Abstract
A novel polyethoxysilsesquiazane ([EtOSi(NH)1.5]n, EtOSZ) was synthesized by ammonolysis at −78 °C of ethoxytrichlorosilane (EtOSiCl3), which was isolated by distillation as a reaction product of SiCl4 and EtOH. Attenuated total reflection-infra red (ATR-IR), 13C-, and 29Si-nuclear magnetic resonance (NMR) spectroscopic analyses of the ammonolysis product resulted in the detection of Si–NH–Si linkage and EtO group. The simultaneous thermogravimetric and mass spectrometry analyses of the EtOSZ under helium revealed cleavage of oxygen-carbon bond of the EtO group to evolve ethylene as a main gaseous species formed in-situ, which lead to the formation at 800 °C of quaternary amorphous Si–C–N with an extremely low carbon content (1.1 wt %) when compared to the theoretical EtOSZ (25.1 wt %). Subsequent heat treatment up to 1400 °C in N2 lead to the formation of X-ray amorphous ternary Si–O–N. Further heating to 1600 °C in N2 promoted crystallization and phase partitioning to afford Si2N2O nanocrystallites identified by the XRD and TEM analyses. The thermal stability up to 1400 °C of the amorphous state achieved for the ternary Si-O-N was further studied by chemical composition analysis, as well as X-ray photoelectron spectroscopy (XPS) and 29Si-NMR spectroscopic analyses, and the results were discussed aiming to develop a novel polymeric precursor for ternary amorphous Si–O–N ceramics with an enhanced thermal stability.
Highlights
Silicon oxynitride (Si2 N2 O) is a unique crystalline compound in the silica (SiO2 )-silicon nitride (Si3 N4 ) binary system, and Si2 N2 O ceramics exhibit attractive properties for its structural application, such as low theoretical density with high hardness and low thermal expansion coefficient [1], low thermal conductivity [2], excellent oxidation resistance up to 1600 ◦ C, and high temperature strength without degradation up to 1400 ◦ C [3]
Nonstoichiometric silicon oxynitride (SiOx Ny ) films can be fabricated by plasma enhanced chemical vapour deposition (PECVD) [12,13,14,15,16,17,18,19]
These results indicate that the EtOSZ that was investigated in this study could be converted to a. These results indicate that the EtOSZ that was investigated in this study could be converted to unique oxygen rich amorphous silicon oxynitride (Si–O–N) by pyrolysis at 800 °C, followed by heat a unique oxygen rich amorphous silicon oxynitride (Si–O–N) by pyrolysis at 800 ◦ C, followed by heat treatment at 1400 °C in N2
Summary
Silicon oxynitride (Si2 N2 O) is a unique crystalline compound in the silica (SiO2 )-silicon nitride (Si3 N4 ) binary system, and Si2 N2 O ceramics exhibit attractive properties for its structural application, such as low theoretical density with high hardness and low thermal expansion coefficient [1], low thermal conductivity [2], excellent oxidation resistance up to 1600 ◦ C, and high temperature strength without degradation up to 1400 ◦ C [3]. Polymerization and cross-linking provide a means to vary the specific properties of the pre-ceramic compounds, such as solubility, fusibility, or viscosity, extensively providing the versatility in processing and shaping capabilities, including thin film and long fiber syntheses that are similar to that successfully achieved with polymer materials. In this route, copolymers of the methylcyclosiloxanes and methylcyclolosilazanes [22], poly(Si-isocyanato-Si-methylpolysilazane) [23], and polysilyloxycarbodiimide [24] were synthesized and successfully converted to both amorphous. The crystallization and phase partitioning behavior of the polymer-derived amorphous SiOx Ny was discussed from a viewpoint to develop a novel polymeric precursor for ternary amorphous Si-O-N ceramics with an enhanced thermally stability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
