Accession Number:

ADA232135

Title:

Transport and Nucleation Processes in the Vapor Growth of Diamond

Descriptive Note:

Progress rept. 1 Jul 1989-31 Dec 1990

Corporate Author:

CASE WESTERN RESERVE UNIV CLEVELAND OH

Report Date:

1991-01-31

Pagination or Media Count:

34.0

Abstract:

Rule-based computer modelling has been used to study the initial stages of diamond nucleation from the vapor and the relationship of observed crystalline morphology to the nucleation and growth mechanisms. The enhanced growth rates of nuclei with multiple twins has been confirmed and plausible mechanisms for the formation of five- and twenty-fold twinned crystals found. Two-dimensional simulations of a hot-filament reactor are being made. The flow field, temperature field and species concentrations for reactors of arbitrary geometry are obtained. At present the chemical reaction is restricted to ten simultaneous reactions. The program is being further modified to handle more complex chemistry. Experimental work on the seeding of diamond nucleation with specific compounds has proceeded in parallel with the modelling studies. This work was done in cooperation with Dr. Micheal Geis of the MIT Lincoln Laboratories. The compound 3, 4, 9, 10-perylene tetracarboxylic acid dianhydride was found to be a strong nucleation promoter, while adamantane and its derivatives were not.

Subject Categories:

  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE