The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
J. C. Li - One of the best experts on this subject based on the ideXlab platform.
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Grain size-dependent diffusion activation energy in nanomaterials
Solid State Communications, 2004Co-Authors: Q.c. Jiang, S H Zhang, J. C. LiAbstract:We report a unified model, free of any adjustable parameter, for size-dependence of intrinsic diffusion activation energy of elements in crystals. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius Relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of N into bcc Fe and Ag into Au nanoparticles.
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Grain size-dependent diffusion activation energy in nanomaterials
Solid State Communications, 2004Co-Authors: Q Jiang, S H Zhang, J. C. LiAbstract:We report a unified model, free of any adjustable parameter, for size-dependence of intrinsic diffusion activation energy of elements in crystals. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius Relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of N into bcc Fe and Ag into Au nanoparticles. © 2004 Elsevier Ltd. All rights reserved.
Q Jiang - One of the best experts on this subject based on the ideXlab platform.
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Grain size-dependent diffusion activation energy in nanomaterials
Solid State Communications, 2004Co-Authors: Q Jiang, S H Zhang, J. C. LiAbstract:We report a unified model, free of any adjustable parameter, for size-dependence of intrinsic diffusion activation energy of elements in crystals. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius Relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of N into bcc Fe and Ag into Au nanoparticles. © 2004 Elsevier Ltd. All rights reserved.
S H Zhang - One of the best experts on this subject based on the ideXlab platform.
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Grain size-dependent diffusion activation energy in nanomaterials
Solid State Communications, 2004Co-Authors: Q.c. Jiang, S H Zhang, J. C. LiAbstract:We report a unified model, free of any adjustable parameter, for size-dependence of intrinsic diffusion activation energy of elements in crystals. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius Relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of N into bcc Fe and Ag into Au nanoparticles.
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Grain size-dependent diffusion activation energy in nanomaterials
Solid State Communications, 2004Co-Authors: Q Jiang, S H Zhang, J. C. LiAbstract:We report a unified model, free of any adjustable parameter, for size-dependence of intrinsic diffusion activation energy of elements in crystals. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius Relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of N into bcc Fe and Ag into Au nanoparticles. © 2004 Elsevier Ltd. All rights reserved.
J T Carstensen - One of the best experts on this subject based on the ideXlab platform.
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examination of a modified Arrhenius Relationship for pharmaceutical stability prediction
International Journal of Pharmaceutics, 1990Co-Authors: K D Ertel, J T CarstensenAbstract:Abstract A modified Arrhenius Relationship was derived and used to treat simulated accelerated stability data. The results obtained were compared to those when the same data were treated according to the traditional method. The modified method presented here is easy to apply and in many cases yields a narrower predicted room temperature stability interval than does application of the traditional Arrhenius method.
F. R. Diaz - One of the best experts on this subject based on the ideXlab platform.
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Thermogravimetric Analysis of Poly(Amide-Carbonate)s and Poly(Amide-Thiocarbonate)s
International Journal of Polymeric Materials, 1999Co-Authors: L. H. Tagle, F. R. Diaz, A. GodoyAbstract:Abstract The thermogravimetric behaviour of poly(amide-carbonate)s and poly(amide-thiocarbonate)s was studied by dynamic thermogravimetry. The thermal decomposition temperatures were determined, showing that for polymers derived from the aliphatic monomer I showed a very similar thermal decomposition temperature, but for those derived from the aromatic monomer II. the poly(amide-carbonate) showed more stability than the corresponding thiocarbonate. The kinetic parameters, activation energy, reaction order and pre-exponential factor were determined by using the Arrhenius Relationship and a computer program.
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Thermogravimetric analysis of polycarbonates and polythiocarbonates with chlorine atoms
International Journal of Polymeric Materials, 1994Co-Authors: L. H. Tagle, F. R. DiazAbstract:Abstract The thermal stability and kinetics parameters of polycarbonates and polythiocarbonates derived from diphenols with chlorine atoms in the aromatic rings were studied, showing that polycarbonates have a higher thermal stability than the polythiocarbonates. All polymers degraded in a single stage in the considered temperature range, and the kinetics parameters were determined by using the Arrhenius Relationship and a computer program. Polycarbonates degraded by a zero order kinetics, while polythiocarbonates by a first order kinetic.
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Thermogravimetric Analysis of Polyesters Derived from 2,2-bis(4-chloroformyl-phenyl)-propane and 4,4′-Biphenyl-Dicarboxyl Chloride
International Journal of Polymeric Materials, 1993Co-Authors: L. H. Tagle, F. R. DiazAbstract:Abstract The thermal stability and the kinetic parameters of a series of polyesters were studied by non-isothermal thermogravimetry. The thermal decomposition temperatures (TDT) depend principally on the nature of the diphenols, in the sense that when the bulk of the diphenol is increased, the TDT values decrease. The kinetic parameters, determined using the Arrhenius Relationship, show that these polyesters degrade by a complex mechanism or possibly two or more superimposed processes, probably due to the complex structure of both diacids and diphenols.
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Thermogravimetric analysis of copoly(carbonate-thiocarbonate)S
Thermochimica Acta, 1991Co-Authors: L. H. Tagle, F. R. DiazAbstract:Abstract The thermal stability and the kinetics parameters of copoly(carbonate-thiocarbonate)s from two diphenols and for three different compositions were studied. No clear relation between the thermal decomposition temperature and the carbonate content was found for the two series of copolymers. The kinetics parameters of the thermal decomposition were determined using the Arrhenius Relationship and indicated a two-step degradation process, the first step being of zero kinetic order and the second of first order. The steps were associated with two different decomposition mechanisms.
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Thermogravimetric analysis of polycarbonates and polythiocarbonates with chlorinated aromatic side-rings
Journal of Thermal Analysis and Calorimetry, 1990Co-Authors: L. H. Tagle, F. R. Diaz, C. MargozziniAbstract:The thermal stability and kinetics parameters of polycarbonates and polythiocarbonates derived from diphenols with chlorinated aromatic side-rings were studied. The polycarbonates exhibited a higher thermal stability than the polythiocarbonates, except for polythiocarbonate Ib, which displayed similar behaviour to that of the analogous polycarbonate. The kinetic parameters of the thermal decomposition were determined by using the Arrhenius Relationship and a computer program. In the considered temperature range, all the polymers degraded in a single stage with first-order kinetics.
