照明控制电路.以AT89C52单片机为核心,采用热释电红外传感器和光照检测相结合的方案,将热释电红外传感器检测到的人体移动信号与光照强弱信号送入单片机,实现在室内环境光照较强或光较弱但室内又无人时切断照明设备,在室内光照较弱且热释电红外传感器检测室内有人时接通照明设备.结果表明,该电路简单可行、成本低、控制灵敏度高,能够有效对室内照明设备进行控制,达到节能照明与科学管理的目的.

  8. Thermal effect on E/M impedance spectroscopy of piezoelectric wafer active sensors

    Science.gov (United States)

    Kamas, Tuncay; Frankforter, Erik; Yu, Lingyu Lucy; Lin, Bin; Giurgiutiu, Victor

    2015-03-01

    This paper presents theoretical predictive modeling and experimental evaluation of the structural health monitoring capability of piezoelectric wafer active sensors (PWAS) at elevated temperatures. Electromechanical impedance spectroscopy (EMIS) method is first qualified using circular PWAS resonators under traction-free boundary condition and in an ambience with increasing temperature. The theoretical study is conducted regarding temperature dependence of the electrical parameters, the capacitance C0, d31 and g31; and the elastic parameters, the in-plane compliance s11 and Young's modulus c11, of piezoelectric materials. The Curie transition temperature must be well above the operating temperature; otherwise, the piezoelectric material may depolarize under combined temperature and pressure conditions. The material degradation is investigated by introducing the temperature effects on the material parameters that are obtained from experimental observations as well as from related work in literature. The preliminary results from the analytical 2-D circular PWAS-EMIS simulations are presented and validated by the experimental PWAS-EMIS measurements at elevated temperatures. Temperature variation may produce pyro-electric charges, which may interfere with the piezoelectric effect. Therefore, analytical simulations are carried out to simulate the pyro-electric response from the temperature effects on a free circular PWAS-EMIS in in-plane mode. For the experimental validation, PWAS transducers are placed in a fixture that provides the traction-free boundary condition. The fixture is then located in an oven integrated with PID temperature controller. The EMIS measurement is conducted during the temperature increase and the first resonance frequency peak in admittance and impedance spectra was acquired.

  9. A3V5O14 (A = K+, Rb+, or Tl+), new polar oxides with a tetragonal tungsten bronze related structural topology: synthesis, structure, and functional properties.

    Science.gov (United States)

    Yeon, Jeongho; Kim, Sang-Hwan; Halasyamani, P Shiv

    2010-08-02

    Three polar noncentrosymmetric (NCS) oxide materials, A(3)V(5)O(14) (A = K(+), Rb(+), or Tl(+)), have been synthesized by hydrothermal and conventional solid state techniques. Their crystal structures and functional properties (second-harmonic generation, piezoelectricity, and polarization) have been determined. The iso-structural materials exhibit a layered structural topology that consists of corner-sharing VO(4) tetrahedra and VO(5) square pyramids. The layers stack parallel to the c-axis direction and are separated by the K(+), Rb(+), or Tl(+) cations. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate the materials exhibit moderate SHG efficiencies of approximately 100 x alpha-SiO(2). Additional SHG measurements, that is, particle size versus SHG efficiency, indicate the materials are type-I phase-matchable. Converse piezoelectric measurements for K(3)V(5)O(14), Rb(3)V(5)O(14), and Tl(3)V(5)O(14) revealed d(33) values of 28, 22, and 26 pm/V, respectively. Pyroelectric measurements, that is, temperature-dependent polarization measurements, resulted in pyroelectric coefficients of -2.2, -2.9, and -2.8 microC/m(2) x K at 65 degrees C, for K(3)V(5)O(14), Rb(3)V(5)O(14), and Tl(3)V(5)O(14) respectively. Frequency-dependent polarization measurements confirmed that all of the materials are nonferroelectric, consistent with our first principle density functional theory (DFT) electronic structure calculations. Infrared, UV-vis, thermogravimetric, and differential scanning calorimetry measurements were also performed. Crystal data: K(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.6970(16) A, c = 4.9434(19) A, V = 323.81(15), and Z = 1; Rb(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.7092(5) A, c = 5.2772(7) A, V = 346.65(5), and Z = 1; Tl(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.7397(8) A, c = 5.0846(10) A, V = 336.34(8), and Z = 1.

  10. Orientación de láminas delgadas de (Pb, CaTiO3

    Directory of Open Access Journals (Sweden)

    Mendiola, J.

    1999-06-01

    Full Text Available Calcium modified PbTiO3 thin films have been prepared on platinized Si, MgO and SrTiO3 substrates. The films were deposited from a sol-gel solution with a concentration of 0.3 M and with a 10% excess of PbO. Two deposits of this solution on the substrates were made by spin-coating, crystallizing each of them by a Rapid Thermal Processing. The resulting films present a single (Pb,CaTiO3 perovskite phase. All the films are textured, but the films deposited on MgO and SrTiO3 show a preferred orientation in the polar direction of the perovskite. As a result of this orientation, pyroelectric coefficients were measured, without any poling, for the films on MgO and SrTiO3. Pyroelectric measurements indicate the application of these films in infrarred sensors.Se han preparado láminas delgadas de PbTiO3 modificado con calcio sobre substratos de Si, MgO y SrTiO3 electrodados con Pt. Las películas se depositaron a partir de una solución sintetizada por sol-gel, con concentración 0.3 M y con un 10 % en exceso de PbO. En cada lámina se hicieron dos depósitos de la solución sobre el substrato mediante la técnica de “spin-coating”, cristalizando cada uno de ellos con un tratamiento térmico rápido. Todas las láminas resultantes presentaban como única fase cristalina la perovskita de (Pb,CaTiO3. Las láminas presentaron una cierta textura, observándose una orientación preferente en la dirección polar en el caso de las películas depositas sobre MgO y SrTiO3. Como resultado de esta orientación, se midieron coeficientes piroeléctricos, sin polarización previa, en las láminas sobre MgO y SrTiO3. Las medidas piroeléctricas de estos materiales evidencian su utilidad en dispositivos para sensores de infrarrojo.

