Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Ionic colloidal crystals of oppositely charged particles

Abstract

Colloidal suspensions are widely used to study processes such as melting, freezing1,2,3 and glass transitions4,5. This is because they display the same phase behaviour as atoms or molecules, with the nano- to micrometre size of the colloidal particles making it possible to observe them directly in real space3,4. Another attractive feature is that different types of colloidal interactions, such as long-range repulsive1,3, short-range attractive5, hard-sphere-like2,3,4 and dipolar3, can be realized and give rise to equilibrium phases. However, spherically symmetric, long-range attractions (that is, ionic interactions) have so far always resulted in irreversible colloidal aggregation6. Here we show that the electrostatic interaction between oppositely charged particles can be tuned such that large ionic colloidal crystals form readily, with our theory and simulations confirming the stability of these structures. We find that in contrast to atomic systems, the stoichiometry of our colloidal crystals is not dictated by charge neutrality; this allows us to obtain a remarkable diversity of new binary structures. An external electric field melts the crystals, confirming that the constituent particles are indeed oppositely charged. Colloidal model systems can thus be used to study the phase behaviour of ionic species. We also expect that our approach to controlling opposite-charge interactions will facilitate the production of binary crystals of micrometre-sized particles, which could find use as advanced materials for photonic applications7.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: CsCl-type binary crystals.
Figure 2: Electric-field-induced melting.
Figure 3: LS 6 -type binary crystals.
Figure 4: LS-type binary crystals.
Figure 5: Theoretical phase diagrams.

Similar content being viewed by others

References

  1. Hachisu, S., Kobayashi, Y. & Kose, A. Phase separation in monodisperse latexes. J. Colloid Interf. Sci. 42, 342–348 (1973)

    Article  ADS  CAS  Google Scholar 

  2. Pusey, P. N. & van Megen, W. Phase behaviour of concentrated suspensions of nearly hard colloidal spheres. Nature 320, 340–342 (1986)

    Article  ADS  CAS  Google Scholar 

  3. Yethiraj, A. & van Blaaderen, A. A colloidal model system with an interaction tunable from hard sphere to soft and dipolar. Nature 421, 513–517 (2003)

    Article  ADS  CAS  Google Scholar 

  4. Kegel, W. K. & van Blaaderen, A. Direct observation of dynamical heterogeneities in colloidal hard-sphere suspensions. Science 287, 290–293 (2000)

    Article  ADS  CAS  Google Scholar 

  5. Pham, K. N. et al. Multiple glassy states in a simple model system. Science 296, 104–106 (2002)

    Article  ADS  CAS  Google Scholar 

  6. Islam, A. M., Chowdhry, B. Z. & Snowden, M. J. Heteroaggregation in colloidal dispersions. Adv. Colloid Interf. 62, 109–136 (1995)

    Article  CAS  Google Scholar 

  7. Vlasov, Y. A., Bo, X. Z., Sturm, J. C. & Norris, D. J. On-chip natural assembly of silicon photonic bandgap crystals. Nature 414, 289–293 (2001)

    Article  ADS  CAS  Google Scholar 

  8. Royall, C. P., Leunissen, M. E. & van Blaaderen, A. A new colloidal model system to study long-range interactions quantitatively in real space. J. Phys. Condens. Matter 15, S3581–S3596 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Hachisu, S. & Yoshimura, S. in Physics of Complex and Supermolecular Fluids (eds Safran, S. A. & Clark, N. A.) 221–240 (Wiley, New York, 1987)

    Google Scholar 

  10. Schofield, A. B. Binary hard-sphere crystals with the cesium chloride structure. Phys. Rev. E 64, 051403 (2001)

    Article  ADS  CAS  Google Scholar 

  11. Hunt, N., Jardine, R. & Bartlett, P. Superlattice formation in mixtures of hard-sphere colloids. Phys. Rev. E 62, 900–913 (2000)

    Article  ADS  CAS  Google Scholar 

  12. Saunders, A. E. & Korgel, B. A. Observation of an AB phase in bidisperse nanocrystal superlattices. Chemphyschem 6, 61–65 (2005)

    Article  CAS  Google Scholar 

  13. Redl, F. X., Cho, K. S., Murray, C. B. & O'Brien, S. Three-dimensional binary superlattices of magnetic nanocrystals and semiconductor quantum dots. Nature 423, 968–971 (2003)

    Article  ADS  CAS  Google Scholar 

  14. Bosma, G. et al. Preparation of monodisperse, fluorescent PMMA-latex colloids by dispersion polymerization. J. Colloid Interf. Sci. 245, 292–300 (2002)

    Article  ADS  CAS  Google Scholar 

  15. Bresme, F., Vega, C. & Abascal, J. L. F. Order-disorder transition in the solid phase of a charged hard sphere model. Phys. Rev. Lett. 85, 3217–3220 (2000)

    Article  ADS  CAS  Google Scholar 

  16. Velikov, K. P., Christova, C. G., Dullens, R. P. A. & van Blaaderen, A. Layer-by-layer growth of binary colloidal crystals. Science 296, 106–109 (2002)

    Article  ADS  CAS  Google Scholar 

  17. Gelinck, G. H. et al. Flexible active-matrix displays and shift registers based on solution-processed organic transistors. Nature Mater. 3, 106–110 (2004)

