(NH4)3FeF6 Mesocrystal Grown by Electric Field-Assisted in-situ Dissolution and Reaction of Anodic Iron Oxides

(NH4)3FeF6 mesocrystalline octahedrons are formed by in-situ dissolution and reaction of anodic iron oxides, followed by a non-classical crystal growth process involving electrical polarization and subsequent alignment of primary (NH4)3FeF6...

Wide-area multilayered self-assembly of fluorapatite nanorods vertically oriented on a substrate as a non-classical crystal growth

Oriented attachment of homogeneously shaped nanoblocks, such as nanocubes and nanorods, is attracting attention as a fundamental process of non-classical crystal growth to produce specific ordered architectures of functional materials....

A Mechanistic Understanding of Non-Classical Crystal Growth in Hydrothermally Synthesized Sodium Yttrium Fluoride Nanowires

Sodium yttrium fluoride (NaYF₄) is an upconverting material with many potential uses in chemistry, materials science, and biology that can be synthesized hydrothermally in both cubic (α) and hexagonal (β) crystallographic polymorphs. Understanding the mechanisms underlying the phase conversion between the cubic and hexagonal polymorphs is of great interest to help inform future efforts to synthesize atomically-precise quantum materials with well-defined sizes and morphologies. In this work, we use a combination of analytical transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), powder X-ray diffraction (XRD), in situ liquid cell TEM, atom probe tomography (APT), and extended x-ray absorption fine structure (EXAFS) measurements to show evidence suggesting that the hexagonal NaYF₄ nanowires form through a non-classical crystal growth mechanism involving the formation and subsequent oriented attachment of mesocrystals consisting of cubic (α) plase units. EXAFS spectroscopy also suggests that substitutional Yb³⁺ point defects within NaYF₄ are distributed evenly throughout the crystal lattice without clustering, and also that they may exhibit selective substitution into one of the two possible trivalent yttrium sites in the unit cell for hydrothermally synthesized NaYF₄.

A Mechanistic Understanding of Non-Classical Crystal Growth in Hydrothermally Synthesized Sodium Yttrium Fluoride Nanowires

Sodium yttrium fluoride (NaYF₄) is an upconverting material with many potential uses in chemistry, materials science, and biology that can be synthesized hydrothermally in both cubic (α) and hexagonal (β) crystallographic polymorphs. Understanding the mechanisms underlying the phase conversion between the cubic and hexagonal polymorphs is of great interest to help inform future efforts to synthesize atomically-precise quantum materials with well-defined sizes and morphologies. In this work, we use a combination of analytical transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), powder X-ray diffraction (XRD), in situ liquid cell TEM, atom probe tomography (APT), and extended x-ray absorption fine structure (EXAFS) measurements to show evidence suggesting that the hexagonal NaYF₄ nanowires form through a non-classical crystal growth mechanism involving the formation and subsequent oriented attachment of mesocrystals consisting of cubic (α) plase units. EXAFS spectroscopy also suggests that substitutional Yb³⁺ point defects within NaYF₄ are distributed evenly throughout the crystal lattice without clustering, and also that they may exhibit selective substitution into one of the two possible trivalent yttrium sites in the unit cell for hydrothermally synthesized NaYF₄.

Non-classical crystal growth on a hydrophobic substrate: learning from bivalve nacre

The hydrophobic substrate has an effect on the non-classical crystallization of nacreous aragonite crystals.

Connection of crystal faceting with the mechanism of its formation

The observed formation of nano- and microcrystals devoid of faceting in low-temperature processes of their formation can be associated with the implementation of a non-classical crystal growth mechanism by aggregation and oriented splicing of particles. The observation is illustrated on CaF2 examples.

Reversed Crystal Growth

In the last decade, a reversed growth route has been found in many crystal growth processes. In these systems, a single crystal does not develop from a single nucleus. The precursor molecules/ions or nanocrystallites aggregate into some large amorphous or polycrystalline particles. Multiple-nucleation on the surface of the amorphous particles or surface re-crystallization of the polycrystalline particles then takes place, forming a single crystal shell with a regular morphology. Finally, the crystallization extends from the surface to the core to form single crystals. This non-classical crystal growth route often results in some special morphologies, such as core-shell structures, hollow single crystals, sandwich structures, etc. This article gives a brief review of the research into reversed crystal growth and demonstrates that investigation of detailed mechanisms of crystal growth enables us to better understand the formation of many novel morphologies of the crystals. Some unsolved problems are also discussed.

An Improved Crystal Violet Assay for Biofilm Quantification in 96-Well Microtitre Plate

Microplates are essential tools for biofilm research since it allows high throughput screening of biofilm forming strains or in the assay of anti-biofilm drugs. However, 96 well microtitre plate based assays share the issue of “edge effect”. The primary cause of the “edge effect” phenomenon is evaporation. As edge effect causes a significant increase in plate rejection rate by introducing experimental error, we improvised the classical crystal violet assay to reduce water loss from the peripheral wells. The improvised method showed a significant reduction in edge effect and minimised error in crystal violet assay

On the Choice of the Power Law Flow Rule and its Consequences in Crystal Plasticity

Three types of power law flow rules are commonly used in classical crystal plasticity. These laws are purely phenomenological. The foremost point is how to define operative or effective stress and drag or slip system resistance. Specific choice of the definition leads to a unique number of implications including lattice rotation and slip activities, and we will highlight a few of them. We examined these three flow rules within finite strain framework with a single crystalline Al-rich TiAl binary alloy at very high homologous temperature with three strain rate controlled experimental data . It is revealed that two internal variables based flow rules give better results with a wide variety of applicability in plasticity and related phenomena.