Pyroelectric hot spots.
Electromagnetic irradiation of pyroelectric hot spots and regional variation of response
PYROELECTRICITY↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Pyroelectric heat-transfer sensors for hypersonic impulse facilities.
Pyroelectric heat-transfer sensor performance compared with thin skin thermocouple heat sensors, noting discrepancy in measurement results in severe environment
PYROELECTRICITY↗
Pyroelectric Heat Detection for Calibrated Measurement of Atomic Layer Deposition Reaction Heat
Atomic layer deposition (ALD) precursors and processes have been identified that enable the deposition of materials that span the periodic table. However, the detailed mechanisms, kinetics, thermodynamics, and complexities of even the most well-studied ALD half-reactions remain insufficiently resolved experimentally to test present computational hypotheses. In this work, a pyroelectric calorimeter is designed, implemented, calibrated, and electrically modeled to enable quantitative ALD reaction heat detection. The operation and response of three ALD calorimeter designs were evaluated for use as absolute ALD half-reaction heat detectors. The most effective design was calibrated in situ before being utilized to measure the heat generated by the reaction of trimethylaluminum with a hydroxylated alumina surface to produce 96 μJ/cm 2 over a reaction time of ~30 ms. With thermal and temporal resolutions down to 0.1 μJ/cm 2 and 50 ns, respectively, this sensitive and ultrafast probe is poised to improve our fundamental understanding of numerous ALD reaction mechanisms through quantitative comparison with first-principles computation predictions.
36 MATERIALS SCIENCE↗
Capabilities of GaN/AlN/GaN structures as high-intensity pyroelectric laser sensors
The use of transparent Al{sub 2}O{sub 3}/GaN/AlN/GaN structures as pyrometric sensors for measuring the parameters of high-intensity laser pulses is proposed. The peculiarities of the employment of such sensors in laser fusion facilities are analysed. Post-pulse distributions of the absorbed energy density are obtained for various parameters of both GaN layers. The local maxima of these distributions are minimised by varying the ratio of donor concentration and the ratio of their thicknesses under the condition of invariance of the total absorbed energy. The optimal structure configuration is established in terms of reducing the possible negative effect of laser impact on the pyroelectric coefficient stability. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Pyroelectric transducers for the measurement of heat transfer under conditions of hypersonic flow.
Pyroelectric transducers of barium titanate for heat transfer measurement under hypersonic flow, discussing calibration
Burdick, G. A.↗
Pyroelectric effect in barium titanate ceramic
Pyroelectric coefficient extrema measurement at constant stress in barium titanate ceramic at various temperature ranges for various transition points
Lang, S. B.↗
PVF pyroelectric radiometer
Polyvinylfluoride (PVF) plastic film was found to be a good pyroelectric material. Radiometers using PVF were developed that exhibit high sensitivity and frequency response. Normalized detectivities of greater than 10 to the 8th power cm/Hz/w and responsivities on the order of 100,000 V/W were measured (500 C BB source, 0.1 Hz chopping frequency and 1 Hz bandwidth.)
Russell, L. D.↗
Optical damage and internal fields in pyroelectrics.
The physical conditions under which the models of optical damage in pyroelectrics suggested by Johnston (1970) and by Amodei (1971) might be valid are described. Whether the zero-internal-field final state described by Johnston or the no-current-flow steady state of Amodei can be reached depends on the pattern of excitation and the dynamics of the damage process. In view of the small carrier diffusion lengths, the one-dimensional models generally used may not be entirely satisfactory for investigation of dynamics.
Wood, V. E.↗
Evaluation of commercial pyroelectric detectors
A series of commercially available pyroelectric detectors made from PVF2, LTO, SBN, and TGS were evaluated in terms of responsivity and detectivity as a function of frequency. The performance of the detectors evaluated was very different, depending upon the manufacturer of the detector, and this dependency was primarily related to the thickness of the various detectors. The best detectors of each material were comparable in performance at frequencies around 10 Hz but differed radically at frequencies above 100 Hz.
