Effect of barium on the surfaces and the reductibility
of rare earth oxides La2O3, Nd2O3 and Sm2O3
M. Ghelamallah*, M. Sebane, S. Kacimi
Materials and Catalysis Laboratory, Department of Chemistry, Faculty of Sciences,
Djillali Liabes University, P.O. Box 89 Larbi Ben M’hidi City, 22000 Sidi Bel-Abbes, Algeria.
* Corresponding author. E-mail:firstname.lastname@example.org
Received: 22 November 2006; revised version accepted: 27 March 2007
Rare earth oxides (REO), type Ln2O3 (where Ln = La, Nd and Sm), were hydrolysed in neutral medium. By addition of BaCO3 three series of samples, designed noted LnBaX (where X = % atomic Ba), are obtained. These were calcined at 723 and 1423 K. The effects of barium on REO are followed by BET, XPS and RTPH2 measurements. After calcinations at 723 K, barium appears without effect on surfaces of La2O3 and Nd2O3, on the other hand 15 % in this element double the surface of Sm2O3. After calcinations at 1423 K, surface of the REO increase when the rate of barium increase. In particular with 15 % of barium the surfaces of Sm2O3 triple and of La2O3 double. The XPS have detected three peaks C1s, dues to the contamination by carbon, carbon linked to an oxygen C-O and carbon linked to two oxygen O-C=O. Three other peaks O1s correspondent to O2-, carbonates and oxygen linked to H result by adsorbed H2O. The RTPH2 profiles indicate that reduction reactions are added to the effects of the temperature, especially during the dismutation of barium carbonate to BaO and CO2 in the range of 1003 – 1023 K. The global consumption of hydrogen increase with rate of barium added.
Keywords: REO; Barium; Hydrolysis; Calcinations; Surface; RTPH2