Very rich nitrogen concentration with the dominant C centres and some A centres are found in diamonds grown from a Fe90Ni10-C-high-content NaN3 additive system.The concentrations of C centres rapidly increase with increasing content of NaN3 additive,while the concentrations of A centres increase slowly.The total nitrogen concentration tends to increa.rapidly with increasing content of NaN3 additive when the content of NaNa is below 0.7wt%.However,the total concentration of nitrogen in the diamonds increases slowly when the content of NaN3 is further increased up to 1.0wt%,and the total nitrogen average concentration are calculated to be around 2230ppm for most of the analysed synthetic diamonds.Furthermore,the nitrogen impurities in different crystal sectors of the diamonds are inhomogeneously distributed.The nitrogen impurities in the diamonds in [111] zones are incorporated more easily than that in[100].