III. Concepts of Material Science

1. 1 III. Concepts of Material Science In this section, the fundamental concepts of material science will be presented. The ultimate purpose is to create the basis for understanding matter at the nanoscale level, that is the Nanostructured Materials Nanocrystalline MaterialsCarbon Nanotubes/FullerenesDendrimers (Organic Nanoparticles)Polyhedral Silsesquioxanes (Inorganic-Organic Hybrid Nanoparticles)Nano-IntermediatesNanocomposites The classes of nanoparticles listed on this slide serve as the building blocks of nanomaterials and devices . Nanocrystalline Materials. include ceramics, metals, and metal oxide nanoparticles. Nanocrystallites of bulk inorganic solids have been shown to exhibit size dependent properties, such as lower melting points, higher energy gaps, and nonthermodynamic structures Carbon Nanotubes / Fullerenes.� Carbon nanotubes (CNTs) are hollow cylinders of carbon atoms. Carbon nanotubes (CNTs) were first isolated and characterized by Ijima in 1991.17 The unique physical and chemical properties of CNTs, such as structural rigidity and flexibility generate considerable interest. CNTs are extremely strong, about 100 times stronger (stress resistant) than steel at one-sixth the weight. Dendrimers (Organic Nanoparticles. These nanometer sized, polymeric systems are hyperbranched materials having compact hydrodynamic volumes in solution and high, surface, functional group content. Polyhedral Silsesquioxanes (Inorganic-Organic Hybrid Nanoparticles)� Hybrid inorganic-organic composites are an emerging class of new materials designed with the good physical properties of ceramics and the excellent choice of functional group chemical reactivity associated with organic chemistry. Nano-Intermediates�Nanostructured films, dispersions, high surface area materials, and supramolecular assemblies are the high utility intermediates to many products with improved properties such as solar cells and batteries, sensors, catalysts, coatings, and drug delivery systems. Nanocomposites� Nanocomposites are materials with a nanoscale structure that improve the macroscopic properties of products. Typically, nanocomposites are clay, polymer or carbon, or a combination of these materials with nanoparticle building blocks.Nanocrystalline Materials. include ceramics, metals, and metal oxide nanoparticles. Nanocrystallites of bulk inorganic solids have been shown to exhibit size dependent properties, such as lower melting points, higher energy gaps, and nonthermodynamic structures Carbon Nanotubes / Fullerenes.� Carbon nanotubes (CNTs) are hollow cylinders of carbon atoms. Carbon nanotubes (CNTs) were first isolated and characterized by Ijima in 1991.17 The unique physical and chemical properties of CNTs, such as structural rigidity and flexibility generate considerable interest. CNTs are extremely strong, about 100 times stronger (stress resistant) than steel at one-sixth the weight. Dendrimers (Organic Nanoparticles. These nanometer sized, polymeric systems are hyperbranched materials having compact hydrodynamic volumes in solution and high, surface, functional group content. Polyhedral Silsesquioxanes (Inorganic-Organic Hybrid Nanoparticles)� Hybrid inorganic-organic composites are an emerging class of new materials designed with the good physical properties of ceramics and the excellent choice of functional group chemical reactivity associated with organic chemistry. Nano-Intermediates�Nanostructured films, dispersions, high surface area materials, and supramolecular assemblies are the high utility intermediates to many products with improved properties such as solar cells and batteries, sensors, catalysts, coatings, and drug delivery systems. Nanocomposites� Nanocomposites are materials with a nanoscale structure that improve the macroscopic properties of products. Typically, nanocomposites are clay, polymer or carbon, or a combination of these materials with nanoparticle building blocks.

2. 2 Controlling Matter Nanotechnology promises to make manifestly real our ability to control matter beyond what matter seems to be ordained to do based on its molecular and atomic structure and properties that average out to the bulk matter properties we are familiar with. Before entering the world of nano-scale matter, it is advisable to learn about the traditional properties of bulk matter in terms of its molecular and atomic structure and ensuing electric and optical properties and the classification of matter types on the basis of these properties. Nano-science and nanotechnology will inevitably push our traditional understanding and implementation of material properties in the service of social needs, in new directions in electronics and microelectronics, biology, medicine, plasmonics, fluidics, composites, and in yet unimaginable domains of technology. To derive insights into the realm of nano-scale matter, this unit on traditional knowledge on the structure of matter is a proper starting point.Nano-science and nanotechnology will inevitably push our traditional understanding and implementation of material properties in the service of social needs, in new directions in electronics and microelectronics, biology, medicine, plasmonics, fluidics, composites, and in yet unimaginable domains of technology. To derive insights into the realm of nano-scale matter, this unit on traditional knowledge on the structure of matter is a proper starting point.

