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Mineral Physics

University of Nevada, Las Vegas

Physics & Astronomy Faculty Research

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Full-Text Articles in Physical Sciences and Mathematics

Structure-Strength Relations Of Distinct Mon Phases From First-Principles Calculations, Cheng Lu, Changfeng Chen Apr 2020

Structure-Strength Relations Of Distinct Mon Phases From First-Principles Calculations, Cheng Lu, Changfeng Chen

Physics & Astronomy Faculty Research

Molybdenum mononitrides (MoN) exhibit superior strength and hardness among the large class of transition-metal light-element compounds, but the underlying atomistic mechanisms for their outstanding mechanical properties and the variations of those properties among various MoN phases adopting different crystal structures remain largely unexplored and require further investigation. Here we report first-principles calculations that examine the stress-strain relations of these materials, and systematically compare results under pure and indentation shear deformations. In particular, we examine the distinct bonding structures and the associated mechanical properties in four different crystal phases of MoN that have been experimentally synthesized and stabilized under various physical …


Indentation-Strain Stiffening In Tungsten Nitrides: Mechanisms And Implications, Cheng Lu, Changfeng Chen Apr 2020

Indentation-Strain Stiffening In Tungsten Nitrides: Mechanisms And Implications, Cheng Lu, Changfeng Chen

Physics & Astronomy Faculty Research

We report on a systematic computational study of ideal strengths, i.e., the lowest stresses needed to destabilize a perfect crystal under a variety of loading conditions for six stable and metastable tungsten nitrides identified by advanced crystal structure search algorithms. We employ first-principles calculations to determine stress-strain relations and examine the corresponding atomistic bonding changes for a microscopic understanding of the structural deformation modes. The obtained results show that, in stark contrast to many previously studied transition-metal borides, carbides, and also most nitrides, the tungsten nitrides exhibit surprisingly broad and common patterns of strain-stiffening effects under indentation strains. These extraordinary …


Revisiting Polymorphism Of Molecular Crystals From The Melt, Alexander Shtukenberg, Qiang Zhu, Bart Kahr Mar 2018

Revisiting Polymorphism Of Molecular Crystals From The Melt, Alexander Shtukenberg, Qiang Zhu, Bart Kahr

Physics & Astronomy Faculty Research

No abstract provided.