Pre-Crystallization Criteria and Triple Crystallization Kinetic Parameters of Amorphous-Crystalline Phase Transition of As40S45Se15 Alloy

This framework focuses mainly on a detailed study of the pre-crystallization criteria that characterize the As40S45Se15 glassy alloy in various heating rates ranging from 5 to 40 (K/min.) by DSC thermo-grams in the range of (300-575 K). These criteria aim to clarify the relationship of the tendency of glass-forming by the heating rate for the investigated glassy alloy. As well, the present framework demonstrates the criteria of thermal stability. Continuously, the various nucleation and growth pathways. The transformation in activation energy with the volume of the crystalline portion was deduced and, through this, we were able to determine the surface resistance of the analyzed bulk alloy in the crystallization region. The crystalline structure of the study sample was recognized by X-ray diffraction (XRD) and electron scanning microscope (SEM).

Improving dispersive mixing in compatibilized polystyrene/polyamide-6 blends via extension-dominated reactive single-screw extrusion

Extensional mixing elements (EMEs) that impose extension-dominated flow via stationary single-plane or double-plane hyperbolic converging-diverging channels were previously designed for twin-screw and single-screw extruders (TSE and SSE, respectively). In a recently published work by the authors, reactive extrusion was performed on PS/PA6 polymer blends TSE using EMEs and a crystalline phase transition of the minor phase in these droplets was observed as the size of droplet decreases from micron to submicron. Herein, we expand upon this work to SSE and study: a) The ability of the EMEs to improve dispersive mixing in the same blends; b) Assess the possibility of achieving the same crystalline phase transition in SSEs. The final blends were characterized by DSC, rheologically and morphologically via SEM, and the results show that while EME-based SSE leads to much improved mixing, better than non-EME TSE, the reduction in size of the PA6 disperse phase is not enough to induce the phase transition observed in EME-based TSE.

Revealing 3D atomic packing in liquid-like solids

Liquids and solids are two fundamental states of matter. However, due to the lack of direct experimental determination, our understanding of the 3D atomic structure of liquids and amorphous solids remained speculative. Here we advance atomic electron tomography to determine for the first time the 3D atomic positions in monatomic amorphous materials, including a Ta thin film and two Pd nanoparticles. We observe that pentagonal bipyramids are the most abundant atomic motifs in these amorphous materials. Instead of forming icosahedra, the majority of pentagonal bipyramids arrange into a novel medium-range order, named the pentagonal bipyramid network. Molecular dynamic simulations further reveal that pentagonal bipyramid networks are prevalent in monatomic amorphous liquids, which rapidly grow in size and form icosahedra during the quench from the liquid state to glass state. The experimental method and results are expected to advance the study of the amorphous-crystalline phase transition and glass transition at the single-atom level.

Further Investigations of Crystal-to-Crystal Phase Transition of a [2]Pseudorotaxane Composed of Ferrocene-terminated Dialkylammonium and Dibenzo[24]crown-8-ether

[2]Pseudorotaxane [(FcCH2NH2CH2C6H4-4-Me)(DB24C8)][PF6] ([1][PF6]; Fc = ferrocenyl, DB24C8 = dibenzo[24]crown-8-ether) undergoes crystalline phase transition at 128 °C upon heating and at 106 °C upon cooling (α-phase at low temperature; β-phase at...