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Full-Text Articles in Physical Sciences and Mathematics
Phase Transitions And Change Of Type In Low-Temperature Heat, Ralph A. Saxton, Katarzyna Saxton
Phase Transitions And Change Of Type In Low-Temperature Heat, Ralph A. Saxton, Katarzyna Saxton
Mathematics Faculty Publications
Classical heat pulse experiments have shown heat to propagate in waves through crystalline materials at temperatures close to absolute zero. With increasing temperature, these waves slow down and finally disappear, to be replaced by diffusive heat propagation. Several features surrounding this phenomenon are examined in this work. The model used switches between an internal parameter (or extended thermodynamics) description and a classical (linear or nonlinear) Fourier law setting. This leads to a hyperbolic-parabolic change of type, which allows wavelike features to appear beneath the transition temperature and diffusion above. We examine the region around and immediately below the transition temperature, …
Phase Shifts In Frustrated Total Internal Reflection And Optical Tunneling By An Embedded Low-Index Thin Film, R. M.A. Azzam
Phase Shifts In Frustrated Total Internal Reflection And Optical Tunneling By An Embedded Low-Index Thin Film, R. M.A. Azzam
Electrical Engineering Faculty Publications
Simple and explicit expressions for the phase shifts that p- and s-polarized light experience in frustrated total internal reflection (FTIR) and optical tunneling by an embedded low-index thin film are obtained. The differential phase shifts in reflection and transmission Δr,Δt are found to be identical, and the associated ellipsometric parameters ψr,ψt are governed by a simple relation, independent of film thickness. When the Fresnel interface reflection phase shifts for the pand s polarizations or their average are quarter-wave, the corresponding overall reflection phase shifts introduced by the embedded layer are also quarter-wave for all values of film …
Annealing Effects On The Crystallite Size And Dielectric Properties Of Ultrafine Ba1-Xsrxtio3 (0 < X < 1) Powders Synthesized Through An Oxalate-Complex Precursor, Gabriel Caruntu, Charles J. O'Connor
Annealing Effects On The Crystallite Size And Dielectric Properties Of Ultrafine Ba1-Xsrxtio3 (0 < X < 1) Powders Synthesized Through An Oxalate-Complex Precursor, Gabriel Caruntu, Charles J. O'Connor
Chemistry Faculty Publications
Nanocrystalline Ba12xSrxTiO3 (0 , x , 1) nanopowders were prepared through the oxalate route and the influence of the thermal history on their dielectric properties was investigated. For pelletized samples obtained by decomposing the corresponding oxalate intermediates at 600 uC and then annealed at different temperatures ranging from 600 to 1000 uC the dielectric constant decreases upon increasing the strontium content of the samples. Similar behavior was observed with decreasing the temperature of the thermal treatment of the pellets, a trend which is presumably ascribed to a synergic effect of decreasing the porosity of the samples, the increase of the …
The Integral Cohomology Of The Group Of Loops, Craig Jensen, Jon Mccammond, John Meier
The Integral Cohomology Of The Group Of Loops, Craig Jensen, Jon Mccammond, John Meier
Mathematics Faculty Publications
No abstract provided.
Magnetic And Transport Properties Of Nimnal Thin Films, Andriy Vovk, Minghui Yu, Leszek Malkinski, Charles O'Connor, Zhenjun Wang, Eden Durant, Jinke Tang, Vladimir Golub
Magnetic And Transport Properties Of Nimnal Thin Films, Andriy Vovk, Minghui Yu, Leszek Malkinski, Charles O'Connor, Zhenjun Wang, Eden Durant, Jinke Tang, Vladimir Golub
Physics Faculty Publications
The magnetic and transport properties of Ni2MnAl thin films prepared using pulse laser deposition were investigated. It was shown that the films are granular and multiphase. Contrary to the data reported earlier we observe nonmonotonic temperature dependence of resistance with minimum in the vicinity of 100 K for the films deposited on substrates held at 773 K and negative magnetoresistance (MR) values of about 2.5% at 5 K and 1.6% at RT in magnetic field of 50 kOe. These values of MR are the highest reported up to date for Ni2MnAl films. Large negative MR in …
Aberration-Free Negative-Refractive-Index Lens, Jiajun Chen, Cosmin Radu, Ashok Puri
Aberration-Free Negative-Refractive-Index Lens, Jiajun Chen, Cosmin Radu, Ashok Puri
Physics Faculty Publications
The aberrations of a spherical lens composed of left-handed materials are studied in this letter. Five Seidel aberrations (spherical, coma, astigmatism, field curvature, and distortion) as a function of the refractive index n and shape factor q of the lens are considered. Our numerical calculations show that the negative refractive index gives much larger windows of small values of aberrations than the positive index, which will significantly enhance the flexibility for the design of an optical lens. Two possible regions with optimized aberrations are proposed: n = −1, q = −2.2 and n = −0.81 and q = 0.83