Table Of ContentContributors
Karl T. Aust Yu. Ivanisenko
University of Toronto University of Ulm
Toronto, Ontario, Canada Ulm, Germany
Teruo Bitoh George E. Kim
Akita Prefectural University Perpetual Technologies, Inc.
Yurihonjo, Japan Quebec, Canada
Donald Brenner Carl Koch
North Carolina State University North Carolina State University
Raleigh, NC, USA Raleigh, NC, USA
Gan-Moog Chow Sara Majetich
National University of Singapore Carnegie Mellon University
Kent Ridge, Singapore Pittsburgh, PA, USA
Jürgen Eckert Akihiro Makino
IFW Dresden, Institute for Tohoku University
Complex Materials Sendai, Japan
Dresden, Germany
Gino Palumbo
Uwe Erb Integran Co.
University of Toronto Toronto, Ontario, Canada
Toronto, Ontario, Canada
Balaji Prabhu
Hans Fecht University of Central Florida
University of Ulm Orlando, Florida
Ulm, Germany
Wolfgang Sprengel
Joanna Groza University of Stuttgart
University of California, Davis Stuttgart, Germany
Davis, CA, USA
Cheng-jun Sun
Akihisa Inoue National University of
Tohoku University Singapore
Sendai, Japan Kent Ridge, Singapore
xv
xvi Contributors
C. Suryanarayana Julia Weertman
University of Central Florida Northwestern University
Orlando, FL, USA Evanston, IL, USA
Michel Trudeau Shi Yu
Hydro-Quebec Research Institute Singapore-Massachusetts Institute
Varennes, Quebec, Canada of Technology Alliance
Singapore
Raphael Tsu
University of North Qi Zhang
Carolina—Charlotte Advanced Photonix, Inc.
Charlotte, NC, USA Dodgeville, WI, USA
Preface to Second Edition
Introduction
Nanostructure science and technology has become an identifiable, if
very broad and multidisciplinary, field of research and emerging applica-
tions in recent years. It is one of the most visible and growing research
areas in materials science in its broadest sense. Nanostructured materials
include atomic clusters, layered (lamellar) films, filamentary structures,
and bulk nanostructured materials. The common thread to these various
material forms is the nanoscale dimensionality, i.e., at least one dimen-
sion less than 100nm, more typically less than 50nm. In many cases, the
physics of such nanoscale materials can be very different from the
macroscale properties of the same substance. The different, often supe-
rior, properties that can then occur are the driving force behind the explo-
sion in research interest in these materials. While the use of nanoscale
dimensions to optimize properties is not new, as will be outlined below,
the present high visibility and definition of the field is mainly attributable
to the pioneering work of Gleiter and coworkers in the early 1980s [1].
They synthesized nanoscale grain size materials by the in situ consolida-
tion of atomic clusters. The study of clusters preceded this work by
researchers such as Uyeda [2]. The International Technology Research
Institute, World Technology Division (WTEC), supported a panel study
of research and development status and trends in nanoparticles, nanos-
tructured materials, and nanodevices between 1996 and 1998. The main
results of this study have been published [3] and formed one of the drivers
for the U.S. National Nanotechnology Initiative. This report attempted to
cover the very broad field of nanostructure science and technology and
included assessments of the areas of synthesis and assembly, dispersions
and coatings, high surface area materials, functional nanoscale devices,
bulk nanostructured materials and biologically related aspects of nano-
particles, nanostructured materials, and nanodevices. Aconclusion of the
report is that while many aspects of the field existed well before it was
identified as a field in the last decade, three related scientific/technologi-
cal advances have made it a coherent area of research. These are:
xvii
xviii Preface
1. New and improved synthesis methods that allow control
of the size and manipulation of the nanoscale “building
blocks,”
2. New and improved characterization tools for study at the
nanoscale (e.g., spatial resolution, chemical sensitivity), and
3. Better understanding of the relationships between nanos-
tructure and properties, and how these can be engineered.
With the recent intense interest in the broad field of nanostructure
science and technology, a number of books, articles, and conference pro-
ceedings have been published on this broad topic. Apartial listing of these
publications is given in the bibliography below, starting with the review
of Gleiter in 1989. Atwo-fold justification was given for another book in
this rapidly advancing field in the preface of the first edition. These were,
first that since many areas of the field are moving rapidly with increased
understanding from both experiment and simulation studies, it would
appear useful to record another “snapshot” of the field. This justification
is certainly true for the second edition since in the over four years since
the first edition was published, many new advances have occurred and the
updated chapters reflect them. The second justification for the first edition
was that because this field is so broad, the book has been designed to focus
mainly on those areas of synthesis, characterization, and properties rele-
vant to application that require bulk, and mainly inorganic materials. An
exception was the article by Tsu and Zhang on electronic and optoelec-
tronic materials. The exceptions in this second edition are the updated
chapter by Tsu and Zhang on the above area, and a new chapter on mag-
netic nanoparticles and their applications by Majetich. Before a brief
description of the updated chapters, the new chapters, changes in some
authorship, and the organization of the book is presented, a historical per-
spective will be given to suggest how the field has developed and what
new information has been provided by reaching the limit of the nanoscale.
