Superfine Sr2CeO4:RE3+ (RE=Eu, Sm) phosphors were synthesized at relatively low temperature by a modified sol-gel method using nitrates as raw materials, ethylenediaminetetraacetic acid (EDTA) as complexing agent. Single phase phosphors could be obtained at calcination temperature above 800 °C and pH value higher than 6.4 of initial solution. The as-prepared powders consisted of uniform crotch-like grains. The preparation process was monitored by thermogravimetric and differential thermal analysis (TG-DTA) and Raman spectra. The obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and photoluminescence. Photoluminescence study indicated that strong energy transfer occurred between Eu3+/Sm3+ and host. The Sr2CeO4:RE3+ emission could be tuned from blue to white and red light by varying the concentration of RE3+. The strong emission and controllable light color are suitable for applications in advanced lighting and displaying fields.
Using organo-tin Sn(OC4H9)4 as precursor, sodium dodecyl sulfonate (SDS) and SDS-gelatin (SDS-G) complex as template, two tin dioxide colloidal particles were prepared by a self-assembly method. Both SnO2 products were respectively labelled SnO2-B particles with SDS and SnO2-C particles with SDS-G, which are applied in fabricating SnO2 gas sensors corresponding to SnO2-B' and SnO2-C' sensors. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo-gravimetry and different thermal analysis (TG/DTA) were used for characterizations. The experimental results show that SnO2-B colloidal particles are composed of mesoporous piece-like particles, while SnO2-C particles mainly consist of spherical particles. Gas sensing measurements show that SnO2-B' sensor performs the best sensing response to all target gases, including H2, C2H5OH and liquid petroleum gas (LPG). In particular, the sensing response of SnO2-B' sensor is achieved at 32 in H2 atmosphere at the concentration of 1000×10-6 M. The gas sensing mechanism was purposely discussed from the electron transfer process and the microstructures of the as-prepared SnO2 products. It is found that serious agglomerations in SnO2-B' particles facilitate the high gas sensing performance of SnO2-B' sensor, while mesoporous structures in SnO2-C' particles decrease the gas sensing response of SnO2-C' sensor.
Energy is the most important scientific and technological issue facing in the 21st century[1]. It is a tremend...
Yuxi Sun,a,b Qingli Hao,a, Lude Lu,a,* Xujie Yang,a Xin Wang,a, a Key Laboratory of Education Ministry for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Nanjing 210094