  11. An investigation on phase transition behaviors in MgO-doped Pb{sub 0.99}(Zr{sub 0.95}Ti{sub 0.05}){sub 0.98}Nb{sub 0.02}O{sub 3} ferroelectric ceramics by Raman and dielectric measurements

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junxia, E-mail: wjunxia2002@163.com [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Genshui; Chen, Xuefeng [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Hu, Zhigao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Nie, Hengchang; Cao, Fei [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Dong, Xianlin, E-mail: xldong@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-03-15

    Highlights: • The phase transition behaviors were strongly dependent on MgO concentration. • The F{sub R(LT)}–F{sub R(HT)} phase transition temperature obviously shifted toward a lower temperature with increasing MgO addition. • The F{sub R(HT)}–cubic paraelectric (P{sub C}) phase transition changed to a higher temperature with increasing MgO addition. • The distortion of BO{sub 6} oxygen octahedron caused by B-site replacement of Mg{sup 2+} ions is proposed to explain the observed behaviors. • Superior room-temperature pyroelectric properties were obtained in 0.1 wt% MgO-modified PZTN 95/5 ceramics during F{sub R(LT)}–F{sub R(HT)} phase transition. - Abstract: The phase transition behaviors of Pb{sub 0.99}(Zr{sub 0.95}Ti{sub 0.05}){sub 0.98}Nb{sub 0.02}O{sub 3} ferroelectric ceramics doped with different MgO concentrations (0–0.2 wt%) were systematically investigated by Raman and dielectric measurements. Raman results showed that the phase transitions were strongly dependent on MgO concentration. It was found that the low temperature rhombohedral (F{sub R(LT)})–high temperature rhombohedral (F{sub R(HT)}) ferroelectric phase transition shifted toward a lower temperature with increasing MgO concentration up to 0.1 wt%, while the F{sub R(HT)}–cubic paraelectric (P{sub C}) phase transition changed to a higher temperature. The Raman results were in good agreement with phase transition determined by dielectric measurements. Moreover, it was indicated that the changes of Raman active modes were related to distortion of BO{sub 6} octahedra during the phase transitions. Then, the distortion of BO{sub 6} octahedron caused by B-site replacement of Mg{sup 2+} ions was proposed to explain the observed behaviors. In addition, the effects of MgO doping on the dielectric, ferroelectric and pyroelectric properties were also discussed.

  12. Interaction of light with impurities in lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Schwesyg, Judith Renate Marie-Luise

    2011-06-06

    Congruent lithium niobate (LiNbO{sub 3}) and 5-mol% MgO-doped LiNbO{sub 3} (MgO:LN) crystals are widely used as nonlinear-optical crystals in frequency-conversion devices due to their large nonlinear-optic coefficients. These devices usually require high optical pump powers, but absorption of photons by impurities limits their usability due to heat accumulation that leads to thermo-optic refractive index changes. These refractive index changes distort the beam shape and disturb the phase-matching condition. Furthermore pyroelectric fields can build up. In this thesis the residual optical absorption in congruent LiNbO{sub 3} (CLN) and MgO:LN crystals is studied. Absorption spectra of CLN and MgO:LN crystals between 400-2000 nm reveal a residual absorption up to 0.04 cm{sup -1}. This absorption is mainly caused by transition metal impurities. Between 2300-2800 nm unknown hydrogen absorption bands in CLN and MgO:LN are revealed on the order of 0.001 cm{sup -1}. High-temperature annealing is applied to the CLN and MgO:LN crystals, which decreases optical absorption by up to one order of magnitude. As an application, the operation of a 1550-nm pumped singly-resonant CW optical parametric oscillator, resonant around 2600 nm, using a low-loss, periodically-poled, annealed CLN crystal is demonstrated. Another issue that affects CLN is photorefractive damage (PRD), i.e. light-induced refractive index changes. In contrast, MgO:LN crystals do not suffer from PRD even at high optical intensities. However, it is shown in this thesis that PRD can occur within seconds in MgO:LN, using green laser light at light intensity levels as low as 100 mW/cm{sup 2}, if the crystal is heated by several degrees Celsius during or before illumination. Photorefractive damage does not occur in CLN crystals under the same conditions. We show that the pyroelectric effect together with an elevated photoconductivity compared to that of CLN causes this beam distortion and that this effect also

  13. PMN-PT/P(VDF-TrFE)复合材料的制备与电性能研究%Studies on preparation and electrical properties of PMN-PT/P(VDF-TrFE)composites

    Institute of Scientific and Technical Information of China (English)

