The invention discloses a method for preparing a
silicon nitride nano-material by using
solid phase reaction at a low temperature. The method comprises the following steps:
silicon powder, powdery thiosemicar bazide,
sodium azide and
iodine are evenly mixed according to the
mole ratio of 0.386 to 0.926:0.476 to 0.953:1:0.171 to 0.256 and sealed in a high-pressure
autoclave, and react for 12 plus or minus 0.5 hours at the temperature of 60 plus or minus 5 DEG C; or the
silicon powder, the powdery thiosemicar bazide, the
sodium azide and alluminium
powder are evenly mixed according to the
mole ratio of 0.386 to 0.926:0.716 to 1.193:1:0.804 and sealed in the high-pressure
autoclave, and react for 10 plus or minus 0.5 hours at the temperature of 170 plus or minus 5 DEG C; or the silicon powder, the powdery thiosemicar bazide and the
sodium azide are evenly mixed according to the
mole ratio of 0.386 to 0.926:0.716 to 1.193:1 and sealed in the high-
pressure reactor, and react for 10 plus or minus 0.5 hours at the temperature of 170 plus or minus 5 DEG C; the pH of the product is neutral though water cleaning and
water washing;
centrifugal separation and
drying are performed; then acid is added for scrubbing, monatomic silicon is removed; and the
silicon nitride nano-materials are obtained. The method has the advantages that the
reaction temperature is lower; the appearance of the obtained product is good; the diameters of the nano-rods are even; and the method is suitable for large-scale industrial production.