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- Ferroelectric Materials (3)
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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Vortex Lattice Symmetry And Electronic Structure In Yba₂Cu₃O₇, Bernhard Keimer, Wan Y. Shih, Ross W. Erwin, Jeffrey W. Lynn, Fatih Dogan, Ilhan A. Aksay
Vortex Lattice Symmetry And Electronic Structure In Yba₂Cu₃O₇, Bernhard Keimer, Wan Y. Shih, Ross W. Erwin, Jeffrey W. Lynn, Fatih Dogan, Ilhan A. Aksay
Materials Science and Engineering Faculty Research & Creative Works
We report a small angle neutron scattering study of the vortex lattice in YBa2Cu3O7 in magnetic fields of 0.5≤H≤5 T applied along and close to the c axis. Over the entire field range, the vortices form an oblique lattice with two nearly equal lattice constants and an angle of 73°between primitive vectors. Numerical calculations suggest that variations of the superconducting order parameter near the vortex core are important in stabilizing this structure. An analysis that accounts for the fourfold symmetry of the vortex core qualitatively explains both the symmetry and the orientation of the observed …
Method Of Manufacture Of Multiple-Element Piezoelectric Transducer, Lawrence J. Busse, Jeffry W. Stevenson, Wayne Huebner
Method Of Manufacture Of Multiple-Element Piezoelectric Transducer, Lawrence J. Busse, Jeffry W. Stevenson, Wayne Huebner
Materials Science and Engineering Faculty Research & Creative Works
An improved method for fabrication of a multiple-element piezoelectric transducer and the transducer produced thereby. A green precursor tape is produced by doctor-blade tape-casting of a slurry containing lead zirconate-titanate (PZT) powder. After drying, individual strips of the tape are stacked between flat plates of previously sintered PZT, and sintered to form PZT strips; Pb from the previously sintered PZT plates makes up any Pb lost from the surfaces of the tape strips during sintering. The PZT strips are stacked interposed by layers of a thermoplastic polymer, and heated to a temperature above the melting point of the polymer, forming …
Nature Of The Ferroelectric Phase Transition In Pbtio₃, Noam Sicron, Bruce D. Ravel, Yitzhak Yacobi, Edward A. Stern, Fatih Dogan, John J. Rehr
Nature Of The Ferroelectric Phase Transition In Pbtio₃, Noam Sicron, Bruce D. Ravel, Yitzhak Yacobi, Edward A. Stern, Fatih Dogan, John J. Rehr
Materials Science and Engineering Faculty Research & Creative Works
We have measured quantitatively the temperature dependence of the local distortions of PbTiO3 crystals below and above the structural ferroelectric phase transition, using x-ray absorption fine-structure (XAFS) measurements. Two probe atoms, Pb and Ti, were used. The results were analyzed by fitting parametrized theoretical XAFS spectra to the experimental results. These measurements provide quantitative distortion parameters defined as the difference between the distance of the probe to its nearest neighbor measured in the actual structure and that in a centrosymmetric structure with the same unit cell dimensions. At low temperatures the Pb-edge spectra were fit using four shells and …
Simple Apparatus For Producing Single Liquid Drops, Dhiren Panda, D. G. C. Robertson
Simple Apparatus For Producing Single Liquid Drops, Dhiren Panda, D. G. C. Robertson
Materials Science and Engineering Faculty Research & Creative Works
A simple experimental apparatus has been used to produce individual mercury and sodium amalgam drops in the size range of 0.3-2.5 mm diam. A high resistance to the flow of liquid was provided by a capillary tube. The cross section consisted of a 0.20 mm o.d. tungsten wire placed in a 0.25 mm capillary bore. By this method, flow rates of 1 μl/s and lower were obtained, which enabled the formation of drops as small as 1 mm diam in a time interval of 20 s. The drops were formed at a plastic tip, and on reaching the desired size, …
