SCHOTTKY AND VACANCY DEFECT BY SMITA

schottky and vacancy defect

1. GURU NANAK KHALSA COLLEGE PHYSICAL CHEMISTRY BY SMITA .S. JADHAV MSC :-1 SEM :-2

2. SOLID STATE CHEMISTRY RECAPITULATION :- STRUCTURES AND DEFECTS IN SOLIDS TYPES OF DEFECTS AND STOICHIOMETRY TOPIC:-

3. TYPES OF ZERO DIMENSIONAL (POINT) DEFECTS :- 1)VACANCY DEFECT 2) SCHOTTKY DEFECT (MATHEMATICAL DERIVATION ) ONE DIMENSIONAL (LINE) DEFECT :- 1) EDGE DISLOCATION 2) SCREW DISLOCATION CONTENT:-

4. At the any finite temprature sum of the latice point normally occupied by metal ions are vacant giving rise to vacancy defect. Number of vacancy defects in a given crystalline material depends upon temprature. Total number of metal atoms and average energy required to create a vacancy. If “n” is a number of vacancy and “N” is total number of atoms or ions and “EV” is average energy required to create a vacancy then we have, n= f(T, N,EV) VACANCY DEFECT:-

5. Schottky defects arise if same of the latice point in a crystals are unoccupied the points which are unoccupied are called lattice vacancies. The adjusant of two vacancies one due to misinng a Na + ions and other due to missing Cl - ions . The crystalise as a hole remains natural because missing number of positive and negative ions are same. Schottky defect appears generally ionic crystals in which positive and negative ions do not differ much in size . Because of schottky defect the electrical cunductivity of solid increases. SCHOTTKY DEFECT :-

6. In Edgedislocation , extra half plane of atoms is inserted into crystal latice as shown in fig, The crystal plane above and below contains some miss match and dislocation extends along a line perpendicular to the plane the crystal is strain in gricinity of dislocation inorder to occumated extra. SCREW DISLOCATION :- Formation of screw dislocation can be visualised by cutting a ruber bulb parallel to its axis and then to shift one end so that the jog is created such displacement of atom is called as screw dislocation. EDGE DISLOCATION:-

7. SOLID STATE 2 nd EDITION, LESLEY SMART AND ELAINE MOORE , PAGE NO:-159,160, 166-203 ANTHONY R . WEST , JOHN WILEY AND SONS , PAGE NO:-320-355 Dr K . YADAV , PAGE NO:- 79-99 Dr . HARISH CHANDER ALFA PUBLICATIONS , (NEW DELHI) – 110002 , PAGE NO:-15-21 M.G.ARORA , PAGE NO:- 115-121 REFERENCES:-