Series of Selected Papers from Chun-Tsung Scholars,Peking University(2003)
SYNTHESIS AND STRUCTURE
K2Ti6O13 NANOWIRES
DETERMINATION
OF
Ruihong WANG1, Bolu WANG2, Qing CHEN2 and Lian-Mao PENG2,1
1
Beijing Laboratory of Electron Microscopy, Institute of Physics, P.O. Box 603,
Chinese Academy of Sciences, Beijing 10080, China
2
Department of Electronics, Peking University, Beijing 100871, China
Nanoscale materials, such as nanotubes and nanowires, are among
important advanced materials that are expected to exhibit unusually
chemical and physical properties, which may be different from that
of bulk materials. Among
these nanoscale materials, titanate
nanotubes and nanowires have many important applications in areas
such as photo-catalyst, gas sensors, high energy cell and
environmental purification[1-2]. Many methods have been developed to
synthesize titanate whiskers[3], but typically the diameters of the
products were in micron. In our previous work, titanate nanotubes
and potassium titanate nanowires, both having diameter around 10nm,
were synthesized using a simple one step hydrothermal reaction
among TiO2 particles and alkali solution[4,5]. In this paper we report
a successful synthesis of potassium titanate nanowires using
hydrothermal reaction among layered Na2Ti3O7 and KOH solution.
K2Ti6O13 nanowires were prepared in the following way: layer
structured Na2Ti3O7 powder was added into a 10M KOH aqueous solution.
The specimen was statically heated in a furnace at 200 º C for 24
hours. The final white product was filtered and washed with deionized water at room temperature. TEM sample was prepared by
dispersing the powder in alcohol by ultrasonic treatment, dropping
onto a holey carbon film supported on a copper grid, and then dried
in air. TEM and EDX studies were carried out using Tecnai 20, and
HREM using Tecnai F30. Image simulations were performed using the
Cerius2 software.
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Series of Selected Papers from Chun-Tsung Scholars,Peking University(2003)
Figure.1 is a low magnification TEM image showing many nanowires
with diameters around 10 nm, and length around several hundreds
nanometers. EDX was performed on isolated nanowires using nanoprobe
mode on Tecnai 20. Figure 2 is a typical EDX spectrum, showing that
there exist only K, Ti and O elements in the nanowires. Comparing
with the spectrum taken from K2Ti6O13 nanowires made via reaction
between TiO2 and KOH we found that the atomic ratios in the present
nanowires are the same, i.e. K:Ti:O = 2:6:13.
Figure 3 shows a SAED pattern taken from an area containing many
nanowires. The pattern can be indexed using K2Ti6O13 structure. The
axis of the nanowires is determined to be along the [010] direction
using SAED analysis on isolated nanowires. The atomic structure of
the nanowire was also investigated using HRTEM and image simulations.
Experimental images were taken from nanowires along different zone
axes. Figure 4 shows an experimental HREM image with an inserted
simulated image. This image was taken along the [001] zone axis. The
image was simulated for 300 keV primary beam, Cs=1.2mm and
underfocus 50nm. The good agreement between the experimental and
simulated images confirms that the nanowire is indeed K2Ti6O13
nanowire.
Fig.1: Low magnification TEM image.
Fig.2: A typical EDX spectrum from nanpowires.
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Series of Selected Papers from Chun-Tsung Scholars,Peking University(2003)
Fig. 3: SAED ring pattern taken from many
nanowires.
Fig. 4: Experimental HREM image taken
along the [001] zone axis, with an inserted
simulated image.
REFERENCES
[1] G. Dagan, and M. Tomkiewicz, J. Phys. Chem. 97, 12651(1993).
[2] A. Fujishima and K. Honda, Nature 238,37(1972).
[3] J. K. Lee, K. H. Lee and H. Kim, J. Mater. Sci 31, 5493(1996).
[4] Q. Chen, W. Zhou, G. H. Du and L. M. Peng, Adv. Mater., 14, 1208 (2002).
[5] G. H. Du, Q. Chen, P. D. Han, Y. Yu and L. M. Peng, Phys. Rev. B, 67, 035323 (2003).
[6] This work was supported by the Ministry of Science and Technology (Grant No
001CB610502) and National Science Foundation of China (Grant Nos 90206021 and
60271004).
Author introduction:
Bolu.Wang, female, born in Chengdu, Sichuan, P.R.China on
Sept.11th, 1982. Entered Dept. Geographic Physics of Peking
University from Chendu Liewu Middle School in 2000. Transferred to
Dept. Electronic Science as top 1 in the transferring exam in 2001.
Study very hard and was chosen from over 120 students in Dept.
Electronic Science to join the Chun-Tsung project lunched by
professor T.D.Lee as a junior. Began research in the Center of
Nanotechnology in Peking University in 2002 with the direction of
Professor Qing.Chen. During the research process, received a lot of
help from professor Qing.Chen, Dr.Shuang.Zhang, Dr.Ruihong.Wang and
other group members. Already published a paper on Chemical Physics
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Series of Selected Papers from Chun-Tsung Scholars,Peking University(2003)
Letters and submitted a paper to the Proceedings of BCEIA
2003.Further work is continuing.
Sentiment:
I have entered a very good group. My mentor didn’t ask me just
to help other group members or wash cuvette in the lab. She
encouraged me to read a lot of papers and to form my own ideas. It
is she who tries to teach me to be creative. Thanks to her again
here. Also, I would like to mention Dr.Shuang.Zhang, he does not
avoid discussing with me just because I am still an undergraduate.
During the discussion with him, I have learned a lot. I will never
forget my precious days here.
Mentor introduction:
陈清，女，信息科学学院教授，博士生导师。1994 年获博士。曾留学英国
剑桥大学材料系、日本金属材料研究所和美国亚力桑那州立大学物理系。曾获
北京市优秀青年骨干教师称号，并获得教育部优秀青年教师资助计划。主要从
事纳米结构分析、纳米加工和纳米材料研究。
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