Shock-wave synthesis

The general subject of solid-state chemical reaction in shock-wave compression, or shock-wave synthesis, has recently become an important part of the... 

For the dynamic high pressure conversion, also known as shock wave synthesis, an explosive shock wave is used for the conversion of h-BN into c-BN. High pressure and high temperature are reached for a short period of time (milliseconds). To guarantee a fast temperature decrease a metal powder, like copper, is added to h-BN in an amount of 5% [181]. 

Shock Wave Synthesis of Nanosized Composite Metal Oxides... 

These results demonstrate tliat shock-wave synthesis is a novel metliod to prepare nanosized materials with some unique physical and chemical properties. In the light of the experimental results, nanosized zinc ferrite and nickel ferrite synthesized by shock-wave treatment may Iiave potential applications as magnetic materials and photocatalysts. 

The experimental results indicate that in the range of nanometers other rules apply to the stability of different carbon structures than would on a macroscopic scale. This is evident, for example, from the spontaneous formation of various diamond materials with nanoscopic particles in different methods of preparation like CVD or detonation and shock wave synthesis. The products obtained include polycrys-taUine materials with particle dimension of 1-60 (tm that consist of primary par-... 

As discussed in Section 5.2.2, nanodiamond particles produced by detonation or shock wave synthesis exhibit a primary surface functionalization right from the preparation. It comprises a multitude of different groups, so it should be possible to make use of these functional groups. To ensure a reproducible quality of the secondary products obtained, however, a homogenization of the primary functionalities is required. There are several strategies to achieve this (Figure 5.29). 

Gas pressure, hydrostatic pressing, hot pressing, isostatic pressing, shock wave synthesis Ultra-vacuum technology... 

D. L. Williamson, Chemical Synthesis Under High Pressure Shock Loading, in Shock Waves in Condensed Matter (edited by Y.M. Gupta), Plenum, New York, 1986, pp. 693-711. 

The chapters presented by different experts in the field have been structured to develop an intuition for the basic principles by discussing the kinematics of shock compression, first from an extremely fundamental level. These principles include the basic concepts of x-t diagrams, shock-wave interactions, and the continuity equations, which allow the synthesis of material-property data from the measurement of the kinematic properties of shock compression. A good understanding of these principles is prerequisite... 

The reactions can also be initiated through the application of a shock wave from a mechanical source, and synthesis of GaAs has been achieved without any external heating, which would lead to arsenic evaporation, being applied to the mixture of the elements. 

For the terrorist, TATP and HMTD offer easy sources of primary explosives. Consulting the do-it-yourself literature, it can be seen that there are two other commonly recommended primary explosives—lead azide Pb(N3)2 and mercury fulminate Hg(ONC)2, but these are difficult to prepare cleanly. The synthesis of diazodinitrophenol (DDNP) (Fig. 2.5), common in commercial detonators, is reported in such publications, but apparently is rarely attempted by clandestine chemists. Typically, the brisance of a primary is less than TNT, but the efficacy is the fact that a shock wave can result from a relatively mild insult. 

A quite different set of dynamic high-pressure techniques are based on the use of chemical or nuclear explosions to produce transient shock waves of high peak pressure but short duration. With such methods, one can often penetrate the high-T, P regions where kinetic barriers become unimportant and a catalyst is unnecessary. However, the same kinetics that allows facile conversion of graphite to diamonds as the shock front arrives also allows the facile back-conversion as the shock wave passes. As a pioneer of shock-wave diamond synthesis remarked ruefully, We were millionaires for one microsecond [B. J. Alder and C. S. Christian. Phys. Rev. Lett. 7, 367 (1961) B. J. Alder, in W. Paul and D. M. Warschauer (eds). Solids under Pressure (McGraw-Hill, New York, 1963), p. 385]. 

The energy from the decay of radioactive elements was probably not an important energy source for the synthesis of organic compounds on the primitive earth since most of the ionization would have taken place in silicate rocks rather than in the reducing atmosphere. The shock wave energy from the impact of meteorites on the earth s atmosphere and sur-... 

E-BN (E = explosion) is described as high pressure phase by a few scientists. For synthesis shock wave methods [25, 26] were used and also reactions at normal pressure with photon [27] or electron [28, 29] assistance. In a special three-dimensional phase-diagram (pressure, temperature, electrical field) the existence of the metastable E-BN was described [30]. 

Today BN synthesis by shock-wave methods is mainly used to produce superhard boron-carbon-nitrogen mixtures called heterodiamond [182, 183]. 

Barak I, Bar-Nun A. The mechanisms of amino acid synthesis by high temperature shock-waves. Orig Life 1975 6 483. 

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