    孟佳; 罗文博; 吴传贵; 孙翔宇; 张平; 俞玉澄; 帅垚

    2015-01-01

    Lead magnesium niobate-lead titanate (PMN-PT)ceramic prepared by columbite precursor method and polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE)have been used to fabricate 0-3 composites thick films on ITO substrates by flow casting.The phase structure of PMN-PT was analyzed by XRD and the inter-face of 0-3 composites was characterized by SEM.Variation of dielectric constant (εr )and electric field applied to the ceramic phase (E c )with temperature were studied to optimize the polarization temperature.Further-more,compared with the conventional polarization in stages,PMN-PT ceramic content effect on pyroelectric properties of composites was also discussed under optimized polarization condition.The results showed that the pyroelectric coefficient increases to 58.6 μC/(m2 •K)at a ceramic mass fraction of 55% by polarizing tempera-ture with 1 10 ℃.%以铌铁矿预产物法合成的铌镁酸铅-钛酸铅(PMN-PT)陶瓷粉体和聚二氟乙烯-三氟乙烯共聚物 P (VDF-TrFE)为原料,采用流延法在 ITO 衬底上制备了不同质量配比的 PMN-PT/P (VDF-TrFE)复合厚膜.采用 XRD 及 SEM 分别分析了 PMN-PT 粉体的物相结构和复合材料的界面特征.通过测试复合材料的介电-温度曲线,计算出加载在陶瓷相上的极化分压与温度的关系,得到优化的极化温度.与常规的分步极化相比,探讨了在优化极化条件下陶瓷相含量对复合材料热释电性能的影响,结果表明在极化温度为110℃,PMN-PT 质量分数为55%时,得到了热释电系数为58.6μC/(m2•K)的热释电复合厚膜材料.

  14. RTIA readout circuit for infrared focal plane array using active resistor%有源电阻RTIA红外焦平面读出电路

    Institute of Scientific and Technical Information of China (English)

    胡滨; 李威; 李平; 阙滨城

    2012-01-01

    提出了一种基于有源电阻的电阻反馈跨导放大器(RTIA)红外焦平面读出电路,该电路采用工作在亚阈区的MOS管实现1011Ω以上的有源大电阻,不仅能与热释电红外探测器的高阻抗良好匹配,而且配合两管共源放大器可针对热释电微弱信号进行高增益电流放大.同时,简单的三管单元结构能够方便地置于像元之下,相比于采用特殊高阻材料实现的RTIA,不附加材料和工艺.经上华0.5 μmCMOS工艺流片验证,在5V电源电压下,该电路增益40 dB,输出摆幅3V,在高低温测试下表现出了良好的增益带宽稳定性,适用于PZT和BST等热释电大阵列探测器.%A Resistive Trans-impedance Amplifier (RTIA) readout circuit for Uncooled Focal Plane Array (UFPA) using active resistor was proposed in this paper. By using a sub-threshold MOSFET as a 1011 Ω and above feedback resistor, a high gain current amplifier could be realized by common source structure which consisted of two transistors. The simple three transistors could be easily integrated under pixel and it had good impedance matching with pyroelectric infrared detector. Compared with traditional RTIAs which use special high-resistance materials as feedback resistor, the novel RTIA was low cost because no additional materials and processes were needed. The circuit was successfully manufactured by 0.5 μm standard CMOS process of CSMC foundry. 40 dB gain and 3 V output swing were realized by this design and the gain and bandwidth of the chip kept stable during high and low temperature tests. So it can be used for large arrays pyroelectric detectors such as Lead Zirconate Titanate (PZT) and Barium Strontium Titanate (BST), etc.

  15. Magnetic ordering and conduction mechanism of different electroactive regions in Lu2NiMnO6

    Science.gov (United States)

    Chanda, Sadhan; Saha, Sujoy; Dutta, Alo; Krishna Murthy, J.; Venimadhav, A.; Shannigrahi, Santiranjan; Sinha, T. P.

    2016-10-01

    The magnetodielectric response of a double perovskite oxide Lu2NiMnO6 (LNMO) synthesised by the sol-gel process has been investigated. The Rietveld refinement of the X-ray diffraction data indicates that the room-temperature crystal structure of LNMO is monoclinic with the space group P21/n, which contains an ordered array of alternate MnO6 and NiO6 octahedra. X-ray photoelectron spectroscopy studies confirm the mix valence state of Mn (4+ and 3+) and Ni (2+ and 3+). The optical band gap (Eg = 1.56 eV) obtained from the UV-Visible absorption spectrum suggests that LNMO is a semiconductor. The field cooled and zero-field cooled measurements show the ferromagnetic behaviour of the sample with the transition temperature (Tc) = 45 K and a saturation magnetization of 5.2 μB/f.u. is observed at 2.5 K. The temperature and frequency dependent dielectric measurements reveal colossal values of the dielectric constant, which are interpreted by the Maxwell-Wagner interfacial polarization. The temperature dependence of the bulk dc conductivity indicates a variable-range-hopping mechanism. The saturation polarization value is estimated to be 232 μC/m2 from the pyroelectric current measurement. A negative magnetodielectric effect of 1% is observed at the paramagnetic to ferromagnetic transition temperature. The electronic structure calculations based on density functional theory have been performed to analyse the magnetic properties of LNMO.

  16. Automated characterization of varnishes photo-degradation using portable T-controlled Raman spectroscopy

    Science.gov (United States)

    Osticioli, I.; Ciofini, D.; Mencaglia, A. A.; Siano, S.

    2017-02-01

    In this work, a portable-Raman device (excitation wavelength 1064 nm) was employed for the first time for continuously monitoring the complex molecular dynamics of terpenoid resins (dammar, mastic, colophony, sandarac and shellac), which occur during their ageing under artificial light exposure. The instrumentation was equipped with a pyroelectric sensor allowing for temperature control of the sample's irradiated surface while the acquisition of spectra occurs by setting fixed maximum temperature and total radiant exposure. Resins were dropped into special pits over a dedicated rotating wheel moved by a USB motor. The rotation allowed samples sliding between the positions designated for the acquisition of the Raman spectra and that for artificial ageing. Samples were exposed to artificial light for 45-days and almost 400 spectra for each resin sample were collected. The exposure to artificial light led to significant changes allowing the characterization of the alteration process. The automated acquisition of a large number of spectra overtime during light-exposure has given the possibility to distinguish fast dynamics, mainly associated to solvent evaporation, from those slower due to resins photo-degradation processes.

