Name: synthesis and microdiffraction at extreme pressures and temperatures
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Description: Watch this Scientific Journal Video about Synthesis and Microdiffraction at Extreme Pressures and Temperatures at JoVE.com

The University of Nevada, Las Vegas (UNLV) High Pressure Science and Engineering Center is supported by Department of Energy-National Nuclear Security Administration (NNSA) Cooperative Agreement DE-NA0001982. This work was performed at the High Pressure Collaborative Access Team (HPCAT) (Sector 16), and at the GeoSoilEnviroCARS (GSECARS) (Sector 13), Advanced Photon Source (APS), Argonne National Laboratory (ANL). HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. GeoSoilEnviroCARS is supported by the National Science Foundation&#8212;Earth Sciences (EAR-0622171) and Department of Energy (DOE)&#8211;Geosciences (DE-FG02-94ER14466). APS is supported by DOE-BES, under Contract DE-AC02-06CH11357. We thank GSECARS and COMPRES for the use of the Gas Loading System.

1. Diamond Anvil Cell and Gasket Preparation
<ol>
	<li>Select a pair of diamond anvils with conical design12 and matching culet size. The conical anvil design is chosen for the wide angular x-ray windows it provides, allowing to collect relatively high resolution x-ray microdiffraction data. The culet (flat or beveled tip of a diamond anvil) is selected according to the maximum target pressure. The diameter of the flat part of the culet ranges from about 1-0.07 mm for target pressures from 10 to more than 20...

<ol>
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Res. 28, 225-235 (2008).</li><li>Boehler, R., De Hantsetters, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+anvil+designs+in+diamond-cells.">New anvil designs in diamond-cells.</a> High Press. Res. 24, 391-396 (2004).</li><li>Lorenzana, H. E., Bennahmias, M., Radousky, H., Kruger, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Producing+diamond+anvil+cell+gaskets+for+ultrahigh-pressure+applications+using+an+inexpensive+electric+discharge+machine.">Producing diamond anvil cell gaskets for ultrahigh-pressure applications using an inexpensive electric discharge machine.</a> Rev. Sci. Instrum. 65, 3540-3543 (1994).</li><li>Barnett, J., Block, S., Piermarini, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+fluorescence+system+for+quantitative+pressure+measurement+in+diamond-anvil+cell.">Optical fluorescence system for quantitative pressure measurement in diamond-anvil cell.</a> Rev. Sci. Instrum. 44, 1-9 (1973).</li><li>Piermarini, G., Block, S., Barnett, J., Forman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calibration+of+pressure-dependence+of+R1+ruby+fluorescence+line+to+195+kbar.">Calibration of pressure-dependence of R1 ruby fluorescence line to 195 kbar.</a> J. Appl. Phys. 46, 2774-2780 (1975).</li><li>Mao, H., Bell, P., Shaener, J., Steinberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+volume+measurements+of+Cu,+Mo,+Pd,+and+Ag+and+calibration+of+ruby+R1+fluorescence+pressure+gauge+from+0.06+to+1+Mbar.">Specific volume measurements of Cu, Mo, Pd, and Ag and calibration of ruby R1 fluorescence pressure gauge from 0.06 to 1 Mbar.</a> J. Appl. Phys. 49, 3276-3283 (1978).</li><li>Dorfman, S. M., Prakapenka, V. B., Meng, Y., Duffy, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=+Intercomparison+of+pressure+standards+(Au,+Pt,+Mo,+MgO,+NaCl+and+Ne)+to+2.5+Mbar."> Intercomparison of pressure standards (Au, Pt, Mo, MgO, NaCl and Ne) to 2.5 Mbar.</a> J. Geophys. Res. 117, (2012).</li><li>Rivers, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+COMPRES/GSECARS+gas-loading+system+for+diamond+anvil+cells+at+the+advanced+photon+source.">The COMPRES/GSECARS gas-loading system for diamond anvil cells at the advanced photon source.</a> High Press. Res. 28, 273-292 (2008).</li><li>Jeanloz, R. W., Heinz, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experiments+at+high-temperature+and+pressure+-+laser-heating+through+the+diamond+cell.">Experiments at high-temperature and pressure - laser-heating through the diamond cell.</a> J. Phys. 45, 83-92 (1984).</li><li>Shen, G., Mao, H. K., Hemley, R. J., Duffy, T. S., Rivers, M. 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Every step of the described protocol must be performed with great care to avoid risks of experimental failure via catastrophic shatter of the anvils, gasket instability and loss of pressure, inability to achieve target temperature, sample contaminations, severe non-hydrostaticity, etc.
The greatest challenge of high P-T synthesis is the interpretation of x-ray diffraction data, a problem too extensive to be summarized here. While structural solution is inherently a non-trivial problem...

