CONTENTS:• Introduction• History• Definition• Schematic view of laser pyrolysis• Particle Growth• Advantages• Disadvantages

HISTORY OF PYROLYSIS• Pyrolytic Gasification is by no means new. The principles were

first brought forth in 1958 at Bell Laboratories within the United States of America. Thereafter, a number of universities and organizations around the world started R&D programs.

• The word Pyrolysis meaning, chemical change brought about by heat is widely used, even by incineration technologies, which have tried to escape their roots in oxidation and combustion because of the problems prevalent with both. Gasification is a term being used to describe the chemical reaction and molecular break down, or degradation of materials

DEFINITIONLaser pyrolysis • Decomposition or transformation of compound

caused by Heat.• Transformation of a substance produced by the

action of heat• A platform technology to produce functional

nano scale materials for a range of applications

SYNTHESIS APPROACH:LASER PYROLYSIS

LASER PYROLYSIS

PARTICLE GROWTH

The composition, the diameter and the particle growth are directly dependent of the temperature which in turn depends on chosen precursors1. pressure in the reaction chamber2. laser power3. flow rate of the gaseous precursors

IRON OXIDE COMPOSITEFILAMENTARY IRON OXIDE COVERED IRON NANOPARTICLES,PRODUCED LIKE A SPIDER-WEB INSIDE THE REACTION CHAMBER

IMAGE OF AN IRON NANOPARTICLE SURROUNDED BY A THICK FE3O4 LAYER

IRON/IRON OXIDES MORPHOLOGIES ANDPARTICLE SIZE DISTRIBUTIONS

Medium-resolution TEM micrographs exhibitingchain-like agglomeration of iron nanoparticlesat two different scales

Particle size distribution of iron nanoparticlesobtained by laser synthesis of Fe(CO)5/ C2H4.

ADVANTAGE OF THIS METHOD:

• pure products (no contact with surface of the chamber)• extremely fine powders (d < 50 nm)• small distribution of sizes• continuous synthesis• well defined reaction zone• variable reaction conditions (temperature, pressure, ...)• homogenous nucleation• control of growing rate and residence time in reaction zone

DISADVANTAGE OF THIS METHOD:

• gas (vapour) precursor of the material• the use of gas sensitizers (possible shift of reaction routes)• often small reaction yield

REFERENCE1. J. S. Haggerty, “Sinterable Powders from Laser-Driven Reactions”, in

her-inducedChemical Processes, Editor, J.I. Steinfeld, 1981, Plenum Press: New York.2. Xiang-Xin Bi, B. Ganguly, G. Huffman. E. Huggines. M. Endo, and P. C.

Eklund, J. ofMaterial Research, Submitted, 1992.3. J. T. d. Maleissye. F. Lempereur, and C. Marsal, C. R. Acad. Sci., Paris,

Ser., 275: p. 1153.1972.4. Y. P. Yampolskii, Y. V. Maximov, N. P. Novikov, and K. P. Lavrovskii, Khim.

Vys. Energ.,5. Y. Schwob, “Acetylene Black: Manufacture., Properties, and

Applications”, in Chem’srry and Physics of Carbon, Editor, J. Philip L. Walker and P.A. Thrower, 1979, Marcel Dekker.

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