Because of technique difficulties in achieving the extreme high-pressure and high-temperature (HPHT) simultaneously, direct observation of the structures of carbon at extreme HPHT conditions has not been possible. Banhart and Ajayan discovered remarkably that carbon onions can act as nanoscopic pressure cells to generate high pressures. By heating carbon onions to approximately 700 degrees C an...

Single-crystal diamond, with its unique optical, mechanical and thermal properties, has emerged as a promising material with applications in classical and quantum optics. However, the lack of heteroepitaxial growth and scalable fabrication techniques remains the major limiting factors preventing more wide-spread development and application of diamond photonics. In this work, we overcome this di...

Diamond is a very attractive material for many potential applications due to its outstanding properties. In particular, highly boron-doped conductive diamond films prepared by CVD process have received attention from electrochemists owing to the superior electrochemical properties such as wide potential window, very low background current, chemical and physical stability. In this project, the e...

Single-crystal diamond nanomechanical resonators are being developed for countless applications. A number of these applications require that the resonator be operated in a fluid, that is, a gas or a liquid. Here, we investigate the fluid dynamics of single-crystal diamond nanomechanical resonators in the form of nanocantilevers. First, we measure the pressure-dependent dissipation of diamond na...

Undoped, high-quality diamond is, under almost all circumstances, one of the best insulators known. However, diamond covered with chemically bound hydrogen shows a pronounced conductivity when exposed to air. This conductivity arises from positive-charge carriers (holes) and is confined to a narrow near-surface region. Although several explanations have been proposed, none has received wide acc...

The process monitoring and mechanics of fixed abrasive diamond wire saw machining are investigated in this study. New techniques to affix diamond particles to a steel wire core have advanced to make this process feasible for the machining of ceramics, wood, and foam materials. Developments in fixed abrasive diamond wire machining are first reviewed. Advantages of using fixed abrasive diamond wi...

In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fa...

We consider the class of (C4, diamond)-free graphs; graphs in this class do not contain a C4 or a diamond as an induced subgraph. We provide an efficient recognition algorithm for this class. We count the number of maximal cliques in a (C4, diamond)-free graph and the number of n-vertex, labeled (C4, diamond)-free graphs. We also give an efficient algorithm for finding a largest clique in the m...

Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800 km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies ...