Manufacturing Bits: Sept. 22

Superconductor puddles; looking for anatase; U.S. nanotech project.


Superconductor puddles
Superconductors are devices that have zero electrical resistance, making them attractive for a range of applications. But superconductors must be cooled down to temperatures near zero to work, which, in turn, limits their applications.

High-temperature superconductors are more promising technologies, but once again, they must be cooled down to function.

The industry hopes to gain a better understanding of high-temperature superconductors. And one group may have taken a step forward in this arena.

Using high-energy X-rays, the Deutsches Elektronen-Synchrotron (DESY) organization and others have discovered the inner structure of a special class of ceramic high-temperature superconductors. This, in turn, could one day enable high-temperature superconductors at room temperature.

The superconducting current (red tubes) running in the interstitial space between puddles of electronic crystals (Source: DESY)

The superconducting current (red tubes) running in the interstitial space between puddles of electronic crystals (Source: DESY)

In the lab, DESY and others investigated the structure of a high-temperature cuprate superconductor (HgBa2CuO4+y) using high-energy X-rays at DESYs synchrotron light source. The X-ray source, dubbed DORIS, is a 4.5 GeV storage ring.

Researchers used scanning micro X-ray diffraction to look at the electrons in the crystalline domains. In traditional semiconductors, the electrons move in a homogenous fashion, much like a liquid spreading out evenly in a canal, according to DESY.

In contrast, the electrons in high-temperature cuprate superconductors form puddles at minus 20 degrees Celsius. The average puddle measures about 4nm, but some are as large as 40nm.

The puddles also leave free interstitial space. And the electric current flows around the puddles. “These results open new avenues for the design of superconducting materials, and thus could advance the search for a room temperature superconductor,” said Alessandro Ricci of DESY, on the organization’s Web site.

Others also contributed to the research, including RICMASS, CNR, ESRF, Elettra, the University of Twente in The Netherlands, the Queen Mary University of London, the Swiss Federal Institute of Technology, Moscow State University and Ghent University.

Looking for anatase
Using scanning probe microscopy, the National Institute for Materials Science (NIMS) found the atoms and defects in the anatase form of titanium dioxide.

Anatase, one of the mineral forms of titanium dioxide, is attractive because of its ability to convert solar energy into electricity. But it’s challenging to grow large single crystals of anatase, according to NIMS.

AFM (a) and STM (b) images of the surface of anatase titanium dioxide. The model of anatase (c). (Source: NIMS)

AFM (a) and STM (b) images of the surface of anatase titanium dioxide. The model of anatase (c). (Source: NIMS)

So, it is critical to gain an understanding of anatase at the atomic level. To determine the make-up of the structure, researchers combined atomic force microscopy (AFM) and scanning tunneling microscopy (STM) measurements.In a regular STM, it is difficult to image anatase. But simultaneous operation of AFM and STM allowed imaging the surface with atomic resolution. Researchers used single water molecules as atomic markers. In doing so, they identified the atomic species of this surface.

Nanotech project
The National Science Foundation (NSF) in the United States will provide a total of $81 million over five years to support 16 sites and a coordinating office as part of a new National Nanotechnology Coordinated Infrastructure (NNCI).

The awards involve several disciplines of nanoscale science, engineering and technology. The awards are up to five years and range from $500,000 to $1.6 million each per year. Nine of the sites have at least one regional partner institution. These 16 sites are located in 15 states and involve 27 universities across the nation.

The NNCI sites will provide researchers from academia, government, and companies with access to leading-edge fabrication and characterization tools and instrumentation.

The NSF provided awards to the following entities: Mid-Atlantic Nanotechnology Hub for Research, Education and Innovation; Texas Nanofabrication Facility; Northwest Nanotechnology Infrastructure; Southeastern Nanotechnology Infrastructure Corridor; Midwest Nano Infrastructure Corridor; Montana Nanotechnology Facility; Soft and Hybrid Nanotechnology Experimental Resource; The Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure; North Carolina Research Triangle Nanotechnology Network; San Diego Nanotechnology Infrastructure; Stanford Site; Cornell Nanoscale Science and Technology Facility; Nebraska Nanoscale Facility; Nanotechnology Collaborative Infrastructure Southwest; The Kentucky Multi-scale Manufacturing and Nano Integration Node; and The Center for Nanoscale Systems at Harvard University.