Computation of Temperature-Pressure Phase Diagrams of High-Pressure Nitrides

2006 ◽  
Vol 987 ◽  
Author(s):  
Peter Kroll
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Phase Diagrams ◽  
Noble Metal ◽  
Lower Boundary ◽  
Explicit Scheme ◽  
First Principle ◽  
Fugacity Coefficient ◽  
Pressure Phase ◽  
High Temperature High Pressure

AbstractWe propose an explicit scheme to include the fugacity of nitrogen in computations of phase diagrams of nitride compounds at high-temperature/high-pressure conditions. The assessment is based on available thermochemical data and two kind of extrapolating functions to provide upper and lower boundary for the fugacity coefficient as a funtion of p and T. The procedure is applied to investigate the synthesis of novel nitrides of tantalum, tungsten, and platinum. The combination of first-principle and thermochemical calculations let us predict the synthesis of a new high-pressure phase of Ta3N5 at about 27 GPa. Synthesis of WN2 becomes feasible at about 45 GPa. We furthermore explain why the synthesis of the noble metal subnitride, PtN2, occurs at about 40 GPa, and why PtN is not accessible in high-pressure experiments.

Advances in Computation of Temperature-Pressure Phase Diagrams of High-Pressure Nitrides

2008 ◽  
Vol 403 ◽  
pp. 77-80 ◽  
Author(s):  
Peter Kroll
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Elevated Temperature ◽  
Total Energy ◽  
Phase Diagrams ◽  
High Pressures ◽  
First Principle ◽  
Energy Calculations ◽  
High Pressure High Temperature ◽  
Pressure Phase

A combination of first-principle and thermochemical calculations is applied to compute the phase diagrams of rhenium-nitrogen and of ruthenium-nitrogen at elevated temperature and high pressure. We augment total energy calculations with our approach to treat the nitrogen fugacity at high pressures. We predict a sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, ReN will form from Re and nitrogen at about 32 GPa. A ReN2 with CoSb2-type structure may be achieved at pressures exceeding 50 GPa at this temperature. Marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa by reacting Ru with nitrogen.

Prediction of superconducting ternary hydride MgGeH6: from divergent high-pressure formation routes

2017 ◽  
Vol 19 (40) ◽  
pp. 27406-27412 ◽  
Author(s):  
Yanbin Ma ◽  
Defang Duan ◽  
Ziji Shao ◽  
Da Li ◽  
Liyuan Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Ab Initio ◽  
Phase Diagrams ◽  
High Temperature Superconductivity ◽  
High Pressure Phase ◽  
Pressure Phase

Invigorated by the high temperature superconductivity in some binary hydrogen-dominated compounds, we systematically explored high-pressure phase diagrams and superconductivity of a ternary Mg–Ge–H system usingab initiomethods.

scholarly journals High-pressure phase diagrams of FeSe1−xTex: correlation between suppressed nematicity and enhanced superconductivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
K. Mukasa ◽  
K. Matsuura ◽  
M. Qiu ◽  
M. Saito ◽  
Y. Sugimura ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Phase Diagrams ◽  
High Temperature Superconductivity ◽  
High Pressure Phase ◽  
Recent Theory ◽  
Magnetic Fluctuations ◽  
End Point ◽  
Enhanced Superconductivity ◽  
Pressure Phase

AbstractThe interplay among magnetism, electronic nematicity, and superconductivity is the key issue in strongly correlated materials including iron-based, cuprate, and heavy-fermion superconductors. Magnetic fluctuations have been widely discussed as a pairing mechanism of unconventional superconductivity, but recent theory predicts that quantum fluctuations of nematic order may also promote high-temperature superconductivity. This has been studied in FeSe1−xSx superconductors exhibiting nonmagnetic nematic and pressure-induced antiferromagnetic orders, but its abrupt suppression of superconductivity at the nematic end point leaves the nematic-fluctuation driven superconductivity unconfirmed. Here we report on systematic studies of high-pressure phase diagrams up to 8 GPa in high-quality single crystals of FeSe1−xTex. When Te composition x(Te) becomes larger than 0.1, the high-pressure magnetic order disappears, whereas the pressure-induced superconducting dome near the nematic end point is continuously found up to x(Te) ≈ 0.5. In contrast to FeSe1−xSx, enhanced superconductivity in FeSe1−xTex does not correlate with magnetism but with the suppression of nematicity, highlighting the paramount role of nonmagnetic nematic fluctuations for high-temperature superconductivity in this system.

New Metal Nitride Compounds: Can they be Synthesized at High-Pressures?

2007 ◽  
Vol 1040 ◽  
Author(s):  
Peter Kroll
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Phase Diagrams ◽  
High Pressures ◽  
Type Structure ◽  
First Principle ◽  
Metal Nitride ◽  
Temperature Conditions ◽  
High Pressure High Temperature

AbstractWe apply our procedure of including nitrogen fugacity into thermochemical calculations to compute phase diagrams in the rhenium-nitrogen and ruthenium-nitrogen systems. The combination of first-principle and thermochemical calculations let us predict the sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, Re will react with nitrogen at about 32 GPa yielding ReN. Formation of ReN2 with CoSb2-type structure is predicted for pressures exceeding 50 GPa at this temperature. The recently proposed marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa from a mixture of Ru and RuN2.

Homogeneous carbon doping of magnesium diboride by high-temperature, high-pressure synthesis

2014 ◽  
Vol 104 (16) ◽  
pp. 162603 ◽  
Author(s):  
M. A. Susner ◽  
S. D. Bohnenstiehl ◽  
S. A. Dregia ◽  
M. D. Sumption ◽  
Y. Yang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Magnesium Diboride ◽  
Carbon Doping ◽  
High Pressure Synthesis ◽  
Pressure Synthesis ◽  
High Temperature High Pressure

High temperature-high pressure synthesis of a new phase of LaCuO3

1989 ◽  
Vol 137 (4-5) ◽  
pp. 205-206 ◽  
Author(s):  
A.W. Webb ◽  
E.F. Skelton ◽  
S.B. Qadri ◽  
E.R. Carpenter ◽  
M.S. Osofsky ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Pressure Synthesis ◽  
Pressure Synthesis ◽  
New Phase ◽  
High Temperature High Pressure
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