Nonstoichiometry and Point Defect Structure of Olivines, (FexMg1-x)2SiO4

1994 ◽  
Vol 369 ◽  
Author(s):  
Tse-Lun Tsai ◽  
R. Dieckmann
Keyword(s):  
Transition Metal ◽  
Point Defect ◽  
Noble Metal ◽  
Defect Structure ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Experimental Results ◽  
Cationic Composition ◽  
Gel Method ◽  
Point Defect Structure

AbstractA thermogravimetric study was conducted on synthetic olivines (FexMg1-x)2SiO4' prepared either by a conventional ceramic methodor a sol-gel method, to determine the nonstoichiometry and the point defect structure. Measurements were carried out as a function of oxygen activity and cationic composition at elevated temperatures. To avoid the dissolution of transition metal components of the silicate into noble metal containers, commonly used in previous investigations, quartz containers were used. The analysis of the point defect structure of olivines based on the new experimental results is presented.

Application of Nanometer Metal Oxides in Infrared Ray Shielding Transparent Thin Film

2011 ◽  
Vol 474-476 ◽  
pp. 195-199 ◽  
Author(s):  
Ai Hong Guo ◽  
Xue Jiao Tang ◽  
Su Juan Zhang
Keyword(s):  
Thin Film ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Sol Gel ◽  
Volume Ratio ◽  
Experimental Results ◽  
Mass Ratio ◽  
Gel Method ◽  
Water Based ◽  
Better Than

Water-based infrared ray shielding coating, that is, nanometer metal oxide is added to the water-based paint, which has anti-IR features without affecting the transparency of the paint. In this paper, the nanometer oxides are prepared by sol-gel method, added into polypropylene sour. In order to improve the infrared ray shielding of the thin film, two kinds of nanometer oxides are added into the polypropylene sour with different volume ratios, the shielding performance of the paint is studied. Experimental results show: in the 8000 ~ 4000cm-1 range, the transmittances of infrared ray is 30% to 75%; in 4000 ~ 400cm-1 range, transmittances decrease significantly; 3% ZnO, 3% Fe2O3, 3% Y2O3, 2% Al2O3 are the best mass ratio of every single nanometer oxide; the infrared shielding rate of Fe2O3 and Y2O3 mixture with the volume ratio of 1 to 4 is better than Fe2O3 and Y2O3 single.

Identification of ZnO Defect Structure by PL Spectroscopy

2011 ◽  
Vol 393-395 ◽  
pp. 135-138 ◽  
Author(s):  
Peng Fei Cheng ◽  
Han Chen Liu ◽  
Ying Tang Zhang
Keyword(s):  
Defect Structure ◽  
Sol Gel ◽  
Optoelectronic Devices ◽  
Good Deal ◽  
Intrinsic Defect ◽  
Zno Film ◽  
Gel Method ◽  
Zno Crystal ◽  
Almost All ◽  
Intrinsic Defect Structure

Defect structure of ZnO determines the optoelectronic characteristics of ZnO crystal and film. The identification and modulation of the defect structure is the foundation of the manufacture of optoelectronic devices. Although a good deal of research has been carried out about intrinsic defects and doping defects in ZnO, it is difficult to obtain a conclusive result accepted by all. In the paper, ZnO film is prepared by sol-gel method and the defect structure is expressed by photoluminescent (PL) spectroscopy. Based on some basic rules the intrinsic defect structure of ZnO is confirmed and the interaction of impurity Li and intrinsic defect is discussed. At the same time, some new electronic levels are proposed. It is surprising that although there are fourteen peaks in PL spectra of ZnO film, almost all the peaks can be identified by these basic rules.

Fabrication of Bi-2223 Powders Using Sol-Gel Method

2011 ◽  
Vol 412 ◽  
pp. 125-128 ◽  
Author(s):  
Ming Ya Li ◽  
Xiao Yan Wang ◽  
Cheng Li Ye ◽  
Feng Lin Xue
Keyword(s):  
Heat Treatment ◽  
Sol Gel ◽  
Chelating Agent ◽  
Experimental Results ◽  
Main Phase ◽  
Gel Method ◽  
Sol Gel Method ◽  
Dwelling Time ◽  
Metal Nitrates ◽  
Gel Technique

The Bi-2223 powders were fabricated by the sol-gel technique. Metal nitrates were used as starting materials, and ethylenediamineteracetic acid was used as chelating agent. The solution was heated until it turns to gel. Then the organic was removed at a temperature of 240°C, and the nitrite was removed at 500°C. The powder was calcined at different temperature, varying the dwelling time. Experimental results show that the main phase of samples after heat treatment is Bi-2212 phase.

Effect of Transition Metal Ion Doping on the Photocatalytic Activities of TiO2 Synthesized by Sol-Gel Method

2012 ◽  
Vol 562-564 ◽  
pp. 260-264
Author(s):  
Min Zhong ◽  
Jing Jing Yu ◽  
Zhi Hao Wei ◽  
Ping Zhan Si
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Absorption Edge ◽  
Metal Ion ◽  
Sol Gel ◽  
Photocatalytic Property ◽  
Transition Metal Ions ◽  
Photocatalytic Properties ◽  
Gel Method ◽  
Sol Gel Method

Pure TiO2 , Ti 0.75 Fe0.25 O2, Ti0.75 Ni0.25 O2, Ti0.75 Co0.25 O2 nanocrystals were prepared by low temperature sol-gel method. The samples were characterized by using transmission electron microscope, X-ray diffractometer and ultraviolet-visible spectrophotometer to study the effect of transition metal ions on the photocatalytic properties of TiO2 nanocrystals. The results show that the pure TiO2 and Ti0.75 Fe0.25 O2, Ti0.75 Ni0.25 O2, Ti0.75 Co0.25 O2 nanocrystals were granular and the size of which is 3.5, 2.9, 3.6, 3.9 nm, respectively. The titania anatase phases appear in the pure TiO2 , the Ti0.75 Fe0.25 O2, Ti0.75 Ni0.25 O2, Ti0.75 Co0.25 O2. The absorption edge of Ti0.75 Fe0.25 O2occur red shift comparing with that of pure TiO2 and the absorption edge of Ti0.75 Fe0.25 O2and Ti0.75 Fe0.25 O2occur blue shift comparing with that of pure TiO2. The photocatalytic properties of pure TiO2, Ti0.75 Fe0.25 O2, Ti0.75 Fe0.25 O2, Ti0.75 Fe0.25 O2nanocrystals synthesized at low temperature by sol-gel method were investigated by degrading the methyl orange solution under ultraviolet irradiation. The degradation rate of Ti0.75 Fe0.25 O2is the highest (60%) and that of Ti0.75Co0.25O2 (10%) is the lowest among these catalysts after degradation for 120min.The result shows that the photocatalytic property ofTi0.75 Fe0.25 O2nanocrystals synthesized at low temperature is obviously better than that of pure TiO2 and Ti0.75 Fe0.25 O2, Ti0.75 Fe0.25 O2.

Sign in / Sign up

Export Citation Format

Share Document