Superionic Colloidal Crystals: Ionic to Metallic Bonding Transitions

Yange Lin, Monica Olvera De La Cruz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Size-asymmetric binary charged colloidal solutions can assemble into ionic colloidal crystals. These are often stabilized by ionic-type bonding, where the components with smaller size and charge sit at fixed points within the lattice of large particles. Here, we study the transition termed ionic to metallic bonding transition, by which the lattice of the smaller component melts while the crystal of the large particles is preserved, as in metallic bonding. We simulate a charged colloidal crystal in equilibrium with a solution containing small colloidal particles and counterions using the Coulomb interaction between the finite-size components. We find ionic to metallic first-order transitions by increasing either the temperature or the concentration of the small particles in the solution. The transition is accompanied by a lattice expansion and increased absorption of small particles into the crystal. We compute the free energies of the ionic and metallic states using the Madelung constant and Wigner-Seitz cell approaches, respectively, combined with the quasi-harmonic lattice model. The calculation reproduces the simulated transition and reveals that the enthalpic gain is more pronounced than the entropic gain in the transition from ionic to metallic bonding when material is exchanged with the solution.

Original languageEnglish (US)
Pages (from-to)6740-6749
Number of pages10
JournalJournal of Physical Chemistry B
Issue number35
StatePublished - Sep 8 2022

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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