  17. Structural, dielectric and electrical properties of CaBa4SmTi3Nb7O30 ferroelectric ceramic

    Indian Academy of Sciences (India)

    Prasun Ganguly; A K Jha

    2011-07-01

    The polycrystalline sample of CaBa4SmTi3Nb7O30, a member of tungsten bronze family, was prepared by solid-state reaction method. X-ray diffraction analysis shows the formation of single-phase compound with an orthorhombic structure at room temperature. Scanning electron micrograph of the material shows uniform distribution of grains. Detailed studies of dielectric properties of the compound as a function of temperature at different frequencies suggest that the compound has a dielectric anomaly of ferroelectric to paraelectric type at 198°C, and exhibits non-relaxor kind of diffuse phase transition. The ferroelectric nature of the compound has been confirmed by recording polarization–electric field hysteresis loop. Piezoelectric and pyroelectric studies of the compound have been discussed in this paper. Electrical properties of the material have been analyzed using complex impedance technique. The Nyquist plots manifest the contribution of grain boundaries (at higher temperature), in addition to granular contribution (at all temperatures) to the overall impedance. The temperature dependence of dc conductivity suggests that the compound has negative temperature coefficient of resistance (NTCR) behaviour. The frequency dependence of ac conductivity is found to obey Jonscher’s universal power law. The observed properties have been compared with calcium free Ba5SmTi3Nb7O30 compound.

  18. Temperature dependent structural, elastic, and polar properties of ferroelectric polyvinylidene fluoride (PVDF) and trifluoroethylene (TrFE) copolymers

    Science.gov (United States)

    Sun, Fu-Chang; Dongare, Avinash; Asandei, Alexandru; Alpay, Pamir; Nakhmanson, Serge; University of Connecticut Team

    We use molecular dynamics to calculate the structural, elastic, and polar properties of crystalline ferroelectric β-poly(vinylidene fluoride), PVDF (-CH2-CF2-)n with randomized trifluoroethylene TrFE (-CHF-CF2-)n as a function of TrFE content (0-50%) in the temperature range of 0-400 K. There is a very good agreement between the experimentally obtained and the computed values of the lattice parameters, thermal expansion coefficients, elastic constants, polarization, and pyroelectric coefficients. A continuous decrease in Young's modulus with increasing TrFE content was observed and attributed to the increased intramolecular and intermolecular repulsive interactions between fluorine atoms. The computed polarization displayed a similar trend, with the room temperature spontaneous polarization decreasing by 44% from 13.8 μC/cm2 (pure PVDF) to 7.7 μC/cm2 [50/50 poly(VDF-co-TrFE)]. Our results show that molecular dynamics can be used as a practical tool to predict the mechanical and polarization-related behavior of ferroelectric poly(VDF-co-TrFE). Such an atomistic model can thus serve as a guide for practical applications of this important multifunctional polymer.

  19. Systems Analysis for Thermal Infrared ` THz Torch' Applications

    Science.gov (United States)

    Hu, Fangjing; Sun, Jingye; Brindley, Helen E.; Liang, Xiaoxin; Lucyszyn, Stepan

    2015-05-01

    The ` THz Torch' concept was recently introduced by the authors for providing secure wireless communications over short distances within the thermal infrared (10-100 THz). Unlike conventional systems, thermal infrared can exploit front-end thermodynamics with engineered blackbody radiation. For the first time, a detailed power link budget analysis is given for this new form of wireless link. The mathematical modeling of a short end-to-end link is provided, which integrates thermodynamics into conventional signal and noise power analysis. As expected from the Friis formula for noise, it is found that the noise contribution from the pyroelectric detector dominates intrinsic noise. From output signal and noise voltage measurements, experimental values for signal-to-noise ratio (SNR) are obtained and compared with calculated predictions. As with conventional communications systems, it is shown for the first time that the measured SNR and measured bit error rate found with this thermodynamics-based system resembles classical empirical models. Our system analysis can serve as an invaluable tool for the development of thermal infrared systems, accurately characterizing each individual channel and, thus, enables the performance of multi-channel ` THz Torch' systems to be optimized.

  20. Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Rodolfo Araneo

    2014-12-01

    Full Text Available Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews.

  1. An Electronic Worker Service System of the Pig House Based on ATmega16

    Science.gov (United States)

    Li, Liu-An; Jin, Tian-Ming; Yu, Ya-Ping; Zhang, Guo-Qiang; Hong, Tao

    Pork is very important for people in daily life. Quality of livestock environment is closely related to the growth of animals. To improve environmental quality, the paper designed an electronic worker service system of the pig house based on ATmega16, which consisted of 6 detection modules, wireless data collecting, GSM, time circuit, display, anti-th alarm and music player, etc. A small LAN was constructed by wireless transceiver module to test and collect data of temperature, humidity and harmful gas concentration in the pig house. If one detection point exists that harmful pollutant gases concentration exceeds the standard value, GSM module took a message for livestock farmers, so that farmers can promptly arrive at the pig house to ventilate or deal with manure in the pig house, which can effectively prevent from bad things. Time of pyroelectric detector deployment can be freely set, and intrusion information was timely sent to the users. The anti-th alarm function was achieved by the auxiliary light. The music playing module is open by timer module in order to soothing pigs' life state. All are suitable for small farms and can save human resources.

