توليد نانوذرات روي و اكسيد روي به روش چگالش بخار تعليق الكترومغناطيسي و مشخصه يابي آن

چكيده انگليسي :

Fabrication and characterization of Zn and ZnO nanoparticles by Electromagnetic Levitational Gas Condensation Method Majid Vaghayenegar Email address m vaghayenegar@ma iut ac ir Date of Submission 7th April 2010 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor s Name Ahmad Kermanpur Associate Professor ahmad k@cc iut ac ir Mohammad Hassan Abbasi Professor Abbasi32@cc iut ac ir Abstract Zn and ZnO nanoparticles have been the center of attention due to their unique properties In this study Zn and ZnO nanoparticles were fabricated by the novel method of Electormagnetic Leviational Gas Condensation In order to levitate Zn samples successfully a 2D computer simulation model was developed to design the appropriate coil geometry The Zn sample was levitated melted and finally evaporated Zinc vapours ascending from the high temperature levitated Zn droplet were condensed by appropriate inert gases under atmospheric and reduced pressures Effects of gas flow rate oxygen flow rate gas temperature gas type and pressure of the system on the mean particle size size distribution and morphology of Zn and ZnO nanoparticles were investigated XRD SEM TEM DLS and Image analysis were used to evaluate crystallinity morphology and mean size of the particles The particles synthesized at 1 atm were submicron in size although increasing gas flow rate of Ar and He 20 Ar led to decrease in the mean particle size Zn particles synthesized using Ar at 1 atm pressure under flow rates of 10 20 and 25 lit min 1 were spherical in shape with the mean size of 793 79 6 649 3 84 3 and 121 4 4 1 nm respectively Zn particles synthesized using He 20 Ar gas mixtures at 1 atm pressure under flow rates of 10 15 20 and 25 lit min 1 were spherical in shape with the mean size of 782 3 96 4 521 1 90 375 3 150 4 and 199 10 1 nm respectively Decreasing temperature of the He 20 Ar gas mixture about 75 degrees led to formation of faceted crystals This sharp change in morphology from spherical to faceted was attributed to the larger degree of supersaturation and entropy change Condensation of Zn particles at reduced pressure resulted in formation of smaller particles Zn particles synthesized at 460 380 and 300 mmHg using Ar as a carrier gas were spherical in shape with the mean sizes of 130 9 4 0 110 5 7 7 and 107 2 5 2 nm respectively The mean size of the particles synthesized at 300 mmHg using He 20 Ar gas were 39 5 2 7 nm A mechasnim was proposed to explain the effect of pressure on the mean particle size In order to synthesize ZnO nanoparticles oxygen was introduced into the chamber The required oxygen to inert gas molar ratio at 1 atm pressure using Ar He 20 Ar cooled He 20 Ar and at 330 mmHg using He 20 Ar to synthesize ZnO particles were determined to be 0 12 0 177 0 177 and 0 211 respectively The morphology of ZnO particles at all conditions were nanorods and tetrapods The mean length of the rods synthesized at 1 atm pressure using Ar He 20 Ar cooled He 20 Ar and at 330 mmHg using He 20 Ar were 290 6 94 48 78 95 and 82 1 nm respectively and their mean width of them were 132 36 54 68 32 96 and 26 61 nm respectively A possible justification was proposed to describe formation of rod like morphology Keywords Zn nanoparticles ZnO nanoparticles Electromagnetic levitation Gas Condensation

وقايع نگار، مجيد

توليد نانوذرات روي و اكسيد روي به روش چگالش بخار تعليق الكترومغناطيسي و مشخصه يابي آن

چگالشي از فاز بخار