Segregative Crystallization of Several Diamond-like Phases from the Graphitic BC2N without an Additive at 7.7 GPa
Segregative Crystallization of Several Diamond-like Phases from the Graphitic BC2N without an Additive at 7.7 GPa
复制标题
DOI：
10.1021/cm00048a011
复制
发表时间：
1994-12
影响因子：
8.6
通讯作者：
S. Nakano;M. Akaishi;T. Sasaki;S. Yamaoka
中科院分区：
文献类型：
--
作者：
S. Nakano;M. Akaishi;T. Sasaki;S. Yamaoka
一种相对成分为BC_2N的石墨在高压（7.7GPa）和高温（2000-2400 ℃）条件下，通过直接转变探索形成立方相的可能性。粉末X射线衍射分析表明，在2150 ℃以上的温度下，产物中存在多个具有类金刚石结构的立方相。宽的和部分分裂的衍射线的解卷积表明，在2150-2300 ℃下获得的产物由cBN、“金刚石”（含有少量的B和N）和立方BCN物质组成。然而，在2400 ℃下，立方产物倾向于分离成两个主要相，称为cBN和“金刚石”。这一趋势得到了强有力的支持的微观结构和元素观察的产品，使用高分辨率扫描电子显微镜和俄歇电子能谱。本研究的结论是，不是立方BCN化合物，但cBN和金刚石的混合物存在的三元体系中的化学稳定相在所采用的条件下。
A graphite relative of composition BC2N has been subjected to high-pressure (7.7 GPa) and high-temperature (2000—2400 C) conditions to explorethe possibility for the formation of a cubic phase via direct transformation. Severalcubic phases with a diamond-like structure were confirmed in the products above 2150 C by the powder X-ray diffraction patterns. The deconvolution of the broad and partly split diffraction lines suggested that the products obtained at 2150-2300 C consisted of cBN,“diamond”(containing minor amount of B and N), and a cubic BCN substance. At 2400 C, however, the cubic products tended to segregate into two major phases assigned as cBN and “diamond”. This tendency was strongly supported by the microstructural and elemental observation of the products using a highresolution scanning electron microscope and Auger electron spectroscopy. The presentstudy concludes that not a cubic BCN compound but a mixture of cBN and diamond exists as the thermodynamically stable phases in the ternary system under the conditions employed.