Method for synthesizing silicon nitride nano ring by CVD (chemical vapor deposition) method

[0046] Example 1

[0047] Weigh 0.28 g of commercially available 200-mesh silicon powder and 0.6 g of commercially available amorphous silica powder at a molar ratio of 1:1, mix them evenly, and place them in a corundum boat; The boat is placed in the central area of ​​the horizontal tube resistance furnace, and both ends of the horizontal tube resistance furnace are sealed and evacuated to remove the oxygen in the reaction chamber as much as possible; then nitrogen and nitrogen are introduced into the horizontal tube resistance furnace. Ammonia is used as the nitriding reaction gas, the gas flow volume ratio of high-purity nitrogen and ammonia is 3:1, and the atmosphere flow is 120sccm; after the gas flow is stable, the horizontal tube resistance furnace is heated to make it run at a temperature of 5°C/min. The heating rate was increased to 1300 °C; the temperature was kept at 1300 °C for 2 hours, then the heating furnace was turned off, the heating of the horizontal tube resistance furnace was stopped, and the nitriding reaction gas was continued to be passed into the horizontal tube resistance furnace until the reaction chamber was heated. The temperature was lowered to room temperature by natural cooling; finally, the nitridation reaction gas was stopped, and the reaction chamber was opened, and silicon nitride nanorings could be obtained in the middle and downstream of the corundum boat with a yield of 5%.

[0048] Example 2

[0049] Weigh 0.28 g of silicon powder obtained by wet ball milling and 0.6 g of commercially available amorphous silica powder in a molar ratio of 1:1, mix them evenly and place them in a corundum boat; The corundum boat is placed in the central area of ​​the horizontal tube resistance furnace, and the two ends of the horizontal tube resistance furnace are sealed and evacuated to remove the oxygen in the reaction chamber as much as possible; then pass into the horizontal tube resistance furnace Nitrogen gas and ammonia gas are used as nitriding reaction gases. The gas flow volume ratio of high-purity nitrogen gas and ammonia gas is 1:5, and the atmosphere flow rate is 80sccm. The heating rate of min is raised to 1200 °C; the temperature is kept at 1200 °C for 6 hours, then the heating furnace is turned off, the heating of the horizontal tubular resistance furnace is stopped, and the nitriding reaction gas is continuously fed into the horizontal tubular resistance furnace until the reaction chamber is The temperature inside is reduced to room temperature by natural cooling; finally, the nitridation reaction gas is stopped, the reaction chamber is opened, and silicon nitride nanorings can be obtained in the middle and downstream of the corundum boat.

[0050] Example 3

[0051] Weigh 0.28 g of silicon powder obtained by wet ball milling (200-mesh silicon powder commercially available in the market) and 0.6 g of commercially available amorphous silica powder at a molar ratio of 1:1, mix them evenly, and place them in a In the corundum boat; put the corundum boat with the mixed powder into the central area of ​​the horizontal tubular resistance furnace, seal the two ends of the horizontal tubular resistance furnace and evacuate it to remove the oxygen in the reaction chamber as much as possible; Then, nitrogen and ammonia are passed into the horizontal tube resistance furnace as nitriding reaction gas. The gas flow volume ratio of high-purity nitrogen and ammonia is 3:1, and the atmosphere flow is 120sccm. After the gas flow is stable, the horizontal tube is heated. The furnace was heated to 1300°C at a heating rate of 8°C/min; kept at 1300°C for 2 hours, then the heating furnace was turned off, the heating of the horizontal tube resistance furnace was stopped, and the heating of the horizontal tube resistance furnace was continued. Pass the nitridation reaction gas until the temperature in the reaction chamber is reduced to room temperature by natural cooling; finally stop feeding the nitridation reaction gas, open the reaction chamber, and more silicon nitride nanorings can be obtained in the middle and downstream of the corundum boat , the yield is 45%.

[0052] The samples prepared in this example were tested by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM), and the obtained results were as follows: figure 2 and image 3 shown. pass figure 2 The diffraction peaks in the sample can be identified as the single crystal α-phase Si of the hexagonal structure 3 N 4 , the lattice constants are consistent with the unit cell parameters a=7.766?, c=5.629? on the JCPDS standard card No.72-1253. from image 3 The ring structure of silicon nitride can be clearly seen.