Recently, scientists at the University of California, Berkeley and Lawrence Berkeley National Laboratory and their collaborators synthesized a series of metal-organic frameworks (MOFs) with pores up to 98 Å in diameter—large enough to house protein molecules. For the first time the researchers were able to design strategies to overcome three major obstacles to increasing pore capacity...
Although the behavior of conventional superconductors has been explained via the BCS theory, the mechanism of superconductivity in the cuprate high temperature superconductors remains unresolved. One approach to this problem is to explore the phases next to superconductivity on the temperature-doping phase diagram. The pseudogap phase above Tc has been a particular stumbling block because it is not a Fermi liquid as with conventional superconductors.
There has been increasing evidence that the pseudogap phase is distinct from superconductivity and persists below Tc, and not simply a precursor to superconductivity. In a study recently published in PNAS, researchers at SSRL Beam Line 5-4 and Stanford explored the full doping, temperature, and momentum dependence of spectral gaps in the superconducting state of Bi2Sr2CaCu2O8+δ (Bi-2212) with unprecedented precision and completeness.
Olefins are the basic building blocks for many products from the petrochemical industry and are currently produced by steam cracking of naphtha or ethane, but increasing oil and gas prices are driving the industry toward producing olefins from syngas derived from cheaper feedstocks via the Fischer-Tropsch process instead. A team of scientists used full-field Transmission hard X-ray Microscopy (TXM) and a special reactor designed and built at SSRL and installed on SSRL Beam Line 6-2 to learn more about the catalyst at the heart of the Fischer-Tropsch-to-Olefins (FTO) process.
The structural, electronic, and magnetic properties of U and Pu elements and intermetallics remain poorly understood despite decades of effort, and currently represent an important scientific frontier toward understanding matter. The last decade has seen great progress both due to the discovery of superconductivity in PuCoGa5 and advances in theory that finally can explain fundamental ground state properties in elemental plutonium, such as the phonon dispersion curve, the non-magnetic ground state, and the volume difference between different phases of the pure element.
A new magnetic state called a quantum spin liquid has been observed by a large international team of investigators from ten institutions1, including a group using SSRL. When magnetic ions are located within a crystal lattice there are usually strong local magnetic and electric forces between them. At low temperatures such forces lead to a preferred alignment of the atomic moments – in ferromagnets such as iron for example, the atomic magnets are aligned parallel to each other while in anti-ferromagnets they are antiparallel.
Dramatic improvements in energy storage devices are essential to meet the increasing need to move away from fossil fuels and toward clean, renewable energy. Rechargeable lithium-sulfur (Li-S) batteries hold great potential for high-performance energy storage systems because they have a high theoretical specific energy, low cost, and are eco-friendly; but a better understanding of how the battery functions is required to design improvements for higher efficiency and capacity.
Much of our manufactured environment - many metals, plastics, glasses, ceramics, fiberglass and papers - consists of extrusion-molded products. To minimize waste, extrusion-molding plants must balance quality of product, speed of process and cost of production (primarily electricity) for each particular material. They need to know how fast each material can be processed at what energy cost while maintaining the quality of the finished bulk material. Fundamental changes in the macromolecular arrangement of materials occur at critical deformation rates.
Since the discovery of high-temperature superconductor by Bednorz and Müller in 1986, this field has become one of the most important research topics in solid state physics. In the past 20 years many unconventional properties have been discovered in this new class of materials. These have challenged our conventional wisdom and driven the development of many novel theories.
A collaboration between scientists at SSRL and the department of Applied Physics at Stanford University has determined the phase diagram of a new family of prototypical charge density wave (CDW) compounds. These compounds have the chemical formula RTe3, where R represents a rare earth element from La to Tm. In research, the collaborators have used X-ray diffraction and resistivity measurements to determine the factors affecting the symmetry of the CDW state, specifically whether the CDW runs in one direction or two.
Researchers working in part at SSRL Beam Lines 8-1 and 10-1 recently characterized the band offsets in a promising semiconductor material that could lead to smaller and faster electronic devices of the future. The results are published in the September 13, 2007 edition of Applied Physics Letters.
