Engineering Materials Week 9
12.11 Iron titanate forms in the ilmenite crystal structure that consists of an HCP arrangement of ions. (a). Which type of interstitial site will the ions occupy? Why? Since this ratio is between 0.414 and 0.732, the ions will occupy octahedral sites (b). Which type of interstitial site will the ions occupy? Why? Since this ratio is between 0.414 and 0.732, the ions will also occupy octahedral sites. (c). What fraction of the total tetrahedral sites will be occupied? No tetrahedral sites will be occupied.

(d). What fraction of the total octahedral sites will be occupied? For every formula unit, there are three ions, and, therefore, three octahedral sites; since there is one ion in each of and, two-thirds of these octahedral sites will be occupied. 12.21...

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