Method for controlling the crystal morphology of silicon nitride

A method for producing silicon nitride wherein the crystal morphology of said silicon nitride is controlled, said method comprising:

• (a) heating a mixture consisting essentially of a chlorosilane and ammonia at a temperature of at least about 300.degree. C. for a sufficient time to produce silicon chloroimide as an intermediate product;
• (b) commminuting said intermediate product by a comminuting method selected from the group consisting of milling, compacting and combinations thereof, to control the bulk density of said intermediate to greater than about 0.3 g/cc to result in said silicon nitride having a crystal morphology which is essentially all equiaxial, or comminuting said intermediate product by said comminuting methods to control the bulk density of said intermediate to between about 0.1 g/cc and about 0.3 g/cc to result in said silicon nitride having a crystal morphology which is a mixture of fibrous and equiaxial;
• and
• (c) heating the resulting intermediate product having controlled bulk density at a temperature of at least about 700.degree. C. for a sufficient time in a non-oxidizing atmosphere to produce the controlled crystal morphology silicon nitride.