lunes, 14 de julio de 2014

nuevo material no es negro, es super negro

Este nuevo material no es negro, es super negro ... y no puedes verlo


El uso de los nanotubos, los investigadores han creado Vantablack, un nuevo material que es tan, tan oscuro que sus ojos no pueden sentirlo. 



http://pda.sciencealert.com.au/news/20141407-25870.html

martes, 17 de junio de 2014

Superconducting secrets solved after 30 years

A breakthrough has been made in identifying the origin of superconductivity in high-temperature superconductors, which has puzzled researchers for the past three decades.

By identifying other materials which have similar properties, hopefully it will help us find new superconductors at higher and higher temperatures


Harnessing the enormous technological potential of high-temperature superconductors – which could be used in lossless electrical grids, next-generation supercomputers and levitating trains – could be much more straightforward in future, as the origin of superconductivity in these materials has finally been identified.

Researchers from the University of Cambridge have found that ripples of electrons, known as charge density waves or charge order, create twisted ‘pockets’ of electrons in these materials, from which superconductivity emerges.

Low-temperature, or conventional, superconductors were first identified in the early 20th century, but they need to be cooled close to absolute zero (zero degrees on the Kelvin scale, or -273 degrees Celsius) before they start to display superconductivity.

What is different about superconductors is that the electrons travel in tightly bound pairs.

http://www.cam.ac.uk/research/news/superconducting-secrets-solved-after-30-years

miércoles, 7 de mayo de 2014

El grafeno tricapa, un cristal que se puede reconfigurar con un campo eléctrico


La estructura de este metal se puede controlar con campos eléctricos


Su estado cambia de forma reversible y controlada


El estudio puede llevar a una nueva clase de dispositivos electrónicos



http://www.rtve.es/noticias/20140506/grafeno-tricapa-cristal-se-puede-reconfigurar-campo-electrico/933606.shtml

lunes, 3 de febrero de 2014

@ScienceNewsOrg: Bone inspires strong, lightweight material (tiny synthetic structures are as sturdy as metal) http://ow.ly/tf6B3 http://twitter.com/ScienceNewsOrg/status/430450106601443328/photo/1
Compartido por Tweetcaster

viernes, 20 de septiembre de 2013

RV: Study to generate electricity from waste heat points to global energy solution

 

 

Fuente: Science and Technology Facilities Council News and Press Releases
Expuesto el: jueves, 12 de septiembre de 2013 11:13
Autor: Science and Technology Facilities Council News and Press Releases
Asunto: Study to generate electricity from waste heat points to global energy solution

 

A major milestone in the quest to find more efficient ways of generating electricity from waste heat, and to reduce carbon emissions, has real potential in a vast range of applications - from reducing the energy consumption of cars by converting exhaust heat into electrical power, to cooling hot spots on computer chips and solid state refrigerators, even powering deep-space missions.

This important research, which was led by the University of London's Royal Holloway, and included STFC's Scientific Computing department, is reported in Nature Materials. This approach will pave the way for the design of a new, environmentally-friendly generation of thermoelectric materials, that is more effective than any currently in existence – and which can convert heat into electricity which can also be used for cooling.

As part of the project, the team conducted a series of experiments on thermoelectric sodium cobaltate at STFC's ISIS pulsed neutron and muon source at its Rutherford Appleton Laboratory, as well as at the European Synchrotron Radiation Facility (ESRFC) and the Institut Laue-Langevin in Grenoble, UK access to both of which is funded by STFC.

"The global target to reduce carbon emissions has brought thermoelectric materials research into centre stage," said Professor Jon Goff from the Department of Physics at Royal Holloway. "If we can design better thermoelectric materials, we will be able to reduce the energy consumption of cars by converting waste heat in exhausts into electrical power, as well as cooling hot spots on computer chips using solid state refrigerators .The development of thermoelectric oxides offers an environmentally clean alternative to current materials that contain elements that are harmful, such as lead, bismuth or antimony, or are in limited supply, such as tellurium."

Advanced computer calculations, which were central to the interpretation of the experiments, were performed by STFC's Scientific Computing Department. Dr Keith Refson, Computational Scientist at STFC, said:

"These supercomputer simulations, based on STFC's world-leading expertise in this discipline, have given us a far deeper understanding of the findings from our cutting-edge experiments and are making it easier to realise environmental benefits from the future generation of electricity from waste heat."

View the full press release.

END

Notes to Editors

This research paper has been published in Nature Materials - "Suppression of thermal conductivity by rattling modes in thermoelectric sodium cobaltate" - D. J. Voneshen, et al, paper reference: doi:10.1038/nmat3739.

