Formation of cubic C-BN by crystallization of nano-amorphous solid at atmosphere
- PDF / 176,796 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 48 Downloads / 200 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Formation of cubic C-BN by crystallization of nano-amorphous solid at atmosphere Bin Yao Department of Physics, Jilin University, Changchun 130023, People’s Republic of China and State Key Lab of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, People’s Republic of China
L. Liu Department of Physics, Jilin University, Changchun 130023, People’s Republic of China
W. H. Su Department of Physics, Jilin University, Changchun 130023, People’s Republic of China and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110015, People’s Republic of China (Received 14 July 1997; accepted 3 February 1998)
An amorphous carbon-boron nitride (C-BN) solid was prepared by ball milling the mixture of graphite and hexagonal BN powders for a period of 120 h. After annealing the amorphous C-BN solid for 1 h at atmosphere in the temperature range from 800 to 900 K and then quenching it to room temperature, a small amount of cubic C-BN solid solutions with diamond-like structure, which belong to a high energy phase and can only be synthesized previously under high pressure and temperature (30 GPa, 2000 K), were observed in the annealed amorphous C-BN solid. The lattice constant of the cubic C-BN solid solution was 0.3587 nm, and its grain size was in the range of 10 to 50 nm.
The similarity in structure between graphite (C) and boron nitride (BN), including a hexagonal-graphite structure as their stable form at ambient conditions, and a high-pressure-temperature hexagonal (w¨urtzite) structure as well as the diamond-like form,1–4 has motivated the synthesis of C-BN compounds with graphite-like layered structure and C-BN solid solutions with diamond-like structure. It is expected that the C-BN compounds behave as a semiconductor with various band energies5 and the C-BN solid solutions have some physical properties similar to diamond and cubic BN (borason). They are of potential technological importance.6 In the past ten years, the chemical vapor deposition (CVD) method has been used to prepare graphite-like layered C-BN thin film semiconductors having various band gap energies and conductive types, with BCl3 , CCl2 , H2 , and N2 or acetonitride and boron trichloride, etc. as starting materials.7–10 However, there are few reports about the synthesis of the C-BN compounds by solid-state reaction with graphite and hexagonal BN as raw materials, and there have not been any reports up to now about the synthesis of amorphous C-BN materials. Since diamond11 and borason,2 which are the hardest of all known solids and have been used widely, were synthesized, the study on the synthesis of new superhard materials using the light elements of C, B, N, O, etc. as starting materials, for example, C3 N4 ,9 cubic CBN,15,16 and B7 O,12 has been a hot problem. Much of the research work on the synthesis of C-BN superhard J. Mater. Res., Vol. 13, No. 7, Jul 1998
materials was carried out in recent years. The C-BN superhard materials are high energy p
Data Loading...
