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 ...

Diamond amplifiers demonstrably are an electron source with the potential to support high-brightness, highaverage-current emission into a vacuum. We recently developed a reliable hydrogenation procedure for the diamond amplifier. The systematic study of hydrogenation resulted in the reproducible fabrication of high gain diamond amplifier. Furthermore, we measured the emission probability of dia...

Density functional theory-based electronic structure computations on small models of the diamond {100} surface have enabled prediction of the energetics and activation parameters of a number of plausible mechanistic steps for boron incorporation into, and boron loss from, the growing diamond surface. Initial proving calculations for the carbon-only case show, as in previous work, that the rate-...

Anodically pretreated diamond electrodes have been used for the detection of chlorophenols (CPs) in environmental water samples after high-performance liquid chromatographic (HPLC) separation. The anodization of as-deposited boron-doped polycrystalline diamond thin-film electrodes has enabled the stable determination of phenols over a wide concentration range. Prior to the HPLC analysis, a comp...

We report the discovery of a novel pathway for the transformation from highly oriented pyrolytic graphite foils into amorphous diamond platelets. This pathway consists of three stages of neutron irradiation, shock compression, and rapid quenching. We obtained transparent platelets which show photoluminescence but no diamond Raman peak, similar to the case of amorphous diamond synthesized from C...

Diamond has some of the most extreme physical properties of any material, yet its practical use in science or engineering has been limited due its scarcity and expense. With the recent development of techniques for depositing thin films of diamond on a variety of substrate materials, we now have the ability to exploit these superlative properties in many new and exciting applications. In this p...

A homoepitaxic single-crystal diamond (111) film grown by microwave-assisted chemical vapour deposition (CVD) and fractured along the [110] directions to form small triangles was investigated by X-ray double-crystal topography. The X-ray topographic image showed that all parts of the cleaved CVD diamond film sections uniformly reflected X-rays at the peak position of the rocking curve, which wa...

We have performed ab initio pseudopotential calculations for the diamond (111) surface with nitrogen or boron replacing the surface carbon atoms. Surface boron atoms form planar sp2 bonds with carbon atoms and the compressive stress from the underlying bulk diamond lattice squeezes the B-C bonds significantly. Bulk and shear moduli in the surface region increase substantially, surpassing those ...

We present a comprehensive computational study of sp-carbon allotropes based on the topologies proposed for zeolites. From E600000 zeolite nets we identified six new allotropes, lying by at most 0.12 eV per atom above diamond. The analysis of cages in the allotropes has revealed close structural relations to diamond and lonsdaleite phases. Besides the energetic and mechanical stability of new a...

We investigate the vibrational properties of ultrananocrystalline diamond (UNCD) using molecular dynamics simulations. We compare the vibrational spectra of two UNCD models of average grain size 2 and 4 nm with single crystal diamond and an isolated nanodiamond (ND) particle. The vibrational spectra of the ND particle and UNCD models exhibit the effect of phonon confinement as well as undercoor...