Solid-state NMR examination of the formation of β-sialon by carbothermal reduction and nitridation of halloysite clay

Elucidation of the Formation Mechanism of β‐SiAlON from a Zeolite

“…The compositions of the powders obtained were measured by a carbon/nitrogen analyzer using an infrared absorbance technique (EGMA-650, HORIBA, Kyoto, Japan), making corrections to the calibration curve with standard samples. The 27 Al MAS NMR spectra were obtained at 11.7 T using a Bruker AMX 500 (Rheinstetten, Germany) and a Varian Unity 500 spectrometer (Palo Alto, CA) at a frequency of 130.3 MHz. A Doty high-speed MAS probe was used, at spinning speeds of up to 12.2 kHz and a 151 pulse of 1 ms with a recycle time of 1 s. The 29 Si spectra were obtained on the Unity 500 spectrometer at spinning speeds of about 8 kHz, with a 901 pulse and 300 s recycle time to accommodate the long relaxation times encountered in some of the SiAlON and carbide phases.…”

“…A Doty high-speed MAS probe was used, at spinning speeds of up to 12.2 kHz and a 151 pulse of 1 ms with a recycle time of 1 s. The 29 Si spectra were obtained on the Unity 500 spectrometer at spinning speeds of about 8 kHz, with a 901 pulse and 300 s recycle time to accommodate the long relaxation times encountered in some of the SiAlON and carbide phases. The 27 Al chemical shifts were measured with reference to AlCl 3 in a 1M aqueous solution, and the 29 Si shifts were referenced to tetramethylsilane (TMS).…”

“…21 The 29 Si and 27 Al NMR spectra have also been reported for a number of phases encountered in the reduction nitridation reaction sequence, [22][23][24][25][26] and a brief study has indicated the potential of MAS NMR in monitoring the progress of SiAlON formation in halloysite 27 and kaolinite, 28 and for shedding light on the intermediates formed during the formation of b-SiAlON from organosilicon polymers. 29 Therefore, in this study, b-SiAlON was synthesized from Y-type zeolite and its formation mechanism was determined using 27 Si and 27 Al NMR spectroscopy and powder XRD.…”

“…13,14 Other reports have also shown that b-SiAlON powder can be synthesized from kaolinite (Al 2 Si 2 O 5 (OH) 4 ), 15 20 X-ray diffraction (XRD) continues to be the primary technique for characterizing these reaction sequences, but 29 Si and 27 Al solid-state nuclear magnetic resonance (NMR) with magicangle spinning (MAS NMR) has provided useful complementary information about related thermal reactions in clay minerals. 21 The 29 Si and 27 Al NMR spectra have also been reported for a number of phases encountered in the reduction nitridation reaction sequence, [22][23][24][25][26] and a brief study has indicated the potential of MAS NMR in monitoring the progress of SiAlON formation in halloysite 27 and kaolinite, 28 and for shedding light on the intermediates formed during the formation of b-SiAlON from organosilicon polymers. 29 Therefore, in this study, b-SiAlON was synthesized from Y-type zeolite and its formation mechanism was determined using 27 Si and 27 Al NMR spectroscopy and powder XRD.…”

NMR study on the formation mechanism of β-SiAlON from zeolite by nitridation using ammonia gas

“…nitridation behavior and changes in the local atomic arrangement, is not yet well understood. 29 Si and 27 Al solid-state nuclear magnetic resonance with magic angle spinning (MAS NMR) has provided useful complementary information on nitridation reactions, 13),18), 19) and a brief study has indicated the potential of MAS NMR in monitoring the progress of SiAlON formation in halloysite 20) and kaolinite, 21) and for shedding light on the intermediates formed during the formation of β-SiAlON from organosilicon polymers. 22) Therefore, in this study, β-SiAlON was synthesized from a zeolite by NH3 gas nitridation and its formation mechanism was investigated using 29 Si and 27 Al NMR spectroscopy.…”