CHEM 001B Lecture Notes - Lecture 13: Fluorite, Sphalerite, Zinc Sulfide
9 Mar 2018
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Document Summary
Cubic closest-packing of cl- ions with na+ ions in octahedral holes. Sphalerite (zns: fcc unit cell of s2- with zn2+ in four of the eight tetrahedral holes. Fluorite (caf2: ca2+ ions form an expanded fcc array to accommodate the larger f- ions, which occupy all eight tetrahedral holes. Practice: lattice structures: sphalerite (zns) has s2- ions in an fcc structure with zn2+ occupying four of the eight tetrahedral holes in the unit cell. Alloy a blend of a host metal and one or more other elements, which may or may not be metals, that are added to change the properties of the host metal. Homogeneous alloy a solution in which atoms of host and added elements are randomly and uniformly changed. Heterogeneous alloys a (cid:373)atri(cid:454) of host (cid:373)etal ato(cid:373)s with (cid:862)isla(cid:374)ds(cid:863) of ato(cid:373)s of added elements interspersed. Substitutional alloy atoms of non-host metal replace host atoms in the crystal lattice.
