When I synthesized nickel ferrite nanoparticles using the same method and washed them only with ethanol multiple times, they exhibited a crystalline structure. However, when I synthesized them again using the same method but washed them with both water and ethanol at the end, an amorphous structure was formed. What could be the reason for this?
Nushaba Gadirova
When synthesizing nickel ferrite, hydroxides are formed first, and then oxides. Hydroxides are amorphous, and oxides are crystalline. In order to form crystalline iron and nickel oxides in ferrite, the resulting hydroxides are calcined. If the crystalline structure of the ferrite is not fully formed... and you wash it with acetone, it continues to form. If you wash it with water, amorphous hydroxides are formed and the formation of the crystalline structure is delayed...
Article Magnetic properties of nickel ferrite nanoparticles prepared...
Yes, altering the washing solvent can modify the crystalline structure of nanoparticles by influencing surface energy, phase stability, polymorphism, and ligand interactions.
Yes, the crystalline structure of nanoparticles can change depending on the washing solvent used. In your case, the shift from crystalline nickel ferrite to an amorphous structure when washing with both water and ethanol suggests that the washing process affected the final particle structure. Here are some possible reasons:
1. Hydrolysis and Structural Disorder
Water can cause partial hydrolysis of the nickel ferrite surface, leading to structural disorder or partial dissolution.
2. Surface Energy and Reorganization
Water interaction can change surface energy and induce defects. Ethanol helps maintain crystallinity by reducing particle aggregation and allowing slow evaporation.
3. Different Drying Rates
Ethanol evaporates faster than water, supporting rapid drying. Water slows this process, potentially trapping disorder before crystallization completes.
4. Formation of Hydrated or Defective Phases
Water can form hydrated phases, which are often less crystalline. It may also leach out ions, disrupting stoichiometry.
Solutions
· Dry nanoparticles rapidly after water washing.
· Use minimal water and prefer ethanol-based washing.
Thank you Charalampos Tsekeridis How can I determine if structural disorder is present? If the XRD peaks are amorphous, how can I be sure that it is truly nickel ferrite and not its oxide or another phase?
Does the formation of the structure continue until drying is complete? I thought this process would stop after synthesis.
Only if solvent doesn't have active functional group for nanoparticles under observation
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