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Electron diffraction pattern of PbS nanoparticles
in zeolite X
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In this work, published in AZojomo*, by M.
Flores-Acosta, R. Pérez-Salas, M. Sotelo-Lerma, F. F.
Castillón-Barraza and R. Ramírez-Bon from Unidad Querétaro,
Universidad de Sonora and Universidad Nacional Autónoma de México, PbS
nanoparticles were synthesized in zeolite Na-X by means of ionic
exchange processes in alkaline aqueous solutions. They reported the
optical and structural properties of the system PbS-Na-X zeolite.
The 4.0nm PbS nanoparticles have spherical shape,
the crystalline structure of galena and are embedded uniformly in the
zeolite matrix. The 1se-1ph and 1pe-1ph excitonic transitions observed
in the absorption spectra of the PbS-Na-X system is explained in terms
of the crystalline quality of the PbS nanoparticles.
The results show that spherical PbS nanoparticles
are formed not inside the zeolite cages but outside, embedded in the
zeolite matrix. The absorption spectra of the samples display exciton
absorption bands at much higher energy than the fundamental absorption
edge of bulk PbS. This result is a consequence of strong quantum
confinement effects produced by the reduced size of the PbS
nanoparticles as compared to the exciton Bohr diameter of bulk PbS. |
