We present an experimental investigationfocused on the effects of alpha and deuteron irradiation ondifferent silica nanoparticles. The study has been devotedalso to characterize the induced point defects and theeventual structural modifications to evaluate the effects ofthe different irradiation source in comparison with the bulkmaterials. After irradiation up to about 10^16 ions cm^-2, weperformed electron paramagnetic resonance (EPR), photoluminescence(PL), infrared (IR) absorption, Raman, andatomic force microscopy (AFM) measurements. We foundthat the two types of irradiation qualitatively induce comparableeffects. Furthermore, irradiation generates the socalledtwofold coordinated Si and the H(I) point defects,originating from the reaction of the former with hydrogenatoms. The occurrence of these defects is a not trivial andinteresting finding due to its connection to irradiationinducedoxygen deficiency, not yet evidenced by otherirradiation of silica nanoparticles. We also detected theE'Si paramagnetic centers and found that their lineshape atthe highest fluence, independently from the nanoparticlessize and irradiation source, is different from the oneobserved in the bulk. Furthermore, the integral of the E0Sisignal does not depend significantly on the nanoparticlessize differing from previous irradiation with b-ray of thesame nanoparticles. AFM images indicate the absence ofsignificant radiation induced sintering between the nanoparticlesin the plan orthogonal to the irradiation directionsuggesting the absence of morphological changes, whereasIR measurements suggest the occurrence of some structuralmodifications in all the nanoparticles, which consist in thedecrease of the peak value of the Si–O–Si angle distribution.Finally, irradiation effects are induced not uniformlyalong the irradiation direction, as supported also by micro-Raman investigation of an irradiated bulk silica materialand simulations of ions penetration profiles. These resultssuggest the occurrence of some irradiation effects due tolight ion bombardment specific of nanoparticles.
|Numero di pagine||10|
|Rivista||Journal of Materials Science|
|Stato di pubblicazione||Published - 2014|
All Science Journal Classification (ASJC) codes