  2. A High End Building Automation and Online Video Surveillance Security System

    Directory of Open Access Journals (Sweden)

    Iyer Adith Nagarajan

    2015-02-01

    Full Text Available This paper deals with the design and implementation of a building automation and security system which facilitates a healthy, flexible, comfortable and a secure environment to the residents. The design incorporates a SIRC (Sony Infrared Remote Control protocol based infrared remote controller for the wireless operation and control of electrical appliances. Alternatively, the appliances are monitored and controlled via a laptop using a GUI (Graphical User Interface application built in C#. Apart from automation, this paper also focuses on indoor security. Multiple PIR (Pyroelectric Infrared sensors are placed within the area under surveillance to detect any intruder. A web camera used to record the video footage is mounted on the shaft of a servo motor to enable angular motion. Corresponding to which sensor has detected the motion; the ARM7 LPC2148 microcontroller provides appropriate PWM pulses to drive the servo motor, thus adjusting the position and orientation of the camera precisely. OpenCV libraries are used to record a video feed of 5 seconds at 30 frames per second (fps. Video frames are embedded with date and time stamp. The recorded video is compressed, saved to predefined directory (for backup and also uploaded to specific remote location over the internet using Google drive for instant access. The entire security system is automatic and does not need any human intervention.

  3. The Effect of Temperature Dependent Material Nonlinearities on the Response of Piezoelectric Composite Plates

    Science.gov (United States)

    Lee, Ho-Jun; Saravanos, Dimitris A.

    1997-01-01

    Previously developed analytical formulations for piezoelectric composite plates are extended to account for the nonlinear effects of temperature on material properties. The temperature dependence of the composite and piezoelectric properties are represented at the material level through the thermopiezoelectric constitutive equations. In addition to capturing thermal effects from temperature dependent material properties, this formulation also accounts for thermal effects arising from: (1) coefficient of thermal expansion mismatch between the various composite and piezoelectric plies and (2) pyroelectric effects on the piezoelectric material. The constitutive equations are incorporated into a layerwise laminate theory to provide a unified representation of the coupled mechanical, electrical, and thermal behavior of smart structures. Corresponding finite element equations are derived and implemented for a bilinear plate element with the inherent capability to model both the active and sensory response of piezoelectric composite laminates. Numerical studies are conducted on a simply supported composite plate with attached piezoceramic patches under thermal gradients to investigate the nonlinear effects of material property temperature dependence on the displacements, sensory voltages, active voltages required to minimize thermal deflections, and the resultant stress states.

  4. Large piezoelectricity in electric-field modified single crystals of SrTiO3

    Science.gov (United States)

    Khanbabaee, B.; Mehner, E.; Richter, C.; Hanzig, J.; Zschornak, M.; Pietsch, U.; Stöcker, H.; Leisegang, T.; Meyer, D. C.; Gorfman, S.

    2016-11-01

    Defect engineering is an effective and powerful tool to control the existing material properties and produce completely new ones, which are symmetry-forbidden in a defect-free crystal. For example, the application of a static electric field to a single crystal of SrTiO3 forms a strained near-surface layer through the migration of oxygen vacancies out of the area beneath the positively charged electrode. While it was previously shown that this near-surface phase holds pyroelectric properties, which are symmetry-forbidden in centrosymmetric bulk SrTiO3, this paper reports that the same phase is strongly piezoelectric. We demonstrate the piezoelectricity of this phase through stroboscopic time-resolved X-ray diffraction under alternating electric field and show that the effective piezoelectric coefficient d33 ranges between 60 and 100 pC/N. The possible atomistic origins of the piezoelectric activity are discussed as a coupling between the electrostrictive effect and spontaneous polarization of this near-surface phase.

  5. Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging.

    Science.gov (United States)

    Hack, Erwin; Valzania, Lorenzo; Gäumann, Gregory; Shalaby, Mostafa; Hauri, Christoph P; Zolliker, Peter

    2016-02-06

    In terahertz (THz) materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8-14 μm wavelength range, but are based on different absorber materials (i) vanadium oxide; (ii) amorphous silicon; (iii) a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv) a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed.

  6. Anisotropy-based crystalline oxide-on-semiconductor material

    Science.gov (United States)

    McKee, Rodney Allen; Walker, Frederick Joseph

    2000-01-01

    A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

  7. Static Human Detection and Scenario Recognition via Wearable Thermal Sensing System

    Directory of Open Access Journals (Sweden)

    Qingquan Sun

    2017-01-01

    Full Text Available Conventional wearable sensors are mainly used to detect the physiological and activity information of individuals who wear them, but fail to perceive the information of the surrounding environment. This paper presents a wearable thermal sensing system to detect and perceive the information of surrounding human subjects. The proposed system is developed based on a pyroelectric infrared sensor. Such a sensor system aims to provide surrounding information to blind people and people with weak visual capability to help them adapt to the environment and avoid collision. In order to achieve this goal, a low-cost, low-data-throughput binary sampling and analyzing scheme is proposed. We also developed a conditioning sensing circuit with a low-noise signal amplifier and programmable system on chip (PSoC to adjust the amplification gain. Three statistical features in information space are extracted to recognize static humans and human scenarios in indoor environments. The results demonstrate that the proposed wearable thermal sensing system and binary statistical analysis method are efficient in static human detection and human scenario perception.

