Dubrovinskaia N, Wirth R, Wosnitza J, Papageorgiou T, Braun H F, Miyajima N, Dubrovinsky L
Mineralphysik und Strukturforschung, Mineralogisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany.
Proc Natl Acad Sci U S A. 2008 Aug 19;105(33):11619-22. doi: 10.1073/pnas.0801520105. Epub 2008 Aug 12.
The discovery of superconductivity in polycrystalline boron-doped diamond (BDD) synthesized under high pressure and high temperatures [Ekimov, et al. (2004) Nature 428:542-545] has raised a number of questions on the origin of the superconducting state. It was suggested that the heavy boron doping of diamond eventually leads to superconductivity. To justify such statements more detailed information on the microstructure of the composite materials and on the exact boron content in the diamond grains is needed. For that we used high-resolution transmission electron microscopy and electron energy loss spectroscopy. For the studied superconducting BDD samples synthesized at high pressures and high temperatures the diamond grain sizes are approximately 1-2 mum with a boron content between 0.2 (2) and 0.5 (1) at %. The grains are separated by 10- to 20-nm-thick layers and triangular-shaped pockets of predominantly (at least 95 at %) amorphous boron. These results render superconductivity caused by the heavy boron doping in diamond highly unlikely.
在高温高压下合成的多晶掺硼金刚石（BDD）中发现超导性[叶基莫夫等人（2004年）《自然》428:542 - 545]引发了许多关于超导态起源的问题。有人认为金刚石的重硼掺杂最终导致了超导性。为了证实这些说法，需要有关复合材料微观结构以及金刚石晶粒中确切硼含量的更详细信息。为此，我们使用了高分辨率透射电子显微镜和电子能量损失谱。对于所研究的在高温高压下合成的超导BDD样品，金刚石晶粒尺寸约为1 - 2微米，硼含量在0.2（2）至0.5（1）原子百分比之间。晶粒被10至20纳米厚的层以及主要为（至少95原子百分比）非晶硼的三角形口袋分隔开。这些结果使得由金刚石中的重硼掺杂导致超导性的可能性极低。
