scholarly journals High-temperature phonon stabilization ofγ-uranium from relativistic first-principles theory

2012 ◽  
Vol 85 (6) ◽  
Author(s):  
Per Söderlind ◽  
B. Grabowski ◽  
L. Yang ◽  
A. Landa ◽  
T. Björkman ◽  
...  
Keyword(s):  
High Temperature ◽  
First Principles

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.

scholarly journals Strong anharmonicity and high thermoelectric efficiency in high-temperature SnS from first principles

2019 ◽  
Vol 100 (21) ◽  
Author(s):  
Unai Aseginolaza ◽  
Raffaello Bianco ◽  
Lorenzo Monacelli ◽  
Lorenzo Paulatto ◽  
Matteo Calandra ◽  
...  
Keyword(s):  
High Temperature ◽  
First Principles ◽  
Thermoelectric Efficiency ◽  
Strong Anharmonicity

scholarly journals Superconducting Hydrides Under Pressure

2020 ◽  
Vol 11 (1) ◽  
pp. 57-76 ◽  
Author(s):  
Chris J. Pickard ◽  
Ion Errea ◽  
Mikhail I. Eremets
Keyword(s):  
Hydrogen Sulfide ◽  
High Temperature ◽  
Critical Temperature ◽  
First Principles ◽  
High Temperature Superconductors ◽  
Microscopic Structure

The measurement of superconductivity at above 200 K in compressed samples of hydrogen sulfide and in lanthanum hydride at 250 K is reinvigorating the search for conventional high temperature superconductors. At the same time, it exposes a fascinating interplay between theory, computation, and experiment. Conventional superconductivity is well understood, and theoretical tools are available for accurate predictions of the superconducting critical temperature. These predictions depend on knowing the microscopic structure of the material under consideration, which can now be provided by computational first-principles structure predictions. The experiments at the megabar pressures required are extremely challenging, but, for some groups at least, permit the experimental exploration of materials space. We discuss the prospects for the search for new superconductors, ideally at lower pressures.

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.

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