Syntéza nanokrystalického oxidu ceričitého dopovaného Sm,Gd a Y v přítomnosti ultrazvuku a za hydrotermálních podmínek

Synthesis of nanocrystalline ceria doped by Sm, Gd and Y in presence of ultrasound and under hydrothermal conditions

conference paper

Czech

In the present study, the hydrothermal conditions and ultrasound fields were used for synthesis of nanocrystalline ceria doped by Sm, Gd and Y. The aim of this work was study of the effect of reaction conditions on phase composition, microstructure, particle size distribution, surface area and agglomeration of the product particles. Doped ceria (molar ratio CeO2/Re2O3=9) was precipitated from an isopropanol solution of nitrates in the presence of the mixture of ammonium hydroxide and hydroperoxide. In the first type of experiment made in/without presence of ultrasound field (60-70C/1h) the recieved precipitates were hydrothermal treated at 150C for 4 hours (marked UN-untreated, US-ultrasound, HT-hydrothermal treated, US+HT-ultrasound+hydrothermal treated). In the second type of exepriment the precipitations were performed under hydrothermal conditions at 150C for 4 hours (marked HTP-hydrothermal precipitation). The final products were repeatly washed by isopropanol. The alcohol suspensions were used for determination of particle size distribution and microstructure of the product. Dried product (100C/2h) was analysed by RTG diffraction (phase composition and crystallinity size) and BET (surface area). In all synthesized products the only crystalline monophase doped ceria - Ce0,8ReO,2O1,9 (corresponding to molar ratio of reactants) was found. Phase composition was not affected by reaction conditions (by reaction temperature respectively) and crystallite size of the products was comparable (about 2,0-5,0 nm). It was found that ultrasound had an effect on the agglomeration of particles. Whereas the agglomerate size of UN and HT products was 2,2-2,5 ěm, the agglomerate size of US and US+HT synthesed products was 0,7-1,6 ěm. This effect was confirmed by the HTP products, which agglomerate size was to 3,9 ěm. Hydrothermal conditions had no effect on the agglomeration of the particles. Surface area of ceria particles (US and US+HT) was 49,5-86,0 m2/g. These results agree with determined crystallite size of these products.

In the present study, the hydrothermal conditions and ultrasound fields were used for synthesis of nanocrystalline ceria doped by Sm, Gd and Y. The aim of this work was study of the effect of reaction conditions on phase composition, microstructure, particle size distribution, surface area and agglomeration of the product particles. Doped ceria (molar ratio CeO2/Re2O3=9) was precipitated from an isopropanol solution of nitrates in the presence of the mixture of ammonium hydroxide and hydroperoxide. In the first type of experiment made in/without presence of ultrasound field (60-70C/1h) the recieved precipitates were hydrothermal treated at 150C for 4 hours (marked UN-untreated, US-ultrasound, HT-hydrothermal treated, US+HT-ultrasound+hydrothermal treated). In the second type of exepriment the precipitations were performed under hydrothermal conditions at 150C for 4 hours (marked HTP-hydrothermal precipitation). The final products were repeatly washed by isopropanol. The alcohol suspensions were used for determination of particle size distribution and microstructure of the product. Dried product (100C/2h) was analysed by RTG diffraction (phase composition and crystallinity size) and BET (surface area). In all synthesized products the only crystalline monophase doped ceria - Ce0,8ReO,2O1,9 (corresponding to molar ratio of reactants) was found. Phase composition was not affected by reaction conditions (by reaction temperature respectively) and crystallite size of the products was comparable (about 2,0-5,0 nm). It was found that ultrasound had an effect on the agglomeration of particles. Whereas the agglomerate size of UN and HT products was 2,2-2,5 ěm, the agglomerate size of US and US+HT synthesed products was 0,7-1,6 ěm. This effect was confirmed by the HTP products, which agglomerate size was to 3,9 ěm. Hydrothermal conditions had no effect on the agglomeration of the particles. Surface area of ceria particles (US and US+HT) was 49,5-86,0 m2/g. These results agree with determined crystallite size of these products.

hydrothermal synthesis, ultrasound synthesis, doped ceria

ČÁSTKOVÁ, K., CIHLÁŘ, J.

2003

1. 1. 2002

VUT v Brně, FSI

Ostrava

80-7329-027-8

Proceedings of the National Conference Nano 02

první

257

260

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