Effect of rare earth (Sc, Y, La, Sm and Gd) doping on mechanical and thermodynamic properties of Al12Mg17 intermetallic compounds

2019 ◽  
Vol 33 (35) ◽  
pp. 1950442 ◽  
Author(s):  
Fei Zhao ◽  
Bao Chen ◽  
Chuan-Hui Zhang
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Thermal Stability ◽  
Thermodynamic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Structural Parameters ◽  
High Energy ◽  
High Energy Electrons ◽  
Thermal Stability Of

The structural, electronic, mechanical and thermodynamic properties for [Formula: see text] and [Formula: see text] (RE = Sc, Y, La, Sm and Gd) compounds have been calculated by first-principles theory. The obtained structural parameters and elastic constants of two kinds of doped [Formula: see text] are compared with some theoretical and experimental data. The electronic structure analysis, such as density of states, explains the bonding character of Al–Mg–RE. All the doped [Formula: see text] are influenced by the high-energy electrons directly. Furthermore, the basic mechanical properties which are derived from the elastic constants and the thermal stability of doped [Formula: see text] are discussed. The predicted brittleness of [Formula: see text] and [Formula: see text] is consistent with the available experiments.

Deep Defects in 3C-SiC Generated by H+- and He+-Implantation or by Irradiation with High-Energy Electrons

2010 ◽  
Vol 645-648 ◽  
pp. 439-442 ◽  
Author(s):  
Michael Weidner ◽  
Lia Trapaidze ◽  
Gerhard Pensl ◽  
Sergey A. Reshanov ◽  
Adolf Schöner ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Charge State ◽  
Cross Section ◽  
Capture Cross Section ◽  
Pulse Length ◽  
High Energy ◽  
Capture Cross ◽  
Intrinsic Defects ◽  
High Energy Electrons ◽  
Thermal Stability Of

Intrinsic defects in 3C-SiC are generated by implantation of H+- and He+-ions or irra¬diation with high energy electrons. The defect parameters and the thermal stability of the observed defects are determined. The capture-cross-section of the W6-center is directly measured by variation of the filling pulse length. The charge state of the W6-center is obtained from double-correlated DLTS investigations according to the Poole-Frenkel effect.

First-principles study of structural, elastic and thermodynamic properties of AuIn2

2015 ◽  
Vol 29 (34) ◽  
pp. 1550222 ◽  
Author(s):  
Hai Ying Wu ◽  
Ya Hong Chen ◽  
Chen Rong Deng ◽  
Peng Fei Yin ◽  
Hong Cao
Keyword(s):  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Pressure Effect ◽  
Structural Parameters ◽  
Text Structure ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Theoretical Results

The structural, elastic and thermodynamic properties of [Formula: see text] in the [Formula: see text] structure under pressure have been investigated using ab initio plane wave pseudopotential method within the generalized gradient approximation. The calculated structural parameters and equation of state are in excellent agreement with the available experimental and theoretical results. The elastic constants of [Formula: see text] at ambient condition are calculated, and the bulk modulus obtained from these calculated elastic constants agrees well with the experimental data. The pressure dependence of the elastic constants, bulk modulus, shear modulus and Young’s modulus has also been investigated. The Debye temperature presents a slight increase with pressure. [Formula: see text] exhibits ductibility and low hardness characteristics, the ductibility increases while the hardness decreases with the increasing of pressure. The pressure effect on the heat capacity and thermal expansion coefficient for [Formula: see text] is much larger.

Thermal Stability of Defect Centers in n- and p-Type 4H-SiC Epilayers Generated by Irradiation with High-Energy Electrons

2010 ◽  
Vol 645-648 ◽  
pp. 423-426 ◽  
Author(s):  
Sergey A. Reshanov ◽  
Svetlana Beljakowa ◽  
Bernd Zippelius ◽  
Gerhard Pensl ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Systematic Study ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
High Energy ◽  
Defect Centers ◽  
High Energy Electrons ◽  
Transient Spectroscopy ◽  
P Type ◽  
Thermal Stability Of

This paper comprises a systematic study of the thermal stability of defect centers observed in n- and p-type 4H-SiC by deep level transient spectroscopy (DLTS); the defects are generated by irradiation with high-energy electrons of 170 keV or 1 MeV.

