Which of the following statements is/are correct:a)In an anti-fluorite...
Correct Statements:
A) In an anti-fluorite structure anions form FCC lattice and cations occupy all tetrahedral voids.
C) An atom/ions transferred from a lattice site to an interstitial position in Frenkel defect.
Explanation:
A) Anti-fluorite structure is a type of crystal structure in which the anions form the face-centered cubic (FCC) lattice and the cations occupy all the tetrahedral voids. This arrangement is opposite to that of the fluorite structure, hence the name anti-fluorite. In this structure, the anions are larger than the cations, which allows them to form the FCC lattice. The cations occupy all the tetrahedral voids between the anions, which results in a coordination number of 4 for the cations.
C) Frenkel defect is a type of point defect in which an atom or ion is transferred from its lattice site to an interstitial position. This type of defect is common in ionic crystals where the cations and anions have different sizes. In Frenkel defect, the cation or anion moves from its lattice position to an interstitial site, leaving behind a vacancy in the lattice. This type of defect does not affect the stoichiometry of the crystal and is usually observed in crystals with low coordination numbers.
Incorrect Statements:
B) If the radius of cations and anions are 0.2 and 0.95 then coordinate number of cation in the crystal is 4.
D) Density of crystal always increases due to substitution impurity defect.
Explanation:
B) The coordination number of a cation in a crystal structure depends on the size of the cation and the anion, as well as the type of crystal structure. Hence, it cannot be determined solely based on the radii of the cation and anion.
D) The effect of substitution impurity defect on the density of a crystal depends on the size and mass of the impurity atom or ion. In some cases, the substitution impurity may have a larger size and mass than the host atom, which can result in an increase in the density of the crystal. However, in some cases, the substitution impurity may have a smaller size and mass than the host atom, which can result in a decrease in the density of the crystal. Hence, it cannot be generalized that the density of the crystal always increases due to substitution impurity defect.
Which of the following statements is/are correct:a)In an anti-fluorite...
Anti florite structure is like Na2O .where O form FCC lattice and Na occupy td void.