A Novel Simple Route to Synthesize Aqueous Niobium and Tantalum Precursors for Ferroelectric and Photocatalytic Applicat
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A Novel Simple Route to Synthesize Aqueous Niobium and Tantalum Precursors for Ferroelectric and Photocatalytic Applications Ai-Dong Li1, Jin-Bo Cheng2, Rong-Lu Tang2, Qi-Yue Shao2, Yue-feng Tang2, Di Wu2, and Nai-Ben Ming3 1 National Lab. of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu, 210093, China, People's Republic of 2 Materials Science and Engineering Department, Nanjing University, Nanjing, Jiangsu, 210093, China, People's Republic of 3 National Lab. of Solid State Microstructures, Physics Department, Nanjing University, Nanjing, Jiangsu, 210093, China, People's Republic of
ABSTRACT A simple novel route to synthesize aqueous tantalum and niobium precursors has been developed using cheap and stable Nb2O5 or Ta2O5 as starting source, based on basic flux technique. Various analytical techniques have been employed to characterize the purity, and thermal decomposition features of the precursors. Using home-made Ta and Nb precursors, several photocatalysts and ferroelectric powders such as LiNbO3, LiTaO3, Sr0.75Ba0.25Nb2O6, and SrBi2Ta2O9 have been prepared at lower processing temperature by a polymerizable complex route successfully. INTRODUCTION Due to the great potentials of tantalate and niobate materials in ferroelectric [1,2] and photocatalytic applications [3,4], the development of proper tantalum or niobium precursors is urgently needed. In wet chemical syntheses of Ta-based or Nb-based oxide such as sol-gel and metalorganic decomposition, alkoxides of tantalum and niobium are most frequently used as starting sources. However, some inherent problems are associated with Ta or Nb alkoxides, including relatively high cost and great sensitivity to moisture [5]. Alternatively, TaCl5 or NbCl5 has been utilized as a Ta or Nb precursor due to less sensitivity to moisture and cheaper price [6]. However, a small concentration of residual chloride might cause the degradation of optoelectronic and dielectric properties of the final materials. And TaCl5 or NbCl5 is still unstable in the presence of water or humid ambient. Recently a simple polymerizable complex (PC) route, known originally as the Pechini method, has been developed to solve these problems [7,8]. However, air-stable water-soluble tantalum and niobium precursors are still not easily available so far. In this paper, a simple novel processing starting from Ta2O5 and Nb2O5 was for the first time developed to synthesize aqueous tantalum and niobium precursors based on the conventional
basic flux method [9]. Aqueous Ta and Nb precursors with high purity over 99.5% have been obtained at low reaction temperature. The thermal decomposition features of the precursors have been investigated. Using home-made Ta or Nb precursor, several photocatalysts and ferroelectric powders such as LiNbO3, LiTaO3, and Sr0.75Ba0.25Nb2O6 (SBN), SrBi2Ta2O9 (SBT) have been prepared at lower processing temperature by Pechini-type PC method. EXPERIMENTAL DETAILS Ta2O5 and Nb2O5 (wt % >99.5
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