Structure of Materials

This course is a part of xMinor in Materials for Electronic, Optical, and Magnetic Devices, a 4-course XSeries series from edX.

Structure determines so much about a material: its properties, its potential applications, and its performance within those applications. This course from MIT’s Department of Materials Science and Engineering explores the structure of a wide variety of materials with current-day engineering applications.

The course begins with an introduction to amorphous materials. We explore glasses and polymers, learn about the factors that influence their structure, and learn how materials scientists measure and describe the structure of these materials.

Then we begin a discussion of the crystalline state, exploring what it means for a material to be crystalline, how we describe directions in a crystal, and how we can determine the structure of crystal through x-ray diffraction. We explore the underlying crystalline structures that underpin so many of the materials that surround us. Finally, we look at how tensors can be used to represent the properties of three-dimensional materials, and we consider how symmetry places constraints on the properties of materials.

We move on to an exploration of quasi-, plastic, and liquid crystals. Then, we learn about the point defects that are present in all crystals, and we will learn how the presence of these defects lead to diffusion in materials. Next, we will explore dislocations in materials. We will introduce the descriptors that we use to describe dislocations, we will learn about dislocation motion, and will consider how dislocations dramatically affect the strength of materials. Finally, we will explore how defects can be used to strengthen materials, and we will learn about the properties of higher-order defects such as stacking faults and grain boundaries.

What you'll learn

• University-level chemistry
• Single-variable calculus
• Some basic linear algebra
• How we characterize the structure of glasses and polymers
• The principles of x-ray diffraction that allow us to probe the structure of crystals
• How the symmetry of a material influences its materials properties
• The properties of liquid crystals and how these materials are used in modern display technologies
• How defects impact numerous properties of materials—from the conductivity of semiconductors to the strength of structural materials
• Structure of materials roadmap
• States of matter and bonding
• Descriptors: concept and function
• Free volume
• Pair distribution function
• Glass processing methods
• Continuous network model
• Network modifiers
• Random walk model
• Chain-to-chain end distance
• Order and disorder in polymers
• Translational symmetry
• The crystalline state in 2D
• The crystalline state in 3D
• Miller indices
• Real space
• Reciprocal space
• Bragg’s Law
• Diffraction examples
• Translation, mirror, glide and rotation symmetry
• Allowed rotational symmetries in crystals
• An introduction to crystallographic notation
• The five 2D lattice types
• The 17 plane groups in 2D
• Inversion, Roto-Inversion, and Roto-reflection
• Screw symmetry
• Space point groups
• Stereographic projection
• Crystal lattices
• Space groups
• Symmetry constraints on materials properties
• Coordinate transformation
• Quasi crystals
• An introduction to plastic and liquid crystals
• Liquid crystal descriptors
• Liquid crystal applications
• Thermodynamics of point defects
• Vacancies, interstitials, solid solutions and nonequilibrium defects
• Kröger-Vink notation
• Extrinsic defects
• Diffusion
• Intro d shear stress
• Strengthening Mechanisms
• Surface free energy
• Wulff shape
• Surface defects
• Stacking faults
• Grain boundaries
• Surface reconstruction
• Linear defects in liquid crystals