Preparation, Characterization and Optical Properties of (MCM-41)-La2O3 Nanocomposite Material

Nanoscale MCM-41 molecular sieve was prepared in alkaline medium by hydrothermal method using cetyltrimethylammonium bromide as template, tetraethoxysilane as silica resource. La2O3 was incorporated into the mesoporous channels of the MCM-41 molecular sieve by solid phase thermal diffusion method. The (MCM-41)-La2O3 nanocomposite materials with different concentrations were prepared. By means of chemical analysis, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), low temperature nitrogen adsorption-desorption technique at 77 K, solid state diffuse reflection absorption spectroscopy, Ramam spectroscopy, scanning electronic microscopy (SEM) and luminescence spectra, the host-guest nanocomposites materials were characterized. Powder XRD results showed that after La2O3 was encapsulated into the channels of the molecular sieve, the frameworks of the prepared materials were not destroyed. The framework structures of the MCM-41 still had high ordered property in the prepared (MCM-41)-La2O3 host-guest nanocomposite materials. As the increase in the concentration of the embedded guest material, the degree of order of the composite materials decreased. Infrared spectra showed that the host molecular sieve frameworks of the prepared nanocomposite materials were intact. The low-temperature nitrogen adsorption -desorption technique indicated that the La2O3 has been partially occupied the pores of the MCM-41 molecular sieve, which resulted in the decrese in surface area and pore volume of the molecular sieve. The solid state diffuse reflection absorption spectra showed that for the absorption peaks of absorption spectra blue shift phenomena took place and the quantum confinement effect exhibited. It indicated that La2O3 has been encapsulated in the pores of the MCM-41 molecular sieve. Raman spectra showed that for the prepared composite materials no new characteristic peak appeared, showing La2O3 has been encapsulated into the channels of the MCM-41 molecular sieve. SEM showed that the appearance of the (MCM-41)-La2O3 sample was very orderly and the mainly presented form was globular structure. When the content of La2O3 was 10%, the average particle diameter of the (MCM-41)-La2O3 was (114 +/- 10) nm. The research results of luminous spectra showed that the (MCM-41)-La(2)O(3)sample prepared has good luminous properties at 396 nm. Thus, the (MCM-41)-La2O3 have the potential foreground as luminous material.