Thermal Expansion Of GaN And Ain

1997 ◽  
Vol 482 ◽  
Author(s):  
Kai Wang ◽  
Robert R. Reeber
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Lattice Parameter Data ◽  
Equations Of State ◽  
Lattice Parameter ◽  
Epitaxial Films ◽  
Residual Stress Distribution ◽  
Interatomic Potentials ◽  
Semiempirical Models

AbstractThe temperature dependence of the thermal expansion and the bulk modulus are critical for predicting the residual stress distribution in epitaxial films and provides information relevant for interatomic potentials and equations of state. The thermal expansions of aluminum nitride (AIN) and gallium nitride (GaN) are calculated with two models that employ the limited elastic and lattice parameter data. These semiempirical models allow prediction of the thermal expansions to higher temperatures. Calculated results are compared with experimental data.

scholarly journals Thermal Residual Stress Modeling in AlN and GaN Multi Layer Samples

1999 ◽  
Vol 4 (S1) ◽  
pp. 209-214 ◽  
Author(s):  
Kai Wang ◽  
Robert R. Reeber
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Thermal Expansion ◽  
Optical Properties ◽  
Epitaxial Films ◽  
Residual Stress Distribution ◽  
Thermal Residual Stresses ◽  
Modeling Analysis ◽  
Device Lifetime ◽  
Residual Stress Modeling

Thermal residual stresses can detrimentally affect the electronic and optical properties of epitaxial films thereby shortening device lifetime. Based on our earlier work on thermal expansion of nitrides, we provide a finite element modeling analysis of the residual stress distribution of multilayered GaN and AlN on 6H-SiC. The effects of thickness and growth temperatures are considered in the analysis.

Thermal Residual Stress Modeling in Ain and GaN Multi Layer Samples

1998 ◽  
Vol 537 ◽  
Author(s):  
Kai Wang ◽  
Robert R. Reeber
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Thermal Expansion ◽  
Optical Properties ◽  
Epitaxial Films ◽  
Residual Stress Distribution ◽  
Thermal Residual Stresses ◽  
Modeling Analysis ◽  
Device Lifetime ◽  
Residual Stress Modeling

AbstractThermal residual stresses can detrimentally affect the electronic and optical properties of epitaxial films thereby shortening device lifetime. Based on our earlier work on thermal expansion of nitrides, we provide a finite element modeling analysis of the residual stress distribution of multilayered GaN and AlN on 6H-SiC. The effects of thickness and growth temperatures are considered in the analysis.

scholarly journals Residual Stress Distribution in Feal Weld Overlay on Steel

1994 ◽  
Vol 364 ◽  
Author(s):  
X.-L. Wang ◽  
S. Spooner ◽  
C. R. Hubbard ◽  
P. J. Maziasz ◽  
G. M. Goodwin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Post Weld Heat Treatment ◽  
Residual Stress Distribution ◽  
Element Analysis ◽  
Weld Overlay

AbstractNeutron diffraction was used to measure the residual stress distribution in an FeAl weld overlay on steel. It was found that the residual stresses accumulated during welding were essentially removed by the post-weld heat treatment that was applied to the specimen; most residual stresses in the specimen developed during cooling following the post-weld heat treatment. The experimental data were compared with a plasto-elastic finite element analysis. While some disagreement exists in absolute strain values, there is satisfactory agreement in strain spatial distribution between the experimental data and the finite element analysis.

Thermal Expansion of β-Sic, Gap and Inp

1995 ◽  
Vol 410 ◽  
Author(s):  
Robert R. Reeber ◽  
Kai Wang
Keyword(s):  
Thermal Expansion ◽  
Indium Phosphide ◽  
Gallium Phosphide ◽  
Electronic Devices ◽  
Epitaxial Films ◽  
Interatomic Potentials ◽  
Harmonic Model ◽  
Melting Points ◽  
Model Calculations ◽  
Semi Empirical

ABSTRACTThermal expansion is important for predicting residual stresses in epitaxial films, composites and electronic devices as well as for providing information relevant to an understanding of interatomic potentials and the equation of state of materials. Model calculations have many assumptions, both inherent and implicit, and have difficulty accurately representing thermal expansion at high temperatures and pressures. We utilize a semi-empirical quasi-harmonic model to evaluate available data for β-silicon carbide, gallium phosphide and indium phosphide. The model allows prediction of the thermal properties of these semiconductors from near 0 K to the vicinity of their melting points. The approach, consisting of a simplified frequency spectrum with several Einstein terms, provides a convenient mathematical method where a minimum of empirical parameters represent the thermal property.

Quenching of Aluminum Solid Cylinder: Numerical Study

2019 ◽  
Author(s):  
Shahriar Jahanian
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Reasonable Agreement ◽  
Numerical Study ◽  
Residual Stress Distribution ◽  
Solid Cylinder ◽  
Temperature Dependent Properties ◽  
Sine Law

A numerical method is presented for evaluating the residual stress distribution in a long aluminum solid cylinder subjected to rapid cooling. An analytical model is developed for the temperature distribution. For the boundary conditions, experimental data for the outer surface of the cylinder are used, and a reasonable agreement between the predicted temperature distribution at the center of the cylinder and the experimental data is observed. For the numerical analysis, a quasi-static, uncoupled thermoelastoplastic analysis, based on a hyperbolic sine law, is presented. The numerical results are presented for the temperature distribution as well as the thermoelastoplastic stress distribution in a solid cylinder with temperature-dependent properties. The residual stress distribution is compared with the results of other investigators who used the Finite Element Method, and a reasonable agreement between our results and previous results is observed. The conclusion is reached that the temperature dependency of the yield stresses and the problem of post-yielding are two important factors to be considered when developing a model for predicting the residual stresses in quenched bodies.

