- Tytuł:
- Positron annihilation study of iron oxide nanoparticles in mesoporous silica MCM-41 template
- Autorzy:
-
Surowiec, Z.
Wiertel, M.
Zaleski, R.
Budzyński, M.
Goworek, J. - Powiązania:
- https://bibliotekanauki.pl/articles/148449.pdf
- Data publikacji:
- 2010
- Wydawca:
- Instytut Chemii i Techniki Jądrowej
- Tematy:
-
positron annihilation
Mössbauer effect
MCM-41 porous silica
superparamagnetic nanoparticles - Opis:
- The subject of investigation were the samples obtained by impregnation of MCM-41 template with an aqueous solution prepared from Fe(NO3)3ź9H2O. As a result of such a procedure, iron oxides deposits on MCM-41 were formed. The Mössbauer studies revealed an occurrence of Fe3O4 nanocrystallites in the both ferri- and superparamagnetic states. Almost 80% small particles exist in a paramagnetic state. The positron annihilation lifetime spectroscopy (PALS) spectra were measured in air or in vacuum. The long-lived ortho-positronium (o-Ps) components and their intensities are time dependent due to air molecules interaction with iron oxide nanocrystallites and silica walls surfaces. The adsorption of air on the nanocrystallites surface causes a total screening of their surface and a raise of the o-Ps lifetime values. Observed anti-quenching effect is a result of competition of two phenomena: practically switching off a pick-off mechanism related to interaction of o-Ps with magnetite nanoparticles and considerably weaker usual quenching by paramagnetic oxygen molecules.
- Źródło:
-
Nukleonika; 2010, 55, 1; 91-96
0029-5922
1508-5791 - Pojawia się w:
- Nukleonika
- Dostawca treści:
- Biblioteka Nauki
Artykuł