21. Introduction to Glasses

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Session Overview

Modules Amorphous Materials
Concepts amorphous solids, glass formation, silicate and metallic glass, engineering glass properties: network formers, network modifiers
Keywords glass, amorphous solid, disordered solid, short-range order, metalloid, atomic mobility, rate of cooling, viscosity, silicate glass, network former, network modifier, solidification, molar volume, supercooled liquid, coefficient of thermal expansion, melting point, glass transition temperature, quenching, excess volume, processing temperature, chain scission, fluidity, bridging oxygen, terminal oxygen, index of refraction, metallic glass, free volume
Chemical Substances SiO2/silicates, B2O3/borates, GeO2/germanates, P2O5/phosphates, V2O5/vanadates, As2O5/arsenate, SbO5/stibnates, polymers, sulfur (S), quartz, Fe80B20, calcium oxide (CaO), lithium oxide (Li2O), sodium oxide (Na2O), magnesium oxide (MgO), lanthanum oxide (La2O3), yttrium oxide (Y2O3), scandium oxide (Sc2O3), lead oxide (PbO), tin oxide (SnO), cristobalite, water
Applications bottles, jars, food and beverage containers, windows, glass cookware, plastic wrap, food canning, optical fibers, computer screens, anti-theft tags, mercury thermometer, lead crystal


Before starting this session, you should be familiar with:

Learning Objectives

After completing this session, you should be able to:

  • Explain why materials form amorphous rather than crystalline solids.
  • Compare crystalline and amorphous solids in terms of their composition, molar volume, atomic structure, transition temperature, band gap, and desirable impurities.
  • Describe the effect of network modifiers at the molecular level.
  • Design a processing sequence for glass to achieve a given set of physical properties.


Archived Lecture Notes #7 (PDF)

Book Chapters Topics
Buy at Amazon [JS] 4.5, "Noncrystalline Solids – Three-Dimensional Imperfections." Random network theory of solids; long-, medium-, and short-range order; oxide, semiconductor, and metallic glasses; network formers and modifiers
Buy at Amazon [JS] 12.2, "Glasses – Noncrystalline Materials." Network formers, modifiers, and intermediates; commercial silicate glasses; nonsilicate glasses; applications of amorphous solids

Lecture Video

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Lecture Slides (PDF - 1.0MB)

Lecture Summary

Amorphous solids lack long-range order, but may have small regions of local order surrounded by a non-crystalline network. Commonly called "glass", they may form from inorganic compounds (e.g. SiO2/silicates, B2O3/borates, GeO2/germanates, P2O5/phosphates, V2O5/vanadates, As2O5/arsenate, SbO5/stibnates), organic compounds (e.g. polymers), elements (e.g. sulfur), and even metal alloys (e.g. Fe80B20). Glasses form when liquids with low atomic mobility are cooled too quickly to create an ordered crystal. The rate of cooling determines the transition temperature, excess volume, and degree of order present in the resulting glass. The addition of network modifiers (e.g., calcium oxide (CaO), lithium oxide (Li2O), sodium oxide (Na2O), magnesium oxide (MgO), lanthanum oxide (La2O3), yttrium oxide (Y2O3), scandium oxide (Sc2O3), lead oxide (PbO), tin oxide (SnO)) increase fluidity in liquid glass via chain scission, facilitating processing at lower temperatures.


Problems (PDF)

Solutions (PDF)

For Further Study

Supplemental Readings

Stookey, Stanley Donald. The Hydrogen-Lead, Hydrogen-Palladium, and Deuterium-Palladium Equilibria. Ph. D. thesis, Massachusetts Institute of Technology, 1940.

Chang, Kenneth. "The Nature of Glass Remains Anything But Clear." New York Times, July 29, 2008.


Dale Chihuly

Buy at Amazon Kuspit, Donald B. Chihuly. New York, NY: Harry N. Abrams, 1999. ISBN: 9780810963733.

Buy at Amazon Chihuly, Dale. Chihuly: Form From Fire. Seattle, WA: University of Washington Press, 1993. ISBN: 9780933053069.

Other OCW and OER Content

Content Provider Level Notes
Fracture of Glass DoITPoMS Undergraduate  


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