Term Paper on Imperfection in Solids
TERMPAPER
TOPIC:- imperfection in solid’s
NAME:-MILAN RAJAWAT
Regd. No.:-11004886
Section:-M2R16
Roll No.:-B16
Subjet:-MEC208
INTRODUCTION
For a crystalline solid we have tacitly assumed that perfect order exists throughout the material on an atomic scale. However, such an idealized solid does not exist; all contain large numbers of various defects or imperfections. As a matter of fact, many of the properties of materials are profoundly sensitive to deviations from crystalline perfection; the influence is not always adverse, and often specific characteristics are deliberately fashioned by the introduction of controlled amounts or numbers of particular defects, as detailed in succeeding chapters.
By ‘‘crystalline defect’’ is meant a lattice irregularity having one or more of its dimensions on the order of an atomic diameter. Classification of crystalline imperfections is frequently made according to geometry or dimensionality of the defect. Several different imperfections are discussed in this chapter, including point defects (those associated with one or two atomic positions), linear (or one-dimensional) defects, as well as interfacial defects, or boundaries, which are two-dimensional. Impurities in solids are also discussed, since impurity atoms may exist as point defects. [pic]Finally, techniques for the microscopic examination of defects and the structure of materials are briefly described.[?]
Imperfection in Solids
Nothing is perfect. The crystalline structures that we have looked at all have imperfections. We will quantify these imperfections here.
Crystalline Defects
A crystalline defect is a lattice irregularity having one or more of its dimensions on the order of an atomic dimension. There are 5 major categories of crystalline defects:
□ Zero dimensional: Point defects □ One dimensional: Linear defects (dislocations) □ Two dimensional: Planar (surface) defects
TOPIC:- imperfection in solid’s
NAME:-MILAN RAJAWAT
Regd. No.:-11004886
Section:-M2R16
Roll No.:-B16
Subjet:-MEC208
INTRODUCTION
For a crystalline solid we have tacitly assumed that perfect order exists throughout the material on an atomic scale. However, such an idealized solid does not exist; all contain large numbers of various defects or imperfections. As a matter of fact, many of the properties of materials are profoundly sensitive to deviations from crystalline perfection; the influence is not always adverse, and often specific characteristics are deliberately fashioned by the introduction of controlled amounts or numbers of particular defects, as detailed in succeeding chapters.
By ‘‘crystalline defect’’ is meant a lattice irregularity having one or more of its dimensions on the order of an atomic diameter. Classification of crystalline imperfections is frequently made according to geometry or dimensionality of the defect. Several different imperfections are discussed in this chapter, including point defects (those associated with one or two atomic positions), linear (or one-dimensional) defects, as well as interfacial defects, or boundaries, which are two-dimensional. Impurities in solids are also discussed, since impurity atoms may exist as point defects. [pic]Finally, techniques for the microscopic examination of defects and the structure of materials are briefly described.[?]
Imperfection in Solids
Nothing is perfect. The crystalline structures that we have looked at all have imperfections. We will quantify these imperfections here.
Crystalline Defects
A crystalline defect is a lattice irregularity having one or more of its dimensions on the order of an atomic dimension. There are 5 major categories of crystalline defects:
□ Zero dimensional: Point defects □ One dimensional: Linear defects (dislocations) □ Two dimensional: Planar (surface) defects