| Giant Magnetocaloric Materials Could Have Large Impact on The Environment
Materials that change temperature in magnetic fields could lead to new refrigeration technologies that reduce the use of greenhouse gases, thanks to new research at the US Department of Energy's Argonne National Laboratory and Ames National Laboratory.
Scientists carrying out X-ray experimentation at the Advanced Photon Source at Argonne, the nation's most powerful source of X-rays for research, are learning new information about magnetocaloric materials that have potential for environmentally friendly magnetic refrigeration systems.
Magnetic refrigeration is a clean technology that uses magnetic fields to manipulate the degree of ordering (or entropy) of electronic or nuclear magnetic dipoles in order to reduce a material's temperature and allow the material to serve as a refrigerant. New materials for refrigeration based on gadolinium-germanium-silicon alloys display a giant magnetocaloric effect due to unusual coupling between the material's magnetism and chemical structure.
Understanding this coupling is essential to moving this technology from the laboratory to the household. Magnetic refrigeration does not rely on hydrofluorocarbons (HFCs) used in conventional refrigeration systems. HFCs are greenhouse gases that contribute to global climate change when they escape into the atmosphere.
A collaboration between researchers from Argonne and Ames has now revealed key atomic-level information about these new materials that makes clear the role played by the nominally non-magnetic germanium-silicon ions in the giant magnetocaloric effect. In an article published in the June 15 issue of Physical Review Letters, the researchers describe how they used high-brilliance, circularly-polarized X-ray beams at the Advanced Photon Source to probe the magnetism of gadolinium and germanium ions as the material underwent its bond-breaking magneto-structural transition. In addition to the expected strong magnetization of gadolinium ions, the researchers found significant magnetization attached to the germanium ions.
“This is surprising and important,” said Argonne physicist Daniel Haskel, who led the research team. “Germanium was expected to be non-magnetic. Its magnetization is induced by the hybridization, or mixing, of otherwise non-magnetic germanium atomic orbitals with the magnetic gadolinium orbitals. This hybridization dramatically changes at the germanium-silicon bond-breaking transition, causing the destruction of magnetic ordering and leading to the giant magnetocaloric effect of these materials.”
By combining the novel experimental results with detailed numerical calculations of the electronic structure carried out at Ames Laboratory, the researchers were able to conclude that the magnetized germanium orbitals act as “magnetic bridges” in mediating the magnetic interactions across the distant gadolinium ions.
The magnetocaloric effect, a change in temperature accompanying a change in a material's magnetization, is largest near a material's intrinsic magnetic ordering temperature. In the case of rare-earth gadolinium, this ordering occurs near room temperature and results in a temperature increase of 3 to 4 K/per Tesla when a magnetic field is applied, making gadolinium the current material of choice for magnetic refrigeration near room temperature.
The prospects for a viable magnetic refrigeration technology recently became brighter with the report of a giant magnetocaloric effect in gadolinium-silicon-germanium alloys. The addition of non-magnetic silicon and germanium ions brings about a giant entropy change when germanium-silicon chemical bonds connecting the magnetism-carrying gadolinium ions are quickly formed or broken, respectively, by the application or removal of a magnetic field. As an added bonus, the magnetic ordering temperature can be tuned by changing the ratio or germanium to silicon.
"As a result of this work we now have a better understanding of the role of nonmagnetic elements, such as germanium, in enhancing magnetic interactions between the rare-earth metals in these materials,” said co-author and Ames Laboratory senior scientist Vitalij Pecharsky. “This discovery is counterintuitive, yet it opens up a range of exciting new opportunities towards the engineering of novel magnetic materials with predictable properties."
Other authors in the paper are Y. Lee, B. Harmon, Y. Mudryk, and K. Gschneidner of Ames and Z. Islam, J. Lang, and G. Srajer at Argonne.
Allegro Introduces a New Low Voltage, Bi-Directional DC Motor Driver in a 2.0 x 2.0 mm  Package
Allegro MicroSystems, Inc. has introduced a new low voltage bi-directional DC motor driver with an input voltage range of 3.0 V to 5.5 V and output currents up to 500 mA. The unique output full-bridge incorporates source side linear operation to allow a constant voltage supply across the motor coil. This regulated output minimizes motor voltage change due to I*Rdson variation and battery voltage tolerance. Allegro’s new motor driver is targeted at the portable and instrumentation markets.