SIZE AND TEMPERATURE EFFECT ON THERMAL EXPANSION COEFFICIENT AND LATTICE PARAMETER OF NANOMATERIALS

2013 ◽  
Vol 27 (25) ◽  
pp. 1350180 ◽  
Author(s):  
RAGHUVESH KUMAR ◽  
GEETA SHARMA ◽  
MUNISH KUMAR
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Temperature Dependence ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Size Dependence ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Parameter ◽  
Model Predictions ◽  
Good Agreement

A simple theoretical model is developed to study the effect of size and temperature on the coefficient of thermal expansion and lattice parameter of nanomaterials. We have studied the size dependence of thermal expansion coefficient of Pb , Ag and Zn in different shape viz. spherical, nanowire and nanofilm. A good agreement between theory and available experimental data confirmed the model predictions. We have used these results to study the temperature dependence of lattice parameter for different size and also included the results of bulk materials. The temperature dependence of lattice parameter of Zn nanowire and Ag nanowire are found to present a good agreement with the experimental data. We have also computed the temperature and size dependence of lattice parameter of Se and Pb for different shape viz. spherical, nanowire and nanofilm. The results are discussed in the light of recent research on nanomaterials.

scholarly journals PASCal: a principal axis strain calculator for thermal expansion and compressibility determination

2012 ◽  
Vol 45 (6) ◽  
pp. 1321-1329 ◽  
Author(s):  
Matthew J. Cliffe ◽  
Andrew L. Goodwin
Keyword(s):  
Thermal Expansion ◽  
Lattice Parameter Data ◽  
Principal Axis ◽  
Molecular Conformation ◽  
Variable Temperature ◽  
Lattice Parameter ◽  
Mechanical Anisotropy ◽  
Variable Pressure ◽  
Coordination Polyhedra ◽  
Compressibility Effect

This article describes a web-based tool (PASCal; principal axis strain calculator; http://pascal.chem.ox.ac.uk) designed to simplify the determination of principal coefficients of thermal expansion and compressibilities from variable-temperature and variable-pressure lattice parameter data. In a series of three case studies,PASCalis used to reanalyse previously published lattice parameter data and show that additional scientific insight is obtainable in each case. First, the two-dimensional metal–organic framework [Cu2(OH)(C8H3O7S)(H2O)]·2H2O is found to exhibit the strongest area negative thermal expansion (NTE) effect yet observed; second, the widely used explosive HMX exhibits much stronger mechanical anisotropy than had previously been anticipated, including uniaxial NTE driven by thermal changes in molecular conformation; and third, the high-pressure form of the mineral malayaite is shown to exhibit a strong negative linear compressibility effect that arises from correlated tilting of SnO6and SiO4coordination polyhedra.

Effect of Bauschinger Effect and Yield Criterion on Residual Stress Distribution of Autofrettaged Tube

2005 ◽  
Vol 128 (2) ◽  
pp. 212-216 ◽  
Author(s):  
X. P Huang ◽  
W. C. Cui
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Stress Distribution ◽  
Strain Hardening ◽  
Bauschinger Effect ◽  
Present Model ◽  
Yield Criterion ◽  
Residual Stress Distribution ◽  
Hardening Model ◽  
End Conditions

Many analytical and numerical solutions for determining the residual stress distribution in autofrettaged tube have been reported. The significance of the choice of yield criterion, the Bauschinger effect, strain hardening, and the end conditions on the predicted residual stress distribution has been discussed by many authors. There are some different autofrettage models based on different simplified material strain-hardening behaviors, such as a linear strain-hardening model, power strain-hardening model, etc. Those models give more accurate predictions than that of elastic–perfectly plastic model, and each of them suits different strain-hardening materials. In this paper, an autofrettage model considering the material strain-hardening relationship and the Bauschinger effect, based on the actual tensile-compressive stress-strain curve of material, plane-strain, and modified yield criterion, has been proposed. The predicted residual stress distributions of autofrettaged tubes from the present model are compared to the numerical results and the experimental data. The predicted residual stresses are in good agreement with the experimental data and numerical predictions. The effect of Bauschinger effect and yield criterion on residual stress is discussed based on the present model. To predict residual stress distribution accurately, it is necessary to properly model yield criterion, Bauschinger effect, and appropriate end conditions.

Low TCE Polyimides from Polyamic Acid Blends and Copolymers: Preparation and Characterization Studies

1992 ◽  
Vol 264 ◽  
Author(s):  
Krishna G. Sachdev ◽  
Sandra Graham-Ode ◽  
Thomas L. Nunes ◽  
Paul S. Ho
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Silicon Wafers ◽  
Chain Segment ◽  
Flexible Chain ◽  
Polyamic Acid ◽  
Characterization Studies

AbstractA series of polyimides prepared from BPDA-PDA and BTDA-PDA polyamic acid blends and the corresponding (BPDA-PDA)x-(BTDA-PDA)y copolymers have been investigated for the mechanical properties, the thermal expansion, and the residual stress in films cured on silicon wafers. To determine the effect of inclusion of a highly flexible chain segment into BPDA-PDA structure, a BPDA-PDA/BDAF copolyimide has also been characterized. The experimental data are correlated with the chemistry and the composition of the blends and the copolyimides.

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