DOI: 10.1021/cg100123q
Synthesis of Monodispersed Tantalum(V) oxide Nanospheres by an Ethylene Glycol Mediated Route
2010, Vol. 10 3424–3428
Babita Baruwati and Rajender S. Varma* Sustainable Technology Division, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West M. L. K. Drive, MS 443, Cincinnati, Ohio 45268 Received January 26, 2010; Revised Manuscript Received June 18, 2010
ABSTRACT: Tantalum(V) oxide (Ta2O5) nanospheres have been synthesized by a very simple two-step process mediated via the formation of glycolate nanoparticles and their subsequent hydrolysis at room temperature in an acetone-water mixture and calcination at 700 °C. The synthesized particles were characterized by XRD, TEM, SEM, and DLS for their phase, morphology, and particle size distribution. The particle sizes could be tailored from 50 to 500 nm or more by changing the reaction conditions. The larger particles are actually constituted by crystallites of around 15-16 nm that could be seen from the X-ray diffraction pattern as well as the TEM micrographs of the calcined samples. The particles obtained are highly dispersed under appropriate reaction conditions, and the process does not require any specific equipment or high vacuum technique for the production of the nanoparticles.
Introduction Tantalum(V) oxide (Ta2O5) is an interesting functional material for the scientific community as it has been used in various applications such as dynamic random access memory (DRAM) devices, antireflection coating layers, gas sensors, photocatalysts, and capacitors owing to its high dielectric constant, high refractive index, chemical stability, and high temperature piezoelectric properties.1-7 With the increasing practical applications of nanosized materials, there have been tremendous efforts in developing new synthetic methodologies for the production of these materials with size and shape specificity. Although there have been a plethora of publications related to the synthesis of nanomaterials, including metals and metal oxides with controlled morphologies, the number of reports related to the synthesis of tantalum oxide nanoparticles have been few. Particularly, the number of reports via the chemical route to size- and shape-selective synthesis of tantalum oxide nanoparticles is very scarce. The majority of the work focuses on the synthesis of mesoporous Ta2O5 for various organic transformation reactions without any detailed specifications on the size and shape.8,9 Chueh et al. reported the synthesis of SiO2/Ta2O5 core-shell nanotubes, Ta2O5 nanotubes, and Ta2O5 nanowires by using SiO2 nanowires as the template. The structures were prepared by annealing SiO2 nanowires in an atmosphere of Ta at 950 °C at a pressure of 1