Logic input pins are provided to control the motor direction of rotation, brake and standby (< 500 nA supply current) modes and to allow optional PWM of the sink drivers. Internal protection circuitry includes thermal shut down, under voltage lockout, and crossover (shoot through) protection.
Allegro’s A3903 is supplied in a 2.0 mm by 2.0 mm by 0.575 mm nominal, 8-lead DFN package, with exposed thermal pad (package suffix "EE"). This small footprint package is lead (Pb) free, with 100 percent matte tin leadframe plating. It is priced at $0.45 in quantities of 1,000 and has a 12-week typical lead-time to market.
austriamicrosystems Introduces AS5046, a 12-bit Magnetic Rotary Encoder IC 
austriamicrosystems , a designer and manufacturer of analog integrated circuits (ICs) for communications, industrial, medical and automotive applications, has introduced the AS5046, a new 12-bit resolution magnetic rotary encoder offering rotation, tilt and vertical distance detection of a magnet placed above the IC. The device can detect vertical distances over several millimeters, offering a suitable solution for contactless, multi-axis human interface devices, such as navigational knobs.
The AS5046 is a complete system-on-a-chip, combining both Hall-elements and a signal processor on one silicon chip. In addition to rotation detection mode, the AS5046 also supports the detection of magnet tilt with push-button functionality. This opens attractive new possibilities in human interface applications such as joysticks.
“This innovative device is an exciting addition to our industry-leading magnetic rotary encoder portfolio. To implement the joystick functionality, users only have to replace the diametrically polarized magnet with an axially polarized one,” said Josef Janisch, product manager Integrated Magnetic Sensors at austriamicrosystems. “We currently work with selected customers on joystick applications based on the AS5046. The AS5046 allows users to build extremely small form factor joystick solutions for applications not only in industrial but also in consumer and communications markets”.
The AS 5046 is the latest product in austriamicrosystems’ highly successful family of contactless magnetic rotary encoders, available in 8-, 10- and 12-bit resolutions, with different interfaces and for ambient temperatures of up to 150°C. The device communicates with an external microcontroller over a 2-wire serial interface. For standalone operation, the AS5046 provides a programmable ratiometric analogue output.
The AS5046 is available in a lead-free SSOP16 package. It can be operated at either 3.3 V or 5.0 V supply and is specified for -40°C to 125°C ambient temperature. Samples and demo boards are available immediately. Detailed application notes are available along with demo boards and free software tools to facilitate customer designs based on the AS5046.
For more information visit http://www.austriamicrosystems.com/03products/20_rotary_encoders.htm
iWatt and E&E Magnetics Enter Agreement to Promote Patented IKOR Coupled Inductor Technology
iWatt, Inc. and E&E Magnetic Products Ltd. will be working together to bring high-efficiency coupled inductor solutions to high performance applications such as servers. The combination of iWatt’s propriety coupled inductor technology and E&E’s high volume manufacturing capability will provide high-performance power solutions that save space, reduce cost and maximize efficiency while still meeting tough CPU voltage regulation requirements.
“IKOR Coupled inductor technology promises to bring the next level of cost and space savings to voltage regulators for CPU and other high-performance point-of-load applications,” said Doyle Slack, vice-president of Marketing at iWatt. “We are very excited to be joining forces with E&E to help us to promote our technology.”
"The E&E management is pleased to partner with iWatt in promoting IKOR coupled inductor technology to our global customers,” said Mark Saxon, vice-president of Marketing at E&E. “The combination of both iWatt and E&E’s technical expertise and manufacturing capabilities will provide optimum solutions to the power industry."
As part of the agreement, iWatt and E&E will work together on reference designs and provide design-in support to customers for their high-performance VR designs. E&E will sell inductors to customers worldwide. The purchase of these inductors will grant end-users a per-use license to use the patented IKOR technology in their end products.
Vacuumschmelze has Signed a Share Purchase Agreement with Neorem Magnets
Vacuumschmelze GmbH & Co. KG has signed a Share Purchase Agreement with Neorem Magnets Oy in Ulvila, Finland, a company producing sintered Rare Earth permanent magnets, which are used in applications such as large electric motors and generators (e.g. for wind power generators) and sensor magnets (e.g. for telecommunication).
Neorem Magnets Oy will continue as a part of the VAC Group with its own trademark, Neorem. The management of Neorem remains on board as minority shareholders of the company. Both VAC and the management of Neorem have strongly committed to further development and expansion of the operations of Neorem Magnets Oy. The technical know-how of both companies will be combined to give an even better service to the customers. This acquisition will strengthen the position of Vacuumschmelze Permanent Magnet Division in Europe in those applications and regions where Neorem is focused.
