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HWAHAK KONGHAK Vol. 38, No. 1, February, 2000, pp. 43-46 (Journal of the Korean Institute of Chemical Engineers)

43

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(1998j 8ú 11¢ 7>, 1999j 10ú 8¢ j)

Synthesis of Nanocrystalline PbS Particles in Reverse Micelles

Sungsoo Lee and Sung Min Cho^†

Department of Chemical Engineering, SungKyunKwan University, Suwon 440-746, Korea (Received 11 August 1998; accepted 8 October 1999)

º £

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;WB îšff b>º b" AOT~ jö V¢ îšf~ ’V& ¢æ² >– š¢ šÏ~ W>º PbS ã

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;~æ pj z× – ’V~ PbS 㶢 áj > ìî. ;W>º PbS ã¶~ çã" w 8f F;'ž jf&ê¢

&b–  jfç>º 1.8‚ ’šr.

Abstract−Nanocrystalline PbS particles were synthesized in reverse micelles. The size of reverse micelles derived from a functional surfactant AOT was controlled by changing the water-surfactant molar ratio(w=[H₂O]/[AOT]), and so the PbS syn- thesis reaction was allowed to occur only in the reverse micelles. The average sizes of PbS nanocrystals were in a range of 18ç-31ç in diameter, when the value of w changed from 1 to 8. At the higher values for w, the reverse micelles were not so stable that it was impossible to obtain the larger PbS nanocrystals controllably. The diameter of PbS nanocrystals was found to show a linear proportionality to the w value, of which the constant was 1.8.

Key words: Reverse Micelles, Nanocrystal, PbS, Microemulsion, Surfactant

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†E-mail: [email protected]

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[S²⁻]) ₃)₂f

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after different length of time.

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(2)

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š >š îšf~ ;Wš ®n;~ ¢;‚ ’V~ PbS «¶&

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£ 60%;ê Ôf Ö"¢ &.

PbS ã¶~ Wö 'Ëj "º æ>º w 8 šžö >wb~ j

ž x 8 (x=[Pb²⁺]/[S²⁻])

∆E E_g² 2h²E_g(2π⁄D)² ---m∗

+

1 2⁄

=

Fig. 2. Absorption spectra of PbS particles for different water/surfactant molar ratios.

Fig. 3. Absorption spectra of PbS particles for different water/surfactant molar ratios; (a) w=8, (b) w=10, (c) w=20, (d) w=40.

Fig. 5. Absorption spectra of PbS particles for different [Pb²⁺] / [S²⁻] molar ratios; (a) x=0.25, (b) x=1.0, (c) x=2.0.

Fig. 4. The dependence of PbS particle diameter on the water content and optical bandgap of the particles. The optical bandgap of the particles was calculated from the hyperbolic band model as a function of the particle diameter.

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^^ò

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Fig. 6. Comparison of the normalized absorption spectra of (a) PbS particles in microemulsion with (b) PbS particles extracted from the microemulsion.