Long-ranged and high temperature ferromagnetism in (Mn,C)-codoped ZnO studied by first-principles calculations

2010 ◽  
Vol 107 (3) ◽  
pp. 033903 ◽  
Author(s):  
Xue-ling Lin ◽  
Shi-shen Yan ◽  
Ming-wen Zhao ◽  
Shu-jun Hu ◽  
Xin-xin Yao ◽  
...  
Keyword(s):  
High Temperature ◽  
First Principles ◽  
First Principles Calculations

Defect Complexes and Non-Equilibrium Processes Underlying the P-Type Doping of GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
Fernando A. Reboredo ◽  
Sokrates T. Pantelides
Keyword(s):  
High Temperature ◽  
Experimental Evidence ◽  
First Principles ◽  
Final Anneal ◽  
First Principles Calculations ◽  
Defect Complexes ◽  
Equilibrium Processes ◽  
Open Questions ◽  
High Temperature Anneal ◽  
P Type

AbstractIt is well known that hydrogen plays a key role in p-type doping of GaN. It is believed that H passivates substitutional Mg during growth by forming a Mgs-N-Hi complex; in subsequent annealing, H is removed, resulting in p-type doping. Several open questions have remained, however, such as experimental evidence for other complexes involving Mg and H and difficulties in accounting for the relatively high-temperature anneal needed to remove H. We present first principles calculations in terms of which we show that the doping process is in fact significantly more complex. In particular, interstitial Mg plays a major role in limiting p-type doping. Overall, several substitutional/interstitial complexes form and can bind H, with vibrational frequencies that account for hitherto unidentified observed lines. We predict that these defects, which limit doping efficiency, can be eliminated by annealing in an atmosphere of H and N prior to the final anneal that removes H.

First-principles calculations and high thermoelectric performance of La–Nb doped SrTiO3 ceramics

2019 ◽  
Vol 7 (1) ◽  
pp. 236-247 ◽  
Author(s):  
Yan Li ◽  
Qing-Yu Hou ◽  
Xiao-Huan Wang ◽  
Hui-Jun Kang ◽  
Xinba Yaer ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermoelectric Material ◽  
First Principles ◽  
Waste Heat ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
High Temperature Application ◽  
Temperature Application ◽  
Electrical Generation ◽  
Srtio3 Ceramics

SrTiO3 is a promising thermoelectric material for high temperature application of waste heat electrical generation.

scholarly journals Properties of Cu1-xWx alloys at high pressure and high temperature from first-principles calculations

2014 ◽  
Vol 63 (20) ◽  
pp. 206501
Author(s):  
Zhai Dong ◽  
Wei Zhao ◽  
Feng Zhi-Fang ◽  
Shao Xiao-Hong ◽  
Zhang Ping
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
First Principles ◽  
First Principles Calculations

Low-pressure superconductivity in lithium-doped methane predicted by first principles

2020 ◽  
pp. 2150032
Author(s):  
Ning Lu ◽  
Yu-Long Hai ◽  
Hai-Yan Lv ◽  
Wen-Jie Li ◽  
Chun-Lei Yang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
High Temperature ◽  
Crystal Field ◽  
First Principles ◽  
Pressure Range ◽  
High Temperature Superconductor ◽  
Low Pressure ◽  
First Principles Calculations ◽  
A Charge ◽  
Low Pressures

To explore the high-temperature superconductor at low pressures, we have investigated the crystal structures, electronic properties, and possible superconductivity in the case of methane (CH4) doped by lithium in the pressure range of [Formula: see text][Formula: see text]GPa, based on the first-principles calculations. The results show that Li-intercalated CH4 (Lix(CH4)[Formula: see text]) can realize metallization and superconductivity at low pressures, even 5[Formula: see text]GPa. We find that there is a charge transfer between Li and CH4, but the metallization is driven by the change of crystal field induce by doping instead of charge transfer. The critical temperture is predicted from 3.8[Formula: see text]K at 5[Formula: see text]GPa for LiCH4 to 12.1[Formula: see text]K at 100[Formula: see text]GPa for Li(CH4)4. The low-pressure superconductivity of Lix(CH4)[Formula: see text] can be further optimized by adjusting component and pressure.

Property of mono-vacancy in MAX phase M3AC2 (M=Ti, A=Al, Si, or Ge): First-principles calculations

2018 ◽  
Vol 32 (15) ◽  
pp. 1850160 ◽  
Author(s):  
L. Chen ◽  
G. Duan ◽  
X. F. Gao ◽  
C. L. Wang
Keyword(s):  
High Temperature ◽  
First Principles ◽  
Radiation Resistance ◽  
Atomic Layer ◽  
Experimental Results ◽  
Max Phase ◽  
Vacancy Formation ◽  
First Principles Calculations ◽  
Density Of State ◽  
And Migration

The formation and migration energies of the mono-vacancy in M3AC2 have been investigated using first-principles calculations. The results have shown that M element vacancy formation is the most energetically difficult in M3AC2. The A atomic layer is the most active one. It was also found that the energies of mono-vacancy formation and migration in Ti3AlC2 are higher than that in Ti3SiC2 and Ti3GeC2. Moreover, our calculation of the density of state confirms the conclusion that Ti3AlC2 is the most stable in the selected M3AC2 materials under high-temperature or irradiation environment conditions. These results could provide theoretical insights for the experimental results that Ti3AlC2 has a better radiation resistance than Ti3SiC2 and Ti3GeC2.

scholarly journals First-principles calculations on high-temperature desorption loss from iridium

2020 ◽  
Vol 184 ◽  
pp. 109897
Author(s):  
Insung Seo ◽  
Shunsuke Yokota ◽  
Yousuke Imai ◽  
Yoshihiro Gohda
Keyword(s):  
High Temperature ◽  
First Principles ◽  
First Principles Calculations

scholarly journals First Principles Calculations on Elastic, Thermodynamic and Electronic Properties of Co2Zr and Co2Ti at High Temperature and Pressure

2020 ◽  
Vol 10 (6) ◽  
pp. 2097
Author(s):  
Mi-An Xue ◽  
Xiaoli Yuan ◽  
Cheng Zhong ◽  
Peng Wan
Keyword(s):  
High Temperature ◽  
Electronic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

Co2Zr and Co2Ti are both cubic crystals with a Cu2Mg-type structure. The elastic, thermodynamic and electronic properties of the intermetallic compounds Co2Zr and Co2Ti are investigated by using ab initio plane-wave pseudopotential density functional theory (PWPDFT) and generalized gradient approximation (GGA) under high temperature and pressure. The partially calculated results are consistent with the available experimental data. The elastic properties of Co2Zr and Co2Ti under high pressure were first studied by first principles calculations. The results indicate that the elastic constants, elastic modulus and Poisson’s ratio are functions of pressure, indicating that the effect of pressure on the ductility and anisotropy is significant. The thermodynamic properties are also calculated by the quasi-harmonic Debye model. In the range of 0~100 GPa pressure and 0~1500 K temperature, the Debye temperature Θ, the heat capacity CV and the thermal expansion α vary with pressure and temperature. Co2Ti has a higher Debye temperature than Co2Zr under the same pressure. Decreasing temperature and increasing pressure have the same effects on CV and α. The electron density difference and density of states of Co2Zr and Co2Ti are finally investigated. The results show that both Co2Zr and Co2Ti are typically metal crystals but Co2Zr has greater covalence than Co2Ti.

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