The structural, vibrational, and magnetic properties of maghemite nanoparticles functionalized with zeolite type 5A and synthesized by coprecipitation were studied in detail. Crystallite and particle sizes were determined and discussed based on the polydispersity index. Its value of 0.4 has suggested the presence of a broad particle distribution with particle sizes between 3 and 20 nm. Three samples were successfully functionalized either before or after the formation of the maghemite nanoparticles. Infrared studies have shown that the functionalization has occurred by hydrated surface groups present in the zeolite type 5A surface, which have favored strong bindings and highly concentrated regions of maghemite nanoparticles. From the temperature dependence of the hyperfine magnetic field obtained by Mössbauer spectroscopy, the effective magnetocrystalline anisotropy constants of the three nanohybrids were determined. They are one order of magnitude higher than for the bulk counterpart, and there is evidence for strong interparticle interactions for the three studied nanohybrids. These strong magnetic interactions of the nanoparticles in the zeolite framework have favored a superspinglass-like behavior for all samples with transition temperatures located at 74 and 208 K, as confirmed by AC susceptibility measurements.
Bibliographical noteFunding Information:
The authors thank the Universidad Nacional Mayor of San Marcos, IPKM-TUBS, and UFES for support. Edson Caetano Pas-samani also thanks FAPES and CNPq for supporting his research studies at UFES.
© 2021 Author(s).