BetaSi3N4coatings were obtained by chemical vapor deposition in a fused‐silica reaction tube by outside heating of the system SiCl4‐NH3‐N2at a deposition temperature (reaction tube temperature) of 1300°C, whereas α‐ and α+β‐phase coatings were obtained at depositon temperatures of 1150° and 1250°C, respecively. Formation of β‐phase coatings at relatively low temperatures is explained in terms of the effect of a catalytic impurity, SiO vapor from the reaction tube. The X‐ray diffraction patterns and sulface morphologies of the c