Synthesis of quenchable amorphous diamond

Zhidan Zeng,Liuxiang Yang,Wenge Yang,Jianguo Wen,Dean J Miller,Qiaoshi Zeng,Wendy L Mao,Hongbo Lou,Yue Meng,Hongwei Sheng,Ho-Kwang Mao

doi:10.1038/s41467-017-00395-w

Abstract

Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp3-carbon network bonding. Crystallinity is another major controlling factor for materials properties. Although other Group-14 elements silicon and germanium have complementary crystalline and amorphous forms consisting of purely sp3 bonds, purely sp3-bonded tetrahedral amorphous carbon has not yet been obtained. In this letter, we combine high pressure and in situ laser heating techniques to convert glassy carbon into “quenchable amorphous diamond”, and recover it to ambient conditions. Our X-ray diffraction, high-resolution transmission electron microscopy and electron energy-loss spectroscopy experiments on the recovered sample and computer simulations confirm its tetrahedral amorphous structure and complete sp3 bonding. This transparent quenchable amorphous diamond has, to our knowledge, the highest density among amorphous carbon materials, and shows incompressibility comparable to crystalline diamond.

Highlights

Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp3-carbon network bonding
In contrast to the tetrahedral network structure in amorphous silicon (a-Si) and a-Ge, this high-pressure phase still maintained a layered structure quite similar to the starting glassy carbon material according to its X-ray diffraction (XRD) patterns, and the pressure-induced sp2-sp[3] transition was reversible upon decompression
Glassy carbon samples were compressed to 50 GPa at room temperature in a diamond anvil cell (DAC), followed by laser heating at approximately 1800 K until the sample became transparent

Summary

Introduction

Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp3-carbon network bonding. Our X-ray diffraction, high-resolution transmission electron microscopy and electron energy-loss spectroscopy experiments on the recovered sample and computer simulations confirm its tetrahedral amorphous structure and complete sp[3] bonding. This transparent quenchable amorphous diamond has, to our knowledge, the highest density among amorphous carbon materials, and shows incompressibility comparable to crystalline diamond. It is very interesting to reach the extreme end of order where translational periodicity completely disappears (i.e. purely sp3-bonded tetrahedral amorphous carbon) This carbon form is expected to have unique properties combining the advantages of crystalline diamond and amorphous materials and even beyond. Amorphous diamond is optically transparent, dense, and shows ultrahigh incompressibility (bulk modulus) comparable to crystalline diamond

Methods

Results

Conclusion