Nanodot-to-Rod Transition and Particle Attachment in Self-Organized Polycrystalline Aggregates

Knoll, Pamela; Steinbock, Oliver

doi:10.1021/acs.cgd.9b00085

Cited by 10 publications

(14 citation statements)

References 36 publications

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“…Remarkably, X-ray diffraction (XRD, Figure C) reveals that the nanocrystals inside the nanocomposites are composed of hydroromarchite (Sn 3 (OH) 2 O 2 ) with an average grain size of 33 nm (see Supporting Information). , Thus, besides the barium cations being replaced for tin, the carbonate anions are also substituted with oxyhydroxide. Infrared spectroscopy (IR) confirms that the characteristic carbonate fingerprint peak (∼1450 cm –1 ) of BaCO 3 disappears after the conversion (Figure D).…”

Section: Resultsmentioning

confidence: 99%

Shaping Tin Nanocomposites through Transient Local Conversion Reactions

Hendrikse

Hémon-Charles

Helmbrecht

et al. 2021

Crystal Growth & Design

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Shape-preserving conversion offers a promising strategy to transform self-assembled structures into advanced functional components with customizable composition and shape. Specifically, the assembly of barium carbonate nanocrystals and amorphous silica nanocomposites (BaCO 3 /SiO 2 ) offers a plethora of programmable three-dimensional (3D) microscopic geometries, and the nanocrystals can subsequently be converted into functional chemical compositions, while preserving the original 3D geometry. Despite this progress, the scope of these conversion reactions has been limited by the requirement to form carbonate salts. Here, we overcome this limitation using a single-step cation/anion exchange that is driven by the temporal pH change at the converting nanocomposite. We demonstrate the proof of principle by converting BaCO 3 /SiO 2 nanocomposites into tin-containing nanocomposites, a metal without a stable carbonate. We find that BaCO 3 /SiO 2 nanocomposites convert in a single step into hydroromarchite nanocomposites (Sn 3 (OH) 2 O 2 /SiO 2 ) with excellent preservation of the 3D geometry and fine features. We explore the versatility and tunability of these Sn 3 (OH) 2 O 2 /SiO 2 nanocomposites as a precursor for functional compositions by developing shape-preserving conversion routes to two desirable compositions: tin perovskites (CH 3 NH 3 SnX 3 , with X = I or Br) with tunable photoluminescence (PL) and cassiterite (SnO 2 )—a widely used transparent conductor. Ultimately, these findings may enable integration of functional chemical compositions into advanced morphologies for next-generation optoelectronic devices.

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Section: Resultsmentioning

confidence: 99%

Shaping Tin Nanocomposites through Transient Local Conversion Reactions

Hendrikse

Hémon-Charles

Helmbrecht

et al. 2021

Crystal Growth & Design

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“…The step‐like feature in Figure 6e is also visible in Figure 6c and magnified further in Figure 6f. It has a grainy appearance which might indicate that the hair‐like structures formed through the attachment of smaller witherite nanoparticles as recently reported for barium‐based biomorphs; [20] however, at this point we cannot dismiss texture changes due to coating.…”

Section: Resultsmentioning

confidence: 72%

“…Our measurements yield a ratio of 3.8 which is comparable to values reported earlier for traditional intact biomorphs (Table S1). For instance, we recently found EDX‐based ratios between 3.4 and 4.2 for biomorph sheets formed under similar conditions [20] …”

Section: Resultsmentioning

confidence: 90%

“…The microscopic growth process of biomorphs likely involves the attachment of nanoparticles to the active growth zone [20] and hence constitutes an example of self‐assembly‐based, unconventional crystallization [21] . In our experiments, the typical diameter of these particles ranges between 5–50 nm.…”

Section: Introductionmentioning

confidence: 99%

“…In our experiments, the typical diameter of these particles ranges between 5–50 nm. [12,14] Over a period of up to 10 min, the nanodots fuse into nanorods of very high aspect ratios that are co‐aligned in the direction of the original biomorph growth (Figure 1d) [20] . The overall composition of biomorphs is a mixture of polycrystalline witherite (about 70 %) and amorphous silica (about 30 %), [14] but can be altered postsynthetically to perovskites and other materials without loss of the characteristic nano‐to‐micro architecture and overall microshape [22] .…”

Section: Introductionmentioning

confidence: 99%

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Fibrous Bundles in Biomorph Systems: Surface‐Specific Growth and Interaction with Microposts

et al. 2021

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Biomorphs are polycrystalline assemblies that form when barium, silicate, and carbonate ions react in basic solutions. Their micrometer‐scale morphologies include leaf‐like sheets, helices, and cones, while their nanoscale architecture is based on co‐aligned witherite nanorods. We report a biomorph shape that resembles hair strands that smoothly curl into spirals or twisting fiber ribbons. They can thicken through continuous fractal‐like branching or abrupt events in which fibers split simultaneously. Raman and energy dispersive X‐ray spectroscopy as well as optical polarization microscopy reveal that their composition is very similar to classical biomorphs. They are most abundant in the absence of glass substrates and at high pH values. However, if a glass surface is covered by a thin SU‐8 resin layer, their growth is observed and photolithographically produced SU‐8 posts serve as nucleation sites. The hair‐like structures can detach resin posts from the glass surface and reposition them due to continued growth at the hair‐resin interface. Collisions of growing biomorph sheets with SU‐8 posts result in overgrowth or a sheet‐to‐hair transition.

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Nonclassical Crystallization Causes Dendritic and Band‐Like Microscale Patterns in Inorganic Precipitates

et al. 2023

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The self‐organization of complex solids can create patterns extending hierarchically from the atomic to the macroscopic scale. A frequently studied model is the chemical garden system which consists of life‐like precipitate shapes. In this study, we examine the thin walls of chemical gardens using microfluidic devices that yield linear Ni(OH)2 precipitate membranes. We observe distinct light‐scattering patterns within the compositionally pure membranes, including disorganized spots, dendrites, and parallel bands. The bands are tilted with respect to the membrane axis and their spacing (20–100 μm) increases with increasing flow rates. Scanning electron microscopy reveals that the bands consist of submicron particles embedded in a denser material and these particles are also found in the reactant stream. We propose that dendrites and bands arise from the attachment of solution‐borne nanoparticles. The bands are generated by particle‐aggregation zones moving upstream along the slowly advancing membrane surface. The speed of the aggregation zones is proportional to the band distance and defines the system's dispersion relation. This speed‐wavelength dependence and the flow‐opposing motion of the aggregation zones are likely caused by low particle concentrations in the wake of the zones that only slowly recover due to Brownian motion and particle nucleation.

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Nanodot-to-Rod Transition and Particle Attachment in Self-Organized Polycrystalline Aggregates

Cited by 10 publications

References 36 publications

Shaping Tin Nanocomposites through Transient Local Conversion Reactions

Shaping Tin Nanocomposites through Transient Local Conversion Reactions

Fibrous Bundles in Biomorph Systems: Surface‐Specific Growth and Interaction with Microposts

Nonclassical Crystallization Causes Dendritic and Band‐Like Microscale Patterns in Inorganic Precipitates

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