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June 2002
Volume XXXVII
No. 2
Polymer Optical Waveguide Amplifiers
For optical
telecommunications, a number of devices are required to direct the light signals to their
proper locations with a minimum of signal loss. These
devices, like splitters, couplers, multiplexers, demultiplexers, and amplifiers, can be
made on one planar substrate, and this is called integrated optics. A review article, “Rare-earth doped polymers
for planar optical amplifiers,” by L. H. Slooff, A. van Blaaderen, A. Polman, Gs. A.
Hebbink, S. I Klink, F. C. J. M. Van Veggel,
D. N. Reinhoudt, and J. W. Hofstraat, J. Appl. Physics 91 [7] 3955-3980
(2002), covers two different methods of doping polymer waveguides with rare-earth ions.
An optical
waveguide directs the signal forward and prevents the signal from straying through the
surrounding material with the use of total internal reflection at the interfaces between
the high refractive index guiding layer and the lower index cladding layer. The traditional optical conductor is the SiO2-based optical
fiber. Polymer materials are a low-cost
alternative, with similar refractive indices that results in low coupling losses when used
with traditional optical fibers. There are
other optical losses that occur in the signal, such as absorption and scattering losses in
the waveguide or intrinsic intensity losses. These
losses can be made up for by using an optical amplifier, which is made by doping the
guiding layers with an active element that results in optical gain. Nd and Er are especially suited for
telecommunications applications as their transitions are at 1.34 mm and 1.53 mm,
respectively, which are standard wavelengths for those applications. The only problem with using rare earths with
polymers is that rare earth salts are not very soluble in polymeric matrices. The two approaches reviewed help provide solutions
to the problem.
The first
approach is to dissolve organic rare-earth complexes into a polymer matrix. Organic cage-like complexes can be used to
encapsulate the rare-earth ion. The organic
complexes mentioned in this article are polydentate cage complexes. They provide coordination sites to bind the Er3+ ion and stability to the compound. The cage format may also shield the Er3+ ion from impurities that can quench erbium’s
luminescence. Sample preparation is briefly
covered, as is optical characterization and three possible luminescence quenching
mechanisms. The optical gain calculation is
also included. Terphenyl-based Nd3+ complexes with highly absorbing lissamine antenna
chromophores are another option. The
chromophore transfers its excitation energy to the rare-earth ion by a Dexter mechanism,
thus reducing the quenching effects of the polymer. For
these compounds, the preparation processes are mentioned, the luminescence properties are
examined, and photo-degradation over time is discussed.
This approach also results in quenching of the luminescence. An optical waveguide system using these materials
is described. It consists of two parallel
waveguides to optimize the pumping of planar waveguide amplifiers.
The second
approach is to dope silica colloids with Er3+ using ion-implantation. The silica colloids can then be deposited on a
substrate and coated with a polymer film. The
advantage of the silica colloids is reduction of some of the quenching problems associated
with the previous polymer examples, and thus a longer luminescence lifetime is the result. There does appear to be some concentration
quenching (at higher doping levels of Er), and some quenching from adsorbed water. The water adsorption problem is reduced when the
colloids are coated with the polymer. The
performance and optical characteristics of this approach are discussed.
The outlook
for rare-earth doped polymer waveguide amplifiers is also analyzed. The article is supported by 6 tables, 23 equations,
37 figures, and 85 references. For more
information on this topic, L. H. Slooff can be reached at the FOM Institute for Atomic and
Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands, e-mail: slooff@ecn.nl.
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HONOR ROLL
30 years
Atomergic Chemetals Corp., USA
Treibacher Auermet Produktionsges mbH, Austria
20 years
Rhodia, USA
10 years
Daiden Co.
Ltd., Japan
Dr. Ekkehard
Geinacher, Germany
Manetbarik
Schramberg GmbH and Co., Germany
Pacific
Industrial Development Corp., USA
We would
like to honor 7 supporters for their dedicated support of the Rare-earth Information Center. Thank you to these companies for their long and
continued support. We look forward toe serving
these and all our supporters for years to come.
