Accession Number : AD0825139

Title :   THE CONDENSATION COEFFICIENT OF SI3N4.

Descriptive Note : Technical rept. 1 Feb 66-1 Feb 67,

Corporate Author : CINCINNATI UNIV OH

Personal Author(s) : Hoch, Michael ; Jamison, Warren E.

Report Date : MAY 1967

Pagination or Media Count : 79

Abstract : Samples of silicon nitride containing high concentrations of the N14 and N15 isotopes of nitrogen were prepared by reacting compressed pellets of powdered silicon with nitrogen gas in an induction heated vacuum furnace. The condensation coefficient, beta, of these materials was evaluated by a nitrogen isotope exchange technique in a Knudsen type effusion apparatus attached to a time-of-flight mass spectrometer. The condensation coefficient was determined to decrease linearly with increasing temperature, and was evaluated in the temperature range 1625K to 1710K as beta x 1000 = 20.26 - 9.4 x 0.001T where T is the temperature in degrees K. The vaporization of silicon nitride proceeds by a mechanism which depletes the interior of the solid in nitrogen, leaves a thin coating of 'stoichiometric' silicon nitride on the surface, and decreases the apparent density of the solid. (Author)

Descriptors :   (*SILICON COMPOUNDS, CONDENSATION), (*NITRIDES, CONDENSATION), SILICON, VAPOR PLATING, ISOTOPES, EXCHANGE REACTIONS, MASS SPECTROSCOPY, VAPORIZATION, THERMOCHEMISTRY.

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE