Zhu Zhiguang, Chen Chengke, Lu Shaohua, Li Xiao, Hu Xiaojun
College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.
Moganshan Diamond Research Center, De Qing, Huzhou, 313200, P. R. China.
Adv Sci (Weinh). 2025 Mar;12(10):e2411504. doi: 10.1002/advs.202411504. Epub 2025 Jan 22.
The transformation of graphite into diamond (2-10 nm) at ordinary pressure by monodispersed Ta atoms was recently reported, while the effects of Ta concentration on the transition process remain obscure. Here, by regulating the Ta wire treatment time, as well as the annealing time and temperature, larger diamond grians (5-20 nm) are successfully synthesized, and the transition process of graphite to diamond is revealed to vary with Ta concentration. Specifically, short Ta wire treatments (5-10 min) induce graphite to form a "circle" structure and transforms into diamond directly after annealing. Long Ta wire treatments (15-25 min) produce larger and more "circle" structures, containing an increased number of graphite layers. After annealing at 1100 °C for 30-120 min, graphite first transforms into amorphous carbon, then to i-Carbon and n-Diamond, and finally to diamond. Notably, a large amount of n-Diamond and diamond are formed after 120 min annealing. By modulating the annealing temperature from 500 to 1200 °C for 30 min, diamond is already obtained at 500 °C, and hexagonal diamond up to 20 nm in size at 1200 °C. This provides a fresh insight into the graphite/diamond transition process and an approach for diamond synthesis.
最近有报道称，单分散的钽原子可在常压下将石墨转化为金刚石（2 - 10纳米），然而钽浓度对转变过程的影响仍不清楚。在此，通过调节钽丝处理时间以及退火时间和温度，成功合成了更大尺寸的金刚石颗粒（5 - 20纳米），并且揭示了石墨向金刚石的转变过程随钽浓度而变化。具体而言，短时间的钽丝处理（5 - 10分钟）会使石墨形成“环状”结构，并在退火后直接转变为金刚石。长时间的钽丝处理（15 - 25分钟）会产生更大且更多的“环状”结构，其中包含更多的石墨层。在1100℃退火30 - 120分钟后，石墨首先转变为无定形碳，然后转变为i - 碳和n - 金刚石，最终转变为金刚石。值得注意的是，退火120分钟后会形成大量的n - 金刚石和金刚石。通过在500至1200℃范围内调节退火温度30分钟，在500℃时即可获得金刚石，在1200℃时可获得尺寸达20纳米的六方金刚石。这为石墨/金刚石转变过程提供了新的见解以及一种金刚石合成方法。