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Permanent Magnet and Power Electronics
Conference
Permanent Magnet Systems and Power Electronics for Motion Control
will be held September
9-11, 2002 at the Hyatt
Regency Cincinnati Hotel in Cincinnati, Ohio. The conference is being hosted by Gorham Advanced
Materials, Inc. The subtitle to the conference
is Global Markets, Applications, New and Emerging Technologies, and Business
Opportunities.
The
conference will cover the major techno-business issues related to current and emerging
applications for permanent magnet systems and power electronics used in motion control. Coverage includes global markets, innovations and
trends in R&D and manufacturing technology, and business opportunities. Specific topics to be discussed include linear and
rotary actuators, sensors, cables and connectors, motion control electronics, brushless
motors and motor control drive electronics, power electronics, and thermal management
products. Key decisions that are made in the
selection of high tech systems for motion control applications will be highlighted, and
choices of components in the context of costs, design enablers, and competing and emerging
technologies will be evaluated. The format of
the conference will include presentations, panels, workshops, and open-forum Q&A
sessions.
The
objective of the conference is to bring together senior personnel in companies involved
with research, design, manufacture, sales, and applications of permanent magnets and power
electronics used in motion control systems and devices.
The conference aims to facilitate producer-user contacts and to bridge
knowledge gaps, both to the benefit of all participants.
The
co-chairs of the conference are Burley Semones, Principal of MTM Consulting, and Walter
Benecki, Consultant. A conference brochure
will be available in June. To obtain a copy or
for more information on the conference, contact Deedra Manter or Michael Concannon at
Gorham Conferences, 209 Mosher Road, Gorham, ME 04038 USA, Tel: (207) 892-5445, Fax: (207)
892-2210, e-mail: gorham@goradv.com, or visit www.goradv.com.
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MMM
2002
The 47th Annual Conference on Magnetism and Magnetic
Materials will be held November
11-15, 2002 in Tampa, Florida, USA.
The
conference will include all basic and applied science and technology related to the field
of magnetism. The technical subject categories
are Fundamental properties and cooperative phenomena, Magnetoelectronic materials and
applications, Computational magnetics and imaging, Soft magnetic materials and
applications, Hard magnetic materials and applications, Structured materials, Other
magnetic materials, Magnetic recording, and Other applications and interdisciplinary
topics. The abstract deadline is July 8, 2002, and
abstracts must be submitted online.
For
more information on the conference and abstract submission rules, visit http://www.magnetism.org.
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Conference
Calendar
Note:
Reach as many potential conference attendees as possible!
Send us your conference announcement and we will publish it here.
June ’02
14th
International Symposium on Boron, Borides, and Related Compounds (ISBB’02)
St.
Petersburg, Russia
June 9-14,
2002
RIC News XXXVI, [3] 3 (2001)
July ’02
The 23rd
Rare Earth Research Conference
Davis, California, USA
July 13-18,
2002
RIC News XXXV, [2] 4 (2000)
RIC News XXXVI, [4]
(2001)
5th
International Conference on Solvothermal Reactions
East Brunswick, New Jersey, USA
July 22-26,
2002
RIC News XXXVII, [1] 2
(2002)
August
’02
Applied
Superconductivity Conference (ASC 2002)
Houston, Texas, USA
August 4-9,
2002
RIC News XXXVI,
[3] 1 (2001)
17th
International Workshop on Rare-Earth Magnets and their Applications
Newark, Delaware, USA
August
18-22, 2002
RIC News XXXV, [4] 3 (2000)
RIC News XXXVI, [4] (2001)
September
‘02
Permanent
Magnet Systems and Power Electronics for Motion Control
Cincinnati, Ohio, USA
September
9-11, 2002
* this issue
November
‘02
47th Annual
Conference on Magnetism and Magnetic Materials (MMM 2002)
Tampa, Florida, USA
November
11-15, 2002
* this issue
July ’03
International
Conference on Magnetism (ICM’2003)
Rome, Italy
July
27-August 1, 2003
RIC News XXXVI, [1] 4 (2001)
August
’03
Scandium
Symposium
Oslo, Norway
August
17-23, 2003
RIC News XXXVI, [4] (2001)
5th
International Conference on f-elements (icfe5)
Geneva, Switzerland
August
24–29, 2003
RIC News XXXVI, [4]
(2001)
November
‘04
Rare Earths
‘04 in Nara, Japan
Nara, Japan
November
7-12, 2004
*this issue
*this issue
denotes a story on this conference appears in this issue of the RIC News.
