Imperfection of solid

When Cat-ion and Anion regular arrange in crystal than some ion dislocate their position or missing their crystal that indicate imperfection of solid.

             Some ion (Cat-ion or anion) arrange at 0 degree Kelvin which is called ideal solid.

·         There are different type of defect

.    1. Impurity defect :-  Impurity defects are foreign atoms that replace some of the atoms making up the solid or that squeeze into the interstices; they are important in the electrical behavior of semiconductors, which are materials used in computer chips and other electronic devices.

    2.  Stoichiometric defect  :-    The compounds in which the number of positive and negative ions are exactly in the ratios indicated by their chemical formulae are called stoichiometric compounds. The defects do not disturb the stoichiometry (the ratio of numbers of positive and negative ions) are called stoichiometric defects.

    Schottky defect:-  when  atom or ion regular arrange in crystal then same number of cation and anion missing their crystal which is called schottky defect.

   Density decreases in schottky defect. AgBr source frenkel defect and schottky defect.

Frenkel defect:-  When atom or ion arrange in crystal then one cation dislocated their position but present in crystal that is called frenkel defect.

    Vacancy defect:- In this defect when atom or ion regular arrange in crystal then sometime iron are vacant their position and electron occupy their space which is called vacancy defect.

·         Vacancy defect develop in presence of heat.

·         In vacancy defect F-center are develop.

      Interstitial defect:-  Interstitials defects are a variety of crystallographic defects where atoms assume a normally unoccupied site in the crystal structure. In interstitial defects, two or more atoms may share one lattice site, thereby increasing its total energy.

    3.     Non-stoichiometry defect:-  

     Metal Excess defect:- when metal and nonmetal regular arrange in crystal then number of metal is higher than number of non-metal that is fold metal excess defect.

                                             

    Metal Deficiency defect:- Metal and nonmetal regular range in crystal then number of metal is lower than number of non-metal, which is called metal deficiency defect.