کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1525295 | 1511839 | 2010 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Synthesis and characterisation of nanostructured neodymium titanium oxides by sol-gel process: Controlling the phase composition, crystal structure and grain size
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Nanocrystalline neodymium titanium oxide thin films and powders with different phase compositions with mesoporous structure were produced by a straightforward particulate sol-gel route. The sols were prepared in various Nd:Ti molar ratios and they showed a narrow particle size distribution in the range 20-26 nm. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders contained mixtures of Nd4Ti9O24, Nd2Ti4O11, Nd3Ti4O12 for titanium dominant powders (Nd:Ti â¤Â 45:60), mixtures of Nd2TiO5 and Nd2O3 for neodymium dominant powders (Nd:Ti â¥Â 75:25) and pure Nd3Ti4O12 phase for equal molar ratio of Nd:Ti, depending on the annealing temperature and Nd:Ti molar ratio. Moreover, it was found that Nd:Ti molar ratio influences the preferable orientation growth of the neodymium titanium oxide compounds. Transmission electron microscope (TEM) images confirmed that the average crystallite size of the powders annealed at 400 °C was in the range 1.0-2.8 nm and a gradual increase was occurred up to 6.7 nm by heat treatment at 1000 °C. The activation energy of crystal growth reduced with a decrease of Nd:Ti molar ratio, calculated in the range 6.90-18.12 kJ molâ1. Low activation energies indicating that the grain size will not change much with increase in temperature. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had uniform, mesoporous and nanocrystalline structure. Moreover, atomic force microscope (AFM) images presented that the thin films had a columnar like morphology with average grain size in the range 17-30 nm at 600 °C and 47-60 nm at 800 °C, depending upon the Nd:Ti molar ratio. Based on Brunauer-Emmett-Taylor (BET) analysis, the synthesized powders showed mesoporous structure containing pores with sphere like shapes. The surface area of the powders was enhanced by increasing Nd:Ti molar ratio and reached as high as 110 m2 gâ1 for the powder containing Nd:Ti = 75:25 (molar ratio) at 400 °C. In addition, the mesoporous structure of the powders was stable at high annealing temperatures up to 900 °C.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Chemistry and Physics - Volume 122, Issues 2â3, 1 August 2010, Pages 512-523
Journal: Materials Chemistry and Physics - Volume 122, Issues 2â3, 1 August 2010, Pages 512-523
نویسندگان
M.R. Mohammadi, D.J. Fray,