User:Aaronujl/sandbox
Commercially important materials prepared by CVD[edit]
Graphene[edit]
Many variations of CVD can be utilized to synthesize graphene.
- Carbon source
The most popular carbon source used to produce graphene is methane gas. Less popular choices include petroleum asphalt, notable for being inexpensive but more difficult to work with.[1]
- Use of catalyst
The use of catalyst is viable in changing the physical process of graphene production. Notable examples include iron nanoparticles, nickel foam, and gallium vapor. These catalysts can either be used in situ during graphene buildup,[1][2] or situated at some distance away at the deposition area.[3] Some catalysts require another step to remove them from the sample material.[2]
- Physical conditions
Physical conditions such as surrounding pressure, temperature, carrier gas, and chamber material play a big role in production of graphene.
Most systems use LPCVD with pressures ranging from 1 to 1500 Pa.[1][3][4][5] However, some still use APCVD.[2] Low pressures are used more commonly as they help prevent unwanted reactions and produce more uniform thickness of deposition on the substrate.
On the other hand, temperatures used range from 800-1050°C.[1][2][3][4][5] High temperatures translate to an increase of the rate of reaction. Caution has to be exercised as high temperatures do pose higher danger levels in addition to greater energy costs.
- Carrier gas
Hydrogen gas and inert gases such as argon are flowed into the system.[1][2][3][4][5] These gases act as a carrier, enhancing surface reaction and improving reaction rate, thereby increasing deposition of graphene onto the substrate.
- Chamber material
Standard quartz tubing and chambers are used in CVD of graphene.[1][2][3][4][5] Quartz is chosen because it has a very high melting point and is chemically inert. In order words, quartz does not interfere with any physical or chemical reactions regardless of the conditions.
- Methods of analysis of results
Raman spectroscopy, X-ray spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are used to examine and characterize the graphene samples.[1][2][3][4][5]
Raman spectroscopy is used to characterize and identify the graphene particles; X-ray spectroscopy is used to characterize chemical states; TEM is used to provide fine details regarding the internal composition of graphene; SEM is used to examine the surface and topography.
Sometimes, atomic force microscopy (AFM) is used to measure local properties such as friction and magnetism.[4][5]
See also[edit]
References[edit]
- ^ a b c d e f g Liu, Zhuchen; Tu, Zhiqiang; Li, Yongfeng; Yang, Fan; Han, Shuang; Yang, Wang; Zhang, Liqiang; Wang, Gang; Xu, Chunming (2014-05-01). "Synthesis of three-dimensional graphene from petroleum asphalt by chemical vapor deposition". Materials Letters. 122: 285–288. doi:10.1016/j.matlet.2014.02.077.
- ^ a b c d e f g Patel, Rajen B.; Yu, Chi; Chou, Tsengming; Iqbal, Zafar (2014-01-01). "Novel synthesis route to graphene using iron nanoparticles". Journal of Materials Research. 29 (14): 1522–1527. doi:10.1557/jmr.2014.165. ISSN 2044-5326.
- ^ a b c d e f Murakami, Katsuhisa; Tanaka, Shunsuke; Hirukawa, Ayaka; Hiyama, Takaki; Kuwajima, Tomoya; Kano, Emi; Takeguchi, Masaki; Fujita, Jun-ichi (2015-03-02). "Direct synthesis of large area graphene on insulating substrate by gallium vapor-assisted chemical vapor deposition". Applied Physics Letters. 106 (9): 093112. doi:10.1063/1.4914114. ISSN 0003-6951.
- ^ a b c d e f Zhang, CanKun; Lin, WeiYi; Zhao, ZhiJuan; Zhuang, PingPing; Zhan, LinJie; Zhou, YingHui; Cai, WeiWei (2015-09-05). "CVD synthesis of nitrogen-doped graphene using urea". Science China Physics, Mechanics & Astronomy. 58 (10): 1–6. doi:10.1007/s11433-015-5717-0. ISSN 1674-7348.
- ^ a b c d e f Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Hwangbo, Yun; Yoon, Jong-Hyuk; Lee, Eun-Kyu; Ryu, Jaechul; Lee, Hak-Joo; Cho, Seungmin. "Synthesis of CVD-graphene on rapidly heated copper foils". Nanoscale. 6 (9). doi:10.1039/c3nr06434d.