Irene Ling Li

Publications (3)9.91 Total impact

• Article: Study of the Mechanism of Carbonization of Template in Silicon-Substituted Aluminophosphate Zeolite Crystals

  Jian Pang Zhai, Wei Wei Peng, Irene Ling Li, Shuang Chen Ruan, Zi Kang Tang
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  ABSTRACT: Silicon-substituted microporous aluminophosphate AlPO4-11 zeolite crystals (SAPO-11) were synthesized by a hydrothermal method. The dipropylamine (DPA) molecules were incorporated in the one-dimensional channels of SAPO-11 as organic templates. The DPA molecules can be pyrolyzed at high temperature, and form 0.3 nm single-walled carbon nanotubes (SWNTs). The detailed carbonization process of DPA molecules has been investigated by using Fourier transform infrared measurements (FTIR), mass spectrometry, thermogravimeter (TG), and micro-Raman spectroscopy. During the pyrolysis process, the DPA molecules decompose into propylene and ammonia at 673 K, and then the C−H bonds of C3H6 start to break when temperature is above 698 K. The 0.3 nm SWNTs are formed sequentially in the channels of SAPO-11 crystals at about 723 K.
  07/2008;
• Article: Carbonization Mechanism of Tetrapropylammonium-hydroxide in Channels of AlPO4-5 Single Crystals

  Jian Pang Zhai, Zi Kang Tang, Zhao Ming Li, Irene Ling Li, Fu Yi Jiang, Ping Sheng, Xijun Hu
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  ABSTRACT: We studied the carbonization mechanism of tetrapropylammonium-hydroxide (TPAOH) carbon precursors in the channels of AlPO4-5 crystal, with the aim of producing higher-density and better-quality 4 Å carbon nanotubes. The conversion process of TPAOH was investigated by using a combination of Fourier transform infrared (FTIR) spectra, mass spectrometry, and micro-Raman spectroscopy under various pyrolysis temperatures. During the pyrolysis process, the TPAOH molecules decomposed into lighter amines with the abstraction of propylene, with the stepwise formation of tripropylamine, dipropylamine, and n-propylamine. This leads to the formation of 0.4 nm single-walled carbon nanotubes (SWNTs) at about 723 K. The SWNTs density was found to be higher than that resulting from the carbon precursor of tripropylamine (TPA), because of the larger number of carbon atoms in the unit cell. Thermogravimetry (TG) measurements also indicated a higher loading density (in AlPO4-5 crystals) for the TPAOH carbon precursors.
  02/2006;
• Article: Geometry, phase stability, and electronic properties of isolated selenium chains incorporated in a nanoporous matrix.

  Irene Ling Li, Jian Pang Zhai, Pascale Launois, Shuang Chen Ruan, Zi Kang Tang
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  ABSTRACT: We report the fabrication process of isolated one-dimensional Se chains incorporated in the matrix of AlPO4-5 single crystals and the experimental investigation of the geometry, phase stability, electronic properties, and electron-phonon coupling effect of these Se chains. The structure of the helical Se chains inside the channels is discussed on the basis of X-ray scattering measurements. Thermal analysis and temperature-dependent micro-Raman measurements show that Se single chains are flexible and can convert from a weak distorted phase into another phase with strongly disordered structure ("melting" state) around 340 K. Since the electrons are confined in the one-dimensional channels, the absorption band of the Se chain is obviously blue shifted compared with that of trigonal Se. With increasing temperature, this band shifts linearly to the lower energy side, in sharp contrast to the nonlinear temperature coefficient of trigonal Se, which is attributed to the greatly diminished interchain interaction and the weakening of the electron-optical phonon coupling in a low-dimensional system. In the vicinity of the absorption band, both first-order and second-order Raman signals for the Se chain are enhanced, due to the strong electron-phonon coupling when the excitation laser energy matches the electronic transition in isolated Se chains.
  Journal of the American Chemical Society 12/2005; 127(46):16111-9. · 9.91 Impact Factor