A Career-Focused Introduction to Nanoscale Materials Technology

Copyright © 2015 Tania M. Cabrera.

All rights reserved. No part of this book may be used or reproduced by any means, graphic, electronic, or mechanical, including photocopying, recording, taping or by any information storage retrieval system without the written permission of the author except in the case of brief quotations embodied in critical articles and reviews.

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ISBN: 978-1-4917-8613-0 (sc)

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CONTENTS

DEDICATED TO MY STUDENTS

PREFACE

AUTHOR’S ACKNOWLEDGEMENTS

CHAPTER 1    AN INTRODUCTION — WHAT IS MATERIALS SCIENCE

CHAPTER 2    ATOMS AND BONDING

CHAPTER 3    PHYSICAL PROPERTIES OF MATERIALS

CHAPTER 4    WHAT IS NANO

CHAPTER 5    CARBON NANOMATERIALS

CHAPTER 6    NON-CARBON NANOMATERIALS

CHAPTER 7    SYNTHESIS AND CHARACTERIZATION AT THE NANOSCALE

CHAPTER 8    BIOLOGICAL AND MEDICAL APPLICATIONS OF NANOSCALE MATERIALS

CHAPTER 9    NANOTECHNOLOGY AND ENERGY

CHAPTER 10    ENVIRONMENT

CHAPTER 11    MICROELECTRONICS

CHAPTER 12    ADDITIONAL APPLICATIONS OF NANOTECHNOLOGY

CHAPTER 13    NANOTECHNOLOGY COMPANIES

CHAPTER 14    CAREERS IN NANOTECHNOLOGY

CHAPTER 15    HEALTH AND SAFETY

A Career-Focused Introduction to

Nanoscale Materials Technology

Tania M. Cabrera

Associate Professor of Nanoscale Materials Technology

Division of Math, Science, Technology & Health

Schenectady County Community College

Art by Alicia Faucett, MS

Edited by Teresa Jacques, Ph.D.

Dedicated to My Students

The secret in education lies in respecting the student.

— Ralph Waldo Emerson

Preface

I started my teaching career at a community college in 2009, when I was hired to develop and implement a Nanoscale Materials Technology program. I live in the Albany, New York region, which has since been nicknamed Tech Valley, as we have seen a huge growth in the technology industries in recent years. My background did not necessarily fit the profile of a Nanoscale Materials Technology professor who specializes in semiconductor chip manufacturing. Upon high school graduation, I attended Simmons College in Boston, MA, where I double majored in Chemistry and Physics of Materials. Under the careful guidance of my organic chemistry professor and advisor, Dr. Rich Gurney, I became enamored with materials science research and completed a project doing microcontact printing on gold surfaces. I attended a summer internship program after my sophomore year at Simmons (National Science Foundation’s Research Experience for Undergraduates). The program I got into was at Columbia University in the late Nicholas Turro’s research group. It was during this time that I gained a real passion for nanotechnology, and the curious world that exists at the nanoscale. As a result, I returned to Columbia for graduate school, where I continued my work making functional nanoparticles.

After graduate school, I was hired by my amazing mentor Dr. Ruth McEvoy, former chair of the Math, Science and Technology department at Schenectady County Community College (SCCC). As I mentioned, the school was very forward thinking in developing a Nanoscale Materials Technology program to train technician level students for a new workforce in our area. Despite my lack if background in the area, I spent time studying the subjects I would need to be able to teach students relevant material. I learned a lot from local experts at a company called SuperPower, particularly the late Dr. Adrei Rar, who was always willing to give of his time to bring me up to speed on topics ranging from vacuum science to microscopy to thin film deposition.

As much as I loved teaching and the students at SCCC, I was faced with a somewhat difficult situation. I needed to teach students at a level for which no textbook existed. These students, for example, do not take calculus as traditional engineering students would, but needed more in depth information than could be found in general books about nanotechnology. It is for this reason that I am writing this book. Its goal is to inform at an appropriate level for community college students who are preparing for careers as technicians in the semiconductor manufacturing field.

