Positron Annihilation Studies of Mesoporous Iron-Molybdenum Modified MCM-41 Silica

Z. Surowieca, M. Wiertela, W. Gacb and M. Budzyńskia aInstitute of Physics, M. Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland bFaculty of Chemistry, M. Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland

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Iron-molybdenum modified MCM-41 mesoporous materials were obtained by the application of direct hydrothermal method. An incorporation of iron and molybdenum ions in the synthesis stage led to structural changes of the MCM-41 support. With an increasing metals content, cylindrical pores of silica are destroyed. X-ray diffraction investigations indicated that both iron and molybdenum ions were first embedded in the silica walls and then formed highly dispersed species in the pores. The porous structure of the studied samples was examined by means of N2 adsorption/desorption and PALS methods. The longest-lived o-Ps lifetime component remains constant but its intensity monotonically decreases, except for the sample with the highest metals content. These results indicate that an effect of o-Ps formation inhibition occurs.

DOI: 10.12693/APhysPolA.125.789 PACS numbers: 34.80.Lx, 78.67.Bf, 78.70.Bj, 62.23.Pq, 78.67.Sc