In this paper, large diamond crystals were successfully synthesized under 5.6 GPa at temperature 1513 and 1553 K with melamine (C₃H₆N₆) additive. Fourier transform infrared spectroscopy (FTIR) indicated C₃H₆N₆ is an ideal nitrogen source for large diamond crystal synthesized by temperature gradient method (TGM), but its hydrogen is not absorbed by diamond. With the increase of C₃H₆N₆ content, the colour of diamond changed from yellow to green, and the highest nitrogen content of diamond is 2300 ppm. High synthesis temperature can effectively reduce the formation of defects and play a key role in the formation of C-centers during diamond growth. Surprisingly, diamond is likely to grow into twin crystal when the C₃H₆N₆ content is 0.1 wt%. In the process of diamond growth, carbon atoms of C₃H₆N₆ are likely to serve as carbon source to form plane dislocations, which eventually lead to the formation of twin diamond. Raman spectra show that there are few crystal defects in diamond synthesized with C₃H₆N₆ as dopant.

在本文中，采用三聚氰胺（C ₃ H ₆ N ₆）添加剂在5.6 GPa，1513和1553 K的温度下成功合成了大型金刚石晶体。傅立叶变换红外光谱（FTIR）表明C ₃ H ₆ N ₆是通过温度梯度法（TGM）合成的大型金刚石晶体的理想氮源，但其氢未被金刚石吸收。随着C ₃ H ₆ N ₆的增加含量，钻石的颜色从黄色变为绿色，并且钻石的最高氮含量为2300 ppm。较高的合成温度可以有效减少缺陷的形成，并在金刚石生长过程中对C中心的形成起关键作用。出乎意料的是，当C ₃ H ₆ N ₆含量为0.1wt％时，金刚石很可能长成双晶。在金刚石的生长过程中，C ₃ H ₆ N _6的碳原子很可能作为碳源形成平面位错，最终导致孪晶的形成。拉曼光谱表明，用C ₃ H ₆ N合成的金刚石几乎没有晶体缺陷。₆作为掺杂剂。