My students are my inspiration. As such, you will notice a section at the end of each chapter called NanoSpeak, where I interview some of my former students to give you a real-world feel for their opinions on the field. I asked them a series of questions and told them to answer as if they were speaking to prospective nanotechnology students. These are their exact words, and I hope you will draw from their insights. I also ask you some questions, or things to think about after you read each chapter. Keep thinking and don’t be afraid of making inferences!

The book is formatted to begin with a general introduction to materials science, followed by specific insights into the world of nanoscale materials, and then a bit about careers and working in the industry. I hope you find it helpful, either as an educator, student, or curious party.

Author’s Acknowledgements

I would like to thank Dr. Ruth McEvoy for taking a chance on an unexperienced teacher, and having faith in me to develop and shape Nanoscale Materials Technology education at Schenectady County Community College. Thank you for being an outstanding professional example, mentor and friend.

Thank you to my amazing colleague Syeda Munaim for assisting me with Chapter 8 and being a biology guru.

I would also like to thank Alicia Faucett for making all of the images in this textbook, and Teresa Jacques for spending countless hours editing every single page herein. I am blessed to have both of these women in my life.

Finally, thank you to my family who have helped me out in countless ways, and never fail to support me. I love you Miguel, Sofia, Magdalena, Babbo, Chuqui, Chachi, Bianca, Nelson and Oscar.

CHAPTER 1    AN INTRODUCTION — WHAT IS MATERIALS SCIENCE

KEY TERMS

MATERIALS

PROPERTIES

STRUCTURE

PROCESSING

PERFORMANCE

METAL

ALLOY

CERAMIC

POLYMER

COMPOSITE MATERIAL

ADVANCED MATERIAL

SUPERALLOY

GLASS

AMORPHOUS

CRYSTALLINE

ELASTOMER

THERMOPLASTIC

THERMOSET PLASTIC

CONCRETE

MATRIX

BINDER

REINFORCEMENT

METAL MATRIX COMPOSITE

CERAMIC MATRIX COMPOSITE

REINFORCED PLASTIC

SANDWICH STRUCTURE

Introduction

In this chapter you will be introduced to the field of materials science. You will learn some of the history of materials and their importance to human development, and gain some insight into the major classes of materials. A thorough understanding of materials science will help you to understand what makes nanoscale materials so unique and special. The relationship between the structure and performance of materials will be outlined for you in the introductory chapters of this text, which will then be compared to materials on the nanoscale. Many examples of applications of materials will be given to provide you with a real-world perspective of materials science and nanoscale materials.

Some things to think about:

• What is the difference between a chemical substance and a material?

• What are some everyday examples of useful metal, ceramic, and polymer materials?

• When have you benefitted from the use of a composite material?

1.1    HISTORY

Materials science is generally defined as the science describing the relationship between the structure and properties of materials. Materials can be defined as a substance from which other useful things can be made. The term properties refers to both physical and chemical properties. Properties include how a material reacts to such things as heat, magnetic or electric fields, physical force, or chemicals. The term structure refers to the arrangement individual atoms that make up the material. If we want to change any of a material’s properties, we must do so by changing its structure. This is known as processing, or how we chemically change a material. Finally, we consider how the material can be used, or, its performance. A material’s performance depends on its properties.

Figure 1.1 Relationship between structure, properties, processing and performance of materials

Though you may not think of it, the history of materials goes back many thousands of years. Historians have actually charted man’s development by recognizing which materials were used to make objects such as tools and weapons, for example, the Stone, Bronze, and Iron Ages. The earliest humans used available naturally occurring materials, such as stone and wood. As time passed, man discovered that it was possible to produce materials that had superior properties to those that were naturally occurring. Heat could be used to soften and melt metals. Bronze, made from molten copper and tin, was the first alloy, or mixture of metals. Bronze is much easier to mold and shape than stone, making it a superior material.

