The effect of crystal size on the thermal explosion of α-lead azide

1975 ◽  
Vol 12 (1-2) ◽  
pp. 72-79 ◽  
Author(s):  
M.M. Chaudhri ◽  
J.E. Field
Keyword(s):  
Thermal Explosion ◽  
Crystal Size ◽  
Lead Azide

THE THERMAL EXPLOSION OF LEAD AZIDE

1947 ◽  
Vol 25b (6) ◽  
pp. 548-565 ◽  
Author(s):  
A. S. Hawkes ◽  
C. A. Winkler
Keyword(s):  
Induction Period ◽  
Thermal Explosion ◽  
Crystal Size ◽  
Dibutyl Phthalate ◽  
Volume Ratio ◽  
Lead Azide ◽  
Sharp Change ◽  
Induction Periods ◽  
Self Heating

The minimum explosion temperatures for service and dextrin azides (about 315 °C. and 275 °C., respectively) are increased considerably by increase of surface: volume ratio of the container and by compressing or wetting the charge with dibutyl phthalate before explosion. When wetted, the two azides were found to be similar in respect of minimum explosion temperatures and induction periods prior to explosion. Sensitization of service azide by preheating was found to be permanent. A limit to sensitization below the minimum explosion temperature was observed, and probably exists also for sensitization above this temperature. Wetting the charge with phthalate nullifies the sensitization. Although dextrin azide alone is more thermally sensitive than service azide, mixtures of the two containing 70% or more service azide show a sharp change to service azide properties; the mixtures apparently are not exploded by the dextrin azide they contain. The value of E in the expression [Formula: see text] + constant, where t is the induction period, has been determined for both the initial and final stages of reaction preceding explosion and found to be essentially unaltered. Minimum explosion temperature of single large crystals was shown to increase with crystal size. The data are interpreted as showing that the thermal explosion of lead azide may result from self-heating, the heat of the pre-explosion reaction not being sufficiently dissipated from the material.

Irradiation of explosives with high-speed particles and the influence of crystal size on explosion

1954 ◽  
Vol 227 (1168) ◽  
pp. 22-37 ◽  
Keyword(s):  
Thermal Decomposition ◽  
High Speed ◽  
Crystal Size ◽  
Hot Spot ◽  
Fission Products ◽  
Spot Size ◽  
Lead Azide ◽  
X Rays ◽  
Electron Stream ◽  
Other Substances

The effect of irradiating a number of sensitive explosive crystals (such as lead azide, silver azide, cadmium azide, nitrogen iodide and silver acetylide) with high-speed particles has been studied. They were subjected to irradiation by electrons, by neutrons, by fission products and by X-rays. All these substances were exploded by an intense electron stream, but experiment shows that this is a thermal effect and is due to a bulk heating of the crystal. Nitrogen iodide is exploded by fission products, but this substance is anomalous. With the other substances interesting changes within the crystal are observed and these affect the subsequent thermal decomposition but no explosion results. The experiments show that, in general, the activation of a small group of adjacent molecules is not enough to cause explosion. The effect of crystal size on explosion is also studied. It is shown that if the crystals are heated they do not explode unless their critical size exceeds a certain value, which depends upon the temperature and upon other factors. Under the conditions of these experiments the limiting size for a number of explosives is of the order of a few microns. The work supports the earlier conclusions (arrived at from friction and impact experiments) that the necessary ‘hot-spot’ size is large on a molecular scale ( ca . I0 -5 to 10 -3 cm in diameter); otherwise successful growth to detonation will not occur. Optical and electron microscopy provide some evidence that thermal decomposition takes place preferentially at dislocations inherent in the mosaic structure of the crystal.

The effect of high energy X-rays and pile radiation on the thermal decomposition and thermal explosion of α -lead azide

1958 ◽  
Vol 246 (1245) ◽  
pp. 225-232 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Thermal Explosion ◽  
Energy Deposition ◽  
High Energy ◽  
Sensitivity Test ◽  
Lead Azide ◽  
X Rays ◽  
Decomposition Rates ◽  
Friction Sensitivity

α -lead azide has been irradiated in air with the X-rays from a 1 MV generator and with pile radiation. At dosages below 10 4 r the thermal decomposition and thermal explosion characteristics of the X-irradiated material are indistinguishable from those of the unirradiated material. At higher dosages decomposition rates are changed and explosion times reduced. Pile radiation gives very similar results for the same energy deposition. Samples irradiated at 10 4 and 10 7 r showed no difference from unirradiated material on a friction sensitivity test.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Pengaruh Pendopingan Karbon Terhadap Struktur Kristal dan Morfologi TIO2

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Frastica Deswardani ◽  
Helga Dwi Fahyuan ◽  
Rimawanto Gultom ◽  
Eif Sparzinanda
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Grain Size ◽  
Tio2 Thin Film ◽  
Crystal Size ◽  
Diffraction Peak ◽  
Carbon Doping ◽  
Tio2 Anatase ◽  
Spray Method ◽  
Carbon Analysis

Telah dilakukan penelitian mengenai pengaruh konsentrasi doping karbon pada lapisan tipis TiO2 yang ditumbuhkan dengan metode spray terhadap struktur kristal dan morfologi TiO2. Hasil karakterisasi SEM menunjukkan bahwa penambahan doping karbon dapat meningkatkan ukuran butir. Lapisan TiO2 doping karbon 8% diperoleh ukuran butir terbesar adalah 1.35 μm, sedangkan ukuran tekecilnya adalah 0.45 μm. Sementara itu, untuk lapisan tipis TiO2 didoping karbon 15% memiliki ukuran butir terbesar yaitu 1.76 μm dan terkecil 0.9 μm. Hasil XRD menunjukkan seluruh puncak difraksi lapisan tipis TiO2 dengan doping karbon 8% dan 15% merupakan TiO2 anatase. Ukuran kristal lapisan TiO2 didoping karbon 8% diperoleh sebesar 638,08 Å dan untuk pendopingan 15% karbon ukuran kristal lapisan tipis TiO2 adalah 638,09 Å, hal ini menunjukkan ukuran kristal kedua sampel tidak mengalami perubahan yang signifikan.   TiO2 thin film with carbon doping has been successfully grown by spray method. The research on the effect of carbon doping on crystal structure and morfology of TiO2 has been prepared by varying carbon concentration (8% and 15% carbon). Analysis of SEM showed that the addition of carbon may increase the grain size. Thin film of TiO2 doped carbon 8% has the largest grain size 1.35 μm, while the smallest grain size is 0.45 μm. Meanwhile, for thin film TiO2 doped carbon 15% has the largest grain size 1.76 μm and smallest 0.9 μm. The XRD results showed the entire diffraction peak of thin film TiO2 doped carbon 8% and 15% were TiO2 anatase. The crystal size of thin film TiO2 doped carbon 8% was obtained at 638.08 Å and for thin film TiO2 doped carbon 15% the crystalline size of TiO2 thin film was 638.09 Å, this shows that the crystal size of both samples did not change significantly.    

Sign in / Sign up

Export Citation Format

Share Document