The effect of Ho-doping on the synthesis, structure and magnetic characteristics of ZnFe2O4-based nanopowders

Abstract

The successful production of nanopowders consisting of Ho-doped zinc ferrite (ZnFe2-xHoxO4, with x values ranging from 0 to 0.08) has been accomplished using the glycine-nitrate combustion (GNC) method, followed by calcination in air. Various analytical techniques, such as EDXS, DTA-TG, SEM, PXRD, Raman spectroscopy, and vibrating sample magnetometry (VSM), were employed to examine the resulting samples. The outcomes of our investigation indicated that an excess of fuel during the GNC process yields X-ray amorphous foamy products, which subsequently crystallize after being held at a temperature of 550 °C for a duration of 4 h. PXRD data analysis showed that the obtained samples consist of single-phase Ho-doped zinc ferrite with a spinel structure. The incorporation of holmium into the ferrite spinel structure was established to occur when the calcination temperature is elevated to 700 °C. Rietveld refinement revealed that the degree of inversion varies from 0.078 to 0.309 as the level of Ho-doping increases from x = 0 to x = 0.08. Furthermore, the incorporation of Ho leads to a more than twofold reduction in the crystallite size of ZnFe2-xHoxO4, decreasing from 61.7 to 27.3 nm. The magnetic properties of the nanopowders are shown to be systematically altered by changes in the degree of inversion and the crystallite size of zinc ferrite, which are interrelated with the holmium content. For instance, the saturation magnetization (Ms) increases by 20% and attains a value of 54.9 kOe at x = 0.08. This finding suggests that the magnetic behavior of ZnFe2–xHoxO4 nanoparticles can be deliberately adjusted, making them a promising candidate for functional materials in the field of magnetic hyperthermia. In summary, this research provides valuable insights into the synthesis, structure, and magnetic properties of Ho-doped zinc ferrite nanopowders, underscoring their potential applications in the realm of magnetic hyperthermia.