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Drawing of the frame work structure of zeolite 13X is shown. Non-equivalent four oxygen atoms lie at the centre of each line segments while Si and Al atoms are alternatively present at tetrahedral intersections. Positions of cations other than Si, Al present in the frame work structures are shown in terms of Roman symbols I-IV.
XRD spectra of iron oxide nanoparticles grown in zeolite and subsequent to annealing treatments at different temperatures as mentioned.
Mössbauer spectra obtained at 300 K in the bare and zeolite dispersed superparamagnetic particles of iron oxides in the as prepared condition and subsequent to annealing at different temperatures are shown in left and right panels, respectively.
Variations of hyperfine parameters viz., and relative fraction f1 of iron atoms (associated with superparamagnetic particles) with annealing temperature in the case of bare and zeolite dispersed nanoparticles are shown in the left and right panels respectively. Monotonous changes are seen in the case of bare nanoparticles while the hyperfine parameters as experienced by 57Fe atoms associated with superparamagnetic particles of iron oxides as dispersed in zeolite remain constant for annealing treatments up to 820 K and exhibit sharp change beyond 850 K implying the onset temperature of detrapping of iron oxide nanoparticles.
Mössbauer spectra corresponding to iron oxide nanoparticles formed in zeolite (a) with the application of magnetic field parallel to γ ray direction on the as prepared sample and (b) subsequent to annealing treatment at 893 K.
Mössbauer results on the sample containing bare and zeolite dispersed iron oxide nanoparticles prepared using co-precipitation method subjected to annealing treatments as explained in this work.
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