Elastic Constants and Thermodynamic Properties of Cu, Cu2O and CuO from First-Principles Calculations

2011 ◽  
Vol 335-336 ◽  
pp. 328-332 ◽  
Author(s):  
Na Na Liu ◽  
Jian Lin Sun ◽  
Di Wu
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Elastic Constants ◽  
First Principles ◽  
Heat Capacities ◽  
Copper Oxides ◽  
First Principles Calculations ◽  
Previous Experimental Data ◽  
Specific Heat Capacities

Elastic constants and some thermodynamic properties of Cu and copper oxides were studied by first-principles total energy calculations. The elastic constants of Cu and copper oxides were calculated on pressure. It was shown that the calculated elastic constants of Cu, Cu2O and CuO at zero pressure were well consistent with previous experimental data. The specific heat capacities and thermal expansion coefficient of Cu and copper oxides were successfully obtained. The calculated specific heat capacities of Cu were well consistent with the previous experimental data.

scholarly journals Pressure effect of the mechanical, electronics and thermodynamic properties of Mg–B compounds A first-principles investigations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
GuoWei Zhang ◽  
Chao Xu ◽  
MingJie Wang ◽  
Ying Dong ◽  
FengEr Sun ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Boron Content ◽  
Structural Parameters ◽  
Debye Model ◽  
Total Density ◽  
First Principle ◽  
Volume Deformation ◽  
Temperature And Pressure ◽  
Total Density Of States

AbstractFirst principle calculations were performed to investigate the structural, mechanical, electronic properties, and thermodynamic properties of three binary Mg–B compounds under pressure, by using the first principle method. The results implied that the structural parameters and the mechanical properties of the Mg–B compounds without pressure are well matched with the obtainable theoretically simulated values and experimental data. The obtained pressure–volume and energy–volume revealed that the three Mg–B compounds were mechanically stable, and the volume variation decreases with an increase in the boron content. The shear and volume deformation resistance indicated that the elastic constant Cij and bulk modulus B increased when the pressure increased up to 40 GPa, and that MgB7 had the strongest capacity to resist shear and volume deformation at zero pressure, which indicated the highest hardness. Meanwhile, MgB4 exhibited a ductility transformation behaviour at 30 GPa, and MgB2 and MgB7 displayed a brittle nature under all the considered pressure conditions. The anisotropy of the three Mg–B compounds under pressure were arranged as follows: MgB4 > MgB2 > MgB7. Moreover, the total density of states varied slightly and decreased with an increase in the pressure. The Debye temperature ΘD of the Mg–B compounds gradually increased with an increase in the pressure and the boron content. The temperature and pressure dependence of the heat capacity and the thermal expansion coefficient α were both obtained on the basis of Debye model under increased pressure from 0 to 40 GPa and increased temperatures. This paper brings a convenient understanding of the magnesium–boron alloys.

scholarly journals Controlling the Thermal Stability of Kyanite-Based Refractory Geopolymers

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2903
Author(s):  
Juvenal Giogetti Nemaleu Deutou ◽  
Rodrigue Cyriaque Kaze ◽  
Elie Kamseu ◽  
Vincenzo M. Sglavo
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Strength ◽  
Treatment Temperature ◽  
Strength Development ◽  
Particle Sizes ◽  
Cold Setting ◽  
Thermal Stability Of ◽  
Geopolymer Composites ◽  
Refractory Composites

The present project investigated the thermal stability of cold-setting refractory composites under high-temperature cycles. The proposed route dealt with the feasibility of using fillers with different particle sizes and studying their influence on the thermo-mechanical properties of refractory geopolymer composites. The volumetric shrinkage was studied with respect to particle sizes of fillers (80, 200 and 500 µm), treatment temperature (1050–1250 °C) and amount of fillers (70–85 wt.%). The results, combined with thermal analysis, indicated the efficiency of refractory-based kyanite aggregates for enhancing thermo-mechanical properties. At low temperatures, larger amounts of kyanite aggregates promoted mechanical strength development. Flexural strengths of 45, 42 and 40 MPa were obtained for geopolymer samples, respectively, at 1200 °C, made with filler particles sieved at 80, 200 and 500 µm. In addition, a sintering temperature equal to 1200 °C appeared beneficial for the promotion of densification as well as bonding between kyanite aggregates and the matrix, contributing to the reinforcement of the refractory geopolymer composites without any sign of vitrification. From the obtained properties of thermal stability, good densification and high strength, kyanite aggregates are efficient and promising candidates for the production of environmentally friendly, castable refractory composites.

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