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Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range--of over five orders of magnitude--from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.

Thermal properties of graphene and nanostructured carbon materials

Li-ion battery materials: present and future

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Recent years witnessed a rapid growth of interest of scientific and engineering communities to thermal properties of materials. Carbon allotropes and derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range – of over five orders of magnitude – from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. I review thermal and thermoelectric properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. A special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe prospects of applications of graphene and carbon materials for thermal management of electronics.

Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials

Structural Color: Encoding Localized Strain History Through Wrinkle Based Structural Colors (Adv. Mater. 39/2010)

Due to its exceptional mechanical and tribological properties, nanocrystalline diamond (NCD) has the potential to be used for tool coatings that can enable dry machining of Al alloys. This study explores the friction response of NCD coatings in sliding contact with 319 Al. NCD coatings were grown using microwave plasma CVD with a range of growth conditions to explore key growth modulators governing the tribological response of this material. These coatings were then characterized with Raman spectroscopic analysis at three different wavelengths. Pin-on-disc friction response of these coatings with 319 Al showed that the trans-polyacetylene content as determined by the respective Raman spectrum in NCD is the critical factor controlling friction behavior. This finding can have significant implications in other similar applications where friction response of NCD is a key design factor.

The impact of nanocrystalline diamond grain boundary chemistry on frictional response in sliding contact with 319Al alloy

We propose a non-paraxial diffraction model of the digital micromirror device (DMD) by combining the conventional Fraunhofer diffraction and a simple method of coordinative mapping. It is equivalent to adding aberrations of diffracted wave fields to the aberration-free Fraunhofer diffraction instead of complex integral calculations, allowing the simulated diffraction patterns to be consistent with the actual experimental counterparts. Moreover, it is verified by the experiments and literature that the diffraction angles, orders, and efficiency can all be well predicted for arbitrary incident angles and wavelengths. Especially for diffracted zenith angles within 50°, the predicted values reveal ∼1% error, and in a broader range, the predicted errors of diffracted azimuth angles are less than 4%. To the best of our knowledge, it is the first model capable of describing the non-paraxial diffraction behavior of the DMD. The proposed model with universality and effectiveness will help users to optimally construct DMD-based optical systems by guiding optical layouts, selection of light sources, and utilization and suppression of diffraction effects.

Non-paraxial diffraction analysis for developing DMD-based optical systems.

In einem Beispiel eines Verfahrens zur Verhinderung des Alterns von Platingruppenmetall-(PGM)-Partikeln in einem Katalysator werden PGM-Partikel auf einen Trager aufgebracht. Eine Oberflache der PGM-Partikel wird passiviert, indem die PGM-Partikel bei einer Temperatur gleich oder kleiner als 200 °C mit Kohlenmonoxid beaufschlagt werden, um -CO Gruppen in die Oberflache einzufuhren. Es wird eine Atomlagenabscheidung (ALD) durchgefuhrt, um selektiv eine Barriere rund um die PGM-Partikel auf dem Trager aufzubauen.

Unterdrücken der alterung von metallpartikeln der platingruppe in einem katalysator

To study the small strain shear modulus (Gmax) of saturated sand-silt mixed soil materials, a series of tests were conducted using the bender element apparatus, and the influences of fines content (FC), relative density (Dr), and effective confining pressure (σ′3c) were taken into consideration. The test results indicate that the Gmax of the mixed soil materials decreases first and then increases with the FC up to 100% with Dr = 35% and 50%, while the Gmax decreases with the increasing FC when Dr = 60%. Moreover, for a given Dr, the Gmax increases with the increasing σ′3c, and the increase rate keeps constant under various FCs. The Gmax of specimens under various FCs decreases with the increase of the void ratio (e). The decrease rate between the Gmax and e differs when the σ′3c is given, which is influenced by the FC. The Gmax of the mixed soil materials can be evaluated by the Hardin model when the FC is determined. The best-fitting parameter A of the Hardin model first decreases and then increases as FC increases. The revised Hardin model, considering the influence of FC, σ′3c, and e, can be used to evaluate the Gmax for different types of sand-silt mixed soil materials. The error between the evaluated and tested Gmax is less than 10%.

/pdf/experimental-study-on-the-gmax-characteristics-of-the-sand-5hq1bfob.pdf

Xingcheng Xiao

Papers

Structural Color: Encoding Localized Strain History Through Wrinkle Based Structural Colors (Adv. Mater. 39/2010)

The impact of nanocrystalline diamond grain boundary chemistry on frictional response in sliding contact with 319Al alloy

Non-paraxial diffraction analysis for developing DMD-based optical systems.

Unterdrücken der alterung von metallpartikeln der platingruppe in einem katalysator

Experimental Study on the Gmax Characteristics of the Sand-Silt Mixed Soil Materials Using Bender Element Testing