Thermal conductivities ⌳ of amorphous carbon thin films are measured in the temperatures range 80-400 K using the 3 method. Sample films range from soft a-C:H prepared by remote-plasma deposition (⌳ϭ0.20 W m Ϫ1 K Ϫ1 at room temperature͒ to amorphous diamond with a large fraction of sp 3 bonded carbon deposited from a filtered-arc source (⌳ϭ2.2 W m Ϫ1 K Ϫ1 ). Effective-medium theory provides a phenomenological description of the variation of conductivity with mass density. The thermal conductivities are in good agreement with the minimum thermal conductivity calculated from the measured atomic density and longitudinal speed of sound.

We demonstrate the formation of ferromagnetic Ga 1-x Mn x As films by Mn ion

Failures that occur in titanium-ceramic restorations are of concern to clinicians. The formation of poorly adhering oxide on titanium at dental porcelain sintering temperatures causes adherence problems between titanium and porcelain, which is the main limiting factor in the fabrication of titanium-ceramic restorations. To overcome this problem a 1-microm thick Si3N4 coating was applied to a titanium surface using a plasma-immersion implantation and deposition method. Such a coating serves as an oxygen diffusion barrier on titanium during the porcelain firings. The protective coating was characterized in the as-deposited condition and after thermal cycling. Cross sections of Ti/Si3N4-porcelain interface regions were examined by various electron microscopy methods and by energy dispersive analysis of X-rays to study the Si3N4 film's effectiveness in preventing titanium oxidation and in forming a bond with porcelain. The experiments have shown that this Si3N4 coating enables significant improvement in Ti-ceramic bonding.

We have developed several different embodiments of repetitively pulsed vacuum arc metal plasma gun, including miniature versions, multicathode versions that can produce up to 18 different metal plasma species between which one can switch, and a compact high-duty cycle well-cooled version, as well as a larger dc gun. Plasma guns of this kind can be incorporated into a vacuum arc ion source for the production of high-energy metal ion beams, or used as a plasma source for thin film formation and for metal plasma immersion ion implantation and deposition. The source can also be viewed as a low-energy metal ion source with ion drift velocity in the range 20–200 eV depending on the metal species used. Here we describe the plasma sources that we have developed, the properties of the plasma generated, and summarize their performance and limitations.

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Even the most basic properties of liquid carbon have long been debated due to the challenge of studying the material at the required high temperature and pressure. Liquid carbon is volatile and thus inherently transient in an unconstrained environment. In this paper we use a new technique of picosecond time-resolved x-ray absorption spectroscopy to study the bonding of liquid carbon at densities near that of the solid. As the density of the liquid increases, we see a change from predominantly sp-bonded atomic sites to a mixture of sp, sp2, and sp3 sites and compare these observations with molecular dynamics simulations.

Abstract:The use of energetic particles (ions and atoms) has become increasingly important in physical vapor deposition techniques. These deposition processes can be divide in two main classes: Ion beam assisted deposition and energetic condensation (or deposition).This article focusses on the latter, i.e. processes in which the actual depositing species have energies that far exceed ordinary thermal energies, namely energies greater than 20 eV. The phenomenology of the effect of these high energy particles on the growth of thin films is first presented in general and then specific examples of film deposition are presented. The examples drawn here are of films that have been prepared by Metal Plasma Immersion Implantation and Deposition. The observed microstructures and functional properties of these films are discussed in terms of processing conditions.

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