3. 3 Concepts of Materials Science Unit Goals: Structure Motivation Material properties Structural types for solids Crystalline materials Energy bands Insulators, semiconductors and conductors Energy bands and gaps of semiconductors Optical properties Goals: Provide motivation for the unit: Structure and properties at the macro level Size dependence of properties � many properties of solids depend on the size range over which they are measured. Bulk properties � at the macro- or large scale range (mm to km) the properties we associate with these materials are averaged (e.g., density and elastic modulus); accessible to our senses and to measurements. Nano properties � at the nano-scale range (1 to 100nm) many properties of materials change (e.g., mechanical, electrical, optical). Materials science: structure - property - processing relationships for all size ranges Goals: Provide motivation for the unit: Structure and properties at the macro level Size dependence of properties � many properties of solids depend on the size range over which they are measured. Bulk properties � at the macro- or large scale range (mm to km) the properties we associate with these materials are averaged (e.g., density and elastic modulus); accessible to our senses and to measurements. Nano properties � at the nano-scale range (1 to 100nm) many properties of materials change (e.g., mechanical, electrical, optical). Materials science: structure - property - processing relationships for all size ranges

4. 4 Properties of Materials Goal of materials science and engineering � structure, properties, processing relationships Materials properties: Mechanical Optical Electrical Thermal Chemical Types of materials: conductors, semiconductors, ceramics, polymers, and composites Goals: Provide an overview of materials science and engineering Provide introduction to the concept of material properties with many examples. Introduce examples of traditional types of materials. Optional concepts (may be a review depending on the class): Phases of matter � thermodynamic principles Atomic model (Bohr model) � quantum effects Periodic table and relationship element placement to materials properties. Atomic bonding and relationship element placement to materials properties. Goals: Provide an overview of materials science and engineering Provide introduction to the concept of material properties with many examples. Introduce examples of traditional types of materials. Optional concepts (may be a review depending on the class): Phases of matter � thermodynamic principles Atomic model (Bohr model) � quantum effects Periodic table and relationship element placement to materials properties. Atomic bonding and relationship element placement to materials properties.

5. 5 Structure of Solids Structural types for solids: Crystalline: atoms (or molecules) are arranged in a regular pattern that can extend throughout the crystal (long range order). Examples include diamond and silicon, and generally all minerals Amorphous : atoms (or molecules) lack long range order, but local order may exist (short range order). Examples include glasses and wax Goal: Describe the two general classifications of materials and provide examples. Focus on Crystalline Materials (introduction to crystallography � optional level of detail) Lattice points are points in space where atoms (or molecules) may exist Limited number of geometric lattice patterns allowed Five regular arrangements of lattice points that can occur in 2-D � called Bravais Lattices Fourteen unique Bravais Lattices exist in 3-D A crystal structure is formed by associating with each lattice point an atoms or groups of atoms. Goal: Describe the two general classifications of materials and provide examples. Focus on Crystalline Materials (introduction to crystallography � optional level of detail) Lattice points are points in space where atoms (or molecules) may exist Limited number of geometric lattice patterns allowed Five regular arrangements of lattice points that can occur in 2-D � called Bravais Lattices Fourteen unique Bravais Lattices exist in 3-D A crystal structure is formed by associating with each lattice point an atoms or groups of atoms.

6. 6 Structure of Solids Crystalline structures and Bravais lattices Crystalline structure are classified according to their symmetry and basic geometry. A unit cell is defined for each lattice type. The definition of a unit cell is not unique, but the duplication of that cell in 3-D produces the crystal. Reading Assignment: materials science or solid state physics or chemistry e.g., �Introduction to Materials Science for Engineers� by Shackelford (Chapter 3) Goal: Provide optional � additional detail A Bravais lattice, named after August Bravais is an infinite set of points generated by a set of discrete translation operations. A crystal is made up of one or more atoms (the basis) which is repeated at each lattice point. The crystal then looks the same when viewed from any of the lattice points. In all, there are 14 possible Bravais lattices that fill three-dimensional space. Related to Bravais lattices are Crystallographic point groups of which there are 32 and Space groups of which there are 230 (Wikipedai) The Bravais lattice can be generated by three unit vectors: a1, a2 and a3 and a set of integers k, l and m so that each lattice point is identified by a vector r, where r = ka1 + la2 + ma3 Goal: Provide optional � additional detail A Bravais lattice, named after August Bravais is an infinite set of points generated by a set of discrete translation operations. A crystal is made up of one or more atoms (the basis) which is repeated at each lattice point. The crystal then looks the same when viewed from any of the lattice points. In all, there are 14 possible Bravais lattices that fill three-dimensional space. Related to Bravais lattices are Crystallographic point groups of which there are 32 and Space groups of which there are 230 (Wikipedai) The Bravais lattice can be generated by three unit vectors: a1, a2 and a3 and a set of integers k, l and m so that each lattice point is identified by a vector r, where r = ka1 + la2 + ma3

7. 7 Structure of Solids