Structural and Vibrational Response in Al Modified NiCr2O4

Pristine and Al doped NiCr2O4 [NiCr2-yAlyO4; y = 0.0, 0.05] nanoparticles were prepared using sol-gel auto combustion route. Structural and vibrational studies were examined using X-ray diffraction technique and Raman spectroscopy. From X-ray diffraction pattern it was observed that both samples crystallize in spinel cubic structure with space group Fd3m. Al doping does not affect the crystal structure. A small amount of Cr2O3 is also present in the sample which may due to a higher melting temperature of Cr2O3. Average crystallite size decreases when Cr3+ ions are occupied by Al3+ ions. For vibrational analysis, Raman spectroscopy was performed. All active Raman modes for spinel structure were observed for both samples. Some extra modes between 300 and 400 cm(-1) were observed. These modes might be appearing due to Cr2O3 phase present in the sample.