Diffusion and interactions of interstitials in hard-sphere interstitial solid solutions

Meer, Berend van der; Lathouwers, Emma; Smallenburg, Frank; Filion, Laura

doi:10.1063/1.5003905

Cited by 7 publications

(10 citation statements)

References 34 publications

(48 reference statements)

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“…[1][2][3][4][5] Generally, if the two colloid species are of sufficiently different sizes, the larger colloids will form a lattice while the smaller colloids occupy interstitial sites. [6][7][8][9] In these size asymmetric colloidal systems, many cubic and non-cubic crystals have been detected, including a Frank-Kasper phase. 9 However, under certain conditions, the small particles may delocalize and roam around the crystal while the large particles remain in lattice sites; this is called sublattice melting.…”

Section: Introductionmentioning

confidence: 99%

“…Previously, this behavior had been seen primarily in atomic systems, in materials termed superionics, [10][11][12] where one ionic species delocalizes while the other stays fixed in a lattice. However, recent work has demonstrated sublattice melting in assemblies of hard spheres under pressure, 7,8 oppositely charged colloids with a Debye-Hückle potential, 13 and colloids functionalized with sticky DNA chains. 9 The surprising loss of order of only the sublattice also resembles behavior found in metals.…”

Section: Introductionmentioning

confidence: 99%

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Delocalization Transition in Colloidal Crystals

Lopez-Rios,

Ehlen,

de la Cruz

2020

Preprint

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Sublattice melting is the loss of order of one lattice component in binary or ternary ionic crystals upon increase in temperature. A related transition has been predicted in colloidal crystals. To understand the nature of this transition, we study delocalization in self-assembled, size asymmetric binary colloidal crystals using a generalized molecular dynamics model. Focusing on BCC lattices, we observe a smooth change from localized-to-delocalized interstitial particles for a variety of interaction strengths. Thermodynamic arguments, mainly the absence of a discontinuity in the heat capacity, suggest that the passage from localization-to-delocalization is continuous and not a phase transition. This change is enhanced by lattice vibrations, and the temperature of the onset of delocalization can be tuned by the strength of the interaction between the colloid species. Therefore, the localized and delocalized regimes of the sublattice are dominated by enthalpic and entropic driving forces, respectively. This work sets the stage for future studies of sublattice melting in colloidal systems with different stoichiometries and lattice types, and it provides insights into superionic materials, which have potential for application in energy storage technologies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Delocalization Transition in Colloidal Crystals

Lopez-Rios,

Ehlen,

de la Cruz

2020

Preprint

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“…At a n s :n l of 7:1 or 8:1, however, a fully BCC system would contain 2-4 interstitial defects per unit cell, which is energetically unfavorable. As has been demonstrated by van der Meer et al [33], interstitial defects in colloidal systems show long-range attraction. Therefore, the defects in the BCC system gather when there are strong small-large particle interactions (8 and 10 chains per small particle).…”

Section: First-order Phase Transition Driven By Interstitial Defectsmentioning

confidence: 57%

Metallization of colloidal crystals

Ehlen¹,

Lopez-Rios²,

Cruz³

2021

Preprint

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Colloidal crystals formed by size-asymmetric binary particles co-assemble into a wide variety of colloidal compounds with lattices akin to ionic crystals. Recently, a transition from a compound phase with a sublattice of small particles to a metal-like phase in which the small particles are delocalized has been predicted computationally and observed experimentally. In this colloidal metallic phase, the small particles roam the crystal maintaining the integrity of the lattice of large particles, as electrons do in metals. A similar transition also occurs in superionic crystals, termed sublattice melting. Here, we use energetic principles and a generalized molecular dynamics (MD) model of a binary system of functionalized nanoparticles (NPs) to analyze the transition to sublattice delocalization in different co-assembled crystal phases as a function of temperature (T ), number of grafted chains on the small particles, and number ratio between the small and large particles n s :n l . We find that n s :n l is the primary determinant of crystal type due to energetic interactions and interstitial site filling, while the number of grafted chains per small particle determines the stability of these crystals. We observe first-order sublattice delocalization transitions as T increases, in which the host lattice transforms from low-to high-symmetry crystal structures, including A20 → BCT → BCC, A d → BCT → BCC, and BCC → BCC/FCC → FCC transitions and lattices. Analogous sublattice transitions driven primarily by lattice vibrations have been seen in some atomic materials exhibiting an insulator-metal transition also referred to as metallization. We also find minima in the lattice vibrations and diffusion coefficient of small particles as a function of n s :n l , indicating enhanced stability of certain crystal structures for n s :n l values that form compounds. I. INTRODUCTIONBinary colloids of size-asymmetric particles have been shown to co-assemble into a diverse set of binary crystals [1][2][3][4][5][6][7][8]. These crystals are compounds akin to atomic ionic crystals because the smaller particles occupy interstitial sites of a lattice formed by the large particles.Recently the exploration of binary colloidal crystals with highly size-asymmetric functionalized NPs has yielded the observation of crystal assemblies where the small NPs delocalize, rather than remaining fixed at interstitial sublattice sites [9][10][11].

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“…Namely, we find the Laves phase to be thermodynamically stable for quite a broad range of compositionjust like in atomic binary crystals, where the composition can be tuned through the incorporation of stoichiometric defects. [44][45][46] Hence, binary mixtures of colloids do not only provide an interesting model system of ''big atoms'' 47,48 to study interstitial and substitutional solid solutions, [16][17][18][19][20][21][22][23][49][50][51] but also to study alloying in binary crystals.…”

Section: Discussionmentioning

confidence: 99%