Historical Perspective
Nanoscale microstructural features are not new, either in the natural
world or in materials engineering. There are examples of nanoscale fer-
romagnetic particles found in microorganisms, e.g., 50nm Fe O in the
3 4
organism A. magnetotactum [4]. Anumber of examples exist of improve-
ment in mechanical properties of structural materials when a fine
microstructure was developed. Early in the last century, when
Preface xix
“microstructures” were revealed primarily with the optical microscope, it
was recognized that refined microstructures, for example, small grain
sizes, often provide attractive properties such as increased strength and
toughness in structural materials. Aclassic example of property enhance-
ment due to a refined microstructure—with features too small to resolve
with the optical microscope—was age-hardening of aluminum alloys. The
phenomenon, discovered by Alfred Wilm in 1906, was essentially
explained by Merica, Waltenberg, and Scott in 1919 [5], and the
microstrutural features responsible were first inferred by the x-ray studies
of Guinier and Preston in 1938 [6]. With the advent of transmission elec-
tron microscopy (TEM) and sophisticated x-ray diffraction methods, it is
now known that the fine precipitates responsible for age-hardening, in
Al-4% Cu alloys, for example, are clusters of Cu atoms—Guinier-Preston
(GP) Zones—and the metastable partially coherent Θ′ precipitate [7,8].
Maximum hardness is observed with a mixture of GPII (or Θ″, coarsened
GP zones) and Θ′, with the dimensions of the Θ′ plates typically about
10nm in thickness by 100nm in diameter. Therefore, the important
microstructural feature of age-hardened aluminum alloys is nanoscale.
Critical length scales often determine optimum properties which are
structure sensitive. Mechanical properties such as strength and hardness are
typical, and as above, microstructural features such as precipitates or dis-
persoids are most effective when their dimensions are nanoscale. In ferro-
magnetic materials, the coercive force has been found to be a maximum if
spherical particles (e.g., Fe C in Fe) which act as domain wall pinners have
3
a diameter about equal to the domain wall thickness, i.e., about 50nm [9].
Similarly, in type II superconductors, it has been found that fluxoid pinning,
which determines the magnitude of the critical current density, is most
effective when the pinning centers typically have dimensions of the order
of the superconducting coherence length for a given material. For the high
field superconductors, the coherence length is usually about 10–20nm, and
indeed the commercial superconductors have pinning centers that appro-
ximate these dimensions. In Nb Sn, the grain boundaries are the major
3
pinning sites and optimum critical current densities are obtained when the
grain sizes are about 50nm [10]. Many other examples could be given of
the long term use of nanoscale materials in fields such as catalysis.
Organization
As was done in the first edition of this book, Part I covers the impor-
tant synthesis/processing methods for the production of nanocrystalline
xx Preface
materials. Part II focuses upon selected properties of nanostructured
materials. Potential, or existing, applications of nanocrystalline materials
are described as appropriate throughout the book.
Chapter 1, “Chemical Synthesis of Nanostructured Particles and
Films,” by Yu, Sun, and Chow, is an updated version of Ch. 1 of the first
edition by Chow and Kurihara. The chemical methods for nanoparticle
synthesis described include aqueous, polyol, sonochemical, precursor,
organometallic, hydrolysis, solvothermal, and sol-gel methods. The cyto-
toxicity of nanoparticles is discussed in this updated chapter. Other
methods discussed are host-derived hybrid materials, surfactant mem-
brane mediated synthesis, and a variety of films and coatings.
Chapter 2, “Synthesis of Nanostructured Materials by Inert-Gas Con-
densation Methods,” by Suryanarayana and Prabhu, is new in this edition.
It covers the important technique that was used by Gleiter and co-workers
that stimulated the present field of nanocrystalline materials. This chapter
reviews the principles of the inert-gas condensation method, explains the
synthesis of nanophase materials via this technique, and discusses the
process parameters that influence the constitution and particle size of
the product phase.
