You are browsing the archives of 2012 February.

New papers that have been accepted for publication in the International Journal of Applied Glass Science are posted to “Early View” on the Wiley website and can be read even before the issue is printed. Below are summaries of selected papers currently available via Early View.

All members of The American Ceramic Society receive free online access to IJAGS. To access any of the ACerS journals, or to become a member, visit www.ceramics.org.

Environmental scanning electron micrographs of an as-corroded and dried sulfophosphate glass after 24-h pure water (20°C) exposure. Credit: IJAGS; Wiley.	Chemical Stability of ZnO-Na2O-SO3-P2O5 Glasses Sergey Sirotkin, Robert Meszaros and Lothar Wondraczek This research team from Germany’s University of Erlangen-Nuremberg report the weight loss, ion release rates and modifications of surface topology as a function of time, temperature and pH value of depolymerized sulfophosphate (ZnO-Na2O-SO3-P2O5) glasses in aqueous solution. The team reports that observations seem consistent with a previously developed structural model of chemical heterogeneity, where sodium and zinc cations cluster selectively in the vicinity of sulfate and phosphate anions, respectively.
Schematic of polishing setup to measure pad wear. Credit: IJAGS; Wiley.	Convergent Pad Polishing of Amorphous Silica Tayyab Suratwala, Rusty Steele, Michael Feit, Richard Desjardin and Dan Mason This Lawrence Livermore National Laboratory research team used convergent pad polishing and a ceria slurry on polyurethane pads to polish fused (amorphous) silica workpieces. The team systematically controlled polishing parameters to prevent nonuniform material removal: moment force; viscoelastic lap relaxation; kinematics; pad wear; and workpiece bending. The team reports removal uniformity of 1.0 micrometer over the surface after 83 micrometers of material removal and a convergence of 0.18 ± 0.04-micrometer peak-to-valley flatness on a 100-millimeter workpiece.
Evolution of the total strain during the relaxation-recovery tests (lines are guides for the eyes). Credit: IJAGS; Wiley.	Photoinduced Fluidity and Viscoelasticity in Chalcogenide Glasses Yann Gueguen, Jean-Christophe Sangleboeuf, Tanguy Rouxeland and Vincent Keryvin These French researchers used relaxation-recovery to characterize delayed elasticity of chalcogenide glasses under irradiation conditions and to investigate the influence of the photon irradiation on viscoelastic behavior. They report that thermally activated and photoinduced processes are decoupled and that viscoplastic deformation under irradiation is the sum of thermally activated and photoinduced processes. In particular, as soon as irradiation ceases, chalcogenide glasses behave as if they never had been irradiated.
Optical images of thin sections of melts from corundum- and gibbsite-containing batches heated in Pt crucibles at 5°C/min. Credit: IJAGS; Wiley.	Effect of Alumina Source on the Rate of Melting Demonstrated with Nuclear Waste Glass Batch David A. Pierce, Pavel Hrma, José Marcial, Brian J. Riley and Michael J. Schweiger These researchers from Pacific Northwest National Laboratory compared the melting behaviors of three glass batches formulated to vitrify high-alumina high-level waste and found that a slowly dissolving refractory component caused excessive foaming. They report that faster-melting gibbsite (Al(OH)3) or boehmite (AlO(OH)) batches produced substantially less foaming than a corundum (Al2O3) batch, because the low viscosity of the latter batch caused the open pores to close prematurely to trap the gases and expand the foam, which explains the slow melting rate of a corundum batch.
Optical microscope and Raman mapping of the iso-density curves for a 20 N Vickers load in side view. Credit: IJAGS; Wiley.	Raman Mapping of the Indentation-Induced Densification of a Soda-Lime-Silicate Glass Assia Kassir-Bodon, Thierry Deschamps, Christine Martinet, Bernard Champagnon, Jérémie Teisseire and Guillaume Kermouche This research team from France used micro-Raman spectroscopy to investigate top surface and cross section residual imprints of Vickers indentation-induced densification in a soda-lime-silica window glass. The team reports that sample preparation of the in-depth densification does not alter the results and that maximum densification ratio measured is about 3.8 percent, which is 60 percent of the maximum densification measured after high-pressure hydrostatic loading.
Damage evolution features as a function of scratching speed (v) at constant applied normal loads (P) of 5 N 0.1 mm/s. The features include ring crack (rc), plastic grooving (g), microcracking (mc), and formation of microwear debris (mwd). The scratch was made from left to right. Credit: IJAGS; Wiley.	Novel Combined Scratch and Nanoindentation Experiments on Soda-Lime-Silica Glass Payel Bandyopadhyay, Arjun Dey and Anoop K. Mukhopadhyay These researchers from India conducted a series of combined nanoindentation and single-pass scratch experiments on a soda-lime-silica glass as a function of various normal loads and scratch speeds. They report that the nanohardness and Young’s modulus at the local microstructural length scale inside the scratch groove decreased dramatically depending on the combination of load and scratching speed and that tribological properties, severity and spatial density of damage evolution were sensitive to the normal loads, scratching speeds and tensile stresses.
SEM-FEG microscopy of a pillar sample. Credit: IJAGS; Wiley.	Micropillar Testing of Amorphous Silica Rémi Lacroix, Vincent Chomienne, Guillaume Kermouche, Jérémie Teisseire, Samuel Queste and Etienne Barthel This French research team assessed the potential of micropillar compression testing for the investigation of micromechanical properties of amorphous silica, calculated the response of amorphous silica micropillars as predicted by finite-element analysis and compared the results with preliminary microcompression tests. They report that amorphous silica is much more amenable than some metals to microcompression experiments because of a comparatively high ratio between yield stress and elastic modulus and that simulations are consistent with the experimental results, except that full agreement must allow for nonlinear response of amorphous silica in the elastic regime.
The distribution of real time temperature Tr of the P-SK57 glass sample at different time during cooling. Credit: IJAGS; Wiley.	Finite-Element Calculation of Refractive Index in Optical Glass Undergoing Viscous Relaxation and Analysis of the Effects of Cooling Rate and Material Properties Lijuan Su and Allen Y. Yi Su, of Ohio State University, and Yi, of Beihang University of Aeronautics and Astronautics, used the Tool-Narayanaswamy-Moynihan model to predict refractive index change by cooling introduced to two low-glass-transition-temperature optical glasses. They report that the finite-element method is capable of predicting refractive index of optical glass undergoing viscous relaxation, that is, a higher cooling rate leads to a lower refractive index and a larger variation of refractive index in glass optics.

