Low temperaturein situformation of cobalt in silicon nitride toward functional nitride nanocomposites

Abstract

A proposed reaction scheme for in situ controlled low-temperature formation of metallic-Co at the early stage of pyrolysis of perhydropolysilazane (PHPS) coordinated with CoCI2.

Mechanistic Investigation of the Formation of Nickel Nanocrystallites Embedded in Amorphous Silicon Nitride Nanocomposites

“…This is well illustrated in the recent reports on Si 3 N 4 -based nanocomposites, such as titanium nitride (TiN)/Si 3 N 4 [ 29 , 30 ] and vanadium nitride (VN)/Si 3 N 4 [ 31 ]. However, we recently succeeded in the formation of cobalt (Co)/Si 3 N 4 nanocomposites through the PDCs route, using PHPS as amorphous Si 3 N 4 (labeled a-SiN) precursor coordinated with CoCl 2 as Co source [ 32 ], although it was not possible to isolate samples free of ammonium chloride at low temperature while keeping the Si 3 N 4 matrix amorphous, which is required for catalytic activity [ 27 ]. Moreover, the composites were synthesized in flowing NH 3 , for instance, it was impossible to avoid the formation of ammonium chloride as a bi-product via the metal ammine chloride complex formation, especially at lower temperatures, which affected the in situ formation of nanocomposites.…”

From design to characterization of zirconium nitride/silicon nitride nanocomposites

“…Tetramethylsilane (TMS) was used as a reference for the NMR data. Solid-state 13 C CP MAS, 15 N CP MAS and 29 Si MAS NMR spectra were recorded on a Bruker AVANCE 300 spectrometer (7.0 T, ν0( 1 H) 300.29 MHz, ν0( 13 C) 75.51 MHz, ν0( 15 N) 30.44 MHz, ν0( 29 Si) 59.66 MHz) using a 7 mm Bruker probe spinning at 5 kHz. 13 C and 15 N CP MAS experiments were recorded with ramped-amplitude cross-polarization in the 1 H channel to transfer magnetization from 1 H to 13 C and 15 N. (Recycle delay 3 s, CP contact time 1 ms, optimized 1 H spinal-64 decoupling).…”

“…Solid-state 13 C CP MAS, 15 N CP MAS and 29 Si MAS NMR spectra were recorded on a Bruker AVANCE 300 spectrometer (7.0 T, ν0( 1 H) 300.29 MHz, ν0( 13 C) 75.51 MHz, ν0( 15 N) 30.44 MHz, ν0( 29 Si) 59.66 MHz) using a 7 mm Bruker probe spinning at 5 kHz. 13 C and 15 N CP MAS experiments were recorded with ramped-amplitude cross-polarization in the 1 H channel to transfer magnetization from 1 H to 13 C and 15 N. (Recycle delay 3 s, CP contact time 1 ms, optimized 1 H spinal-64 decoupling). Single pulse 29 Si MAS NMR spectra were recorded with a recycle delay of 60 s. Chemical shift values were referenced to tetramethylsilane for 13 C and 29 Si and CH3NO2 for 15 N. Spectra were fitted with the DMFit program [40].…”

“…13 C and 15 N CP MAS experiments were recorded with ramped-amplitude cross-polarization in the 1 H channel to transfer magnetization from 1 H to 13 C and 15 N. (Recycle delay 3 s, CP contact time 1 ms, optimized 1 H spinal-64 decoupling). Single pulse 29 Si MAS NMR spectra were recorded with a recycle delay of 60 s. Chemical shift values were referenced to tetramethylsilane for 13 C and 29 Si and CH3NO2 for 15 N. Spectra were fitted with the DMFit program [40]. Chemical analyses of the polymers were performed using a combination of several methods at Mikroanalytisches Labor Pascher (Remagen, Germany).…”

“…For instance, SiC/Si3N4 nanocomposite consists of a promising material for many engineering applications, such as turbine engines, high-performance cutting tools, and wear-resistant parts owing to their excellent mechanical properties and high oxidation and corrosion tolerance [10,11]. Another impactful research area is catalysis [12], which includes Transition Metal (TM) or TM Nitrides (TMN)/Si3N4 such as Co/Si3N4 [13], TiN/Si3N4 [14,15] and VN/Si3N4 [16] compounds. In particular, TiN/Si3N4 nanocomposites [15] demonstrated strong synergy between the nanoscaled TiN, the Si3N4 matrix and the Pt nanoparticles, which were homogeneously deposited onto the nanocomposite support in a second synthesis step.…”