The Response Of Dispersion-Strengthened Copper Alloys To High Fluence Neutron Irradiation At 415⁰C, Danny J. Edwards, Joseph William Newkirk, Frank A. Garner, Margaret L. Hamilton, A. Nadkarni, P. Samal
The Response Of Dispersion-Strengthened Copper Alloys To High Fluence Neutron Irradiation At 415⁰C, Danny J. Edwards, Joseph William Newkirk, Frank A. Garner, Margaret L. Hamilton, A. Nadkarni, P. Samal
Materials Science and Engineering Faculty Research & Creative Works
Various oxide-dispersion-strengthened copper alloys have been irradiated to 150 dpa at 415°C in the Fast Flux Test Facility (FFTF). The Al2O3-strengthened GlidCop™ alloys, followed closely by a HfO2-strengthened alloy, displayed the best swelling resistance, electrical conductivity, and tensile properties. The conductivity of the HfO2-strengthened alloy reached a plateau at the higher levels of irradiation, instead of exhibiting the steady decrease in conductivity observed in the other alloys. A high initial oxygen content resulted in significantly higher swelling for a series of castable oxide-dispersion-strengthened alloys, while a Cr2O3 -strengthened alloys …
The Reduction Of Dielectric Constant By Shaped Porosity, Weiping Cai
The Reduction Of Dielectric Constant By Shaped Porosity, Weiping Cai
Opportunities for Undergraduate Research Experience Program (OURE)
In multi-layer circuits, the reduction of the dielectric constant in substrate materials is becoming increasingly important, as the heat emission of the circuits increases with an increasing number of layers. One way to achieve a lower dielectric constant is to create porosity in the material. In this project, two types of substrate samples were made with coin-shaped porosity. One had holes of 8.0mm in diameter, and the other had holes of 2.5mm in diameter. The total vacuum area was 250mm2, or 7.7% of the total area, in either case. It was hoped to discover a relationship between aspect …
Solubility Of Red Phosphorous In Lead, Sean E. Walker
Solubility Of Red Phosphorous In Lead, Sean E. Walker
Opportunities for Undergraduate Research Experience Program (OURE)
The determination of the solubility of red phosphorus in lead can be used to produce a plot of the solubility with respect to temperature and pressure. The plot is produced with experimental data, activity determination from present thermodynamic data, and compilation of the two sets of data into the semi-regular solution format. A lead-phosphorus solubility diagram is necessary to determine the amount phosphorus that will be absorbed by lead and will remain unreacted in a given process.
Microspheres For Radiation Therapy, D. E. Day, Gary J. Ehrhardt
Microspheres For Radiation Therapy, D. E. Day, Gary J. Ehrhardt
Materials Science and Engineering Faculty Research & Creative Works
Microspheres for radiation therapy of a mammal which have a non-radioactive isotope which emits beta or gamma radiation of therapeutic intensity upon being irradiated. The microspheres also contain elements which do not become radioactive upon irradiation. The chemical durability of the microspheres is such that they do not release a significant amount of radiation emitting radioisotope into the mammal’s system upon administration. Microspheres containing phosphorus or yttrium; and carbon, nitrogen, fluorine, sodium, magnesium, aluminum, silicon, potassium, vanadium, manganese, gallium, niobium, iodine and/or lead.
