Influence of initial pH on the particle size and fluorescence properties of the nano scale Eu(III) doped yttria

Europium doped ytrrium oxide (Eu:Y2O3) was synthesized by a chemical wet method in the presence of tween-80 and epsilon -caprolactam in pH range 4-10. It has been observed that the variation in surface area, pore size, and pore volume of the final product, was strongly dependent on the initial pH of the solution. The powder with a large surface area (similar to 230 m(2)/g) and low pore diameter (similar to 16 nm) was obtained when the powder was processed at pH similar to4. The crystallite sizes of the powders processed at pH similar to4 and 10, were found to be 35 and 198 nm, respectively. The structural, chemical and thermal studies of the powders were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectrophotometer (FTIR), Carbon analyzer and Thermogravimetry (TGA). High resolution transmission electron microscopic (HRTEM) study of heat treated powders showed a polygonal morphology with particle size of 40 nm when powder was derived at pH similar to4. Observations of fluorescence suggested that the D-5(0) --> F-7(2) transition within europium was found to be highly dependent on the initial pH. (C) 2001 Elsevier Science Ltd. All rights reserved.