Phase equilibria and diffusion behavior of high pressure CO 2 in tetra-n-heptyl ammonium bromide

2016 ◽  
Vol 107 ◽  
pp. 370-376 ◽  
Author(s):  
Guifeng Ma ◽  
Yulan Zhou ◽  
Tiezhu Su ◽  
Wenxin Wei ◽  
Yanan Gong ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Equilibria ◽  
Ammonium Bromide ◽  
Diffusion Behavior ◽  
And Diffusion

Sorption and diffusion behavior of actinium(iii) ions in contact with hydroxyapatite as a transporter of medical radionuclides

2020 ◽  
Vol 69 (12) ◽  
pp. 2286-2293
Author(s):  
A. V. Severin ◽  
A. N. Vasiliev ◽  
A. V. Gopin ◽  
K. I. Enikeev
Keyword(s):  
Diffusion Behavior ◽  
And Diffusion ◽  
Medical Radionuclides

scholarly journals Phase Stability of Iron Nitride Fe4N at High Pressure—Pressure-Dependent Evolution of Phase Equilibria in the Fe–N System

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3963
Author(s):  
Marius Holger Wetzel ◽  
Tina Trixy Rabending ◽  
Martin Friák ◽  
Monika Všianská ◽  
Mojmír Šob ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Equilibria ◽  
Phase Stability ◽  
Polymorphic Transition ◽  
Ex Situ ◽  
Stable Phase ◽  
Iron Nitride ◽  
Phase System ◽  
Target Composition ◽  
Heat Treated

Although the general instability of the iron nitride γ′-Fe4N with respect to other phases at high pressure is well established, the actual type of phase transitions and equilibrium conditions of their occurrence are, as of yet, poorly investigated. In the present study, samples of γ′-Fe4N and mixtures of α Fe and γ′-Fe4N powders have been heat-treated at temperatures between 250 and 1000 °C and pressures between 2 and 8 GPa in a multi-anvil press, in order to investigate phase equilibria involving the γ′ phase. Samples heat-treated at high-pressure conditions, were quenched, subsequently decompressed, and then analysed ex situ. Microstructure analysis is used to derive implications on the phase transformations during the heat treatments. Further, it is confirmed that the Fe–N phases in the target composition range are quenchable. Thus, phase proportions and chemical composition of the phases, determined from ex situ X-ray diffraction data, allowed conclusions about the phase equilibria at high-pressure conditions. Further, evidence for the low-temperature eutectoid decomposition γ′→α+ε′ is presented for the first time. From the observed equilibria, a P–T projection of the univariant equilibria in the Fe-rich portion of the Fe–N system is derived, which features a quadruple point at 5 GPa and 375 °C, above which γ′-Fe4N is thermodynamically unstable. The experimental work is supplemented by ab initio calculations in order to discuss the relative phase stability and energy landscape in the Fe–N system, from the ground state to conditions accessible in the multi-anvil experiments. It is concluded that γ′-Fe4N, which is unstable with respect to other phases at 0 K (at any pressure), has to be entropically stabilised in order to occur as stable phase system. In view of the frequently reported metastable retention of the γ′ phase during room temperature compression experiments, energetic and kinetic aspects of the polymorphic transition γ′⇌ε′ are discussed.

Nitrogen Implantation and Diffusion in Silicon

1999 ◽  
Vol 568 ◽  
Author(s):  
Lahir Shaik Adam ◽  
Mark E. Law ◽  
Omer Dokumaci ◽  
Yaser Haddara ◽  
Cheruvu Murthy ◽  
...  
Keyword(s):  
Silicon Oxide ◽  
Gate Oxide ◽  
Nitrogen Diffusion ◽  
Nitrogen Implantation ◽  
Oxide Interface ◽  
Diffusion Behavior ◽  
Czochralski Silicon ◽  
Interface Modeling ◽  
And Diffusion ◽  
Silicon Silicon

ABSTRACTNitrogen implantation can be used to control gate oxide thicknesses [1,2]. This study aims at studying the fundamental behavior of nitrogen diffusion in silicon. Nitrogen at sub-amorphizing doses has been implanted as N2+ at 40 keV and 200 keV into Czochralski silicon wafers. Furnace anneals have been performed at a range of temperatures from 650°C through 1050°C. The resulting annealed profiles show anomalous diffusion behavior. For the 40 keV implants, nitrogen diffuses very rapidly and segregates at the silicon/ silicon-oxide interface. Modeling of this behavior is based on the theory that the diffusion is limited by the time to create a mobile nitrogen interstitial.

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