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In Memoriam – Clifford Glenwood Shull
Clifford G.
Shull was a 1994 Nobel Prize winner in Physics for his work in neutron scattering. He died March 31, 2001, of kidney
failure.
Clifford
Shull majored in physics at Carnegie Tech, and earned his PhD from New York University in 1941. For his dissertation he built a Van de Graaf
accelerator and worked with the scattering of polarized electrons. After graduation, he went to work for Texas Company
(which later became Texaco), where he worked with the characteriza
tion of
catalysts used in making aviation fuel. His
work there gave him much experience with x-ray diffraction and small-angle scattering used
in studying powder samples.
In 1949,
Cliff visited Oak Ridge, where he
met Ernie Wollan. At the time of his visit,
Wollan had already built a two-axis neutron diffractometer.
Cliff was excited about the work with neutron diffraction and scattering,
and he began working at Oak Ridge two months
after his visit. Once there, he and Wollan
first worked to fully understand the scattering of neutrons by powder samples, which was
followed by measuring the neutron coherent scattering amplitudes for almost all the
elements and many isotopes. They also did some
work with neutron patterns from single crystals. However,
Shull and Wollan were most interested in magnetic materials, and they were able to show
that neutron scattering experiments were key to understanding magnetic materials.
Shull left
Oakridge in 1955 to go to MIT, where a new research reactor was being built. He became a Professor of Physics and remained there
until his retirement in 1986. While at MIT he
worked with polarized neutron diffraction and dynamical diffractions and the propagation
of neutron waves in perfect crystals. His
success as an educator can be measured by the distinguished careers of many of his
students.
Besides the
Nobel Prize, his other awards and honors include the Buckley Prize awarded by the APS,
election to the National Academy of Sciences, and having one of the Crystal Islands between Antarctica and Australia named after
him. Some of his work involved rare earths. A Clifford Shull Scholarship Fund has been
established in his honor at Carnegie Mellon University.
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E-Mail Subscription
Subscribers
to the RIC News can request to receive their copies via e-mail. This represents an
improved time-of-delivery over surface and airmail. In fact, the e-mail version will be
available before the print version has even been mailed. It is available in pdf, word,
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To receive
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Magnetic Theory
The Quantum
Theory of Magnetism, by Norberto
Majlis, presents a detailed account of a significant amount of the theory involved in the
study of magnetism. The author states in his
forward that “this is an advanced level textbook” and this is not an
understatement. The book assumes a background
in quantum mechanics, statistical mechanics, and condensed matter physics, and it is
obvious that this experience is necessary to get the most out of the text. The relevance of the work to the rare earths is
evident from the first page; they are listed under the category of atoms with an unfilled
electronic shell, and therefore are atomic systems with a permanent magnetic moment in the
ground state.
The general
topics of the book, as given by the titles of the chapters, are paramagnetism, interacting
spins, mean field approximation, spin waves, Green’s functions methods, dipole-dipole
interactions, itinerant magnetism, indirect exchange, low dimensions, surface magnetism,
two-magnon eigenstates, and other interactions. The
discussions grew out of lecture notes prepared by the author for several graduate courses,
and the text does indeed read like a lecture. According
to the author, some subjects were necessarily excluded due to the limits of the text, and
these include diamagnetism, the kondo effect, magnetic resonance, and disordered systems,
among others. However, detailed descriptions
of the mean field approximation, properties of low-dimension magnetic systems, the RKKY
model, and surface magnetism are not likely to be found in other texts on magnetism. There are many exercises included in the text, and
they are presented as such that their completion is requisite for complete understanding
of the discussion.
This book
would be of great use to anyone who desires in-depth theoretical treatment of magnetism. Each chapter contains many, and in some cases
hundreds, of equations that help elucidate the modeling and description of the theory. Each chapter has a bibliography at the end, and
there are two appendices to the book, one on group theory and the other on time reversal,
and an index also accompanies the book.
The Quantum
Theory of Magnetism is
published by World Scientific Publishing Co. Pte. Ltd., P. O. Box 128, Farrer Road,
Singapore 912805, with a USA office at Suite 1B, 1060 Main Street, River Edge, NJ 07661,
and a UK office at 57 Shelton Street, Covent Garden, London WC2H 9HE. The book was published in 2000 and is ISBN
981-02-4018-X.