Contact details

Wendy Ellison
STFC Press Officer
Tel: 01925 603232
Mob: 07919 548012

STFC

The Science and Technology Facilities Council is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security.

The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC operates or hosts world class experimental facilities including in the UK the ISIS pulsed neutron source, the Central Laser Facility, and LOFAR, and is also the majority shareholder in Diamond Light Source Ltd.

It enables UK researchers to access leading international science facilities by funding membership of international bodies including European Laboratory for Particle Physics (CERN), the Institut Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the European Southern Observatory (ESO). STFC is one of seven publicly-funded research councils.

It is an independent, non-departmental public body of the Department for Business, Innovation and Skills (BIS).

Follow us on Twitter at @STFC_Matters.


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jueves, 19 de septiembre de 2013

RV: New Magnetic Semiconductor Material Holds Promise for ‘Spintronics’

 

 

Fuente: NC State News :: NC State News and Information
Expuesto el: martes, 10 de septiembre de 2013 16:44
Autor: Matt Shipman
Asunto: New Magnetic Semiconductor Material Holds Promise for 'Spintronics'

 

Researchers at North Carolina State University have created a new compound that can be integrated into silicon chips and is a dilute magnetic semiconductor – meaning that it could be used to make "spintronic" devices, which rely on magnetic force to operate, rather than electrical currents.

The researchers synthesized the new compound, strontium tin oxide (Sr3SnO), as an epitaxial thin film on a silicon chip. Epitaxial means the material is a single crystal. Because Sr3SnO is a dilute magnetic semiconductor, it could be used to create transistors that operate at room temperature based on magnetic fields, rather than electrical current.

"We're talking about cool transistors for use in spintronics," says Dr. Jay Narayan, John C. Fan Distinguished Professor of Materials Science and Engineering at NC State and senior author of a paper describing the work. "Spintronics" refers to technologies used in solid-state devices that take advantage of the inherent "spin" in electrons and their related magnetic momentum.

"There are other materials that are dilute magnetic semiconductors, but researchers have struggled to integrate those materials on a silicon substrate, which is essential for their use in multifunctional, smart devices," Narayan says. "We were able to synthesize this material as a single crystal on a silicon chip."

"This moves us closer to developing spin-based devices, or spintronics," says Dr. Justin Schwartz, co-author of the paper, Kobe Steel Distinguished Professor and Department Head of the Materials Science and Engineering Department at NC State. "And learning that this material has magnetic semiconductor properties was a happy surprise."

The researchers had set out to create a material that would be a topological insulator. In topological insulators the bulk of the material serves as an electrical insulator, but the surface can act as a highly conductive material – and these properties are not easily affected or destroyed by defects in the material. In effect, that means that a topological insulator material can be a conductor and its own insulator at the same time.

Two materials are known to be topological insulators – bismuth telluride and bismuth selenide. But theorists predicted that other materials may also have topological insulator properties. Sr3SnO is one of those theoretical materials, which is why the researchers synthesized it. However, while early tests are promising, the researchers are still testing the Sr3SnO to confirm whether it has all the characteristics of a topological insulator.

The paper, "Epitaxial integration of dilute magnetic semiconductor Sr3SnO with Si (001)," was published online Sept. 9 in Applied Physics Letters. Lead author of the paper is Y. F. Lee, a Ph.D. student at NC State. Co-authors include F. Wu and R. Kumar, both Ph.D. students at NC State, and Dr. Frank Hunte, an assistant professor at NC State. The work was supported, in part, by the National Science Foundation.

-shipman-

Note to Editors: The study abstract follows.

"Epitaxial integration of dilute magnetic semiconductor Sr3SnO with Si (001)"

Authors: Y.F. Lee, F. Wu, R. Kumar, F. Hunte, J. Schwartz, and J. Narayan, North Carolina State University

Published: online Sept. 9, Applied Physics Letters

DOI: 10.1063/1.4820770

Abstract: Epitaxial thin films heterostructures of topological insulator candidate Sr3SnO (SSO) are grown on a cubic yttria-stabilized zirconia (c-YSZ)/Si (001) platform by pulsed laser deposition. X-ray and electron diffraction patterns confirm the epitaxial nature of the layers with cube-on-cube orientation relationship: (001)[100]SSOk(001)[100]c-YSZk(001)[100]Si. The temperature dependent electrical resistivity shows semiconductor behavior with a transport mechanism following the variable-range-hopping model. The SSO films show room-temperature ferromagnetism with a high saturation magnetization, and a finite non-zero coercivity persisting up to room temperature. These results indicate that SSO is a potential dilute magnetic semiconductor, presumably obtained by controlled introduction of intrinsic defects.


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