Positron annihilation study of iron oxide nanoparticles in mesoporous silica MCM-41 template

• Autorzy: Surowiec Z. , Wiertel M. , Zaleski R. , Budzyński M. , Goworek J.
• Języki publikacji: EN

Abstrakty

EN

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.

Słowa kluczowe

EN

positron annihilation; Mössbauer effect; MCM-41 porous silica; superparamagnetic nanoparticles

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2010
• Tom: Vol. 55, No. 1
• Strony: 91--96
• Opis fizyczny: Bibliogr. 17 poz., rys.

Twórcy

autor

Surowiec Z.

autor

Wiertel M.

autor

Zaleski R.

autor

Budzyński M.

autor

Goworek J.

• Institute of Physics, Maria Curie-Skłodowska University, 1 M. Curie-Skłodowskiej Sq., 20-031 Lublin, Poland, Tel.: [phone], Fax: [phone],

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