lesson 16 examples of solids we will show

lesson #16: examples of solids we will show the electronic structure (BAND) of significative types of solids (with digressions) • • • Solid State Physics M. Casalboni 2018/’ 19 rare-gas solids large gap insulators ionic crystals covalent semiconductors metals 1/22

lesson #16: examples of solids Rare-gas solids are crystals made up of closed-shell atoms Solid State Physics M. Casalboni 2018/’ 19 They are large gap insulators Ne Ar Kr Xe crystallize in fcc without basis inner core states flat occupied band structure occupied p-states fully occupied p-like band 2/22

lesson #16: examples of solids solid Argon Solid State Physics M. Casalboni 2018/’ 19 3/22

lesson #16: examples of solids solid Argon Solid State Physics M. Casalboni 2018/’ 19 EGAP = 14. 2 e. V 4/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 5/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 experiment: EPS (energy distribution curves of photoemitted electrons) density-of-state of occupied bands shifted by the energy of the impinging UV photon 6/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 Lennard-Jones assumption: only the first neighbours, two-body interaction 7/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 8/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 9/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 Assignments: following the textbook find the for rare-gas solids 10/22

lesson #16: examples of solids Ionic solids are crystals made up of atoms interacting with pure ionic bounds Solid State Physics M. Casalboni 2018/’ 19 Coulomb interaction energy Madelung energy point ion approximation Madelung constant: • dimensionless • caracteristic of the geometry of the crystal 11/22

lesson #16: examples of solids problem in performing the sum (it does not converge rapidly…) Solid State Physics M. Casalboni 2018/’ 19 12/22

lesson #16: examples of solids Methods: Solid State Physics M. Casalboni 2018/’ 19 13/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 crystal structure Madelung constant coesive energy 14/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 Na. Cl 15/22

lesson #16: examples of solids Covalent solids with diamond structure Solid State Physics M. Casalboni 2018/’ 19 • no closed shell • electrons mostly between two near atoms • particularly IV group elements 16/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 17/22

lesson #16: examples of solids Metals Solid State Physics M. Casalboni 2018/’ 19 • most common elemental crystals : 70 / 100 • the highest energy level happens inside a band • a Fermi surface can be defined simplest are the alkali metals Sommerfeld model fits very well 18/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 Fermi surface is almost a sphere 19/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 20/22

lesson #16: examples of solids Noble metals Solid State Physics M. Casalboni 2018/’ 19 21/22

lesson #16: examples of solids Solid State Physics M. Casalboni 2018/’ 19 22/22