High pressure phase evolution under hydrostatic pressure in a single imperfect crystal due to nanovoids

Javanbakht, Mahdi

doi:10.1016/j.mtla.2021.101199

Cited by 25 publications

(7 citation statements)

References 98 publications

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“…At corner E (zone 1, opposite to the AB edges) in figure 7 An intriguing feature of HRTEM images studied here is the topological layer S 1 at h-plates S 2 (seeds) turns down at borders so to cross-link S 1 − S 2 at a self-confined (compressed) structure. It involves a type of a 'S 1 →S 2 transition' over twins mediated via a Bi-rich MnBi 4 type phase (as observed at the lattice and XRD patterns) as an intermediate melt (MI) at the anneals, as noticed at some metals/alloys and PbTiO 3 at a solid S 1 →a solid S 2 phase transition [42][43][44]. In the theoretical studies, the Ginzburge-Landau equations are applied for various nanovoid deformation behaviors of materials and different nanoscale phenomena that can propagate at 'through channels' via a partially or a fully recurring melt phase [43,44].…”

Section: Hrtem Images Of Mn 60 Bi 40 Small H-platesmentioning

confidence: 98%

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties

et al. 2022

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A spin Mn3d5–rich Mn60Bi40 alloy reveals a model system in order to tailor profound magnetic properties at unpaired 3d5 spins in such alloys of a core-shell structure. As annealed (at a critical temperature 573 K in H2 gas), a refined powder (in glycine) grows on α-MnBi seeds (crystallites) present in it at Mn/Bi atoms order over topological layers, preferentially along (110) planes, at a self-confined structure at seeds of an anisotropic shape of hexagonal (h) plates (25 to 85 nm widths). In terms of the HRTEM images, the atoms turn down at edges (at the plates grow up) in a spiral layer, ≤ 2.1 nm thickness, of small core-shells. A spin model is proposed to delineate a way at the spins can pin down at the edges, form single magnetic domains, and raise coercivity (Hc), with no much loss of net magnetic moment. The X-ray diffraction and HRTEM images corroborate the results of topological pacing of atoms at the h-plates at anneals. A novelty is that a core-shell leads to tailor a superb Hc, as much as 11.110 kOe (16.370 kOe at 350 K), with a fairly large magnetization, 76.5 emu/g, at near 300 K. An enhanced Curie point 650.1 K (628 K at Mn50Bi50 alloy) confers a surplus 3d5-Mn spin sensitively tunes α-MnBi stoichiometry and so its final magnetic structure. A refined alloy powder so made is useful to make powerful magnets and devices in the forms of films and bonded magnets in different shapes for uses as small tools, tweezers, and other devices.

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Section: Hrtem Images Of Mn 60 Bi 40 Small H-platesmentioning

confidence: 98%

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties

et al. 2022

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“…Fu et al [ 30 ] suggested that the “strain rate effect” is a combination effect produced by the action of crack propagation, the inertial effect, and the viscous effect of free water. The DIF may not be a material property, but a physical result generated by inertial restraint, microcrack propagation, specimen size, free water and other factors with the increase in the strain rate [ 31 , 32 , 33 , 34 ].…”

Section: Test Results and Discussionmentioning

confidence: 99%

Dynamic Compression Mechanical Properties of Polyoxymethylene-Fiber-Reinforced Concrete