Although we still use bronze today, after approximately 1000 B.C., iron ore obtained from the earth allowed man to work iron. There was no way to melt pure iron, but iron that contained a large percentage of carbon from charcoal could be more easily melted and cast into different shapes. The Iron Age continues today, although many new types of materials have been developed, such as ceramics, glasses, and semiconductors. We have the ability to design many new materials due to our study of materials, their structure, and properties.

1.2    CLASSES OF MATERIALS

We generally classify all solid materials into four main groups: metals, ceramics, polymers, and composites. The classification of metals, ceramics, and polymers is based on the types of atoms within the material, and how the atoms are bonded. There are also materials that are some combination of these three basic categories, which can be classified as composites. In addition to these categories, there are materials used for high-tech applications known as advanced materials. Semiconductors and nanoscale materials are examples of advanced materials.

METALS AND METAL ALLOYS

In the periodic table of the elements, the metallic elements are those that occur on the left-hand side of the chart. As of the year 2006, there are 117 known elements. Of those 117, 88 occur naturally, and of those 88, only 17 are non-metals (for example, oxygen, nitrogen, and chlorine), and 9 are semi-metals (for example, silicon, germanium, and arsenic).

Figure 1.2 Location of Metallic elements on the periodic table

The atoms in a metal are generally arranged in a very ordered manner, and packed in quite densely. Metals may have physical properties such as ductility, resistance to fracture, opaqueness, luster, and ability to conduct heat and electricity. These physical properties are a direct result of a metal’s atoms, and the electrons therein. This will be explained in chapter 2, section 2.6.1.

Materials that are classified as metals may also actually be combinations of metals, known as alloys. Common alloys include steel, brass, and bronze. Steel is a mixture of iron and carbon, brass is composed of the metals copper and zinc, while bronze is a mixture of copper and tin. Superalloys are alloys that exhibit high mechanical strength, good surface stability, and resistance to corrosion and oxidation at high temperatures. Superalloys are generally made using a base of nikel or cobalt.

CERAMICS AND GLASSES

A ceramic can be described as a compound that occurs between a metallic element, and a non-metallic element (usually oxygen, nitrogen or carbon). When we think of the word ceramic, the image of a clay pot made in art class may come to mind, or perhaps the tiles on our kitchen floor. These traditional ceramics are made from what we call clay, a generic term to describe metal oxides often mixed with organic carbon-based materials.

The physical properties of ceramics include stiffness, strength, and the relative inability to conduct heat and electricity. In addition, ceramics are generally very brittle and can fracture easily. Ceramics can be quite useful since they can withstand very high temperatures without melting. These properties arise from the type of bonding that occurs in ceramics, which leads to highly ordered crystalline solids. Further explanation of these bonds can be found in sections 2.6.2 and 2.6.4,

Glasses are a special type of ceramic. While glasses are generally a metal or semimetal bonded to a non-metal, they do not have a crystalline structure like a ceramic. Instead, they are amorphous, meaning the atoms are not ordered in any special way.

Figure 1.3 Crystalline vs. Amorphous structures

POLYMERS

The term polymer comes from the Greek poly, which means many, and meros, which means parts. As such, we can think of polymers as very long molecules that are composed of many repeating parts. A good image to represent such a molecule would be a long chain of paper clips hooked together.

Figure 1.4 Paper clip representation of a polymer material

Thousands of different polymers exist, but we are generally most familiar with those that make up common plastic goods such as drink bottles. Most polymers are carbon- or silicon-based molecules bonded to other non-metals such as hydrogen, oxygen, or nitrogen. The chemical reactivity of polymers is typically quite low, and they can have a wide range of physical properties. In general, polymers are soft, pliable, and easily melted. They also do not conduct heat or electricity well.