Robertson, J. B.↗
Improved detectivity of pyroelectric detectors
High detectivity single-element SBN pyroelectric detectors were fabricated. The theory and technology developments related to improved detector performance were identified and formulated. Improved methods of material characterization, thinning, mounting, blackening and amplifier matching are discussed. Detectors with detectivities of 1.3 x 10 to the 9th power square root of Hz/watt at 1 Hz are reported. Factors limiting performance and recommendations for future work are discussed.
Marshall, D. E.↗
Technique for mounting pyroelectric detector arrays
Technique is developed at Langley Research Center for mounting pyroelectric detector arrays on silicon integrated circuits. Procedure incorporates normal silicon integrated-circuit technology to form quasi-free mounts for detector arrays. Advantages of technique include lower cost, better image registration, and improved reliability.
Breckenridge, R. A.↗
Development of improved lithium tantalate pyroelectric detectors
A program was undertaken to increase the detectivity of LiTaO3 pyroelectric detectors to meet a performance requirement of D star (500 K, 15 Hz)=4x10 to the 9th power cm Hz1/2W-1. Emphasis was placed on reduction of the thermal conductance of the detector element to its surroundings, thinning the detector wafer to a thickness less than 3 micrometers, and increasing the absorptivity of the standard metallic film coatings. During the program, thermal conductance was reduced 41 percent through the use of reticulated (slotted) structures. Self-supported detector wafers less than 2 micrometers thick were fabricated. Multiple layer coatings, including an AR coating, with 16 percent more absorptance, were designed and fabricated. Later refinements in the multilayer design program have absorptivities of 75-80 percent, but detectors with these coatings had to be more than 2 micrometers thick because of a mismatch in the thermal expansion coefficients with LiTaO3.
Byer, N. E.↗
Piezoelectricity and pyroelectricity in polyvinylidene fluoride - Influence of the lattice structure
Piezoelectric and pyroelectric responses of beta-phase (Phase I) polyvinylidene fluoride are predicted for a model system of polarizable point dipoles. The model incorporates the influence of the orthorhombic crystal structure by including the dependence of the internal electric field on the lattice parameters. Strong anisotropy in the piezoelectric response under uniaxial stress is predicted as a consequence of the orthorhombic lattice structure. Predictions are found to be in reasonable agreement with room-temperature experimental data.
Purvis, C. K.↗
Pyroelectric detector development for the Radiation Measurement system
A new class of high detectivity pyroelectric detectors developed for optimization of the radiation measurement system within the framework of the Atmospheric Radiation Measurement program is described. These devices are intended to provide detectivities of up to about 10 exp 11 cm Hz exp 0.5/W with cooling to about 100 K required for the detector focal plane.
Hubbard, G. S.↗
Pyroelectric Applications of the VDF-TrFE Copolymer
VDF/TrFe pyroelectric sensors have now definitely reached the level of a product. Based on a bidimensional staring array, it can be considered as a whole system with a monolithic technology processed on a silicon substrate provided with the integrated read out circuit. The paper will describe the main procedure dealing with the elaboration of a 32 x 32 focal plane array developed, in the context of the PROMETHEUS PROCHIP European Program (EUREKA), as a passive infrared obstacle detection applied to automotive. Additional experimental data suggest that this microsystem could operate in space environment.
Simonne, J. J.↗
Thermally Stable Piezoelectric and Pyroelectric Polymers
A class of thermally stable piezoelectric and pyroelectric polymers, and an improved method of making them, have been invented. These polymers can be used as substrates for a wide variety of electromechanical transducers, sensors, and actuators.
Simpson, Joycelyn O.↗
Improved Ambient Pressure Pyroelectric Ion Source
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.
Beegle, Luther W.↗
Noncollinear magnetic order, in-plane anisotropy, and magnetoelectric coupling in the pyroelectric honeycomb antiferromagnet Ni 2 Mo 3 O 8
Not Available
Yadav, Poonam (ORCID:0000000217451073)↗