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High Temperature Superconductor Bulk Materials.

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Angewandte
Books
Chemie
Polymorphism in the
Pharmaceutical Industry
Edited by Rolf Hilfiker. Wiley-VCH,
Weinheim 2006.
414 pp., hardcover
E 149.00.—ISBN
3-527-31146-7
This book can act both as a textbook for
chemists newly interested in pharmaceutical polymorphism and as an
advanced monograph. Most chapters
are plentifully referenced to original
research papers and review articles for
further reading. Polymorphism, for
many years an apparently esoteric bywater of science, is now a hot topic,
especially in pharmaceutical chemistry,
since industry has been forced to recognize its crucial place in drug development and in regulatory/patenting procedures (as emphasized in the final two
chapters of the book on patents and
regulatory matters).
The 15 chapters of this book cover
an eclectic mix of topics, from thermodynamics to patent issues. Indeed, the
science covered is significantly broader
than the title implies, since it includes
solvates and salts as well as true polymorphs. In fact, I personally found the
chapters on solvates and on hygroscopicity to be particularly valuable. It is,
perhaps, a pity that the title does not
better reflect the contents, because at
present some potential readers may not
recognize its relevance sufficiently to
access the book. Most of the chapters
deal with characterization of the solid
Angew. Chem. Int. Ed. 2006, 45, 6609 – 6610
state, and each is written by an acknowledged expert or experts in the field
covered. However, uniformity of presentation is notoriously difficult to achieve in edited works, and the book does
suffer a little from this problem. For
example, the chapter on vibrational
spectroscopy is quite long (44 pages)
and contains much material on the
various techniques involved—indeed,
one is halfway through the chapter
before polymorphism is mentioned. By
contrast, the chapter on solid-state
NMR spectroscopy (arguably a more
informative and certainly more versatile
method than vibrational spectroscopy)
is less than a third of the length and
contains only one paragraph on the
basics of the subject. Moreover, while I
found every chapter to be interesting
and valuable, there do seem to me to be
some lacunae. For example, a coherent
chapter on crystallization kinetics would
have been useful to complement the one
on crystallization thermodynamics. It is
true that a little about the former is
included in the latter, but crystal growth
and Ostwald ripening are not covered in
detail, nor are effects dependent on
solvent choice and crystal morphology
(or indeed, the kinetics of solid-phase
transformations). Another largely missing topic is quantum-mechanical modeling of polymorphism, in which many
advances have been made recently.
However, despite these defects, the
book should be warmly welcomed and
widely read. I shall frequently want to
refer to it myself, and it will be particularly valuable to students learning
about the subject. The latter advantage
is especially important, given that most
undergraduate courses in chemistry
seem to ignore polymorphism, in spite
of the fact that it is a ubiquitous
phenomenon and is of critical industrial
importance. The text of the book is
generally clearly written and the illustrations are very helpful. The index is
useful and the table of contents is very
clearly set out. I recommend the book to
a wide range of readership in the
pharmaceutical industry and in academia—indeed, to all chemists inter-
ested in the characterization of solid
organic compounds.
Robin K. Harris
Department of Chemistry
University of Durham (United Kingdom)
High Temperature
Superconductor Bulk Materials
By Gernot Krabbes,
Gnter Fuchs, WolfRdiger Canders,
Hardo May and
Ryszard Palka.
Wiley-VCH, Weinheim 2006.
299 pp., hardcover
E 99.00.—ISBN
3-527-40383-3
Since the discovery of high-temperature
superconductivity by Bednorz and
M1ller, materials research on copper
compounds and the conversion of these
materials into superconducting components has become a very active field of
work in the area of applied superconductivity. This book is concerned with
cuprate bulk materials, with particular
emphasis on melt-textured compounds
of the form LnBa2Cu3O7 x (Ln = Y, Nd,
Sm, Eu, Gd, Dy). The aspects covered
range from the manufacture of hightemperature superconducting materials
(physics and chemistry) to their superconducting properties (physics), their
technological applications (engineering
science), and the working models and
prototypes that have been made using
these materials (also engineering science). Such a wide-ranging and comprehensive description, covering both the
fundamentals and the applications in
detail, is a rarity, and that makes it
especially valuable for readers.