  8. Development of intense terahertz coherent synchrotron radiation at KU-FEL

    Science.gov (United States)

    Sei, Norihiro; Zen, Heishun; Ohgaki, Hideaki

    2016-10-01

    We produced intense coherent synchrotron radiation (CSR) in the terahertz (THz) region using an S-band linac at the Kyoto University Free Electron Laser (KU-FEL), which is a mid-infrared free-electron laser facility. The CSR beam was emitted from short-pulse electron bunches compressed by a 180° arc, and was transferred to air at a large solid angle of 0.10 rad. The measured CSR energy was 55 μJ per 7 μs macropulse, and KU-FEL was one of the most powerful CSR sources in normal conducting linear accelerator facilities. The CSR spectra were measured using an uncooled pyroelectric detector and a Michelson-type interferometer designed specifically for the KU-FEL electron beam, and had a maximum at a frequency of 0.11 THz. We found that adjusting the energy slit enhanced the CSR energy and shortened the electron beam bunch length in the CSR spectra measurements. Our results demonstrated that the efficient use of the energy slit can help improve the characteristics of CSR.

  9. Development of intense terahertz coherent synchrotron radiation at KU-FEL

    Energy Technology Data Exchange (ETDEWEB)

    Sei, Norihiro, E-mail: sei.n@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Zen, Heishun; Ohgaki, Hideaki [Institute for Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2016-10-01

    We produced intense coherent synchrotron radiation (CSR) in the terahertz (THz) region using an S-band linac at the Kyoto University Free Electron Laser (KU-FEL), which is a mid-infrared free-electron laser facility. The CSR beam was emitted from short-pulse electron bunches compressed by a 180° arc, and was transferred to air at a large solid angle of 0.10 rad. The measured CSR energy was 55 μJ per 7 μs macropulse, and KU-FEL was one of the most powerful CSR sources in normal conducting linear accelerator facilities. The CSR spectra were measured using an uncooled pyroelectric detector and a Michelson-type interferometer designed specifically for the KU-FEL electron beam, and had a maximum at a frequency of 0.11 THz. We found that adjusting the energy slit enhanced the CSR energy and shortened the electron beam bunch length in the CSR spectra measurements. Our results demonstrated that the efficient use of the energy slit can help improve the characteristics of CSR. - Highlights: • We have developed intense coherent synchrotron radiation (CSR) at KU-FEL. • The elevation angle of the CSR was correctly measured by a new technique. • The CSR power extracted to the air was 55 μJ per 7 μs macropulse. • It was demonstrated that an energy slit was effective to improve the CSR properties.

  10. A new organic nanoporous architecture: dumb-bell-shaped molecules with guests in parallel channels

    Science.gov (United States)

    Muller; Hulliger; Seichter; Weber; Weber; Wubbenhorst

    2000-01-01

    A new type of dumb-bell-shaped host molecule (6-8) has been synthesised, of which 1,8-bis((1)-adamantyl)-1,3,5,7-octatetrayne (8 = BAOT) forms an open porous architecture when cocrystallised with a number of typical solvent molecules. Adamantyl substituents attached to a tetraalkyne spacer build up the walls of parallel channels wherein guest molecules are aligned. Surprisingly, the tetraalkyne unit is significantly bent. Desolvation experiments provide evidence for a reversible inclusion of guests. In the case of the inclusion of 2-butanone, a partial substitution by symmetrical and asymmetrical long-chain chromophores during crystallisation was possible. Stained crystals showed optical frequency doubling. The crystal structure analysis revealed a centric space group, although considerable translational and orientational disorder was present. Application of scanning pyroelectric microscopy revealed that the growth of inclusion compounds with 2-butanone produced polar ordering of guest molecules, which were aligned in two macro-domains of opposing polarity. The resulting orientation of the carbonyl dipoles is in agreement with the theoretical prediction of a Markov model of spontaneous polarity formation based on molecular recognition processes on growing crystal faces. The present case represents a new example of a property-driven supramolecular synthesis.

  11. Design of voice alarm device for automobile handbrake misuse and overspeed based on MCU%基于单片机的汽车手刹使用不当和超速语音提示装置的设计

    Institute of Scientific and Technical Information of China (English)

    贾萍; 梁文鑫

    2012-01-01

    以STC89C52单片机为核心,综合运用霍尔传感、热释电红外传感、无线传输、数字语音等技术,设计了汽车手刹使用不当和超速行驶语音提示装置.该装置增加了无线发射接收模块编码加载道路限速标准,实现了对汽车的智能限速提示,且安装简单、易于实现.%Voice alarm device for misuse of automobile handbrake and overspeed driving were designed. The device comprehensively applied technologies with Holzer sensing, pyroelectric infrared sensor, wireless transmission and digital voice and so on with STC89C52 MCU as the core, thus increasing standards for speed limit to loading road of wireless transmitting and receiving module code and achieving smart prompt to speed limit of automobile, which was characterized by simple installation and easy realization.

  12. Ultra high energy density and fast discharge nanocomposite capacitors

    Science.gov (United States)

    Tang, Haixiong; Sodano, Henry A.

    2013-04-01

    Nanocomposites containing high dielectric permittivity ceramics embedded in high breakdown strength polymers are currently of considerable interest as a solution for the development of high energy density capacitors. However, the improvement of dielectric permittivity comes at expense of the breakdown strength leading to limit the final energy density. Here, an ultra-high energy density nanocomposite was fabricated based on high aspect ratio barium strontium titanate nanowires. The pyroelectric phase Ba0.2Sr0.8TiO3 was chosen for the nanowires combined with quenched PVDF to fabricate high energy density nanocomposite. The energy density with 7.5% Ba0.2Sr0.8TiO3 nanowires reached 14.86 J/cc at 450 MV/m, which represented a 42.9% increase in comparison to the PVDF with an energy density of 10.4 J/cc at the same electric field. The capacitors have 1138% greater than higher energy density than commercial biaxial oriented polypropylene capacitors (1.2 J/cc at 640). These results demonstrate that the high aspect ratio nanowires can be used to produce nanocomposite capacitors with greater performance than the neat polymers thus providing a novel process for the development of future pulsed-power capacitors.

