1. LECTURE 10.2

2. OUTLINE Weekly Reading Weekly Reading Electronic Properties II Electronic Properties II

3. CHAPTER XXXII: SINTERING AND THE FIRING OF CLAY CERAMICS The shaping and firing of clay is common to all early civilizations and typically represents the first successful attempt by man to process a material—to create an engineered solid. The reactions that occur during the firing of clay are complex, but sintering is common to all reactions that aim to consolidate materials in the absence of large scale melting. Hence, Chapter 32 begins by describing the process of sintering, and presents some rather diverse examples of the formation of monolithic solids through sintering, such as the snowball, sedimentary rocks, and high-tech metals and ceramics. The shaping and firing of clay is common to all early civilizations and typically represents the first successful attempt by man to process a material—to create an engineered solid. The reactions that occur during the firing of clay are complex, but sintering is common to all reactions that aim to consolidate materials in the absence of large scale melting. Hence, Chapter 32 begins by describing the process of sintering, and presents some rather diverse examples of the formation of monolithic solids through sintering, such as the snowball, sedimentary rocks, and high-tech metals and ceramics.

4. CHAPTER XXXII: SINTERING AND THE FIRING OF CLAY CERAMICS The chapter then focuses on the firing of clay. The origin of clay is briefly described, as are the reactions that occur during firing. It is shown that, in addition to solid state sintering, the formation of a liquid phase at high firing temperatures can significantly enhance densification and the creation of a dense material.

5. CHAPTER XXXIV: THE PROCESSING OF STEEL Steel is central to the very fabric of our civilization. Steel provides the strength for the high-rise architecture of our downtowns, the flexibility and durability for the nation's infrastructure, and our desire for cheap automobiles. Chapter 34 presents the story of steel, from the raw materials that charge the blast furnaces to the credit card-thick steel sheet that is provided to the automobile manufacturers in places such as Detroit. Steel is central to the very fabric of our civilization. Steel provides the strength for the high-rise architecture of our downtowns, the flexibility and durability for the nation's infrastructure, and our desire for cheap automobiles. Chapter 34 presents the story of steel, from the raw materials that charge the blast furnaces to the credit card-thick steel sheet that is provided to the automobile manufacturers in places such as Detroit.

6. CHAPTER XXXIV: THE PROCESSING OF STEEL Chapter 34 begins with a description of the iron ores that will yield elemental iron and describes the reactions that occur in the blast furnace to produce the pig-iron and a liquid slag. It is shown that the pig-iron contains too many impurities to be of much value in the market place and that this pig-iron needs refining, or converting, to steel.

7. ELECTRONIC PROPERTIES II Free Electrons and Electron Holes in Covalently Bonded Materials Free Electrons and Electron Holes in Covalently Bonded Materials Motion of Free Electrons and Electron Holes Motion of Free Electrons and Electron Holes The Photoresistor The Photoresistor N-Type and P-Type Extrinsic Semiconductors N-Type and P-Type Extrinsic Semiconductors The Solid-State Rectifier or Diode The Solid-State Rectifier or Diode The Solar Cell The Solar Cell

8. COVALENT BONDING AND FREE ELECTRON/ELECTRON HOLE PAIRS

9. CREATION OF ELECTRON/ELECTRON HOLE PAIRS BY LIGHT PHOTONS AND THERMAL VIBRATIONS

10. IONIZATION ENERGIES AND BAND-GAP ENERGIES

11. MOTION OF A FREE ELECTRON AND AN ELECTRON HOLE

12. THE PHOTORESISTOR, OR THE LIGHT METER

13. N-TYPE AND P-TYPE DONOR IMPURITIES p-type (Group III) p-type (Group III) B Al Al Ga Ga In In Tl Tl n-type (Group V) n-type (Group V) N P As Sb Bi

14. A FREE ELECTRON IN AN N- TYPE SEMICONDUCTOR

15. AN ELECTRON HOLE IN A P- TYPE SEMICONDUCTOR

16. MOTION OF AN ELECTRON HOLE

17. FREE ELECTRON/ELECTRON HOLE MOTION IN A “DIODE”

18. CURRENT/VOLTAGE CHARACTERISTICS OF A SOLID- STATE “DIODE”

19. THE SOLAR CELL