Structural and vibrational response in Al modified NiCr 2 O 4

Abstract

Pristine and Al doped NiCr 2 O 4 [NiCr 2-y Al y O 4 ; 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 Cr 2 O 3 is also present in the sample which may due to a higher melting temperature of Cr 2 O 3 . Average crystallite size decreases when Cr 3+ ions are occupied by Al 3+ 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 Cr 2 O 3 phase present in the sample.