  13. A Novel Solid State Non-Dispersive Infrared CO2 Gas Sensor Compatible with Wireless and Portable Deployment

    Directory of Open Access Journals (Sweden)

    Desmond Gibson

    2013-05-01

    Full Text Available This paper describes development of a novel mid-infrared light emitting diode (LED and photodiode (PD light source/detector combination and use within a non-dispersive infrared (NDIR carbon dioxide gas sensor. The LED/PD based NDIR sensor provides fast stabilisation time (time required to turn on the sensor from cold, warm up, take and report a measurement, and power down again ≈1 second, longevity (>15 years, low power consumption and low cost. Described performance is compatible with “fit and forget” wireless deployed sensors in applications such as indoor air quality monitoring/control & energy conservation in buildings, transport systems, horticultural greenhouses and portable deployment for safety, industrial and medical applications. Fast stabilisation time, low intrinsic power consumption and cycled operation offer typical energy consumption per measurement of mJ’s, providing extended operation using battery and/or energy harvesting strategies (measurement interval of ≈ 2 minutes provides >10 years operation from one AA battery. Specific performance data is provided in relation to measurement accuracy and noise, temperature performance, cross sensitivity, measurement range (two pathlength variants are described covering ambient through to 100% gas concentration, comparison with NDIR utilizing thermal source/pyroelectric light source/detector combination and compatibility with energy harvesting. Semiconductor based LED/PD processing together with injection moulded reflective optics and simple assembly provide a route to low cost high volume manufacturing.

  14. Two thermal methods to measure the energy fluence of a brief exposure of diagnostic x rays.

    Science.gov (United States)

    Carvalho, A A; Mascarenhas, S; dePaula, M H; Cameron, J R

    1992-01-01

    This paper describes two simple thermal methods for measuring the energy fluence in J/cm2 from a diagnostic x-ray exposure. Both detectors absorb essentially 100% of the radiation and give a signal that is directly proportional to the energy fluence of the x-ray beam. One detector measures the thermal effect when a pulse of x rays is totally absorbed in the pyroelectric detector of lead-zirconium-titanate (PZT). The other detector measures the expansion of a gas surrounding a lead disk detector in a photoacoustic chamber. The increased pressure of the gas is transmitted through a 1-mm duct to a sensitive microphone. Both detectors have previously been used to measure the energy fluence rate of continuous x-ray beams in the same energy region using a chopped beam and a lock-in amplifier. Measurement of the energy fluence of a pulse of radiation eliminates the need for the beam chopper and lock-in amplifier and results in a simple, rugged, and inexpensive dosimeter. Either method can be combined with the area of the beam to give an estimate of the imparted energy to the patient from a diagnostic x-ray exposure.

  15. Understanding the multiferroicity in TmMn2O5 by a magnetically induced ferrielectric model

    Science.gov (United States)

    Yang, L.; Li, X.; Liu, M. F.; Li, P. L.; Yan, Z. B.; Zeng, M.; Qin, M. H.; Gao, X. S.; Liu, J.-M.

    2016-01-01

    The magnetically induced electric polarization behaviors in multiferroic TmMn2O5 in response to varying temperature and magnetic field are carefully investigated by means of a series of characterizations including the high precision pyroelectric current technique. Here polycrystalline rather than single crystal samples are used for avoiding the strong electrically self-polarized effect in single crystals, and various parallel experiments on excluding the thermally excited current contributions are performed. The temperature-dependent electric polarization flop as a major character is identified for different measuring paths. The magneto-current measurements indicate that the electric polarization in the low temperature magnetic phase region has different origin from that in the high temperature magnetic phase. It is suggested that the electric polarization does have multiple components which align along different orientations, including the Mn3+-Mn4+-Mn3+ exchange striction induced polarization PMM, the Tm3+-Mn4+-Tm3+ exchange striction induced polarization PTM, and the low temperature polarization PLT probably associated with the Tm3+ commensurate phase. The observed electric polarization flop can be reasonably explained by the ferrielectric model proposed earlier for DyMn2O5, where PMM and PTM are the two antiparallel components both along the b-axis and PLT may align along the a-axis. Finally, several issues on the unusual temperature dependence of ferroelectric polarizations are discussed. PMID:27713482

  16. Poly (vinylidene fluoride) / Poly (acrylonitrile)-based Superior Hydrophobic Piezoelectric Solid Derived by Aligned Carbon Nanotube in Electrospinning: Fabrication, the Phase Conversion and Surface Energy.

    Science.gov (United States)

    Aqeel, Salem M; Wang, Zhe; Than, Lisa; Sreenivasulu, Gollapudi; Zeng, Xiangqun

    2015-01-01

    Multifunctional materials have attracted many interests from both fundamental and practical aspects, such as field-effect transistor, electric protection, transducers and biosensor. Here we demonstrated the first superior hydrophobic piezoelectric surface based on the polymer blend of polyvinylidene fluoride (PVDF)-polyacrilonitrile (PAN) assisted with functionalized multiwalled nanotubes (MWNTs), by a modified electrospinning method. Typically the β-phase polyvinylidene fluoride (PVDF) was considered as the excellent piezoelectric and pyroelectric materials. However, polar β-phase of PVDF exhibited a natural high hydrophilicity. As a well-known fact, the wettability of the surface is dominated by two major factors: surface composition and surface roughness. The significant conversions derived by the incorporation of MWNTs, from nonpolar α-phase to highly polar β-phase of PVDF, were confirmed by FTIR. Meanwhile, the effects of MWNTs on the improvement of the roughness and the hydrophobicity of polymer blend were evaluated by atomic force microscopy (AFM) and contact angle (CA). Molar free energy of wetting of the polymer nanocomposite decreases with increasing the wt.% of MWNTs. All molar free energy of wetting of PVDF-PAN/MWNTs were negative, which means the non-wettability of film. The combination of surface roughness and low-surface-energy modification in nanostructured composites leads to high hydrophobicity. Particularly, fabrication of superior hydrophobic surfaces not only has fundamental interest but also various possible functional applications in micro- and nano-materials and devices.

