Section 1c ceramics crysalstructure

Section 1C Ceramics CrysalStructure
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MATE 210 Section 1 Crystalline Structure CERAMICS (Smith: Chapter 11.1-11.3) The term ceramic comes from Greek ( keramikos ) “burnt stuff” ….often form ceramics by high temp heat treatment process called firing….
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MATE 210 Ceramic Structures - compounds b/w metal and nonmetal ions rather than atoms: + cations - anions - ionic bonds - more complex structures than metals more covalent more ionic 2 types of ions
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MATE 210 Charge Neutrality : --Net charge in the structure should be zero. --General form: A m X p m, p determined by charge neutrality CaF 2 : Ca 2+ cation F - F - anions + AX – Zinc Blende, NaCl, CsCl AX 2 – Flourite ABX 3 -- Perovskite
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MATE 210 • Coordination # increases with Issue: How many anions can you arrange around a cation? r cation r anion r cation r anion Coord # < .155 .155-.225 .225-.414 .414-.732 .732-1.0 ZnS (zincblende) NaCl (sodium chloride) CsCl (cesium chloride) 2 3 4 6 8 COORDINATION # & IONIC RADII
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Bonus Problem What type of crystal structures would Ca x F y , Ca x O y x As y form?
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