types of crystal defects

Types of defects in Crystals - The defect, which arises due to the irregularity in the arrangement of atoms or ions are called point defects. Point defects are of three types: Stoichiometric defects Non-stoichiometric h..

The defect, which arises due to the irregularity in the arrangement of atoms or ions are called point defects..

According to third law of thermodynamic it is only at OK that true crystals passes perfect order of arrangement of atoms in pure crystals. But with rise in temperature some derivations from complete order takes place. Presence of impurities also adds to disorder. "Any departure ..

Stoichiometric Defects - If imperfections in the crystal are such that the ratio between the anions and cations remain same as represented by the molecular formula, the defect is called a stoichiometric defect. There are three types of stoichiometri..

In in ionic crystal of the type A + B - , equal number of anions and cations are missing from the lattice sites so that electrical neutrality is maintained it is called schottky defect. fig 2.29 - Schottky defect..

This type of defect is shown by highly ionic compounds which have High coordination number Cations and anions of similar sizes Examples: KCl, NaCl, KBr and Cs..

Group 13 elements such as Ga and Al and group 15 elements such as P and As can enter the crystal structure of group 14 elements Ge or Si substitutionally. Group 15 elements have one excess valence electron as compared to Group 14 elements (Si or Ge). Therefore after forming four covalent..

If an ion is missing from its lattice site (causing a vacancy or a hole there) and it occupies the interstitial site so that electrical neutrality as well as stoichiometry of the compound are maintained. This type of defect is called Frenkel defect. Since the size of ..

Assumption - It is assumed that the atoms are hard spheres of identical size. Packing is done in such a way that they occupy maximum available space. This type of packing is called close packing . The packing of the spheres of equal size latices place as follo..

The Seven Crystal System - Crystals along with suitable examples are listed in the table. System Axial distances Axial angles Examples Cubic a = b = c α = β = γ = 90° NaCl,KCl, Diamond, Cu, Ag Tetragonal a = b ≠ c α = β = γ = 90° Whit..