Shock-induced Transition from C_<60> Fullerene to Amorphous Diamond and Exploring New Carbon Materials.

以C_(60)&GT；富勒烯为原料，采用冲击压缩快冷技术合成了一种新型碳材料--透明“非晶态金刚石”。根据一些衍射和光谱分析，这种材料是长程有序的非晶态和短程有序的金刚石。由于该材料完全由sp3碳组成，并且径向分布函数分析确定了sp3四面体在晶胞尺寸范围内的排列类似于晶体金刚石，因此它被标记为非晶态金刚石而不是非晶态sp3碳。用电子衍射和电子能量损失谱跟踪了它独特的从C&lt；60&gt；富勒烯到非晶态金刚石的转变过程，以探索其结构和电子态的变化。径向分布函数和转变过程的结果表明，如果通过改变起始材料的冲击条件和初始状态来巧妙地控制晶体生长，可以制备出不含sp2组分的纳米晶金刚石块体材料。在本研究中，我们还有效地利用了C_&lt；60&gt；富勒烯转化为金刚石的潜力以及冲击压缩和快速淬火技术的优点，制备了由少数纳米级的金刚石微晶组成的透明的纳米金刚石陶瓷。血小板是透明的，非常坚硬，几乎与IIa型钻石相当。透射电子显微镜和电子能量损失谱表明，单个微晶直接结合或通过非常薄的改性sp3碳层结合在一起，这可能稳定了纳米微晶。纳米织构的尺寸有序性和sp3构型决定了材料的透明性和硬度。

Transparent "amorphous diamond", a new carbon material, has been synthesized from C_<60> fullerene by a shock compression and rapid quenching technique. This material is amorphous in the long-range order and diamond in short-range order, according to some diffractometric and spectroscopic analyzes. Because the material is comprised wholly of sp^3 carbon, and radial distribution function analysis has determined the arrangement of sp^3 tetrahedra as similar to that of crystalline diamond within the range of unit cell size, it has been labeled amorphous diamond rather than amorphous sp^3 carbon. Its unique transition process from C_<60> fullerene to amorphous diamond was tracked by using electron diffraction and electron energy loss spectroscopy to explore changes in structure and electronic state. The results of radial distribution function and of transition process obtained suggest that nanocrystalline diamond bulk material without sp^2 component can be fabricated if crystal growth is skillfully controlled by changing the shock condition and initial state of the starting material. In the present research, transparent and nanocrystalline diamond ceramics, consisting of a few nanometer-sized diamond crystallites that are unstable in themselves because of higher surface energy, were also fabricated by effectively using the potential of C_<60> fullerene to transform into diamond and the advantage of the shock compression and rapid quenching technique. The platelets were transparent and very hard, nearly comparable to type IIa diamond. Transmission electron microscopy and electron energy loss spectroscopy revealed that individual crystallites had combined directly or through a very thin and modified sp^3 carbon layr, which possibly stabilized the nanometer-sized crystallites. The size order and sp^3 configuration of the nanotexture caused the transparency and hardness of the present material.