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German Chancellor Angela Merkel and Chinese Premier Wen Jiabao discussed rare earth supplies in their Feb. 2, 2012 meeting. Credit Xinhua; Xie Huanchi.

There have been long-standing and well-known strains between China and much of the rest of the world over rare earth supplies, but projections for 2012 look like access to the materials won’t be an immediate concern because demand is less than expected. It is hoped that this provides valuable breathing space for other nations and regions to flesh-out their strategic plans (rather than being lulled into believing a crisis has passed) related to critical materials.

Bloomberg News Service earlier this week ran a story about this (with a misleading headline, “China may double rare earth exports as demand rebounds”) about how the external market demand for China’s exports ran below the quotas set for 2011. To be clear, what Bloomberg means is not that China is doubling its export limits. On the contrary, the export quotas for 2012 apparently will be about the same as for 2011, but demand is expected to more closely match the quota maximum.

To put an even finer point on this, according to a recent document on the website of China’s Ministry of Commerce, “China’s rare earth exports totaled 14,750 tons in the first 11 months of 2011, accounting for 49 percent of total export quotas. Large quantity of most export quotas still lay idle. Even though, confronted with huge pressure of resource, environment and domestic demand, in order to guarantee international market demand and keep rare earth supplies basically stable, export quota of 2012 are equal to that of 2011.” In other words, the open demand for Chinese rare earth products shifted in 2011 from being greater than quota amounts to less than half of the quota.

What caused the shift? Of course, the economic problems of North America, Europe, Japan and many other regions were a huge factor. Bloomberg reports that another factor is that the growing prices for some rare earths made consuming businesses decide to tap and deplete their existing inventories before placing new orders.

At least two other factors are also at work. One is that buyers apparently are still finding ways to purchase rare earths through less-than-legal Chinese channels. Second, the higher prices provide an incentive for non-Chinese producers to dig and refine their reserves, so other minor supply streams are at work.

Meanwhile, trade dispute and diplomatic efforts are still being used to reach longer-term solutions. For example, the topic of rare earth supplies came up in a meeting in early February between Chinese Premier Wen Jiabao and German Chancellor Angela Merkel. Wen reportedly told Merkel, “Although we now know that we must develop rare earth metals sustainably, we can still afford to meet 90 percent of global demand with less than 50 percent of the world’s reserves.”

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Tuesday was the first full day of symposia at the MCARE 2012 meeting going on Clearwater Beach, Fla. Credit: ACerS.

The first full day of symposia and tutorials took place today. With four or five concurrent sessions, a comprehensive (or even semi-comprehensive) report on today’s events at the Materials Challenges in Alternative and Renewable Energy would be impossible. Those that want one will have to wait for the proceedings to be published.

But here are of few examples of what I learned today as I hopped from talk to talk.

