Question

Give the difference between:-
(a) Tetrahedral and octahedral voids
(b) Packing efficiency in hcp and ccp structures.
(c) Vacancy defect and Interstitial defect.
(d) Frenkel defect and schottky defect.
(e) Metal excess and Metal deficiency defect.
(f) Ferromagnetic, Antiferromagnetic and Ferrimagnetism.

Answer 1

(a) Tetrahedral Void and Octahedral Void : Generally we can define the void as the unoccupied empty space in unit cell is called void or empty space in unit cell. Voids are also known as holes in unit cell. In three dimensional closed packing of constituent particle shows following two 
(b) Both ccp and hcp are highly efficientlattice; in terms of packing. Thepacking efficiency of both types of close packed structure is 74%, i.e. 74% of the space in hcp and ccp is filled. The hcp and ccp structure are equallyefficient; in terms of packing. Thepacking efficiency of simple cubiclattice is 52.4%.
(c) point defect. noun Crystallography. an imperfection in a crystal's lattice structure, either a missing atom or ion creating a vacancy in the lattice or an extra atom or ion between two normal lattice points creating an interstitial.
(d)A Schottky defect is a type of pointdefect in a crystal lattice named after Walter H. Schottky. In non-ionic crystals it means a lattice vacancydefect. In ionic crystals, the defectforms when oppositely charged ions leave their lattice sites, creating vacancies.
(e)Metal Excess Defect and  Metal Deficiency Defect. Metal excess defect due to anionic vacancies: In this case, negative ions may be missing from their lattice sites leaving holes in which the electrons remain entrapped to maintain the electrical neutrality.
(f) ferrimagnetism in British. a phenomenon exhibited by certain substances, such as ferrites, in which the magnetic moments of neighbouring ions are antiparallel and unequal in magnitude. The substances behave like ferromagnetic materials. See also antiferromagnetism.