XAS investigation of tantalum and niobium in nanostructured TiO2 anatase

被引:46
作者
Sacerdoti, M
Dalconi, MC
Carotta, MC
Cavicchi, B
Ferroni, M
Colonna, S
Di Vona, ML
机构
[1] Univ Ferrara, Dipartimento Sci Terra, I-44100 Ferrara, Italy
[2] Univ Ferrara, Dipartimento Fis, I-44100 Ferrara, Italy
[3] Univ Ferrara, INFM, I-44100 Ferrara, Italy
[4] CNR, Ist Struttura Mat, I-00133 Rome, Italy
[5] Univ Roma Tor Vergata, Dipartimento Sci & Tecnol Chim, I-00133 Rome, Italy
关键词
titania; nanosized powders; XAS; tantalum; niobium;
D O I
10.1016/j.jssc.2003.12.015
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Sol-gel routes were used to prepare Ta 10 at% and Nb 5 at% and 10 at% doped titania nanosized powders. When fired between 410degreesC and 850degreesC the doped titania powders are in the anatase phase; further heating up to 1050degreesC is required to obtain the rutile phase. The presence of dopant atoms delays the rate of transformation as compared with pure titania powders. Doping also affects the rate of grain growth and increases the conductance response to gas. To better understand the role played by dopant atoms in inhibiting both phase transformation to rutile and grain growth, X-ray Absorption Spectroscopy measurements were performed at the LIIIF-L-I absorption edges of Ta and Nb K absorption edge. Analysis was restricted to the anatase phase because the transformation to rutile phase, obtained by firing at 1050degreesC, is accompanied by the formation of undesired Ta and Nb oxides (Ta2O5 and Nb2TiO7, respectively). Extended X-ray Absorption Fine Structure and X-ray Absorption Near-Edge Spectroscopy analysis results indicate that in nanostructured anatase both tantalum and niobium atoms substitute Ti cations with + 5 valence state. (C) 2004 Elsevier Inc. All rights reserved.
引用
收藏
页码:1781 / 1788
页数:8
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