Copyright Warning & Restrictions
The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted material.
Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be “used for any purpose other than private study, scholarship, or research.” If a, user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of “fair use” that user may be liable for copyright infringement,
This institution reserves the right to refuse to accept a copying order if, in its judgment, fulfillment of the order would involve violation of copyright law.
Please Note: The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation
Printing note: If you do not wish to print this page, then select “Pages from: first page # to: last page #” on the print dialog screen
The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty.
ABSTRACT
POLYMERIC NITROGEN BY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION
by El Mostafa Benchafia
With the urgent need for new environmentally-friendly energetic materials, the field of polymeric nitrogen, predicted to be a high energy density energetic, is now at a critical stage in its development. In spite of extensive first principles calculations regarding the existence and stability of different polymeric nitrogen structures, their successful syntheses have been rare. This dissertation describes the first detailed study of a plasma-enhanced chemical vapor deposition (PECVD) approach to the synthesis of polymeric nitrogen. PECVD provides non-equilibrium conditions known to produce high pressure-temperature phases. Molecular nitrogen mixed with hydrogen and argon is used as the gas phase precursor to provide nitrogen and passivating hydrogen species. In addition, either solid sodium and lithium azide or azide solution infiltrated sheets of carbon nanotube substrates have been used to initiate plasma polymerization to a polymeric nitrogen phase. Characterization of the samples produced were conducted using micro-Raman spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, powder X-ray diffraction, and temperature programmed desorption. Sample morphologies and compositions have also been performed using scanning electron microscopy combined with energy- dispersive X-ray analysis. The results show that a mixture of polymeric nitrogen phases is formed that is stable under ambient conditions and decompose near 400◦C.
The long-sought-after cubic-gauche polymeric nitrogen (cg-PN) phase, produced only in a diamond anvil cell at high pressure high temperature conditions and not recoverable under ambient conditions, is shown by the powder diffraction data to be one of the polymeric nitrogen phases synthesized by the plasma process. Density Functional Theory (DFT) calculations were also used to investigate the metastability of cg-PN and that of related nitrogen clusters at ambient conditions in order to understand some of the results. Although these phases were obtained with and without carbon nanotube substrates, the spectroscopic results suggest that carbon nanotubes play a significant role in faster and more efficient plasma synthesis possibly due to stabilization of a PN phase inside the walls of carbon nanotubes. The effect of carbon nanotubes on polymeric nitrogen growth will be investigated by transmission electron microscopy in future studies. POLYMERIC NITROGEN BY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION
by El Mostafa Benchafia
A Dissertation Submitted to the Faculty of New Jersey Institute of Technology and in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Materials Science and Engineering
Interdisciplinary Program in Materials Science and Engineering
January 2015 Copyright c 2015 by El Mostafa Benchafia
ALL RIGHTS RESERVED APPROVAL PAGE
POLYMERIC NITROGEN BY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION
El Mostafa Benchafia
Dr. Nuggehalli M. Ravindra, Dissertation Co-advisor Date Professor, Department of Physics, NJIT
Dr. Zafar Iqbal, Dissertation Co-advisor Date Research Professor, Department of Chemistry and Environmental Science, NJIT
Dr. Xianqin Wang, Committee Member Date Associate Professor, Department of Chemical, Biological and Pharmaceutical Engineering, NJIT
Dr. Frank Owens, Committee Member Date Research Professor, Department of Physics, City University of New York
Dr. Cristiano L. Dias, Committee Member Date Assistant Professor, Department of Physics, NJIT IOG A ICA SKE C
A th r: El Mostafa Benchafia