Impurity atom diffusion into finite slices of semiconductor material

1963 ◽  
Vol 51 (2) ◽  
pp. 372-373 ◽  
Author(s):  
D.P. Kennedy ◽  
P.C. Murley
Keyword(s):  
Impurity Atom ◽  
Semiconductor Material ◽  
Atom Diffusion

Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets

2012 ◽  
Vol 727-728 ◽  
pp. 163-168 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Activation Energy ◽  
Rare Earth ◽  
Transition Metal ◽  
Impurity Atom ◽  
Diffusion Coefficients ◽  
Arrhenius Equation ◽  
Atom Diffusion ◽  
Essential Input

In the case of the modeling of sintering and heat treatments, the diffusion coefficients are an essential input. However, experimental data in the literature about diffusion coefficients for rare-earth transition metal intermetallics is scarce. In this study, the available data concerning diffusion coefficients relevant for rare-earth transition metal magnets are reviewed and commented. Some empirical rules are discussed, for example the activation energy is affected by the size of the diffusing impurity atom. Diffusion coefficients for Dy, Nd and Fe into Nd2Fe14B are given according an Arrhenius equation D=D0exp (-Q/RT). For Dy diffusion into Nd2Fe14B, Q 315 kJ/mol and D08 . 10-4m2/s.

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

Spatiotemporal Control of Amide Radicals During Photocatalysis

2020 ◽  
Author(s):  
Shogo Mori ◽  
Takahiro Aoki ◽  
Kaliyamoorthy Selvam ◽  
Shunichi Fukuzumi ◽  
Jieun Jung ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Nickel Complex ◽  
Nickel Complexes ◽  
Semiconductor Material ◽  
Radical Reactions ◽  
Substitution Reactions ◽  
Carbon Neutrality ◽  
Spatiotemporal Control ◽  
Scalable Production ◽  
Salt Waste

Despite the continuing popularity of radical reactions in organic synthesis, much remains to be explored in this area. Herein, we describe how spatiotemporal control can be exerted over the formation and reactivity of divergent exchangeable formamide radicals using nickel complexes with a semiconductor material (TiO<sub>2</sub>) under irradiation from near-UV–Vis light. Depending on the bipyridine ligand used and the quantity of the nickel complex that is hybridized on or nonhydridized over the TiO<sub>2</sub> surface, these radicals selectively undergo substitution reactions at the carbon center of carbon–bromine bonds that proceed via three different pathways. As the scalable production of formamides from CO<sub>2</sub> does not produce salt waste, these methods could add a new dimension to the search for carbon neutrality through the indirect incorporation of CO<sub>2</sub> into organic frameworks.

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