Foundations Of Materials Science And Engineering 6th Edition By William Smith – Test Bank

Chapter 11, Problem 1
Define a ceramic material.
Chapter 11, Solution 1
Ceramic materials are inorganic, nonmetallic materials that consist of metallic and nonmetallic
elements bonded together primarily by ionic and/or covalent bonds.
Chapter 11, Problem 2
What are some properties common to most ceramic materials?
Chapter 11, Solution 2
While the properties of ceramic materials vary greatly, most ceramic materials are hard and brittle
with low toughness and ductility but good electrical and thermal insulating properties. Also,
ceramic materials typically have high melting temperatures and high chemical stability.
Chapter 11, Problem 3
Distinguish between traditional and engineering ceramic materials and give examples of each.
Chapter 11, Solution 3
Traditional ceramic materials are typically made from three components – clay, feldspar and
silica – whereas engineering ceramics consist of pure or nearly pure compounds such as aluminum
oxide ( Al O2 3 ), silicon carbide (SiC), and silicon nitride ( Si N3 4 ). Examples of traditional ceramics
include bricks, tiles and electrical porcelain while applications of engineering ceramics include
silicon carbide parts for high temperature gas turbine engine components, zirconium dioxide
crucibles for melting superalloys, and high performance ball bearing and races made of titanium
and carbon nitride.
Chapter 11, Problem 4
What two main factors affect the packing of ions in ionic solids?
Chapter 11, Solution 4
The two main factors which affect the packing of ions in ionic solids are:
1. The relative size of the ions in the ionic solid, assuming the ions are hard spheres with definite radii;
2. The need to balance the electrostatic charges to maintain electrical neutrality within the ionic solid.

Chapter 11, Problem 5
Define (a) coordination number and (b) critical radius ratio for the packing of ions in ionic solids.
Chapter 11, Solution 5
(a) The coordination number is the number of anions that surround a central cation.
(b) The critical radius ratio is the ratio of the radius of the central cation to the radius of the
surrounding anions.
Chapter 11, Problem 6
What is the spinel crystal structure?
Chapter 11, Solution 6
The spinel structure has the general form AB O where A represents a metal ion with a +2 2 4
valence,0 and B is a metal cation with a +3 valence. The oxygen ions form an FCC lattice in which
the A and B ions occupy the octahedral and tetrahedral interstitial sites.
Chapter 11, Problem 7
Draw the unit cell for BaF2, which has the fluorite (CaF2) crystal structure. If the Ba2+ ions occupy the
FCC lattice sites, which sites do the F-
ions occupy?
Chapter 11, Solution 7
The BaF2 unit cell is shown below. With the 2 Ba + ions occupying the FCC lattice sites, the F- ions
occupy the tetrahedral interstitial sites.

Chapter 11, Problem 8
What fraction of the octahedral interstitial sites are occupied in the CaF2 structure?
Chapter 11, Solution 8
All eight of the tetrahedral interstitial sites are occupied. However, none of the four octahedral
interstitial sites are occupied; thus the fraction is zero.
Chapter 11, Problem 9
What is the antifluorite structure? What ionic compounds have this structure? What fraction of the
tetrahedral interstitial sites are occupied by cations?
Chapter 11, Solution 9
The antifluorite structure consists of an FCC unit cell with anions occupying the FCC lattice points,
and with cations occupying all eight tetrahedral sites. Thus, the cation and anion positions of the
fluorite structure are reversed. Examples of compounds having this structure are
2 22 2 Li O, Na O, K O, and Mg O. The fraction of the tetrahedral sites occupied by cations is one (1.0).
Chapter 11, Problem 10
Describe the perovskite structure. What fraction of the octahedral interstitial sites are occupied by
the tetravalent cation?
Chapter 11, Solution 10
The perovskite structure (CaTiO3) consists of an FCC unit cell with 2+ Ca cations in the corners,
2 O – anions in the face centers, and a 4+ Ti cation in the center octahedral interstitial site. The
tetravalent cation 4+ Ti fills one- fourth of the octahedral sites.