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Methods of Forming Nanoparticles

a nanoparticle and nanoparticle technology, applied in the field of nanoparticle preparation methods, can solve the problems of high capital expenditure, low yield, and high cost, and achieve the effect of high luminescence and good monodispersity

Inactive Publication Date: 2010-06-10
VICTORIA LINK LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for preparing nanoparticles of group IV metals or alloys thereof by reacting a group IV metal precursor with a decomposition-promoting reagent in a liquid reaction medium comprising a high temperature surfactant. The resulting nanoparticles have a high degree of crystallinity and can be chemically functionalized. The method includes adding a surface-bonding agent prior to adding a decomposition-promoting reagent. The nanoparticles produced have a small size and a narrow size distribution. The method can be completed in less than about 30 minutes and produces nanoparticles with high yields.

Problems solved by technology

However, such approaches produce low yields and are highly capital intensive.
The solution-phase synthesis techniques used to synthesise group II-VI and III-V semiconductors have not been readily applied to group IV materials, largely due to the high temperatures required to produce highly crystalline nanoparticles in a high yield.
In addition, the temperature required to thermally degrade many liquid phase group IV precursors exceeds the boiling points of many typical solvents at atmospheric pressure.
However, the nanoparticles produced by these methods often have extremely broad size distributions and poor visible luminescence efficiencies.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0173]1) Place 4.5 g of hexadecylamine (HAD) or 7.5 ml of oleylamine in a three necked round bottom flask[0174]2) Add 0.05 g triphenylchlorogermane to flask[0175]3) Place flask in a stirring heating mantle under a cold water condenser and nitrogen purge flow[0176]4) Heat to 285-300° C. whilst stirring[0177]5) Inject a solution of 0.005 g sulfur in 1.5 ml trioctylamine[0178]6) Wait approximately 5 minutes[0179]7) Observe swift ([0180]8) Immediately add 0.2-5 ml oleic acid. The solution will rapidly clear[0181]9) Heat to a defined temperature between 285° C. and 360° C. for up to one hour[0182]10) Cool to 150° C. and then quench with a 1:1 mixture of ethanol and toluene, added dropwise[0183]11) Remove from flask. Add ethanol (for hexadecylamine) or methanol (for oleylamine) drop-wise until flocculation is observed[0184]12) Centrifuge out flocculated sediment and remove and keep supernatant[0185]13) Further dilute precipitate with flocculent and centrifuge. Repeat steps 9-11 until requ...

example 2

[0187]An alternative procedure omits steps (2) and (3) from the procedure described in Example 1 and instead utilises solutions of sulfur in oleylamine and triphenylchlorogermane in oleylamine which are injected into the heated solvent at a temperature between 260° C. and 360° C. The procedure is then followed as from step (5) of Example 1.

example 3

[0188]1) Place 4.5 g of hexadecylamine or 7.5 ml of oleylamine in a three-necked round bottom flask[0189]2) Add 0.012 g selenium to flask[0190]3) Place flask in stirring heating mantle under a cold water condenser and nitrogen purge flow[0191]4) Heat to 285-300° C. whilst stirring[0192]5) Inject solution of 0.05 g triphenylchlorogermane in 1.5 ml trioctylamine[0193]6) React for 30 minutes[0194]7) Cool to 150° C. and then quench with a 1:1 mixture of ethanol and toluene, added dropwise[0195]8) Remove from flask. Add ethanol (for hexadecylamine) or methanol (for oleylamine) drop-wise until flocculation is observed[0196]9) Centrifuge out flocculated sediment and remove and keep supernatant[0197]10) Further dilute precipitate with flocculent and centrifuge. Repeat steps 9-11 until required purity is reached. Steps 9-11 may also be repeated on the supernatant to yield size selective precipitation of nanoparticles[0198]11) Resuspend the final precipitated material in toluene, hexane or et...

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Abstract

The present invention provides a method for preparing nanoparticles of group IV elements, particularly nanoparticles of Si, Ge and Sn, and binary and ternary alloys of these elements. The method comprises the solution-phase decomposition of one or more group IV metal precursors at elevated temperature and under an inert atmosphere at atmospheric pressure, using a decomposition-promoting reagent. A surface-bonding agent is added to the reaction mixture to form an organic layer surrounding the nanoparticles and prevent aggregation.

Description

FIELD OF THE INVENTION[0001]The present invention relates to methods for preparing nanoparticles of group IV elements. It relates particularly to the preparation of nanoparticles of Si, Ge and Sn, and binary and ternary alloys of these elements.BACKGROUND TO THE INVENTION[0002]The invention relates to quantum dots, also known as nanoparticles or nanocrystals.[0003]The term “nanoparticle” is generally invoked to refer to particles that have an average diameter between about 1 nm and about 100 nm. Nanoparticles have a size intermediate between individual atoms and macroscopic bulk solids. Nanoparticles that have diameters smaller or comparable to the Bohr exciton radius of the material can exhibit quantum confinement effects. Such effects can alter the optical, electronic, catalytic, optoelectronic, thermal and magnetic properties of the material.[0004]Many nanoparticles exhibit photoluminescence effects that are significantly greater than the photoluminescence effects observed for ma...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22F9/18B22F1/054
CPCB22F1/0018B82Y30/00B22F9/24B22F1/054
Inventor TILLEY, RICHARD DAVIDBUMBY, CHRISTOPHER WILLIAM
Owner VICTORIA LINK LTD
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