• Toyota sees promise in future magnesium-based batteries that appear to be capable of delivering high volumetric capacity, plus are less costly and safer;

• Sion Power, in collaboration with BASF, is making progress on lithium-sulfur batteries for electric vehicles;

• Researchers are optimistic about their work in “third-generation” PV devices that incorporate semiconductor–transparent conductive oxide nanocomposite thin films;

• Alane (aluminum hydride) is a promising hydrogen-storage material that is being studied in several federal labs and by other groups because its superior volumetric and gravimetric densities far exceed that of liquid hydrogen, and significant advancements have been made with tuning decomposition kinetics and efficiently regenerating the material; and

• Versa Power is making progress in developing durable reversible solid oxide fuel cell stacks.

Again, this just scratches the surface of all of today’s presentations.

And, here are some more pictures from today’s talks and evening poster session.

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Networking opportunities were plentiful at the first full day of the MCARE conference. Credit: ACerS.

The first full day of the Materials Challenges in Alternative and Renewable Energy was dedicated to a range of plenary talks that covered the gamut of potential sources and, of course, the materials challenges each one faced. The sessions were MC’d by conference cochairs George Wicks and Jack Simon.

Put succinctly, each technology is “materials hungry,” and whether it’s solar, hydrogen, wind, hydro or nuclear, the materials mantra is: less, lighter, stronger and more efficient. And, by the way, the materials advances also need to lead to improved processing and manufacturing.

In most cases, speakers, such as Dow Corning Solar Solution’s Eric Peeters, spoke of having clear goals and roadmaps. For solar, the target is $1 per Watt (installed) by decade’s end, which would bring it close to $0.12-0.13 per kWh (comparable to natural gas).

For some, the features of the roadmap are clearer than for others. Peeters spoke of plans to use thinner wafers and glass, plus silicone-sealed frameless panels that use conductive adhesives. DOE hydrogen guru Ned Stetson discussed the short-range challenges of storing and transporting H₂ in its pure form (via materials that will permit stronger, lighter cylinders), but that chemical hydrogen storage systems—e.g., metal hydrides—can deliver higher H storage capacity (measured by weight percent) than anything involving just H₂.

GM Global R&D manager Bob Powell outlined the evolutionary steps of moving from electrical assist and hybrid technologies, through the “bridge” technologies of extended range electric vehicles, to, ultimately, fuel cell transportation (and auxiliary power generation). He says some of the challenges for the bridge materials are battery performance degradation, shrinkage–expansion and ability to withstand 5000 charge-discharge cycles.

Megan McCluer and Jim Ahlgrimm of DOE’s Wind & Hydropower Technology programs spoke widely about several traditional and novel wind and hydro (including ocean-based) technologies, but they reported that much of it—especially the strong, stable and better sited offshore wind capacity—is largely untapped. The analogy they use is, “What Saudi Arabia is to oil, the US is to wind energy and power.” But, offshore wind assets bring a new set of challenges: corrosion and biofouling, plus larger-scale blades, drivetrains and generators.

McCluer and Ahlgrimm noted their DOE programs cover a huge variety of wind and hydro generation approaches, so much of their work is based on establishing hypothetical production scenarios (e.g., supplying the US with 15 percent of power from water sources and 20 percent from wind), and then working backwards to figure out what advancements would be needed from each technology stream to meet the goals. Lab-academia-industry collaborations have been set up to address the next generation of blades, bearings/gearings and generators (including, ultimately, light-weight full superconductive generators).

Bhakta Rath from the Naval Research Lab took (friendly) issue with the suggestion that Saudi Arabia is the leader in oil and hydrocarbon-based energy reserves. What makes the US the leader, he says, are the largely untapped shale oil deposits in the Green River region of Western United States, plus rich methane hydrate deposits. Rath also mentioned the progress being made in understanding the potential of power generation based on exploiting ocean thermal energy gradients.

Is nuclear power an alternative or renewable form of energy? Savannah River National Lab’s Tom Sanders thinks there is an argument to be made. He says, in essence, whether solar is classified as alternative or renewable, remember that it is the product of fusion. Sanders, however, thinks along more practical lines than philosophical ones: He says small modular nuclear reactors are going to be manufactured, if not by the US, then by other nations. He says they can be made to deliver nuclear fuel efficiency, safety and security. In addition, their 100-300 MW size corresponds to the emerging sweet spot for modular size that existing electric utilities have found works well for new gas-fired turbines. SMNRs would also allow developing nations to leapfrog many grid infrastructure investments, similar to the way cell phones have eliminated the need for “last-mile” telecommunications wiring investments. Finally, Sanders says SMNRs can aid nonproliferation of nuclear weapons by allowing the U.S. to leverage nuclear fuel supplies at the front and back end of the generation cycles.

