The spinel structure consists of an array of O 2 - ions in fcc arrangement. General formula of spinel is A B 2 O 4 . Cations of A occupy 1/8th the tetrahedral voids and cations of B ions occupy half o

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The spinel structure consists of an array of O 2 - ions in fcc arrangement. General formula of spinel is A B 2 O 4 . Cations of A occupy 1/8th the tetrahedral voids and cations of B ions occupy half of the octahedral voids. If oxide ions are replaced by X - 8 / 3 ions then number of an ionic vacancy per unit cell will be

TestHub · Accepted Answer

These are four O 2 - ions in the unit cell; let these ions are replaced by n, X - 8 / 3 ions. Charge of O 2 - ions = Charge of X - 8 / 3 ions 4(-2) = n (-8/3) n = 3 (i.e., there will one anionic vacancy) Thus, there will be one an ionic vacancy per unit cell.

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