TY - JOUR
T1 - Doping mechanism of Vanadia/Titania nanoparticles in flame synthesis by a novel optical spectroscopy technique
AU - Ren, Yihua
AU - Zhang, Yiyang
AU - Li, Shuiqing
AU - Law, Chung King
N1 - Funding Information:
This work is mainly funded by the National Natural Science Funds of China (Nos. 51176094 , 51390491 ) and by the National Key Basic Research and Development Program (No. 2013CB228506 ). S.Q.L. is grateful to Prof. Stephen Tse at Rutgers for help discussions. We acknowledge Prof. Marshall B. Long from Yale, Prof. Zhongshan Li from Lund, and Prof. Michael Renfro from Connecticut for their invaluable graduate courses delivered at Tsinghua.
Publisher Copyright:
© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
PY - 2015
Y1 - 2015
N2 - Flame synthesis of V-doping TiO2 is studied by in situ diagnostic of phase selective laser-induced breakdown spectroscopy (LIBS). We apply this novel optical spectroscopy to tracing the gas-to-particle phase transition of V and Ti elements, as low-intensity laser only excites V and Ti atoms present in the particle phase but not in the gas phase. Both V and Ti atomic signals appear early at the burner exit and plateau downstream after a distance about 14 mm. Compared with signals in pure TiO2 synthesis, the signal of Ti in the doping synthesis is significantly strengthened due to the lower band gap of V-doped TiO2. The doping mechanism is then inferred from the observations. It is deduced that the substantial collision and mixing of the nucleated V and Ti oxides occur even at the burner rim and persist through the entire process. The signal intensities of both V and Ti atoms increase with laser power and tend to plateau at about 20 mJ/pulse. In the flatten region, the ratio of V and Ti signal intensities is almost proportional to the doping ratio of V and Ti elements in the particle phase, showing feasibility of utilizing the optical method in the doping ratio measurement.
AB - Flame synthesis of V-doping TiO2 is studied by in situ diagnostic of phase selective laser-induced breakdown spectroscopy (LIBS). We apply this novel optical spectroscopy to tracing the gas-to-particle phase transition of V and Ti elements, as low-intensity laser only excites V and Ti atoms present in the particle phase but not in the gas phase. Both V and Ti atomic signals appear early at the burner exit and plateau downstream after a distance about 14 mm. Compared with signals in pure TiO2 synthesis, the signal of Ti in the doping synthesis is significantly strengthened due to the lower band gap of V-doped TiO2. The doping mechanism is then inferred from the observations. It is deduced that the substantial collision and mixing of the nucleated V and Ti oxides occur even at the burner rim and persist through the entire process. The signal intensities of both V and Ti atoms increase with laser power and tend to plateau at about 20 mJ/pulse. In the flatten region, the ratio of V and Ti signal intensities is almost proportional to the doping ratio of V and Ti elements in the particle phase, showing feasibility of utilizing the optical method in the doping ratio measurement.
KW - Flame synthesis
KW - Gas-to-particle conversion
KW - Phase-selective LIBS
KW - V-doped TiO
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U2 - 10.1016/j.proci.2014.05.025
DO - 10.1016/j.proci.2014.05.025
M3 - Conference article
AN - SCOPUS:84964253670
SN - 1540-7489
VL - 35
SP - 2283
EP - 2289
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 2
T2 - 30th International Symposium on Combustion
Y2 - 25 July 2004 through 30 July 2004
ER -