The entropy factor involved in the Hirth and Lothe theory of dislocation velocity in silicon

Entropy as well as enthalpy factors play substantial roles in various chemical phenomena such as equilibrium and reactions. However, the entropy factors are frequently underestimated in most instances, particularly in synthetic chemistry. In reality, the entropy factor can be in competition with the enthalpy factor or can even be decisive in determining the overall free or activation energy change upon molecular interaction and chemical transformation, particularly where weak interactions in ground and/or excited states are significant. In this account, we overview the importance of the entropy factor in various chemical phenomena in both thermodynamics and kinetics and in the ground and excited states. It is immediately apparent that many diastereo- and enantioselective photoreactions are entropy-controlled. Recent advances on the entropy-control concept in asymmetric photoreactions are further discussed. Understanding the entropy-control concept will pave the way to improve, fine-tune, and even invert the chemo- and stereoselectivity of relevant chemical phenomena.1 Introduction2 Role of Entropy in Supramolecular Interactions3 Selected Examples of Entropy-Driven Thermal Reactions4 Classical Examples of Entropy Control in Photoreactions5 Entropy-Driven Asymmetric Photoreactions6 Advances in Entropy Control7 Perspective

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Dislocation velocity in indium phosphide

Applied Physics Letters ◽

10.1063/1.104439 ◽

1991 ◽

Vol 58 (1) ◽

pp. 48-50 ◽

Cited By ~ 25

Author(s):

Ichiro Yonenaga ◽

Koji Sumino

Keyword(s):

Indium Phosphide ◽

Dislocation Velocity

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Instantaneous dislocation velocity measurements for slowly moving dislocations

Scripta Metallurgica ◽

10.1016/0036-9748(89)90490-0 ◽

1989 ◽

Vol 23 (11) ◽

pp. 1959-1962 ◽

Cited By ~ 6

Author(s):

C.S. Kim ◽

T.J. Garosshen ◽

J.M. Galligan

Keyword(s):

Dislocation Velocity ◽

Velocity Measurements

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Comparison of irradiation hardening with dislocation velocity in copper single crystals electron irradiated at 100 K

phys stat sol (a) ◽

10.1002/pssa.2210570221 ◽

1980 ◽

Vol 57 (2) ◽

pp. 631-638 ◽

Cited By ~ 1

Author(s):

M. Wada ◽

M. Meshii

Keyword(s):

Single Crystals ◽

Dislocation Velocity ◽

Irradiation Hardening ◽

Copper Single Crystals

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Dislocation Mobility in HCL-Doped Ice

MRS Proceedings ◽

10.1557/proc-375-287 ◽

1994 ◽

Vol 375 ◽

Cited By ~ 6

Author(s):

Xiaohong Hu ◽

Kunlun Jia ◽

Fuping Liu ◽

Ian Baker ◽

David Black

Keyword(s):

Single Crystals ◽

Dislocation Velocity ◽

Dislocation Mobility ◽

Philosophical Magazine ◽

X Ray ◽

Temperature Range ◽

Basal Dislocation

AbstractDislocation velocities have been measured in both lightly and heavily HCl-doped ice single crystals using synchrotron-based, monochromatic X-ray topography. In the temperature range −10°C to −30°C, a concentration of ˜1 × 10−6M was found not to affect the mobility of either 60° or screw basal dislocations, confirming the earlier observations of C. Shearwood and R. W. Whitworth [Philosophical Magazine A65, 1992, 85]. However, heavier doping (˜1.9 × 10−4M) increased the basal dislocation velocity, compared to pure ice, by a factor of 2.6 at −16.4°C.

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