Vortex Structures In Yba₂Cu₃O₇ (Invited), Bernhard Keimer, Jeffrey W. Lynn, Ross W. Erwin, Fatih Dogan, Wan Y. Shih, Ilhan A. Aksay
Vortex Structures In Yba₂Cu₃O₇ (Invited), Bernhard Keimer, Jeffrey W. Lynn, Ross W. Erwin, Fatih Dogan, Wan Y. Shih, Ilhan A. Aksay
Materials Science and Engineering Faculty Research & Creative Works
Extensive small angle neutron scattering experiments have been conducted on the vortex system in YBa2Cu3O7 in a magnetic field range of 0.5 T≤H≤5 T, and with various orientations of the magnetic field with respect to the crystallographic axes. For H parallel to the c axis, the vortex lattice is oblique with two nearly equal lattice constants and an angle of 73°between primitive vectors. One principal axis of the vortex lattice coincides with the (110) direction of the crystal lattice. It is shown that this structure cannot be explained in the framework of a purely electrodynamic …
A Study Of The Sintering Mechanism Of Pzt-Based Piezoceramics, Wayne Huebner, Pei Wen Lu, Wanrong Xue
A Study Of The Sintering Mechanism Of Pzt-Based Piezoceramics, Wayne Huebner, Pei Wen Lu, Wanrong Xue
Materials Science and Engineering Faculty Research & Creative Works
The densification behavior a PZT-based composition with additions of BiFeO3 as a flux was studied. Two different PZT powders were studied with varying initial particle sizes. Results clearly showed that BiFeO3 forms a low temperature liquid that aids in the densification behavior, with 3 mole% being optimum. Fine particle sizes substantially improved the density at low temperatures, with the net result that ceramics could be densified in air without the aid of a lead source. The corresponding electromechanical properties were typical of a hard PZT formulation.
Correlation Of Wettability And Interfacial Reaction To The Densification And Dielectric Properties Of Fluxed-Batio₃, Sea-Fue Wang, Wayne Huebner, Joseph P. Dougherty
Correlation Of Wettability And Interfacial Reaction To The Densification And Dielectric Properties Of Fluxed-Batio₃, Sea-Fue Wang, Wayne Huebner, Joseph P. Dougherty
Materials Science and Engineering Faculty Research & Creative Works
Reducing the sintering temperature of BaTiO3 has typically been achieved through the use of a fluxing agent to promote densification by liquid phase sintering. Liquid phase formation in these systems is due either to the melting of the flux or to the formation of a eutectic liquid between the flux and BaTiO3. In this paper, the correlation between the wettability and interfacial reactions between fluxes and BaTiO3 with respect to the densification behavior associated with liquid phase sintering, and the resulting dielectric properties is presented. Fluxes used in this study include 5ZnO*2B2O3, 5CdO*2SiO2, Pb5Ge3O11, CuO*TiO2, 3Bi2O3*B2O3, and LiF.
Fabrication Of 2-2 Connectivity Pzt/Thermoplastic Composites For High Frequency Linear Arrays, Wayne Huebner, Mary R. Reidmeyer, L. Busse, Jeffry W. Stevenson
Fabrication Of 2-2 Connectivity Pzt/Thermoplastic Composites For High Frequency Linear Arrays, Wayne Huebner, Mary R. Reidmeyer, L. Busse, Jeffry W. Stevenson
Materials Science and Engineering Faculty Research & Creative Works
An alternate approach for fabricating PZT/polymer composites with 2-2 connectivity with fine scales is described. Thin (less than or equal to 20 micrometers) sintered PZT plates and sheets of a thermoplastic polymer film (less than or equal to 10 micrometers) were bonded together via thermal processing. Stack sintering of tape cast PZT generated the necessary PZT plates, while tape cast polymers were used to control the thermoplastic thickness. Composite blocks were cut to required dimensions for linear arrays, electroded, and poled. Electromechanical properties were measured to evaluate the composites. The significance of this fabrication technique is that it is able …
Processing And Characterization Of Samarium And Manganese Modified Lead Titanate Thin Film, Chen-Lung Fan, Wayne Huebner
Processing And Characterization Of Samarium And Manganese Modified Lead Titanate Thin Film, Chen-Lung Fan, Wayne Huebner
Materials Science and Engineering Faculty Research & Creative Works
Samarium and manganese modified lead titanate thin films were fabricated by spin-coating an amorphous citrate precursor. These films transformed into an oxide film upon heat treatment at 400 degrees Celcius or above. Relatively large area and crack-free thin films could be obtained by this process both easily and inexpensively. The rheological behavior of the precursor solution, as well as its thermal decomposition and phase development were studied by means of DSC/TGA and XRD. The thickness and grain size of the oxide film were examined by TEM and SEM.