Chapter 3 by Kim is an updated version of the chapter by Lau and
Lavernia now entitled “Thermal Sprayed Nanostructured Coatings: Appli-
cations and Development.” Thermal sprayed nanostructured coatings are
a prime example of a method that has already matured to the point of
application. Thermal sprayed nanostructured oxide coatings in particular
have been shown to be practically advantageous for both military and
industrial applications. After reviewing the technology of thermal spray a
number of applications are described.
Chapter 4 by Fecht and Ivanisenko, “Nanostructured Materials and
Composites Prepared by Solid State Processing,” is the updated version
of the chapter by Fecht in the first edition. The methods described, such
as mechanical attrition and other severe plastic deformation methods have
become popular methods to produce nanocrystalline materials from the
“top-down.” The promise to scale up from laboratory to industrial quan-
tities is one of the advantages of these methods. The mechanisms believed
responsible for this nanocrystalline synthesis as well as the stability of the
nanocrystalline microstructures at elevated temperatures are reviewed.
A major problem with nanocrystalline materials made in particulate
form is the requirement for consolidation into bulk for most applications.
Chapter 5 by Groza is an updated version of her chapter in the first edition.
“Nanocrystalline Powder Consolidation Methods” are reviewed and
include conventional sintering methods as well as a variety of full-density
Preface xxi
consolidation techniques. The challenge in processing nanocrystalline
powders is to fully densify them without losing the initial metastable fea-
tures (nanoscale grain size and, sometimes, metastable phases). The state-
of-the-art in consolidation of nanocrystalline powders is presented and the
remaining challenges are discussed.
While chapters 1, 2, and 4 describe processing methods for nanocrys-
talline materials that result in particulates that require subsequent com-
paction, i.e. “two-step” processing, there are one-step processing methods
available that eliminate the need for compaction with its attendant prob-
lems. A notable and commercially attractive one-step method is elec-
trodeposition. Pioneers in this field, Erb, Aust, and Palumbo, update their
former chapter into chapter 6, “Electrodeposited Nanocrystalline Metals,
Alloys, and Composites.” This chapter describes the processing methods
as well as the structure and properties of the electrodeposited nanostruc-
tured materials. Recent breakthroughs in the mechanical and magnetic
properties of electrodeposited nanocrystalline materials are presented. A
variety of applications for electrodeposited nanocrystalline coatings are
reviewed.
Computer simulation of nanomaterials comprises “virtual processing”
and so was included in Part I of the first edition. The chapter in the first
edition was written by Professor Phil Clapp who has subsequently
retired. Chapter 7, now entitled “Computer Modeling of Nanostructured
Materials,” has been written by Professor Donald Brenner. This chapter
describes the various modeling techniques including molecular dynamics
and Monte Carlo modeling, atomic potential energies and forces, and mul-
tiscale modeling. The modeling of nanoparticle properties, microstructure,
sintering and grain growth dynamics, mechanical deformation, and
nanoalloys are reviewed.
Part II of the book deals with selected properties of nanocrystalline
materials. Chapter 8, “Diffusion in Nanocrystalline Materials,” is an
updated version of the chapter by Wurschum, Brossmann, and Schaefer
in the first edition. This chapter is written by Sprengel, a colleague of the
former authors. This chapter reviews the data for diffusion in nanocrys-
talline materials. It describes modeling of interface diffusion, diffusion in
grain boundaries of metals, and then gives examples of diffusion behav-
ior for a variety of nanocrystalline materials including pure metals, soft
magnetic materials, hard magnetic materials, ceramics, and diffusion of
hydrogen in nanocrystalline metals.
Chapter 9, “Nanostructured Materials for Gas Reactive Applications,”
is an updated version by Trudeau of his chapter in the first edition which
brings in important results since the first chapter was written. This large
xxii Preface
important field is reviewed with examples from catalysis and electro-
catalysis, semiconductor gas sensors, and hydrogen storage materials. Of
special interest is the sensitivity to nanocrystalline structure. It is specu-
lated that reducing the nanocrystallite size below 10nm may have more
dramatic effects on such properties as catalysis.
Chapter 10 is a new chapter in this edition. Majetich reviews “Mag-
netic Nanoparticles and Their Applications.” After a brief introduction to
the phenomenon of ferromagnetism, an in-depth description of the physics
of monodomain ferromagnetic particles is given. Applications based upon
magnetic nanoparticles are discussed and include such topics as magnetic
recording media, spin valve devices, and tunnel junction structures as pos-
sible magnetic random access memory. Both current and future applica-
tions based on magnetic nanoparticles are described in terms of their basic
properties, and the material challenges are identified.
