A Simple Method for Synthesis of PbS Nanoparticles Using 2-Mercaptoethanol as the Capping Agent

2012 ◽  
Vol 31 (6) ◽  
pp. 723-725 ◽  
Author(s):  
Gholamreza Nabiyouni ◽  
Parviz Boroojerdian ◽  
Kambiz Hedayati ◽  
Davood Ghanbari

AbstractLead sulfide nanoparticles were synthesized at room temperature via a simple chemical reaction. In this synthesis, 2-mercaptoethanolwas used as the capping agent and sodium sulfide was used as a sulfur source. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy Electron microscopy study showed that without using a capping agent the bulk PbS is obtained, while adding the mercaptoethanol leads to production of nanoparticles. We found that the electronic absorption spectra as well as the particle sizes depend on the used capping agents. Two exitonic peaks with a large blue shift were observed when mercaptoethanol was used.

Author(s):  
M. Parras ◽  
J.M. González-Calbet ◽  
M. Vallet-Regí ◽  
J.C. Grenier

In a previous paper we have shown that compositional variations in BaxLa1-xFeO3-y materials prepared in air. are accommodated in a different way than in other perovskite-related ferrites probably due to the bigger size of barium.When oxidated BaxLa1-xFe3+,4+O3-y samples in the 1/2 ≤ x ≤ 2/3 range, are reduced by annealing at 1100°C for 24h. in flowing Ar-5%H2, all iron,as deduced from chemical analysis data, is found in the III state oxidation. Powder X-ray diffraction data in this range (La1/2Ba1/2FeO2.75-La1/3Ba2/3FeO2.67) can be indexed on the basis of a single cubic perovskite unit cell (ac ≃ 3.95Å)In order to elucidate the way in which anionic vacancies are accommodated in these solids an electron diffraction (ED) and microscopy study was performed, similar results being obtained in both La1/2Ba1/2 FeO2.75 and La1/3Ba2/3FeO2.67samples.


Author(s):  
Dwight R. Acosta ◽  
Isaac Schifter ◽  
José L. Contreras

Synthesis of stereo selective zeolites using Gallium as partial or total substitute instead of aluminum, may lead to obtention of a novel class of zeo lites with modification of channel apertures, cage size and total acidity. Reaction velocity and selectivity for isomerization and cracking processes, for instance, are influenced by acid force of protonic sites, which may be selective or active for particular catalytic reactions.Zeolites Z-683 and Z-691 with a 50% and 100% of A1 atoms substituted respectively, were synthesized using a modified method for ZSM-5 zeolite crystallization as described in the literature. The samples obtained were studied using ammonia (NH3) thermodesorption techniques. X-ray diffraction, high resolution electron microscopy, selected area electron diffraction and optical diffractometry methods were used in order to determine structural characteristics of zeolites above mentioned.Figure 1 shows the results of NH3 thermodesortion studies for three zeolites: Z-601 (ZSM-5), Z-683 (50% A1 - 50% Ga) and Z-691 (100% Ga).


2003 ◽  
Vol 59 (2) ◽  
pp. 182-189 ◽  
Author(s):  
Karen Friese ◽  
Lorenz Kienle ◽  
Viola Duppel ◽  
Hongmei Luo ◽  
Chengtian Lin

Sr_3(Ru_{0.336},Pt_{0.664})CuO_6 crystallizes as a monoclinic structure [space group R12/c; lattice parameters a = 9.595 (15), b = 9.595 (15), c = 11.193 (2) Å and \gamma = 120°]. The crystal structure is pseudotrigonal and the crystal investigated here by single-crystal X-ray diffraction was a multiple twin composed of six individuals. The twin laws are a combination of rhombohedral obverse/reverse twinning plus the threefold axis from the trigonal system. The crystal structure is related to the hexagonal perovskites. Each Pt/Ru atom is coordinated pseudo-octahedrally by O atoms, while the overall coordination polyhedra for Cu atoms can be regarded as a strongly distorted trigonal prism, where the Cu atom is clearly shifted from the center. Each [(Ru_{0.336},Pt_{0.664})O_6] octahedron is connected to two Cu—O polyhedra via a common edge, and thus chains are formed parallel to the crystallographic c axis. Sr^{2+} ions are incorporated between the chains and are coordinated by eight O atoms. All bond distances and angles are in good agreement with literature values. Electron-microscopy studies confirm the results from X-ray diffraction and all observed domain structures can be interpreted exactly with the established twin model. No indication of Pt/Ru ordering was found in either the X-ray or the electron-microscopy investigation.


2001 ◽  
Vol 16 (7) ◽  
pp. 2013-2026 ◽  
Author(s):  
W. Tian ◽  
X. Q. Pan ◽  
J. H. Haeni ◽  
D. G. Schlom

Epitaxial Srn+1TinO3n+1 thin films with n = 1–5 were synthesized on (001) SrTiO3 substrates by reactive molecular beam epitaxy. The structure and microstructure of the films were investigated by x-ray diffraction, transmission electron microbeam diffraction, and high-resolution transmission electron microscopy (HRTEM) in combination with computer image simulations. Both diffraction and HRTEM studies revealed that all the films are epitaxially oriented with their c axis perpendicular to the (001) SrTiO3 plane of the substrate. Detailed investigations using quantitative HRTEM methods indicated that the films have the expected n = 1–5 structures of the Ruddlesden–Popper Srn+1TinO3n+1 homologous series. Among these films, Sr2TiO4, Sr3Ti2O7, and Sr4Ti3O10 thin films are nearly free of intergrowths, while Sr5Ti4O13 and Sr6Ti5O16 thin films contain noticeably more antiphase boundaries in their perovskite sheets and intergrowth defects. We show that these results are consistent with what is known about the thermodynamics of Srn+1TinO3n+1 phases.


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