This activity will combine the different focuses of both companies to secure the production of sintered rare earth magnets in Europe. It will support the joint customer base with application know how and expanded capacities.
For more information visit www.vacuumschmelze.com
Electron Energy Corp. Awarded Air Force STTR Contract to Develop Multiphase Nanocomposite Magnets Capable of Withstanding High Temperature Applications
Michael H. Walmer, president, of Electron Energy Corp. (EEC) has been awarded a Small Business Technology Transfer Research (STTR) contract by the United States Air Force (USAF) to develop multiphase nanocomposite magnets that can withstand high temperature applications.
The US Air Force, AFRL, Office of Scientific Research recently selected the EEC-led team to meet the requirements of Phase II in a two-year, $749,999 contract. EEC will be supported in these efforts by the University of Delaware, Department of Physics and Astronomy led by Dr. George Hadjipanayis. Jinfang Liu, Ph. D., Director of Technology at EEC, an internationally recognized accomplished researcher in rare earth magnet materials and systems, will be the principal investigator for the project.
The main objective of this program is to develop a new class of permanent magnets that will achieve 30 MegaGauss Oersteds (MGOe) or greater at temperatures up to 450°C. These high energy, high temperature magnets will be used in the design of components for future air and space vehicles such as aircraft motors, generators, actuators, bearings, power system components, sensors and traveling wave tubes. The new magnets will directly support the US Air Force development of the “more electric aircraft” through reduction or elimination of hydraulics for engines and associated electrical power units and reducing cooling requirements. Many of the magnet applications will require optimized performance at elevated temperatures and under mechanical stress. Directed energy weapons will also be advanced by improved magnets for power generation components.
For the past several years, University of Delaware has conducted extensive studies on nanocomposite R2Fe14B/a-Fe melt-spun magnets, which were focused on the optimization of both the composition and processing conditions.
EEC and the University of Delaware proposed to develop multiphase nanocomposite magnets, which takes advantage of the extremely high coercivity of SmCo alloys, the high saturation magnetization and moderate intrinsic coercivity of other hard magnetic phases, and the high saturation magnetization of soft magnetic phases (such as a-Fe).
Nanocomposite magnets consist of a fine mixture of soft and hard phases that are exchange coupled. The soft phase provides the high magnetization and the hard phase provides the anisotropy and intrinsic coercivity that resists demagnetization of the soft phase.
EEC and the University of Delaware will collaboratively develop anisotropic core/shell structures by controlled precipitation techniques. This approach would eliminate the need for a separate preparation process for soft and hard magnetic particles and greatly improve the uniformity of the soft phase in the nanocomposite material.
Peter C. Dent, director of Business Development, said, “It would be a major breakthrough if these alternate methods are successful, because nanoparticle preparation and consolidation processes would not be needed for nanocomposite magnets.”
EEC has been issued US patent protection for its ultra-high temperature SmCo magnets capable of operating in the 350 to 550 °C range and has produced these SmCo-UHTmagnets in commercial use for over five years. Competing magnet technologies have energy products several times lower than EEC high temperature magnets. Since 1996, EEC has been granted sixteen STTR or SBIR (Small Business Innovative Research) Phase I and Phase II programs, which resulted in three patents, as well as over 30 papers published in professional journals. EEC produced SmCo magnets are compliant with US Department of Defense preference for specialty metals provisions in DFARS 225.252-7014 (Deviation).
AC-DC Power Supplies Global Market Forecasts and Competitive Environment Eighth Edition Available Now
Research and Markets has added the “AC-DC Power Supplies Global Market Forecasts and Competitive Environment Eighth Edition” to their offering.
Traditionally, the embedded ac-dc power supply market is one of the more staid segments in the power electronics industry. However, several divergent trends are creating a number of opportunities and threats. The ongoing rise of the consumer device market is driving increasing unit sales, but at the same time bringing down the average selling price of power supplies. Additionally, the consumer devices market is shifting from captive production to merchant production. Delta Electronics, the embedded ac-dc power supply market share leader, experienced growth of 43 percent during 2005, partially as a result of a growing focus on providing power supplies for markets that have traditionally been captive production. Many other companies are following a similar path.
