Nano-polycrystalline diamond synthesized through the decomposition of stearic acid
Nano-polycrystalline diamond synthesized through the decomposition of stearic acid
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硬脂酸分解法制备纳米多晶金刚石
DOI：
10.1080/08957959.2019.1708910
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发表时间：
2020-01-21
影响因子：
2
通讯作者：
Ohfuji, Hiroaki
中科院分区：
文献类型：
--
作者：
Kawamura, Hideaki;Ohfuji, Hiroaki
本文报道了一种以硬脂酸（C18 H36 O2）为原料，在高温高压条件下合成纳米多晶金刚石（NPD）的新方法。所获得的NPD显示出类似于由石墨合成的标准NPD的透明暗黄色，并且由极细的金刚石晶粒（类似于10 nm）组成。本发明合成纯透明NPD所需的温度在13和17 GPa下低至1000 ℃，这令人惊讶地低于常规NPD合成的温度（1800-2000 ℃）。由硬脂酸热分解产生的无定形、极差结晶的石墨可能为金刚石提供优先成核位点，并显著降低活化能。从体系中除去分解产生的挥发性组分如H2O是获得无孔透明NPD的关键。菱镁矿、MgCO 3和方镁石、MgO可通过水化反应作为水的有效去除剂。
Here we report a novel route for synthesizing nano-polycrystalline diamond (NPD) using stearic acid (C18H36O2) as a starting material under high pressure and high temperature. The obtained NPD shows a transparent dark-yellowish color similar to the standard NPD synthesized from graphite and consists of extremely fine diamond grains (similar to 10 nm). The temperature required for the present synthesis of pure transparent NPD is as low as 1000 degrees C at 13 and 17 GPa, which is surprisingly lower than that for conventional NPD synthesis (1800-2000 degrees C). The amorphous-like, extremely poorly crystalline graphite produced by the thermal decomposition of stearic acid likely provides preferential nucleation sites for diamond and significantly lower the activation energy. The removal of volatile components such as H2O generated through the decomposition from the system is a key to obtain pore-free transparent NPD. Magnesite, MgCO3 and periclase, MgO can be used as an efficient H2O remover through the hydration reaction.