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Rare
Earths ‘04
Rare Earths ’04 in Nara, Japan will be held November 7-12,
2004, and is an
international conference on rare earths sponsored by the Rare-Earth Society of Japan.
The program
will integrate basic and applied multidisciplinary research that is centered on the f-elements. Forefront results will be featured in the form of
oral talks and posters on topics in chemistry physics, and materials, earth,
environmental, and biological sciences. Specific
topics include, but are not limited to, spectroscopy,
earth science, resources, industries, space science and technology,
luminescence, solid states, organometallics, catalysts, heavy fermions, hydrogen storage
materials, batteries, magnetism and magnetics,
science and technology of ceria, ionic conductors, rare earths in bioscience, phosphors,
separation, metallurgy, superconductors, ceramics, fuel cell systems, laser materials,
theoretical calculations, combinatorial chemistry, analytical chemistry, coordination
chemistry, solution chemistry, alloys and intermetallics, oxides, nonstoichiometries,
lanthanides for molecular recognition, and high temperature or high pressure science.
For more
information, contact Conference Chair Prof. Gin-ya Adachi, President of the Rare-Earth
Society of Japan, Department of Applied Chemistry, Faculty of Engineering, Osaka
University, 2-1 Yamadaoka, Suita, Osaka 565-0871, JAPAN, Tel: +81-6-6879-7353, Fax:
+81-6-6879-7354, e-mail: kidorui@chem.eng.osaka-u.ac.jp,
website: http://kidorui.chem.eng.osaka-u.ac.jp/RE2004.html.
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Consultant’s Corner
To appear in our Consultant’s Corner, any
individual, company, or group must be involved in rare earth or rare-earth-related
consulting activities. Just send us the
appropriate information: contact name, company
name, mailing address, Tel/Fax number(s), email, web address and areas of expertise.
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Search of the Month
Ric Database Preliminary Report
keywords DyF3 AND keywords 1996 1999 1997 1998
Article
Phase diagrams of the
NaF-Rf3 (R = Tb, Dy, Er) systems
(DY,F,NA) (ER,F,NA) (R,F) (R,F,NA) (TB,F,NA) 1996 DYF3 ERF3 FLUORIDE NAF
PHASE-DIAGRAM
RF3
TBF3
Mass spectrometric study
of vaporization process and thermodynamic properties of Dyf3-
Dy2O3 system
(DY,F,O) 1997 DY2O3 DYF3 SYSTEM THERMODYN-PROP VAPOR-PRESSURE VAPORIZATION
Thermal expansion of
liquid and solid DyF3
(DY,F) (GD,F) (LA,F) 1998 CeF3 DENSITY DYF3 EuF3 FLUORIDE GDF3 HoF3 ionic-radius LAF3 liquid mol-volume NDF3 PmF3 PrF3 SMF3 solid structure TbF3
temp-dependenc THERMAL-EXPAN
thermal-prop
Photolectric effects in
silicon switching structures utilizing rare-earth fluorides
(CE,F) (DY,F) (ER,F) 1999 CEF3 DIODE DYF3 EMISSION ERF3 FLUORIDE PHOTOELECTRIC
Monday, May 20, 2002
Page 1 of 1
This
search above satisfies a request for information on DyF3 from the years 1996 - 1999. Many more citations
would have been referenced if other years had been included in the search.
The
Database Preliminary Report, as shown above, is provided s an evaluative tool when the
search is requested, and includes the keywords used for the search, the title of the
article, and the other keywords associated with the reference, for each of the references
found. The Database Report, which is sent when
the search results are purchased, includes full reference information: our document
number, title, authors, bibliographic reference, and keyword list.
The
cost to receive the full report for this search is US$50.00. The minimum cost for any
search is US$50.00, which includes the reference list for up to 25 matches, and any
additional matches are available for US$2.00 each. That means that if a search turns up 30
matches, the full report would cost US$60.00. Supporters may receive as many searches as
desired for US$300.00 per year for corporate memberships, or US$100.00 for individual
memberships. For other support levels available, see “June 2002 Supporters” on
page 8.