Pressure can fundamentally change the properties and bonding of matter. The Earth&#39;s topography, composition, dynamics, magnetism and even the atmosphere composition are profoundly tied to processes occurring at the interior of the planet which is under extremely high pressure and temperature. Deep Earth processes include earthquakes, volcanism, thermal and chemical convection, and differentiation. High pressure and temperature are used to synthesize super-hard materials like diamond and cubic boron nitride. High PT synthesis combined with in situ x-ray diffraction allows researchers to identify the crystal structures of the new materials or high-pressure polymorphs of extreme technological importance. The knowledge of high-pressure structures and properties allows interpretation of the structure and processes of planetary interiors, modeling of the performance of materials under extreme conditions, synthesis and design of new materials, and achievement of a broader fundamental understanding of materials&#39; behavior. The exploration of high pressure phases is technically demanding due to the twofold challenges of controllably generating extreme environmental conditions and probing small samples within bulky environmental cells.
A range of materials and techniques may be used to perform synthesis at extreme conditions2, 3. The most suitable equipment for each particular experiment depends on the material investigated, the target PT, and the probing techniques. Among high pressure devices, the LH-DAC has smallest sample size, but is however capable of reaching the highest static PT (above 5 Mbar and 6,000 K) and allows the highest resolution x-ray structural analysis. The protocol described below led to the discovery of Fe4O5 1 and is applicable to a wide range of materials and synthesis conditions. The LH-DAC is best suited for materials efficiently absorbing the laser wavelength of ~1 &#181;m available at high pressure synchrotron beamlines (e.g. 16-IDB and 13-IDD stations at the Advanced Photon Source, Argonne National Lab), for synthesis pressures up to 5 Mbar and for temperatures greater than about 1,500 K. Fairly complex structures and multiphase samples can be characterized with the x-ray microdiffraction strategies presented here. Other techniques, such as whole DAC heating4 and local resistive heating, are suitable for lower synthesis temperatures. CO2 5 laser heating, with wavelength of about 10 &#181;m, is suitable for the heating of materials transparent to the infrared YLF laser but absorbing the CO2 radiation. Other devices, such as multi-anvil, piston-cylinder and Paris-Edinburgh presses, provide larger volume samples necessary for neutron diffraction experiments, for instance.
In the LH-DAC, invented in 19676, 7, 8, high pressure is generated on a small sample placed between the tips of two opposed diamond anvils. In the laser heating systems installed at synchrotron experimental stations9, 10, 11, laser beams are delivered on a sample from both sides through the diamond anvils while a brilliant x-ray beam is focused on the heated spot. Samples absorbing the laser light are heated while x-ray diffraction is used to monitor the progress of the synthesis. The thermal radiation emitted by the laser heated sample is temperature dependent. Thermal emission spectra collected from both sides of the sample are used to calculate the sample temperature by fitting the spectra to the Plank radiation function assuming black body behavior8.
The crystal structure analysis of products of synthesis in a LH-DAC is carried out using the brilliant synchrotron x-ray beam, high precision motorized stages and the fast x-ray detectors available at dedicated synchrotron experimental stations. We collect x-ray diffraction data in a 2D grid and customize the data collection strategy according to the grain size. This approach allows to: i) map the sample composition; ii) obtain robust data analysis of a complex multiphase sample by combining single crystal, powder and multi-grain diffraction techniques.