Guo

Yan

et al. 2022

Materials

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The excellent overall performance of polyoxymethylene (POM) fiber enables it to show great potential for engineering applications. The effect of POM fibers on the dynamic compression mechanical properties of concrete is an important issue for its application in engineering structures such as airport pavement and bridges. It is necessary to investigate the dynamic compressive mechanical properties of POM-fiber-reinforced concrete (PFRC) under impact loading. The PFRC specimens with various POM fiber lengths (6, 8, 12, 16, and 24 mm) and ordinary-performance concrete (OPC) specimens were tested by utilizing the split Hopkinson pressure bar (SHPB). We studied the effect of fiber length and strain rate on the dynamic compression mechanical properties of PFRC and established a damage dynamic constitutive model for PFRC. The results indicate that the dynamic compressive strength, peak strain, ultimate strain, dynamic peak toughness, dynamic ultimate toughness, and dynamic increase factor (DIF) of the PFRC increased obviously with the increase in strain rate. POM fiber was found to be able to effectively improve the deformation ability and impact toughness of concrete. The dynamic compressive strength and impact toughness of PFRC with a fiber length of 8 mm was optimal at different strain rates. The POM fibers with 16 mm and 24 mm lengths negatively affected the dynamic compressive strength of the concrete. The fiber length variation had an insignificant effect on the DIF of PFRC. The established damage dynamic constitutive model for PFRC was fitted and analyzed, and it was found that the model is able to describe the dynamic characteristics of PFRC well. This study can extend POM fibers to engineering structures that may be subjected to impact loading and act as a reference for the design of PFRC under impact loading.

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“…Moreover, a given fullerene at different sized OLF n shows different T m , indicating that the structural stability of SWF n can be effectively influenced by nanoconfinement. Such melting point profile can be utilized in a more general case, for example, temperature-induced phase transformation or stress-induced nanovoid formation/phase transformation in other structures [66][67][68]. Moreover, from an experimental point of view, novel carbon nanostructures of amorphous carbon@fullerene can be obtained by heating OLF n at critical temperatures.…”

Section: Melting Temperatures Of Swfn and Olfnmentioning

confidence: 99%

Size-dependent melting of onion-like fullerenic carbons: a molecular dynamics and machine learning study

Fu¹,

Xu²,

Shi³

et al. 2022

J. Phys.: Condens. Matter

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The melting thermodynamic characteristics of 2- to 20-layered onion-like fullerenes (OLFn) (C60@C240 to C60@···@C6000···@C24000) are comprehensively explored using first-principles-based ReaxFF atomistic simulations and random forest machine learning (RF ML). It is revealed that OLFn shows lower thermal stability than the counterparts of single-walled fullerenes (SWFn). The melting point of SWFn increases monotonically with increasing size, whereas for OLFn, an unusual size-dependent melting point is observed; OLFn with intermediate size shows the highest melting point. For small OLFn, the melting occurs from the inner to the outer, whereas for large OLFn, it nucleates from the inner to the outer and to intermediate fullerenes. The melting and erosion behaviors of both SWFn and OLFn are mainly characterized by the nucleation of non-hexagons, nanovoids, carbon chains and emission of C2. RF ML model is developed to predict the melting points of both SWFn and OLFn. Moreover, the analysis of the feature importance reveals that the Stone-Wales transformation is a critical pathway in the melting of SWFn and OLFn. This study provides new insights and perspectives into the thermodynamics and pyrolysis chemistry of fullerenic carbons, and also may shed some lights onto the understanding of thermally-induced erosion of carbon-based resources and spacecraft materials.

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High pressure phase evolution under hydrostatic pressure in a single imperfect crystal due to nanovoids

Cited by 25 publications

References 98 publications

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties

Dynamic Compression Mechanical Properties of Polyoxymethylene-Fiber-Reinforced Concrete

Size-dependent melting of onion-like fullerenic carbons: a molecular dynamics and machine learning study

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High pressure phase evolution under hydrostatic pressure in a single imperfect crystal due to nanovoids

Cited by 25 publications

References 98 publications

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn60Bi40 and tailored magnetic properties

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn60Bi40 and tailored magnetic properties

Dynamic Compression Mechanical Properties of Polyoxymethylene-Fiber-Reinforced Concrete

Size-dependent melting of onion-like fullerenic carbons: a molecular dynamics and machine learning study

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Product

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Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties

Structural ordering at magnetic seeds with twins at boundaries of a core–shell alloy Mn₆₀Bi₄₀ and tailored magnetic properties