Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

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2nd Revise Page

154 • Chapter 5 / Imperfections in Solids

Subatomic particles

Atom/ion diameters

Unit cell edge lengths

Dislocations (width)

Second phase particles

Grains

Macrostructural features

(porosity, voids, cracks)

Dimensions of structural feature (m)

Dimensions of structural feature (nm)

10 −^14

10 −^610 −^410 −^21102104106108

10 −^1210 −^1010 −^810 −^610 −^410 −^2

Scanning probe microscopes

Scanning electron microscopes

Optical microscopes

Naked eye

Transmission electron microscopes

Useful resolution ranges (m)

Useful resolution ranges (nm)

10 −^12

10 −^21102104106108

10 −^1010 −^810 −^610 −^410 −^21

(a)

(b)

Figure 5.20 (a) Bar-chart showing size ranges for several structural features found in

materials. (b) Bar-chart showing the useful resolution ranges for four microscopic techniques

discussed in this chapter, in addition to the naked eye. (Courtesy of Prof. Sidnei Paciornik,

DCMM PUC-Rio, Rio de Janeiro, Brazil, and Prof. Carlos P ́erez Bergmann, Federal

University of Rio Grande do Sul, Porto Alegre, Brazil.)

These new SPMs, which allow examination of the surface of materials at the

atomic and molecular level, have provided a wealth of information about a host

of materials, from integrated circuit chips to biological molecules. Indeed, the ad-

vent of the SPMs has helped to usher in the era of nanomaterials—materials whose

properties are designed by engineering atomic and molecular structures.

Figure 5.20ais a bar-chart showing dimensional size ranges for several types of

structures found in materials (note that the horizontal axes are scaled logarithmi-

cally). Likewise, the useful dimensional resolution ranges for the several microscopic

techniques discussed in this chapter (plus the naked eye) are presented in the bar-

chart of Figure 5.20b. For three of these techniques (viz. SPM, TEM, and SEM), an

upper resolution value is not imposed by the characteristics of the microscope, and,

therefore, is somewhat arbitrary and not well defined. Furthermore, by comparing

Figures 5.20aand 5.20b, it is possible to decide which microscopic technique(s) is

(are) best suited for examination of each of the structure types.