As an
added benefit, supporters receive a 2-page monthly newsletter, the RIC Insight,
that reports on late-breaking news of rare earths and how these developments may impact
the rare earth industry. Corporate members can also have space on our website, providing
additional exposure for their company and links to their own webpages.
If you would like us to conduct a search for you, please send your
request to: Angela O’Connor, RIC, 112 Wilhelm Hall, Ames Laboratory, Iowa State
University, Ames, IA 50011-3020 USA; Tel: 515-294-5405; Fax: 515-294-3709; e-mail: ric@ameslab.gov. If you would like to become a
supporter of the RIC, send your name, address, telephone, fax, e-mail address, and your
desired level of support to the above address or to LaVonne Treadway, RIC, 116 Wilhelm
Hall, Ames Laboratory, Iowa State University, Ames, IA 50011-3020 USA, Tel: 515-294-2272;
Fax: 515-294-3709; e-mail: crem_ric@ameslab.gov.
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Magnetic Susceptibility in Non-Fermi Liquids
N. Bernhoeft has written a review called “An analysis of the
dynamical magnetic susceptibility in non-Fermi liquids,” published in J. Phys.:
Condens. Matter 13 R771-R816 (2001). This
topical review presents a unifying model of the dynamical magnetic susceptibility in the
non-Fermi liquid state at a finite temperature above a quantum critical point. The quantum critical point for strongly correlated,
non-Fermi-liquid states occurs at T=0 K, where incipient phase transitions occur. However, since no experiment can be conducted at 0
K, small finite temperatures have to be related to the 0 K properties. The dynamical susceptibility plays a key role in
providing elucidation.
The first
section of the review presents the model. It
covers the model analytical form of the dynamic susceptibility, inferential models for the
distribution of relaxation rates, a brief explanation of the non-Fermi-liquid parameter, a
discussion of the scaling of the dynamical susceptibility, and implications the model
poses for bulk properties. The second section
of the review shows the application of the model to several compounds. Of particular interest are CeCu5.9Au0.1 and doped rare-earth cuprates. After the conclusions end on page R803 comes three
appendices, each providing more detail to the presentation of the model in the first
section.
The review
seems to provide thorough coverage to the topic. The
text is supported by 13 footnotes, 22 figures, 47 references, and 97 equations. The footnotes provide additional comments or
exceptions to the statements made in the discussion and work well as footnotes as they do
not disrupt the flow of the paper.
For more
information, N. Bernhoeft can be contacted at CEA-Grenoble, F-38054 Genoble Cédex, France.
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Anion–Conducting
Glasses
The
discovery of anion conduction in fluoride glasses has sparked an interest in study of
fluoride transport in glassy materials. A
short review of the subject, “Anion-conducting fluoride and oxyfluoride
glasses,” by N. I. Sorokin, was published in Russian Chemical Reviews 70
(0) 801-807 (2001).
The
conduction in glasses is expected to be an improvement over conduction in crystalline
materials, and glasses with high fluoride ion conductivity are especially attractive as
solid electrolyte materials due to technological and cost effectiveness as compared to
crystalline materials. They also attract
attention as they are transparent in the IR region, possess low glass transition
temperatures, and are promising materials for fiber optics.
Theoretical calculations show lower optical transmission losses than in
traditional silicate glasses.
Fluoride
glasses tend toward crystallization. To
prevent or slow this process, various metal fluorides are added. These additions also allow the chemical stability,
thickness of the material, and the usable temperature range to all increase, while
offering the chance to study the effect of each component on ion conduction and the
mobility and concentration of charge carriers. The
keys to anion transport are the formation of fluoride anions and the variation in the
coordination number of the glass-forming cations. The
changes in coordination number of the cations allow the movement of mobile anions. This review analyzes the results of studies of
fluoride-ion-transport in glassy solid electrolyte. The
results are grouped according to the type of the glass-forming fluoride.