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			<td height="21" style="height:21px;width:195px;">diamond anvils</td>
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			<td height="105" style="height:105px;width:195px;">WC seats</td>
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			<td style="width:119px;">The conical housing needs to match the conical shape of the anvil bottom</td>
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			<td height="21" style="height:21px;width:195px;">SX-165 CCD</td>
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			<td height="21" style="height:21px;width:195px;">XRD 1621 xN ES</td>
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			<td height="21" style="height:21px;width:195px;">W needle</td>
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synthesis and microdiffraction at extreme pressures and temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

We show representative microdiffraction data obtained from the high pressure and temperature synthesis of Fe4O5 from a mixture of hematite and iron according to the reaction:
<img src="/files/ftp_upload/50613/50613eq1.jpg" alt="Equation 1" width="450px" fo:content-width="4in" />
Figure 5 illustrates powder diffraction patterns from B locations. Although they were collected a few microns apart, the patterns are remarkably differ...

Watch this Scientific Journal Video about Synthesis and Microdiffraction at Extreme Pressures and Temperatures at JoVE.com

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

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Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing

This paper discusses fluorescent core microcavity-based sensors that can operate in a microfluidic analysis setup. These structures are based on the formation of a fluorescent quantum-dot (QD) coating on the channel surface of a conventional microcapillary. Silicon QDs are especially attractive for this application, owing in part to their negligible toxicity compared to the II-VI and II-VI compound QDs, which are legislatively controlled substances in many countries. While the ensemble emission spectrum is broad and featureless, an Si-QD film on the channel wall of a capillary features a set of sharp, narrow peaks in the fluorescence spectrum, corresponding to the electromagnetic resonances for light trapped within the film. The peak wavelength of these resonances is sensitive to the external medium, thus permitting the device to function as a refractometric sensor in which the QDs never come into physical contact with the analyte. The experimental methods associated with the fabrication of the fluorescent-core microcapillaries are discussed in detail, as well as the analysis methods. Finally, a comparison is made between these structures and the more widely investigated liquid-core optical ring resonators, in terms of microfluidic sensing capabilities.

Fluorescent-core microcavity sensors employ a high-index quantum-dot coating in the channel of silica microcapillaries. Changes in the refractive index of fluids pumped into the capillary channel cause shifts in the microcavity fluorescence spectrum that can be used to analyze the channel medium.

This paper discusses  fluorescent core microcavity-based sensors that can operate in a microfluidic  analysis setup. These structures are based on the ...

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

Colloidal Synthesis of Nanopatch Antennas for Applications in Plasmonics and Nanophotonics

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic nanoscale patch antennas. This includes a detailed procedure for the fabrication of thin films with a well-controlled thickness over macroscopic areas using layer-by-layer deposition of polyelectrolyte polymers, namely poly(allylamine) hydrochloride (PAH) and polystyrene sulfonate (PSS). These polyelectrolyte spacer layers serve as a dielectric gap in between silver nanocubes and a gold film. By controlling the size of the nanocubes or the gap thickness, the plasmon resonance can be tuned from about 500 nm to 700 nm. Next, we demonstrate how to incorporate organic sulfo-cyanine5 carboxylic acid (Cy5) dye molecules into the dielectric polymer gap region of the nanopatch antennas. Finally, we show greatly enhanced fluorescence of the Cy5 dyes by spectrally matching the plasmon resonance with the excitation energy and the Cy5 absorption peak. The method presented here enables the fabrication of plasmonic nanopatch antennas with well-controlled dimensions utilizing colloidal synthesis and a layer-by-layer dip-coating process with the potential for low cost and large-scale production. These nanopatch antennas hold great promise for practical applications, for example in sensing, ultrafast optoelectronic devices and for high-efficiency photodetectors.

