Ptychographic X-ray tomography reveals additive zoning in nanocomposite single crystals

Ihli, Johannes; Levenstein, Mark A.; Kim, Yi‐Yeoun; Wakonig, Klaus; Ning, Yin; Tatani, Aikaterini; Kulak, Alexander N.; Green, David C.; Holler, Mirko; Armes, Steven P.; Meldrum, Fiona C.

doi:10.1039/c9sc04670d

Cited by 17 publications

(15 citation statements)

References 59 publications

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“…It is envisaged that our experimental approach can be used to study processes such as weathering and biomineralization, which will ultimately enable us to predict and control crystallization within porous media. We also expect that the continued development of techniques such as X-ray ptychography [67,68] will offer in situ measurements at enhanced spatial resolution, thereby permitting the observation of earlier stages of crystallization.…”

Section: Discussionmentioning

confidence: 99%

Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate

Anduix‐Canto

Levenstein

Kim

et al. 2021

Adv Funct Materials

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Characterizing the pathways by which crystals form remains a significant challenge, particularly when multiple pathways operate simultaneously.Here, an imaging-based strategy is introduced that exploits confinement effects to track the evolution of a population of crystals in 3D and to characterize crystallization pathways. Focusing on calcium sulfate formation in aqueous solution at room temperature, precipitation is carried out within nanoporous media, which ensures that the crystals are fixed in position and develop slowly. The evolution of their size, shape, and polymorph can then be tracked in situ using synchrotron X-ray computed tomography and diffraction computed tomography without isolating and potentially altering the crystals. The study shows that bassanite (CaSO 4 0.5H 2 O) forms via an amorphous precursor phase and that it exhibits long-term stability in these nanoscale pores. Further, the thermodynamically stable phase gypsum (CaSO 4 2H 2 O) can precipitate by different pathways according to the local physical environment. Insight into crystallization in nanoconfinement is also gained, and the crystals are seen to grow throughout the nanoporous network without causing structural damage. This work therefore offers a novel strategy for studying crystallization pathways and demonstrates the significant impact of confinement on calcium sulfate precipitation, which is relevant to its formation in many real-world environments.

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Section: Discussionmentioning

confidence: 99%

Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate

Anduix‐Canto

Levenstein

Kim

et al. 2021

Adv Funct Materials

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“…This in turn provides sensitivity to mass density, which may in principle be used to retrieve chemical information. [ 39 , 40 , 41 , 42 ] The application of PXCT in catalysis research is still at a relatively early stage, although the potential of the method is clearly shown in several studies of textural/pore structures [ 32 , 33 , 34 , 35 , 36 , 43 , 44 , 45 , 46 ] or chemical heterogeneity. [ 32 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ] Recently, PXCT studies on PTFE membranes could derive porosity and tortuosity information, which was then used to calculate diffusion coefficients and permeability.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Hierarchically Porous Nickel Alumina Catalysts Studied by X‐Ray Ptychography

et al. 2022

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The synthesis of hierarchically porous materials usually requires complex experimental procedures, often based around extensive trial and error approaches. One common synthesis strategy is the sol–gel method, although the relation between synthesis parameters, material structure and function has not been widely explored. Here, in situ 2D hard X‐ray ptychography (XRP) and 3D ptychographic X‐ray computed tomography (PXCT) are applied to monitor the development of hierarchical porosity in Ni/Al2O3 and Al2O3 catalysts with connected meso‐ and macropore networks. In situ XRP allows to follow textural changes of a dried gel Ni/Al2O3 sample as a function of temperature during calcination, activation and CO2 methanation reaction. Complementary PXCT studies on dried gel particles of Ni/Al2O3 and Al2O3 provide quantitative information on pore structure, size distribution, and shape with 3D spatial resolution approaching 50 nm, while identical particles are imaged ex situ before and after calcination. The X‐ray imaging results are correlated with N2‐sorption, Hg porosimetry and He pycnometry pore characterization. Hard X‐ray nanotomography is highlighted to derive fine structural details including tortuosity, branching nodes, and closed pores, which are relevant in understanding transport phenomena during chemical reactions. XRP and PXCT are enabling technologies to understand complex synthesis pathways of porous materials.

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“…Amaranth (a red dye) and Fast Green (a blue dye) both occluded at levels that are 10 times higher than in water alone, and the crystals exhibit pseudo-(001) faces that are characteristic of preferential interaction with the obtuse steps (Figure a–d,m). The Fast Green molecules also exhibit an intra-sectorial zoning effect ,, (Figure d), and SEM images show that there is no relationship between the zoning pattern and the morphology of the crystals (inset in Figure d). Reactive Green (a blue/green dye) was incorporated at levels 11 times higher than in the pure aqueous system and yielded platonic calcite crystals (Figure e,f,m).…”

Section: Resultsmentioning

confidence: 98%

Solvent-Mediated Enhancement of Additive-Controlled Crystallization

Nahi

Kulak

Broad

et al. 2021

Crystal Growth & Design

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Soluble additives are widely used to control crystallization processes, modifying the morphologies, sizes, polymorphs, and physical properties of the product crystals. Here, a simple and versatile strategy is shown to significantly enhance the potency of soluble additives, ranging from ions and amino acids to large dye molecules, enabling them to be effective even at low concentrations. Addition of small amounts of miscible organic cosolvents to an aqueous crystallization solution can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within single crystalsa level that cannot be achieved in pure aqueous solutions at any additive concentration. The generality of this strategy is demonstrated by application to crystals of calcium carbonate, manganese carbonate, and strontium sulfate, with a more pronounced effect observed for co-solvents with lower dielectric constants and polarities, indicating a general underlying mechanism that alters water activity. This work increases the understanding of additive/crystal interactions and may see great application in industrial-scale crystal synthesis.

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Ptychographic X-ray tomography reveals additive zoning in nanocomposite single crystals

Abstract: Ptychographic X-ray computed tomography visualizes the effects crystallography and solution composition have on occlusion motif and occlusion density of crystalline nanocomposites.

Cited by 17 publications

References 59 publications

Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate

Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate

Evolution of Hierarchically Porous Nickel Alumina Catalysts Studied by X‐Ray Ptychography

Solvent-Mediated Enhancement of Additive-Controlled Crystallization

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