Some common categories of polymers are:

• Elastomers

• Thermoplastics

• Thermoset plastics

Thermoplastics become moldable or pliable when warmed to a critical temperature specific to each polymer. They are different from thermoset plastics in that thermoset plastics undergo an irreversible chemical change upon heating, referred to as ‘curing.’ Elastomers are often called ‘rubber,’ and are characteristically very pliable.

COMPOSITES

The term composite comes from composite material, meaning a material that is made up of two or more materials with different physical properties. Once the different materials are combined into a composite, the result is a new material with unique physical properties from the individual starting materials. The materials in a composite do not undergo a chemical reaction with one another when they are joined. Instead, they maintain their chemical character. Generally, a new composite material is engineered to have desirable physical properties such as being lighter, stronger, and less expensive than the original starting materials.

The two main components of a composite material are the bulk of the material known as the matrix, or binder, and the reinforcement, smaller fragments of very strong material encompassed by the matrix.

SUMMARY OF TYPES OF MATERIALS:

*Graphite and diamond are composed of only carbon, and as such are not typical ceramics. They are classified as such based on their physical properties.

Some of the earliest composite materials were bricks made of combining straw with mud as far back as 6,000 years. Other very common composites we still use are plywood, or wood glued together at various angles, and concrete which is a mixture of small, coarse particles embedded in cement.

Newer composite materials include metal and ceramic matrix composites, reinforced plastics, and sandwich structures. As the names would suggest, in a metal matrix composite, a metal serves as the binder material with non-metal reinforcements, and in a ceramic matrix material, the bulk of the material is ceramic. Reinforced plastics are composites wherein a polymer serves as the matrix material. A common reinforcement in a polymer matrix is carbon fiber to add strength to a plastic without making it heavy. A sandwich composite is a material composed of two thin, sturdy skins that are attached to a lightweight, thick core of lower strength, flexible material. The resulting composite is low density and bendable yet stiff.

NANOSPEAK – With Matthew Hudman

1. Where do you work and what is your job title?

GE Global research, Fab operations technician

2. What is your educational background?

AAS Automotive Technologies, AAS Nanoscale Materials Technology from Schenectady County Community College.

3. How did you get interested in nanotechnology/where did you hear about it?

I got interested in nanotech when an injury prevented me from returning to my previous career as an auto technician. I began researching the different programs offered through the community colleges in the area and found the nanoscale program very intriguing.

4. What advice would you give someone who might want to get into the field?

Collaboration and teamwork environments are not going away. Learn to work with others, learn how to present your ideas to others, learn how to communicate effectively. Have a positive attitude towards challenges and have respect for others. One other thing that I have seen is that integrity and knowing when to ask for help is a trait that is highly desirable. The education and training tells the employer that you are teachable. Everything else is just as important if not more so.

Chapter 1 Summary:

• Materials are substances out of which useful things can be made.

• Materials science is an interdisciplinary branch of science and engineering that examines the properties, performance, and processing of materials.

• Historians chart human development based on which materials were used for items such as tools and weapons.

• The main classes of materials are metals, ceramics, polymers, and alloys.

• Metals are materials composed of metallic elements which are found on the left-hand side of the periodic table.

• Metals are generally tough, ductile, dense, and good conductors of heat and electricity.

• Alloys are made of specific mixtures of metals.

• A ceramic is a material made of a metallic element bonded to a non-metallic element (found on the right-hand side of the periodic table).

• Ceramics are stiff, brittle, are able to withstand high temperatures and are electrical insulators.

• Polymers are long molecules made of repeating carbon or silicon units.

• We commonly think of polymers as plastics. They are usually chemically inert, soft, moldable, and cannot conduct heat or electricity.

• Composites are combinations of two or more materials that benefit from properties of each.

• We generally are trying to achieve strong and lightweight properties when combining materials to make a composite.

REFERENCES

1. W. Callister and D. Rethwisch, Materials Science and Engineering, An Introduction, 9th Ed., John Wiley &