The three
main classes of fluorides addressed are MF2, MF3, and MF4, and
oxyfluorides are also discussed. In MF2 the primary conduction mechanism is through an
increase in mobile, non-bridging ions. The
conductivity and structure of several of these glasses are mentioned. The MF3 group includes glasses containing MF3 or AF2. The structure of these compounds is discussed,
along with Raman spectroscopy, conductivity, and mobility along with how the addition of
specific fluorides affects these properties. The
MF4 group includes fluorozirconate glasses. The Zr polyhedra can have variable coordination of
6, 7, or 8. Modifiers increase the
conductivity, and increased concentration of the modifier increases conductivity. Also, the anion conductivity is dependent on the
activation energy of the conductivity. The
activation energy is influenced by the polarizability and the ionic radius of the cation. Several details of the effects of specific
fluorides are included. Oxyfluorides are
essentially mixtures of oxides with fluorides added to make the material glassy. The role of the fluorine can vary depending on the
modifying cation and the fluoride content of the glass.
Higher concentrations of the fluoride (greater than 30% to 50%) lead to
anion conduction. Another section follows
these that discusses the optimization of characteristics of fluoride-conducting glasses
and prospects for their practical application.
This
review is very concise, with a lot of information in very little space. Only 1 table and 2 figures are used in the main
text, but the accompanying 90 references would certainly be useful to fill the details. For more information, N. I Sorokin can be reached
at A. V. Shubnikov Institute of Crystallography, Russian
Academy
of Sciences, Leninsky prosp. 59, 119991 Moscow,
Russian
Federation,
Tel: (7-095) 330 78 74, Fax: (7-095) 135 10 11, e-mail: sorokin1@mail.ru. The original Russian version of the review appeared
in Uspekhi Khimii 70 (9) 901-908 (2001), and was translated by T. N.
Safonova.
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News
from Japan
Thanks to Kensuke Shimomura for the content and
translations for this section.
The Nikkei
Weekly, March 18,
2002: Casio
Computer Co. had developed a small, long-life fuel cell for use in devices such as
notebook computers. The new fuel cell is
reported to last four times longer than current rechargeable batteries. That means a notebook computer can run for 20
hours, versus the 5 hours allowed by lithium-ion batteries.
The fuel cell extracts hydrogen from methanol, and should be able to compete
on a cost-basis once mass production begins. Casio
plans to obtain approximately 120 patents for the technologies used in the fuel cells.
The Asahi
Shimbun-Business, April 6,
2002: Honda Motor
Co. has its new fuel cell powered car on the streets after getting approval for operation
on public roads in February. The model that is
out is merely an approximation of the FCX-V4 that Honda plans to have available for sale
to the public in 2003. The car has a cruising
distance of 315 kilometers, and a maximum speed of 140 kph.
The Japan
Times, April 13,
2002: Honda Motor
Co. and Sanyo Electric Co. are planning to jointly develop nickel-hydrogen batteries for
use in Honda’s hybrid vehicles. Sanyo is
striving to become the largest supplier of batteries for hybrid cars. They already are developing batteries for Ford
Motor Co. Honda’s first hybrid cars use
batteries from Panasonic EV Energy, which also supplies batteries for Toyota Motor Corp. Honda hopes to increase the fuel efficiency of
their cars through using batteries developed by Sanyo, which is also known for its
expertise in cell phone batteries.
The Rare
Metal News, April 16,
2002: A venture
between Sumitomo Special Metals Co. and Super Electronic Co., called Dongguan
Sumitoku-Super Electronic Co., has completed construction of a plant in Dongguan, Guangdong Province, in
March. Operations at the two-story, 6000
square meter plant were slated to begin by the end of April.
The plant will produce Nd-Fe-B sintered magnets called NEOMAX, and will have
an initial production volume of 20 million units per month.
The Nikkei
Weekly, April 29,
2002: Toyota Motor
Corp.’s cumulative worldwide hybrid vehicle sales numbers have topped 100,000, with
102,967 sold by the end of March. That
represents 90% of the global market for environmentally friendly cars. The Prius passenger sedan was launched in Japan in 1997, in North
America in 2000, and
is now being sold in 20 countries. The Prius
is the world’s first mass-produced hybrid car.
The Nikkei
Weekly, May 13,
2002: The storage
and use of fuel cells have been heavily regulated in Japan in several
laws and regulations, which designate them dangerous substances because of their use of
hydrogen. Japanese industry is complaining
that the regulations are interfering with Japan’s
ability to compete with the U.S.A. and Europe in the area
of fuel cell applications. The government now
plans to lift or ease restrictions that are hampering commercial development by 2005. The government will join forces with domestic
automakers to set up five hydrogen refueling stations around Tokyo so the
field-tests of fuel cell powered vehicles can be undertaken on public roads. The government will also add fuel cell powered
vehicles to its official fleet in 2003. Besides
automobiles, fuel cells can also be used in appliances and as an energy source for homes.