A protocol for the colloidal synthesis of silver nanocubes and fabrication of plasmonic nanoscale patch antennas with sub-10 nm gaps is presented.

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic ...

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (&#916;T &#60; 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature.

A simple liquid nitrogen Dewar/cryostat apparatus comprised of a small fused silica optical Dewar, a thermocouple, and a charge-coupled device (CCD) spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, freezing, and alignment, accurate and stable sample temperatures, and small size/portability.

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and ...

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion batteries for use in devices operating at elevated temperatures require thermally stable and non-flammable electrolytes. Ionic liquids (ILs), which are non-flammable, non-volatile, thermally stable molten salts, are an ideal replacement for flammable and low boiling point organic solvent electrolytes currently used today. We herein describe the procedures to: 1) synthesize mono- and di-phosphonium ionic liquids paired with chloride or bis(trifluoromethane)sulfonimide (TFSI) anions; 2) measure the thermal properties and stability of these ionic liquids by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); 3) measure the electrochemical properties of the ionic liquids by cyclic voltammetry (CV); 4) prepare electrolytes containing lithium bis(trifluoromethane)sulfonamide; 5) measure the conductivity of the electrolytes as a function of temperature; 6) assemble a coin cell battery with two of the electrolytes along with a Li metal anode and LiCoO2 cathode; and 7) evaluate battery performance at 100 &#176;C. We additionally describe the challenges in execution as well as the insights gained from performing these experiments.

Here, we describe protocols to prepare phosphonium-based ionic liquid and lithium bis(trifluoromethane)sulfonimide salt electrolytes, and assemble a non-flammable and high temperature functioning lithium-ion coin cell battery.

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion ...

Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures

We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid cooling, to prepare the desired cryogenic temperature phase. Microliter to picoliter size drops are cooled by projection into a liquid nitrogen-argon (N2-Ar) mixture. The cryogenic temperature phase of the drop is evaluated using a visual assay that correlates with X-ray diffraction measurements. The density of the liquid N2-Ar mixture is adjusted by adding N2 or Ar until the drop becomes neutrally buoyant. The density of this mixture and thus of the drop is determined using a test mass and Archimedes principle. With appropriate care in drop preparation, management of gas above the liquid cryogen mixture to minimize icing, and regular mixing of the cryogenic mixture to prevent density stratification and phase separation, densities accurate to &#60;0.5% of drops as small as 50 pL can readily be determined. Measurements on aqueous cryoprotectant mixtures provide insight into cryoprotectant action, and provide quantitative data to facilitate thermal contraction matching in biological cryopreservation.

A protocol for determining the vitreous phase densities of micro- to pico-liter size drops of aqueous mixtures at cryogenic temperatures is described.

We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid ...

Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory

Given their potential for significant property improvements relative to their large grained counterparts, much work has been devoted to the continued development of nanocrystalline metals. Despite these efforts, the transition of these materials from the lab bench to actual applications has been blocked by the inability to produce large scale parts that retain the desired nanocrystalline microstructures. Following the development of a method proven to stabilize the nanosized grain structure to temperatures approaching that of the melting point for the given metal, the US Army Research Laboratory (ARL) has progressed to the next stage in the development of these materials - namely the production of large scale parts suitable for testing and evaluation in a range of relevant test environments. This report provides a broad overview of the ongoing efforts in the processing, characterization, and consolidation of these materials at ARL. In particular, focus is placed on the methodology used for producing the nanocrystalline metal powders, in both small and large-scale amounts, that are at the center of ongoing research efforts.

This paper provides a brief overview of the ongoing efforts at the Army Research Laboratory on the processing of bulk nanocrystalline metals with an emphasis on the methodologies used for the production of the novel metal powders.

Given their potential for significant property improvements relative to their large grained counterparts, much work has been devoted to the continued ...