This document discusses different types of defects that can occur in solid materials, including Schottky and Frenkel defects. It defines lattice structures and unit cells used to represent ionic solids. Equations are provided that calculate the number of Schottky defects and Frenkel defects in a material based on parameters like the number of sites, work required to form the defects, temperature, and gas constant.

1. Structure and defects in solids
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan Manju
Desai College Canacona Goa

2. An unit cell system

3. Lattice

4. Representing ionic solid in 2D

5. Schottky Defect

6. Frenkel Defects

7. Frenkel defect
N= number of sites per cm3 that could
be left vacant
𝑁′= number of alternative interstitial
positions per cm3
Wf= work necessary to form a Frenkel
defect
k=gas constant
T=absolute temperature
Schottky defect
N= number of sites per cm3
Ws= work necessary to form a Schottky
defect
k=gas constant
T=absolute temperature
Number of defects
𝑛 𝑠 = 𝑁 𝑒(−
𝑊𝑠
2𝑘𝑇
)
𝑛 𝑓 = √𝑁𝑁′ 𝑒(−
𝑊 𝑓
2𝑘𝑇
)