Effects of manufacturing process on surface states of commercial silicon nitride powders

Temperature Programmed Desorption (TPD) technique, in the range 40-1300 degrees C, is applied for the qualitative and quantitative analysis of the surface functional groups present on seven kinds of commercial Si(3)N(4) which were synthesized by different production processes with different nitridation media and final treatments. The desorbed species detected for all the powders were the same: H(2), H(2)O, NH(3), and N(2). The spectra of each powder are qualitative and quantitatively unique. Certain similarities observed may be associated with the use of the same nitridation media. The use of ammonia enhances the development of SiNH(2) surface groups for powders synthesized by the diimide precipitation and carbothermal reduction of silica methods. In the case of powders produced using direct nitridation of silicon the same effect is obtained by the application of an acid and water washing final treatment. The use of NH(3) gas or mixture of N(2) with H(2) as nitridation media enhances the development of H terminated functional groups. The same effect is observed when CH(4) is used instead of C in the carbothermal reduction of silica.