In view of the enormous ground to
be covered, the authors have adopted a
concise style of presentation: in the
individual chapters they often refer the
reader to review articles that contain the
necessary detailed descriptions. The
book is constructed in the manner of a
2 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6609
Books
conventional monograph, and contains
no additional material in the form of
digital media, no exercise problems, and
no appendixes. To understand the discussions in this book, readers should
already have sufficient background
knowledge, from other sources, of the
basic facts of superconductivity and the
thermodynamics of the formation of
phases. Despite the wide-ranging
nature of the material, individual
topics are easy to find with the help of
the list of contents.
The book begins with a detailed
description of the manufacture of the
materials, with many phase diagrams
that are essential for understanding the
thermodynamics of the processes. The
different phases that are present play a
crucial role in the formation of the
structure. The nonstoichiometry of the
YBa2Cu3O7 x phase is discussed in great
detail; here the book stands out above
other, mainly physical, monographs and
textbooks on the subject, in which this
aspect is badly neglected. Microstructure images obtained by scanning and
transmission electron microscopy (SEM
and TEM) are shown, from which the
reader learns that the immobilization
(anchoring) of magnetic flux lines that
occurs in LnBa2Cu3O7 x bulk materials
depends critically on extensive crystalstructure defects such as gaps, dislocations, and stacking faults. A whole
chapter is devoted to the effects of
such crystal defects on the immobilization of magnetic flux lines in these
materials. In another separate chapter
the authors discuss the physics of the
vortex state, with particular attention to
the formation of magnetic flux tubes, the
critical current density and the immobilizing strength of the flux tubes, and flux
creep phenomena, and they also
describe the mechanical and plasticity
6610
www.angewandte.org
properties of the superconductor material. It is made clear that precise control
of the superconducting properties of the
material, with special regard to the
physics of the vortex state, as well as to
the thermodynamics of phase formation, oxygen stoichiometry, and the formation of the structure, especially of
crystal defects, is essential for successful
applications.
Many of the applications discussed
in this book use high-temperature superconductors as permanent magnets.
Superconductors show hysteresis in
their magnetization behavior as a
result of the immobilization of flux
lines. That makes it possible to freeze
in magnetic flux, and thus to construct
permanent magnets.
In pure YBa2Cu3O7 x the flux-line
immobilizing strength is too low, and
therefore it is unsuitable for the more
demanding applications. The construction of satisfactory functional elements
or components is only made possible by
changing to systems that are chemically
more complex and have better microstructure and greater flux-line immobilizing strength. The authors list the
highest attainable values for the
frozen-in magnetic flux and describe
the technical requirements for achieving
these
values.
In
the
system
YBa2Cu3O7 x, with the addition of
some silver and zinc, the magnetic field
of a superconducting magnet using this
system has been taken to a maximum
value of 16 T without the appearance of
cracks in the material.
The advantages of superconducting
mechanical bearings compared with
conventional bearings are discussed.
Superconducting bearings have many
potential applications, for example in
static or rotating levitation of turbo
machines, in superconducting motors,
2 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
and in flywheel energy storage devices.
One example that is particularly striking, because it is already operating as a
prototype, is that of trains with magnetic
suspension. Detailed drawings and pictures of working models and prototypes
are presented, giving a fascinating prospect of advanced engineering. The book
contains tables that not only present an
overview of various completed demonstration systems and working models,
but also give technical details of some
machines. Finally, the authors discuss
various applications in magnet construction and energy technology, including
magnet systems for ore separation,
superconducting current cables, current
limiters, and magnetic shielding.
This book appears at a time when
the field has reached maturity. It differs
clearly from textbooks on superconductivity, as it emphasizes the interdisciplinary aspects of the fundamentals and
the applications, although it does not
treat the phenomenon of superconductivity by reference to quantum mechanics or the Ginzburg-Landau theory.
Because of the broad coverage it is
suitable for advanced and postgraduate
students of physics, chemistry, materials
science, and electronics, especially for
those who want to get an overview of
selected areas by using the literature
references in the relevant chapters. For
scientists and engineers working in the
field of superconducting materials, this
is a useful reference source, and will
stimulate ideas for new applications of
superconductivity.
Oliver Eibl
Institut f6r Angewandte Physik
Universit:t T6bingen (Germany)
DOI: 10.1002/anie.200685418
Angew. Chem. Int. Ed. 2006, 45, 6609 – 6610
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