Mechanistic studies of the conversion of borazine polymers to boron nitride
- Sandia National Laboratories, Albuquerque, NM (USA)
- Univ of New Mexico, Albuquerque (USA)
The thermal chemistry of thin films of a borazinylamine polymer deposited on KOH-etched aluminum and sapphire has been examined by thermal decomposition mass spectroscopy, thermogravimetric analysis, and Raman spectroscopy. The majority of the gas evolution chemistry is found to occur below 400{degree}C. All products desorb with the same temperature profile, and the major desorbing species are NH{sub 3} and N{sub 2} (polymer decomposition products) and HCl (side reaction products). The hydrogen remaining in the solid at 400{degree}C ({approx}50%) is continuously lost from 400 to 1,200{degree}C. Facile ring-opening steps are evidenced by the complete isotope mixing that occurs for samples in which the ring nitrogens are labeled with {sup 15}N. With increasing pyrolysis temperature, the Raman spectra change from that characteristic of the polymer (25{degree}C) to an intense featureless fluorescence spectrum (up to 400{degree}C) to an intense three-peak resonance Raman spectrum ({approx}400 to 1,200{degree}C), and finally to a less intense Raman spectrum characteristic of h-BN superimposed on a fluorescence background at 1,600{degree}C. The implications of these observations to the pyrolysis mechanism are discussed.
- OSTI ID:
- 5492322
- Journal Information:
- Chemistry of Materials; (USA), Journal Name: Chemistry of Materials; (USA) Vol. 3:2; ISSN CMATE; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
BORON COMPOUNDS
BORON NITRIDES
CHEMICAL ANALYSIS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
DECOMPOSITION
FILMS
GRAVIMETRIC ANALYSIS
LASER SPECTROSCOPY
MASS SPECTROSCOPY
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
PYROLYSIS
QUANTITATIVE CHEMICAL ANALYSIS
RAMAN SPECTROSCOPY
SPECTROSCOPY
SYNTHESIS
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES
THIN FILMS