Each of the plenary speakers have kindly allowed ACerS to put their Powerpoint Presentations (typically converted to a pdf format) on  the Society’s website, via the MCARE Plenary Speakers page. Just click on the title of each presentation.

How do our engineers and scientists find the lighter, stronger, more efficient and easier-to-use materials? Ah—that’s the topic for the next three days of symposia. Stay tuned.

And, here are some of the photos from MCARE on Monday.

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Check ‘em out:

CMOS-based carbon nanotube pass-transistor logic integrated circuits

(Nature Communications) Field-effect transistors based on carbon nanotubes have been shown to be faster and less energy consuming than their silicon counterparts. However, ensuring these advantages are maintained for integrated circuits is a challenge. Here we demonstrate that a significant reduction in the use of field-effect transistors can be achieved by constructing carbon nanotube-based integrated circuits based on a pass-transistor logic configuration, rather than a complementary metal-oxide semiconductor configuration. Logic gates are constructed on individual carbon nanotubes via a doping-free approach and with a single power supply at voltages as low as 0.4 V. The pass-transistor logic configurarion provides a significant simplification of the carbon nanotube-based circuit design, a higher potential circuit speed and a significant reduction in power consumption. In particular, a full adder, which requires a total of 28 field-effect transistors to construct in the usual complementary metal-oxide semiconductor circuit, uses only three pairs of n- and p-field-effect transistors in the pass-transistor logic configuration.

New magnetic phase diagram of (Sr,Ca)₂RuO₄

(Nature Materials) High-T_c cuprates, iron pnictides, organic BEDT and TMTSF, alkali-doped C60, and heavy-fermion systems have superconducting states adjacent to competing states exhibiting static antiferromagnetic or spin density wave order. This feature has promoted pictures for their superconducting pairing mediated by spin fluctuations. Sr₂RuO₄ is another unconventional superconductor which almost certainly has a p-wave pairing. The absence of known signatures of static magnetism in the Sr-rich side of the (Ca, Sr) substitution space, however, has led to a prevailing view that the superconducting state in Sr₂RuO₄ emerges from a surrounding Fermi-liquid metallic state. Using muon spin relaxation and magnetic susceptibility measurements, we demonstrate here that (Sr,Ca)₂RuO₄ has a ground state with static magnetic order over nearly the entire range of (Ca, Sr) substitution, with spin-glass behaviour in Sr_1.5Ca_0.5RuO₄ and Ca_1.5Sr_0.5RuO₄. The resulting new magnetic phase diagram establishes the proximity of superconductivity in Sr₂RuO₄ to competing static magnetic order.

Space diamonds reveal supernova origins

(Inside Science News Service) Although diamonds are rare on Earth, scientists believe that minuscule “nanodiamonds” abound in space. For years, scientists have found DNA-sized diamonds in meteorites on Earth. New research suggests that these diamonds spring from violent cosmic collisions, which may help scientists unravel mysteries surrounding exploding stars — the birthplaces of ancient materials that predate our solar system. Diamond formation didn’t require blistering temperatures or crushing pressures. Instead, in simulations, diamonds formed when carbon-containing dust grains smashed together at speeds exceeding 10,000 miles per hour.

Apple to build largest end user-owned, onsite solar array in the US, plus largest non-utility fuel cell installation

(Gizmag) Following widespread criticism of its environmental record from groups including Greenpeace, Apple has made efforts to reduce the environmental impact of its products and facilities in recent years. As part of these ongoing efforts, the company has revealed plans to build the United States’ largest end user-owned, onsite solar array at its Maiden, North Carolina iDataCenter. Apple will build a 100-acre, 20-megawatt facility on land surrounding the data center to supply 42 million kWh of renewable energy to the facility annually. the report also reveals the company is building a fuel cell installation that is scheduled to go online later this year. The 5-megawatt facility will be located directly adjacent to the data center and will be 100 percent powered by biogas to provide more than 40 million kWh of round-the-clock baseload renewable energy annually. Upon completion, Apple says it will be the largest non-utility fuel cell installation in the U.S.

Examining nanoporous carbons and silica aerogels

(Oak Ridge National Lab) researcher Yuri Melnichenko and his collaborators continue to use neutrons and small-angle neutron scattering to bore through geological materials such as nanoporous carbons to understand their unique properties as storage media for greenhouse gases and for hydrogen in fuel cells used in transportation. The SANS method also shows promise for strategies for extracting a cleaner form of energy — methane gas — from hard shales. In other recent work on the behavior of CO₂ confined in nanopores, the researchers turned to a silica aerogel model system as a good matrix material. They varied the silica aerogel surface chemistry to see how this influenced the phase behavior of the molecules of stored CO₂.

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