Structural and paramagnetic behavior of spinel NiCr2O4 nanoparticles synthesized by thermal treatment method: Effect of calcination temperature

• NiCr2O4 NPs were synthesized by a simple thermal treatment method in a large scale.
• Spinel phase NiCr2O4 was obtained in calcination temperature between 550 to 850 °C.
• Estimated sizes were ~7 and 64 nm for lowest and highest calcination temperatures.
• Calcined samples at 750 and 850 °C showed paramagnetic behavior.
• For calcined samples at 550 and 650 °C there was no clear resonance signal.

Spinel nickel chromite nanoparticles were synthesized using a simple thermal treatment method. The effect of calcination temperatures on the final properties of obtained materials was carefully examined using various characterization techniques.The infrared spectra of nickel chromite (NiCr2O4) revealed the characteristic bonds of metal–oxygen for NiO and CrO bands around 600 and 470 cm−1, respectively. The powder X-ray diffraction patterns exhibited the formation of normal spinel phase of NiCr2O4 in the calcination process at temperature between 550 and 850 °C. From transmission electron micrographs, nanosized particles with average size of ~7–64 nm were observed at calcination temperatures of 550–850 °C, respectively. The calcined samples at 750 and 850 °C exhibited paramagnetic behavior with g-factor values of 1.92 and 2.15, peak-to-peak line width of 25.59 and 117.02 Oe and resonance magnetic field of 342.04 and 306.49 Oe, respectively. Variation in the value of g-factor, peak-to-peak line width and resonance magnetic field can be attributed to the dipole–dipole and super exchange interactions.