摘要
石墨向金刚石在超高压高温下的转变机理经过了数十年的探讨,至今未形成定论。本文根据固体和分子经验电子理论(EET理论),分别计算了静压超高压高温条件下立方合成立方金刚石过程中石墨和金刚石的价电子结构,获得了石墨和金刚石12组不同组合晶面间的价电子密度。结果表明,在超高压高温下其电子密度差均大于10%,说明石墨/金刚石晶面的价电子结构差异太大,不能诱发石墨向立方金刚石的直接转变。分析认为:超高压高温下,石墨先分解出一亚稳相后再转变成立方金刚石结构。
The formation mechanism of how graphite can be transformed into diamond at ultra high- pressure and high-temperature （UHPHT） has been debated for decades. According to the empirical electron theory of solid and molecules （EET） , the valence electron structures of graphite and diamond were constructed for the conditions of diamond synthesis by the static pressure, respectively. The relative differences in electron density were subsequently obtained for the interfaces of 12 different combinations of crystal planes of graphite and diamond at UHPHT. The results indicate that these relative differences in the static pressure condition are much greater than 10%, the differences of valence electron structures at the graphite/diamond interfaces are too large to induce the direct transformation of graphite into diamond. Therefore, the graphite might have to firstly decompose into a metastable phase before it can be transformed into cubic diamond at UHPHT.
出处
《人工晶体学报》
EI
CAS
CSCD
北大核心
2013年第12期2509-2514,共6页
Journal of Synthetic Crystals
基金
国家自然科学基金(50972084)
山东省自然科学基金(ZR2010EM050)
关键词
石墨
金刚石
超高压高温
EET理论
价电子结构
graphite
diamond
ultra high-pressure and high-temperature
EET theory
valence electron structure