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Newsletter on the Web
The paperless
alternative to receiving an electronic form of the RIC News via e-mail is to access
our website: http://www. ameslab.gov/ric,
where current and previous issues of the RIC News are available, along with general
information about the Rare-earth Information Center and a list of
our sponsors.
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Manganite Physics
Colossal magnetoresistive manganites, like LaMnO3 have been known to exist since 1950. However, they were not well understood then, and
study was abandoned until the 1990s. “The
physics of manganites: Structure and transport,” by Myron B. Salamon and Marcelo
Jaime, was published in Reviews of Modern Physics, 73 583-628 (2001), and
reviews the early work done on these materials, the reasons the work was abandoned, and
why they are so interesting now.
The early
work on manganites was conducted in the 1950s. Much
of the work done resulted in conclusions that were made again in later work, but were not
explained in the same manner or not fully understood.
The review presents the early developments, and points out where later
research provided clarification and how certain behaviors were explained differently. Early theories are discussed, including double
exchange and those regarding magnetic and transport properties, such as band structure,
polaron transport, and the Hall effect. However,
all the different aspects of these materials were not considered simultaneously, so
research in this area dwindled.
The
rediscovery of the manganites came in the mid-1990s, when the metal-insulator transition
close to room temperature, and thus the maximum sensitivity to external fields, was
investigated. These features renewed interest
in the material, and much work has been done to understand the mechanisms involved. It was pointed out that theoretical explanations in
the past did not hold up quantitatively. And
from this is was realized how complex the problem of the manganites really is, and how
interesting to condensed matter physics they are. The
review lays out the present understanding of the physical properties of manganites as
measured with state of the art experiments and analyzed using modern theories.
This is a
thorough review of a very interesting topic. The
main point is to show the variety of possible states and the transitions between them, and
to show how useful manganites are to the general understanding of what makes a metal or an
insulator. The last four words of the review
are “remains to be found,” which leaves the door wide open to more research. The review is supported by 2 tables, 23 equations,
59 figures, and 226 references.
For more
information, Myron B. Salamon is at the Department of Physics and Materials Research
Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA, and
Marvel Jaime is at MST-NHMFL, MS E536, Los Alamos National Laboratory, Los Alamos, New
Mexico 87545 USA.
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Treibacher Acquires Meldform Assets
Treibacher
Auermet Prod. Ges. mbH and Meldform Rare Earths Ltd. have reached an agreement to transfer
Meldform’s Rare Earths assets to Treibacher effective February 28,
2002.
Meldform
Rare Earths Ltd. has been supplying a diverse range of rare earths to a worldwide market
since 1986, and has established itself as one of the leading suppliers with a strong
emphasis on customer service and quality. These
qualities and Meldform’s established supply relationships with China and the CIS
complement Treibacher.
Treibacher
Auermet Prod. Ges. mbH is part of the Austrian-based Group Treibacher Industrie AG. Treibacher has a one hundred year history in the
development and production of rare earths, and their core strengths include research and
development, relationships with customers and suppliers worldwide, sophisticated rare
earths plants in Austria and Slovenia, and
experience in global marketing. Treibacher
currently produces 6000 mt of rare earths annually.
The
acquisition of Meldform’s Rare Earths Assets assists Treibacher in their strategy to
continue their leadership in the worldwide rare earths marketplace. For more information, contact Alexander Bouvier,
Managing Director, Tel: ++43 4262 505 570, e-mail: alexander.bouvier@treibacher.at, website: www.treibacher-auermet.com.
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Magnetism and Heavy Fermions
Heavy fermion systems are defined as metallic compounds and
alloys that contain 4f or 5f ions and that exhibit enhanced effective
conduction electron masses at low temperatures. The
4f or 5f ions usually are Ce, Pr, Yb, or U. Magnetism in Heavy Fermion Systems, edited
by Harry B. Radousky, is a series of review papers that look at, as the title of the book
suggests, magnetic behavior in heavy fermion systems.
Sev
