For Fe78B13Si9 (Allied 2605 S2) amorphous ribbon the extent of annealing embrittlement was measured by a bending test. The stress relief by Joule heating at high temperatures and short times obeys a kinetic relation a...
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For Fe78B13Si9 (Allied 2605 S2) amorphous ribbon the extent of annealing embrittlement was measured by a bending test. The stress relief by Joule heating at high temperatures and short times obeys a kinetic relation and has an activation energy of 25 kJ/mol. Comparing the stress relief at lower temperatures shows the possibility of two consecutive processes. Some atoms at critical positions must diffuse away (due to high activation energy) before the surrounding atoms can rearrange themselves (low activation energy) to relieve the stresses. The stress relief and improvement of magnetic properties could be achieved by Joule heating without much annealing embrittlement.
In light-emitting diodes (LEDs) of standard configuration - Indium-Tin-Oxide (ITO)/polymer/metal, we observed light emission under ac or forward/reverse de bias, using poly(p-phenylene vinylenes) prepared via the sulf...
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In light-emitting diodes (LEDs) of standard configuration - Indium-Tin-Oxide (ITO)/polymer/metal, we observed light emission under ac or forward/reverse de bias, using poly(p-phenylene vinylenes) prepared via the sulfonium salt (S-PPV) or xanthate (X-PPV) routes as active electroluminescent layers. S-PPV devices exhibited approximately symmetrical current-voltage characteristics under forward and reverse de bias with the same onset voltage. The electroluminescence (EL) spectra either under a de forward/reverse bias or ac were identical. X-PPV showed EL under reverse bias at higher voltage than in forward bias. Symmetrical current-voltage characteristics in S-PPV devices is attributed to ionic impurities present in the polymer.
Automotive taillights play crucial roles in providing essential signals about vehicle status, representing brand design identity, and contributing to aesthetic appeal. In this study, a host matrix-free quantum dot (QD...
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A second order phase transformation in a dielectric ceramic superconductor is shown to relate jumps in physical properties to the ratio of state variables, i.e., to the phase boundary, near the critical point. The maj...
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A second order phase transformation in a dielectric ceramic superconductor is shown to relate jumps in physical properties to the ratio of state variables, i.e., to the phase boundary, near the critical point. The major jumps in specific heat, compressibility, permittivity, permeability, and spinodal composition curvature, between the normal and superconducting phases, are found from the continuity of the entropy, volume, electromagnetic fields (with zero fields), and chemical equilibrium. The thermal expansion, pyroelectric effects, and the piezoelectromagnetic effects are important differences between ceramic and metallic superconductors. The most important conclusions from experimental measurements are that the lattice plays a minor role in the superconductor transformation while the magnetoelectric jump may be related to the jump in permeability, i.e., the Meissner effect, and the jump in permittivity. The oxygen miscibility gap which controls order/disorder transformations thermodynamically mandate that only metastable compositions are obtained in the metal oxide, so absolute stability of the system may never be achieved. An explicit criterion to suggest other superconductor systems is given from magnetoelectric materials, i.e., some of the pervoskites.
Measurements of the partial pressure of Hg over Te-saturated Hg1-xCdxTe(s) between 400 and 500 K indicate the formation of a miscibility gap. X-ray diffraction measurements indicate this gap develops most rapidly at t...
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Measurements of the partial pressure of Hg over Te-saturated Hg1-xCdxTe(s) between 400 and 500 K indicate the formation of a miscibility gap. X-ray diffraction measurements indicate this gap develops most rapidly at the surface.
In this paper we explore the crystallization kinetics of poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and miscible blends of PBT with a polyarylate based on Bisphenol A and a 75/25 mole rati...
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In this paper we explore the crystallization kinetics of poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and miscible blends of PBT with a polyarylate based on Bisphenol A and a 75/25 mole ratio of isophthalic and terephthalic acids. For PBT, a regime II --> III transition is indicated near 210-degrees-C (DELTA-T approximately 30-degrees-C) and the fold surface free energy (sigma(e)) was found to be in the range of 57-75 erg/cm2. This leads to a work of chain folding (q) of approximately 3-5 kcal/mol folds. Analysis of the crystallization data of van Antwerpen and van Krevelen for PET shows that crystallization occurs in regime II across a wide range of T(c). Sigma(e) was estimated to be approximately 140 erg/cm2 and q approximately 10 kcal/mol from their data. These values are roughly twice that of PBT, consistent with the longer flexible segments in the PBT repeat unit. Crystallization data for three PBT/PAr blends was analyzed using a modified Lauritzen-Hoffman method and compared to that of pure PBT.
A statistical thermodynamic derivation of the equilibrium equations for two defect models for CdTe(s) at high temperatures is given. In the first the predominant defects are assumed to be doubly ionizable Cd vacancy a...
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A statistical thermodynamic derivation of the equilibrium equations for two defect models for CdTe(s) at high temperatures is given. In the first the predominant defects are assumed to be doubly ionizable Cd vacancy accepters and singly ionizable Te antisite donors in Te rich material and doubly ionizable Te vacancy donors in Cd rich material. A variant in which the Te antisite defect is neutral is readily extracted from the equations by setting the donor level far enough below the conduction band edge. In the second model the Te antisite defect is replaced by a neutral Te interstitial defect. The models are then applied to the high temperature data. It is concluded that the singly ionizable Te antisite model gives the best overall fit and various high temperature properties are calculated with two sets of the adjustable parameters.
The partial pressure of Hg over Te‐saturated has been determined between 385 K, where it is , and 724 K, where it is , by measuring the optical absorbance at 253.7 nm of the vapor phase. The data below the 686 K eute...
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The partial pressure of Hg over Te‐saturated has been determined between 385 K, where it is , and 724 K, where it is , by measuring the optical absorbance at 253.7 nm of the vapor phase. The data below the 686 K eutectic with Te(c) are used to calculate the standard Gibbs energy of formation and to obtain and . Published data for the partial pressures of Hg and between 770 and 943 K are reanalyzed to give the standard Gibbs energy, and , and . The two sets of values agree within the 95% confidence level uncertainties given. However, the standard enthalpy of formation at 298 K differs significantly from the accepted value.
As a ubiquitous substance in nature, ice has attracted substantial research interest across a variety of fields, including physics, environmental science, biology, and cryopreservation. However, the intricate structur...
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Transient (unsteady-state) kinetics, a relatively new technique for studying noncatalytic gas/solid reactions, has been used successfully to further our understanding of char (carbon) gasification. It provides the uni...
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Transient (unsteady-state) kinetics, a relatively new technique for studying noncatalytic gas/solid reactions, has been used successfully to further our understanding of char (carbon) gasification. It provides the unique capability of separately determining the reaction rate constant (site reactivity or turnover frequency) and the number of active sites participating in the reaction (reactive surface area). Its application to the uncatalyzed gasification of coal-derived chars and polymer-derived carbons is illustrated. In particular, the heretofore elusive quantitative understanding of their reactivity variations with conversion has been achieved for gasification in both carbon dioxide and oxygen.
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