As a result of the rise of the consumer market and because of its shift from captive to merchant production, forecasts for both the merchant and merchant/captive markets are provided in this report. Combined worldwide merchant and captive embedded ac-dc power supply units sales are expected to rise from 890.8 million units in 2006 to 1,134.4 million units in 2011, an annualized growth rate of 5.0 percent. During the same period, merchant revenue is projected to rise from $11.2 billion to $14.8 billion, at an annualized rate of 5.8 percent.
In addition to consumer devices, there are several applications and technical trends that are expected to drive the embedded ac-dc power supply market. Within the computer segment, Intel's focus on dual core processors and the move towards the BTX will slow down desktop PCs' continual rise to higher wattages. Blade servers are diminishing enterprise server and traditional server growth, but are providing greater revenue opportunities because they are higher wattage power supplies that require more advanced features, including redundancy and hot-swap ability. The computer storage market is also providing strong growth, as companies' data storage needs increase because of financial regulations and the growing broadband content provided on the web. The communications market is undergoing its own transformation as Voice-over Internet Protocol (VoIP) drives opportunities for Power-over-Ethernet (PoE) and Customer Premises Equipment. Additional communications opportunities can be found as cable operators and traditional telecom carriers duel over triple-play services. Set-top-box sales will remain one of the largest and fastest-growing communications applications.
Smaller niche markets are also providing strong growth. Industrial is benefiting from continued rise of China. Light emitting diodes for signage are also providing growth drivers for ac-dc power supply makers outside of the traditional "three-C" markets of Computers, Communications and Consumer. Power supplies for the medical market are seeing a boom driven by the "consumerization" of medical devices trend. Counter intuitively, the Military/Aerospace market is seeing slower growth than it has in recent years, as military budgets are drawn thin by the prolonged military presence in Iraq and Afghanistan. In order to best describe the multitude of application trends that are driving the embedded ac-dc power supply market, 25 distinct applications are forecasted in four regions and worldwide.
Power levels continue to rise, particularly as servers migrate to blade servers and applications such as PoE gain steam. The potential move to PoE-Plus, which is expected to at least double the power PoE offers, will significantly increase the power level of these devices. Additionally, the move towards the distributed power architectures and, more specifically, the Intermediate Bus Architecture, has created increasing demand for ac-dc front ends. This results in a greater share of rack-mounted power supplies and also brings up the average wattage of power supplies. DIN-Rail power supplies, while still a small market worldwide, are slowly gaining share in North America as companies such as Lambda Electronics have brought this predominately European package to the North America and Asia markets. Also, as the Consumer market becomes more merchant, there has been a growing demand for standard-designed power supplies.
The increasing use of higher wattage power supplies, particularly in the broad computer market, is placing increasing focus on the efficiency of embedded ac-dc power supplies. The US's Environmental Protection Agency's Energy Star Program has already enacted voluntary efficiency standards for external power supplies and Energy Star has begun to focus on embedded power supplies by drafting applications standards that include specifications for the power supply in use. However, driven by regulation or not, the current economic condition requires a move towards more efficient power supplies. Similarly, power factor correction is increasingly being used as the average wattage level of applications increase.
The move towards digital power control and conversion remains in its infancy, but is beginning to play a role in the ac-dc power supply market. While dc-dc converters have received the majority of the attention, a number of digitally controlled ac-dc front ends have come to market that will have implications for future power supply design.
Regionally, Asia and China have become a much larger share of the embedded power supply market, especially as the sales of consumer devices have grown. However, North America and Europe remain large markets, especially for power supplies for higher-end applications, typically with higher wattages. As a result, these two regions maintain strong revenue opportunities, despite slower-growing unit sales.
While the broad economic picture and application trends provide promise for ac-dc power supply makers, the economic trends of the power supply market itself poses greater threats. The market has recently entered a period of consolidation, especially for the major players. Within the last year, three of the top five power supply companies have been involved in major acquisitions. These mergers give the new companies greater economies of scale. As a result, while the ac-dc power supply market is still serviced by hundreds if not thousands of companies, market share of the largest few continues to grow. This is an increasing threat to the other power suppliers in the market and may necessitate more consolidation in an attempt to level the playing field. To capture all of the dynamics in the embedded ac-dc power supply, detailed profiles of more than 40 companies are provided. Additionally, market shares for each of the top-five companies Worldwide and in North America, Europe, and Asia are given.
For more information visit http://www.researchandmarkets.com/reports/c55212. |