    Article  ADS  CAS  Google Scholar 

  18. Dzubiella, J., Hoffmann, G. P. & Löwen, H. Lane formation in colloidal mixtures driven by an external field. Phys. Rev. E 65, 021402 (2002)

    Article  ADS  CAS  Google Scholar 

  19. Löwen, H. & Dzubiella, J. Nonequilibrium pattern formation in strongly interacting driven colloids. Faraday Discuss. 123, 99–105 (2003)

    Article  ADS  Google Scholar 

  20. Pusey, P. N. General discussion. Faraday Discuss. 123, 177 (2003)

    Google Scholar 

  21. Dresselhaus, M. S., Dresselhaus, G. & Eklund, P. C. Science of Fullerenes and Carbon Nanotubes Ch. 8 (Academic, London, 1996)

    Google Scholar 

  22. Caballero, J. B., Puertas, A. M., Fernandez-Barbero, A. & de las Nieves, F. J. Oppositely charged colloidal binary mixtures: A colloidal analog of the restricted primitive model. J. Chem. Phys. 121, 2428–2435 (2004)

    Article  ADS  CAS  Google Scholar 

  23. Maskaly, G. R. Attractive Electrostatic Self-Assembly of Ordered and Disordered Heterogeneous Colloids. PhD thesis, Massachusetts Institute of Technology (2005)

  24. Bartlett, P. & Campbell, A. I. Three-dimensional binary superlattices of oppositely charged colloids. Phys. Rev. Lett. (in the press)

  25. Underwood, S. M., van Megen, W. & Pusey, P. N. Observation of colloidal crystals with the cesium-chloride structure. Physica A 221, 438–444 (1995)

    Article  ADS  CAS  Google Scholar 

  26. Biancaniello, P. L., Kim, A. J. & Crocker, J. C. Colloidal interactions and self-assembly using DNA hybridization. Phys. Rev. Lett. 94, 058302 (2005)

    Article  ADS  Google Scholar 

  27. van Blaaderen, A. & Vrij, A. Synthesis and characterization of colloidal dispersions of fluorescent, monodisperse silica spheres. Langmuir 8, 2921–2931 (1992)

    Article  CAS  Google Scholar 

  28. Hunter, R. J. Zeta Potential in Colloid Science Ch. 4 (Academic, London, 1981)

    Google Scholar 

  29. O'Brien, R. W. & White, L. R. Electrophoretic mobility of a spherical colloidal particle. J. Chem. Soc. Faraday Trans. II 74, 1607–1626 (1978)

    Article  CAS  Google Scholar 

  30. Frenkel, D. & Smit, B. Understanding Molecular Simulations Ch. 5, 10 (Academic, London, 2002)

    Google Scholar 

  31. Weiss, J. A., Oxtoby, D. W., Grier, D. G. & Murray, C. A. Martensitic transition in a confined colloidal suspension. J. Chem. Phys. 103, 1180–1190 (1995)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We thank R. P. A. Dullens, D. Derks, N. A. M. Verhaegh, P. Vergeer and C. M. van Kats for particle synthesis, A. D. Hollingsworth for solvent characterization, J. H. J. Thijssen for help with the pictures of the Bragg reflections and both P.N. Pusey and A.B. Schofield for pointing out the resemblance between our LS6-structure and certain fullerene compounds. This work is part of the research program of the ‘Stichting voor Fundamenteel Onderzoek der Materie’ (FOM), which is financially supported by the ‘Nederlandse organisatie voor Wetenschappelijk Onderzoek’ (NWO). Author contributions M.E.L. and C.G.C. investigated the phase behaviour of the experimental binary systems, A.-P.H. and M.D. performed the computer simulations, A.-P.H. and R.v.R. calculated the Madelung energies, C.P.R. worked on the lane formation, A.I. on the Bragg scattering, A.I.C. made different plus/minus systems and A.v.B. initiated the work and co-wrote the paper together with M.E.L.

Author information

Authors and Affiliations

Authors

Corresponding authors

Correspondence to Mirjam E. Leunissen or Alfons van Blaaderen.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Methods

Experimental details of the laser light powder diffraction measurements that we performed to determine the lattice parameter of the CsCl-type PMMA crystals. (DOC 19 kb)

Supplementary Table S1

Listing of the laser light powder diffraction data of the CsCl-type PMMA crystals, including the diffraction angles, the peak assignments and the calculated lattice parameter. (DOC 26 kb)

Supplementary Figure S1

A photograph of the Bragg reflections from CsCl-type binary crystals under white light illumination, revealing complete freezing of the sample into large, differently oriented crystallites. (DOC 666 kb)

Supplementary Figure S2

Plot of the laser light powder diffraction data of Supplementary Table 1, confirming the peak assignments and giving 2.364±0.010 m for the lattice parameter. (DOC 39 kb)

Supplementary Figure S3

Confocal images of the CsCl-type crystal growth showing the strongly ordered initial liquid phase and the rapid, homogeneous nucleation of differently oriented crystallites. (DOC 918 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Leunissen, M., Christova, C., Hynninen, AP. et al. Ionic colloidal crystals of oppositely charged particles. Nature 437, 235–240 (2005). https://doi.org/10.1038/nature03946

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature03946

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing