Dear Baskaran Palanivel,

I think you will not change significantly a nickel ferrite (NiFe2O4) at such temperature (see for instance S. Corso et al. Preparation conditions of pure and stoichiometric

NixFe3−xO4 bulk ceramics, Solid State Sciences 6 (2004) 791–798) . If you are working in air with NixFe3-xO4 (x

Hi Baskaran,

The composition of ferrites can be changed by controlling the Po2 at a given temperature. If this is not well done you will get phase segregations (Fe2O3, FeO, NiO). In general you need lower partial oxygen pressures at lower temperatures for ferrites but having a good phase diagram will help finding the right Po2. To achieve a lower Po2 you can either add N2 to Air or use a vacuum oven and choosing the O2-flow such that the right Po2 is obtained at 300C. To check for phase segregations you can do powder XRD. 

Hi Philippe Tailhades ,

Thank you for your kind information and valuable suggestions.

I want to make NiFe2O4 - ZnO composite for this how can i make composite in chemical reaction or any other physical reaction. I already tried co-precipitation method in that method i didn't use NiFe2O4 instead i used dried power of NiFe2O4 before calcination process.I put this powder into ZnO prcursor solution after calcination process by this steps i got ZnO- ZnFe2O4-some amount of NiFe2O4 only. These all are confirmed by XRD peaks. If ypou have any other method for make this composites please suggest me.

i read many papers most of all used Hydrothermal process for composites but all are used ZnO as a core. But i want to make NiFe2O4 as a core. What should i do for this?