Growth and characterization of Nd, Yb – Yttrium oxide nanopowders obtained by sol-gel method
|Agnieszka Rzepka 1, Witold Ryba-Romanowski 2, Ryszard Diduszko 1, Ludwika Lipińska 1, Anna Pajaczkowska 1|
1. Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland
Yttrium oxide (Y2O3) is interesting host material for high power laser applications. Y2O3 belongs to group oxides with very high melting point. For yttria this is 2430 0C. At about 2280 0C its structural phase transition is observed. Furthermore its thermal conductivity is higher then well-known yttrium aluminum garnet (YAG) crystals and their thermal expansion coefficient is very similar. Moreover sesquioxide Y2O3 can be doped by rare earth ions and it is a good phosphor used in optical displays and light emitting devices.
In this work the nanosized powders of the following systems: Y2O3; Y2O3:Nd3+; Y2O3:Yb3+; Y2O3:Nd3+, Yb3+ were prepared by sol-gel method using EDTA, 1,2-Ethanediol and citric acid. Finally the one phase compounds of Y2O3 doped 0,5 % Nd and 1, 2 or 4 % Yb were obtained.
The influence of thermal treatment on nanopowders properties were investigated. The gels were dried at 120 oC for 12 h and then grinded in an agate mortar to obtain fine powder. The xerogel powders were heat treated at various temperatures from 600 to 1200 oC in air. The calcining time was changed from 1 to 10 h.
The crystal structures of samples were characterized by X-ray diffraction (XRD) using a Siemens D-500 diffractometer with CuKα radiation at λ = 1.548 Å. The size and morphology of nanopowders were analyzed by scanning electron microscopy (SEM) and were performed with DSM-950 microscope and high resolution scanning electron microscopy (HRSEM) was performed with LEO GEMINI 1530 microscope. Luminescence spectra were recorded with a Dongwoo Optron Fluorometer system.
Average size of crystallites was evaluated using Scherrer formula and the sizes were increased with the calcining temperature (600 ÷ 1200 oC) from 10 to 85 nm. Also morphology of crystallites was changed with the temperature of calcination. The calcining time was changed from 1 to 10 h and it did not influence on the crystallite sizes. There were not (evident) relationships between the crystallite sizes and the time of calcination (1 ÷ 10 h), the concentration of doping elements (Nd, Yb) and the used complexing chemical compounds.
Spectroscopic investigation of nanopowders revealed occurrence of intense emission in near infrared region. Three emission bands characteristic of Nd3+ and one emission band characteristic of Yb3+ were recorded for Y2O3:Nd3+ and Y2O3:Yb3+ samples respectively. For Y2O3:Nd3+, Yb3+ samples the emission consists essentially of one band related to partially overlapping transitions of Yb3+ and Nd3+. Analysis of luminescence decay curves indicates that metastable states of the two ions are linked by fast nonradiative energy transfer processes.
This work was supported by Ministry of Education and Science under the research project no.3T11B00430.
Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Agnieszka Rzepka
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth
Submitted: 2007-01-15 13:01 Revised: 2009-06-07 00:44
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