MATLS 1M03 Study Guide - Final Guide: Elastic Modulus, Fermi Energy, Grain Boundary

160 views3 pages

Document Summary

*bond length distance at which the attractive and repulsive force balance. Fnet = 0 , enet = min ~ equilibrium. * symmetric energy well near bond length low coefficient of thermal expansion. *hexagonal packing bonding to 6 atoms; lowers the overall energy (e efficient) *square packing bonding to 4 atoms; not energy efficient. *apf the space that occupies in a cell. *coordination # - # of bonds it can produce; same for every atoms in the unit cell. Families of direction (h k l) [u v w] = hu +kv + lw = 0. Determines atomic interplanar distances & crystal structure. Bragg"s law: n order wavelength d a lattice spacing. Point defects defects at a single atom position: vacancies and self- interstitials. *vacancies - lattice site with missing atom or ion. Nv vacancy/atom n atom/m3 qv - ev/atom or j/mol. Xv fraction of atoms r 8. 314 j/mol*k or 8. 62*10-5 ev/atom*k.