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Synthesis of Various PbS Nanostructures by Pulsed Laser Ablation in Liquids

Author: LingChen
Tutor: DuXiWen
School: Tianjin University
Course: Materials Science
Keywords: Millisecond pulse laser PbS self-assembled quantum dots PbS nanostructures
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 63
Quote: 0
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Abstract


Preparation of nanomaterials with other methods, the laser method as an environmentally friendly and easy to operate and has been widely used . Since the laser ablation method liquid product by fluid restriction , preparation mechanism and vapor ablation are different. PbS is a narrow band gap semiconductor direct easily prepared with quantum confinement effects of nanomaterials . In this paper, laser ablation liquid Pb target fabrication PbS nanomaterials with different structures and the role of research in the millisecond pulse laser product under the formation mechanism . Dodecanethiol millisecond pulsed laser ablation of Pb target at high frequencies and laser were obtained when the secondary role of self-assembled structure of PbS , rotating target experiments show that the laser frequency is not the cause of the main causes of the structure . Inference mechanism of its formation is: different size nanocrystals selective absorption of infrared laser , the large size of the nanocrystals can continue to absorb the laser energy becomes smaller , the small size of the nanocrystals does not absorb the laser energy , the final dimensions converge. Dodecyl mercaptan sulfur source provided in the reaction , but also play the role of a stabilizer , the prepared nanocrystalline light in the near infrared region . Laser ablation of Pb thioglycolate target different width , frequency effects when they can get a shell structure that produces shell reason: millisecond pulse laser irradiation produces liquid metal target Kirkendall effect occurs , but also in the product found at different stages of its evolution the product . Laser ablation dodecyl mercaptan and n-hexane mixed solution of a different volume , to obtain nanocrystalline Pb , Pb @ PbS shell structure , Pb / PbS heterojunction , PbS nanocrystals , following the same liquid metal theory , and Pb-S system equilibrium phase diagram Pb, S PbS and Pb to match the existing form . In addition, mercapto acetic acid obtained in PbS cube thiophene obtained in nanocrystals, two mercapto acid acts on the single-crystal nanowires obtained in n-hexane, 5:1 volume ratio of dodecanethiol been assembled nanowire structures such PbS the formation mechanism needs further study .

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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