Physical Sciences and Mathematics Commons^™

Study Of Local Structure, Stress And Dynamics In Disordered Materials Using Ab-Initio And Molecular Dynamics Simulation, Madhusudan Ojha

Doctoral Dissertations

Understanding the atomic structure and dynamics in structurally disordered systems has been a long-standing and most challenging problem in physics and material science. To begin with, it is difficult to describe disorder quantitatively and to differentiate the degree of disorder from one system to another. The majorities of experimental and theoretical approaches to the study of disordered systems are either transferred directly from the study of crystals or address the problem in the macroscopic scale where the atomic origin of behavior is obscured. First principle atomic level stresses and dynamic pair distribution functions described in this dissertation represent attempts to …

Studies Of Regolithic Vestan Samples: Brecciated Eucrites And Howardites, Sheryl A. Singerling

Masters Theses

Brecciated eucrites and howardites represent samples of the regolith of asteroid 4 Vesta. As such, they are a valuable source of data for understanding the products of surface alteration. Two different processes are investigated here: impact mixing of comminuted rocks to produce regolith samples, and formation of glasses in the regolith.

Chapter 1 describes four newly discovered eucrite breccias: three presumably paired meteorites, all named NWA 6105, and NWA 6106. For each meteorite, major- and minor-element compositions of minerals were determined using the electron microprobe. Pyroxene Fe-Mn co-variations and bulk-rock oxygen isotope compositions confirm their classification as eucrites. Variations in …