  17. Poly (vinylidene fluoride) / Poly (acrylonitrile)–based Superior Hydrophobic Piezoelectric Solid Derived by Aligned Carbon Nanotube in Electrospinning: Fabrication, the Phase Conversion and Surface Energy

    Science.gov (United States)

    Aqeel, Salem M.; Than, Lisa; Sreenivasulu, Gollapudi

    2015-01-01

    Multifunctional materials have attracted many interests from both fundamental and practical aspects, such as field–effect transistor, electric protection, transducers and biosensor. Here we demonstrated the first superior hydrophobic piezoelectric surface based on the polymer blend of polyvinylidene fluoride (PVDF)–polyacrilonitrile (PAN) assisted with functionalized multiwalled nanotubes (MWNTs), by a modified electrospinning method. Typically the β–phase polyvinylidene fluoride (PVDF) was considered as the excellent piezoelectric and pyroelectric materials. However, polar β–phase of PVDF exhibited a natural high hydrophilicity. As a well–known fact, the wettability of the surface is dominated by two major factors: surface composition and surface roughness. The significant conversions derived by the incorporation of MWNTs, from nonpolar α–phase to highly polar β–phase of PVDF, were confirmed by FTIR. Meanwhile, the effects of MWNTs on the improvement of the roughness and the hydrophobicity of polymer blend were evaluated by atomic force microscopy (AFM) and contact angle (CA). Molar free energy of wetting of the polymer nanocomposite decreases with increasing the wt.% of MWNTs. All molar free energy of wetting of PVDF–PAN/MWNTs were negative, which means the non–wettability of film. The combination of surface roughness and low–surface–energy modification in nanostructured composites leads to high hydrophobicity. Particularly, fabrication of superior hydrophobic surfaces not only has fundamental interest but also various possible functional applications in micro– and nano–materials and devices. PMID:26989486

  18. Design and preparation of stress-free epitaxial BaTiO3 polydomain films by RF magnetron sputtering

    Science.gov (United States)

    Zhang, Wei; Yuan, Meiling; Wang, Xianyang; Pan, Wei; Wang, Chun-Ming; Ouyang, Jun

    2012-06-01

    Domain structures of BaTiO3 thick films grown on (100) SrTiO3 single-crystal substrates were engineered using an RF magnetron sputtering deposition process. By tuning the sputtering power and cooling rate and using an off-axis sputtering technique to prepare conducting perovskite oxide bottom electrode with heteroepitaxial quality, we have deposited epitaxial tetragonal single-domain and polydomain BaTiO3 films with a self-assembled three-domain architecture. The electrical properties and microstructure of the BaTiO3 films were characterized, and a c/a1/a2 cellular polydomain structure was clearly observed in as-grown films by optical microscopy. Such a polydomain structure was a consequence of a complete relaxation of misfit stresses of the film. Engineering of this self-assembled microstructure has great potential in providing large, field-tunable pyroelectric and electromechanical responses in next-generation microelectronic devices and micro-electro-mechanical systems (MEMS).

  19. Design and preparation of stress-free epitaxial BaTiO3 polydomain films by RF magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Wei Zhang, Meiling Yuan, Xianyang Wang, Wei Pan, Chun-Ming Wang and Jun Ouyang

    2012-01-01

    Full Text Available Domain structures of BaTiO3 thick films grown on (100 SrTiO3 single-crystal substrates were engineered using an RF magnetron sputtering deposition process. By tuning the sputtering power and cooling rate and using an off-axis sputtering technique to prepare conducting perovskite oxide bottom electrode with heteroepitaxial quality, we have deposited epitaxial tetragonal single-domain and polydomain BaTiO3 films with a self-assembled three-domain architecture. The electrical properties and microstructure of the BaTiO3 films were characterized, and a c/a1/a2 cellular polydomain structure was clearly observed in as-grown films by optical microscopy. Such a polydomain structure was a consequence of a complete relaxation of misfit stresses of the film. Engineering of this self-assembled microstructure has great potential in providing large, field-tunable pyroelectric and electromechanical responses in next-generation microelectronic devices and micro-electro-mechanical systems (MEMS.

  20. Nanostructural and electrical properties of LA0.5SR0.5CoO3

    Science.gov (United States)

    Bahari, A.; Ramzannezhad, A.; Shajari, D.; Najafi, H.

    2017-02-01

    A group of ABO3 perovskite-type oxides is currently under intensive studies for their potential as chemical sensing, ferroelectric memories, gas separation and computer devices. This group includes LaxSr1‑xCoO3 (LSCO). In the present work, we have synthesized LSCO samples by using the sol-gel method and studied their nano structural and electrical properties with using the scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Current density-voltage (J-V) and Fourier transform infrared spectroscopy (FTIR) techniques. We synthesized nanoparticles with diameters between 50 and 100 nm by calcination of the pulverized gel powders, and then studied its structure. The band gap characteristics of the La0.5Sr0.5CoO3 structure were also analyzed. The obtained results show that La0.5Sr0.5CoO3 with favorable carrier mobility ( ˜ 1.7 × 10‑2 cm2v‑2s‑1) and dielectric constant (16) exhibits a variety of interesting physical properties which include ferroelectric, dielectric, pyroelectric and piezoelectric behavior.