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Your search keyword '"Branicio, Paulo S."' showing total 22 results
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22 results on '"Branicio, Paulo S."'

1. Mechanical properties, failure mechanisms, and scaling laws of bicontinuous nanoporous metallic glasses

Author

Liu, Chang, Yuan, Suyue, Im, Jinwoo, de Barros, Felipe PJ, Masri, Sami F, and Branicio, Paulo S

Subjects
Engineering, Materials Engineering, Nanoporous metallic glass, Mechanical behavior, Scaling laws, Bicontinuous nanoporous, Condensed Matter Physics, Mechanical Engineering, Materials, Materials engineering, Mechanical engineering, Condensed matter physics
Abstract

Molecular dynamics simulations are employed to study the mechanical properties of nanoporous CuxZr1-x metallic glasses (MGs) with five different compositions, x = 0.28, 0.36, 0.50, 0.64, and 0.72, and porosity in the range 0.1 < ϕ < 0.7. Results from tensile loading simulations indicate a strong dependence of Young's modulus, E, and Ultimate Tensile Strength (UTS) on porosity and composition. By increasing the porosity from ϕ = 0.1 to ϕ = 0.7, the topology of the nanoporous MG shifts from closed cell to open-cell bicontinuous. The change in nanoporous topology enables a brittle-to-ductile transition in deformation and failure mechanisms from a single critical shear band to necking and rupture of ligaments. Genetic Programming (GP) is employed to find scaling laws for E and UTS as a function of porosity and composition. A comparison of the GP-derived scaling laws against existing relationships shows that the GP method is able to uncover expressions that can predict accurately both the values of E and UTS in the whole range of porosity and compositions considered.

Published
2022

3. Differences in Sb2Te3 growth by pulsed laser and sputter deposition

Author

Ning, Jing, Martinez, J. C., Momand, Jamo, Zhang, Heng, Tiwari, Subodh C., Shimojo, Fuyuki, Nakano, Aiichiro, Kalia, Rajiv K., Vashishta, Priya, Branicio, Paulo S., Kooi, Bart J., and Simpson, Robert E.

Subjects
Condensed Matter - Materials Science
Abstract

High quality Van der Waals chalcogenides are important for phase change data storage, thermoelectrics, and spintronics. Using a combination of statistical design of experiments and density functional theory, we clarify how the out-of-equilibrium van der Waals epitaxial deposition methods can improve the crystal quality of Sb2Te3 films. We compare films grown by radio frequency sputtering and pulsed laser deposition (PLD). The growth factors that influence the crystal quality for each method are different. For PLD grown films a thin amorphous Sb2Te3 seed layer most significantly influences the crystal quality. In contrast, the crystalline quality of films grown by sputtering is rather sensitive to the deposition temperature and less affected by the presence of a seed layer. This difference is somewhat surprising as both methods are out-of-thermal-equilibrium plasma-based methods. Non-adiabatic quantum molecular dynamics simulations show that this difference originates from the density of excited atoms in the plasma. The PLD plasma is more intense and with higher energy than that used in sputtering, and this increases the electronic temperature of the deposited atoms, which concomitantly increases the adatom diffusion lengths in PLD. In contrast, the adatom diffusivity is dominated by the thermal temperature for sputter grown films. These results explain the wide range of Sb2Te3 and superlattice crystal qualities observed in the literature. These results indicate that, contrary to popular belief, plasma-based deposition methods are suitable for growing high quality crystalline chalcogenides., Comment: 24 pages, 8 figs

Published
2020

19. Differences in Sb2Te3 growth by pulsed laser and sputter deposition

Author

Ning, Jing, primary, Martinez, Jose C., additional, Momand, Jamo, additional, Zhang, Heng, additional, Tiwari, Subodh C., additional, Shimojo, Fuyuki, additional, Nakano, Aiichiro, additional, Kalia, Rajiv K., additional, Vashishta, Priya, additional, Branicio, Paulo S., additional, Kooi, Bart J., additional, and Simpson, Robert E., additional

Published
2020
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22. Molecular Dynamics Simulations of Plane Shock Loading in SiC.

Author

Jingyun Zhang and Branicio, Paulo S.

Subjects
MECHANICAL loads, MECHANICAL properties of metals, SINGLE crystals, ATOMIC structure, MOLECULAR dynamics, PHASE transitions
Abstract

Large-scale molecular dynamics simulations are carried out to investigate 3C-SiC single crystals under plane shock loading. From the analysis of the shock profile and the evolution of the atomic structures, we demonstrate the interplay between the shock induced elastic compression, plastic deformation, and structural phase transformation (SPT). Particle velocity ranges from 0.4-6.0 km/s. The predicted shock Hugoniot is divided into four regions. Below 2 km/s, only elastic shock induced compaction exists. Plastic deformation appears between 2-3 km/s, while the SPT emerges above 3 km/s, when the induced pressure reaches over 90 GPa. Plastic deformation in this cubic crystalline material is marked by extensive deformation twinning while at high pressure the original low pressure zinc blend structure is transformed into the more compact rocksalt structure. For particle velocity above 4.5 km/s, a single overdriven transformation wave propagates in the system. These simulation results provide an atomistic view of the dynamic effects of shock impact on single crystal high-strength ceramics. [ABSTRACT FROM AUTHOR]

Published
2014
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