Chapter 11 by Inoue, Makino, and Bitoh is an updated and expanded
version of the chapter by Inoue and Makino in the first edition. “Magnetic
Properties of Nanocrystalline Materials” focuses on the soft magnetic
properties of bulk ferromagnetic nanocrystalline alloys prepared by the
crystallization of amorphous precursors. The formation of nanogranular
bcc and amorphous structures in the Fe—Zr—Nb—B—Cu, Fe—Zr—
Nb—B, Fe—Nb—B—P—Cu, and Fe—Hf—O systems are described
along with their superior soft magnetic properties and their engineering
applications.
Chapter 12, “Mechanical Behavior of Nanocrystalline Metals” by
Weertman, is an updated review of this dynamic field of research. She
brings in the new results from both experimental studies and the simula-
tion of mechanical behavior by molecular dynamics calculations. An
experimental breakthrough is the observation in some nanocrystalline
materials of both high strength and good ductility. Computer simulation
has allowed access to the smallest nanocrystalline grain sizes that are
difficult to attain experimentally without the introduction of processing
artifacts.
Chapter 13, “Structure, Formation, and Mechanical Behavior of Two-
Phase Nanostructured Materials” by Eckert, is updated from his chapter
in the first edition. The methods used to produce bulk two-phase nano-
structured materials are described. The mechanical behavior of such
materials is then discussed. Of special interest in this updated chapter is
the report of research from the author’s laboratory of enhanced plasticity
in a Ti-base alloy with a nanocrystalline matrix and micron-scale ductile
dendrites. This material exhibited both high strength and good ductility.
Preface xxiii
The subject of “functional” nanostructured materials for electronic and
optoelectronic applications is a large and important area. While this field
is not stressed in this book, it was felt that a chapter outlining some of the
important features of this area should be included. Tsu and Zhang have
updated their chapter from the first edition, entitled “Nanostructured
Electronic and Optoelectronic Materials.” Functional nanocrystalline
materials, typically thin films or quantum dots, are covered. An in-depth
treatment of several topics related to Si semiconductors is given. This
includes the physics of nanostructured materials which covers the dielec-
tric constant, the capacitance, doping and exiton binding energies of a
nanoparticle. Possible devices requiring nanoscale features are described.
Such devices are light emitting diodes (LEDs) and quantum field effect
transistors (QD-FETs).
References
1. Gleiter, H., Progress in Materials Science, 33:223–315 (1989).
2. Uyeda, R., Progress in Materials Science, 35:1–96 (1991).
3. Siegel, R.W., Hu, E., and Roco, M.C., (eds), Nanostructure Science and Tech-
nology, Kluwer Academic Publishers, Dordrecht, Netherlands (1999).
4. Kirschvink, J.L., Koyayashi-Kirschvink, A., and Woodford, B.J., Proc. Nat’l
Acad. Sci., USA, 89:7683–7687 (1992).
5. Merica, P.D., Waltenburg, R.G., and Scott, H., Bulletin AIME, June: 913
(1919).
6. Guinier, A., Nature, 142:569 (1938); Preston, G.D., ibid, 570.
7. Silcock, J.M., Heal, T.J., and Hardy, H.K., J. Institute of Metals, 82:239
(1953–54).
8. Cohen, J.B., Metall. Trans. A., 23A:2685 (1992).
9. Swisher, J.H., English, A.T., and Stoffers, R.C., Trans. ASM, 62:257 (1969).
10. Scanlan, R.M., Fietz, W.A., and Koch, E.F., J. Appl. Phys., 46:2244 (1975).
Bibliography
Gleiter, H., Nanocrystalline Materials, Progress in Materials Science,
33:223–315 (1989).
Siegel, R.W., Nanostructured Materials-Mind Over Matter, NanoStructured
Materials, 3:1 (1993).
Hadjipanayis, G.C., and Siegel, R.W., Nanophase Materials: Synthesis-
Properties-Applications, Kluwer Press, Dordrecht, Netherlands (1994).
Gleiter, H., Nanostructured Materials: State of the Art and Perspectives, Nano-
Structured Materials, 6:3 (1995).
Edelstein, A.S., and Cammarata, R.C., (eds.), Nanomaterials: Synthesis, Proper-
ties, and Applications, Institute of Physics, Bristol (1996).
xxiv Preface
Suryanarayana, C., and Koch, C.C., Nanostructured Materials, in Non-
Equilibrium Processing of Materials, edited C. Suryanarayana, Pergamon,
Elsevier Science Ltd., Oxford, UK (1999) p. 313.
Dekker Encyclopedia of Nanoscience and Nanotechnology, Marcel Dekker Inc.,
New York, NY(2004).
Carl C. Koch October, 2006
Raleigh, North Carolina
