Influence of Cr doping on the structural, optical, magnetic, and photoluminescence behavior of Zn0.96−xNi0.04CrxO nanostructures

• DOI: 10.1007/s10854-020-05170-0
• Publication Date: 2021-01-19T19:03:01Z
• Authors: P. Gokula Krishnan; S. Muthukumaran; V. Raja
• Keywords: Ionic radius; Hexagonal phase

Ni, Cr, co-doped ZnO nanostructures with different Cr concentrations from 0 to 4% have been synthesized using sol–gel route. Hexagonal structure of ZnO and phase purity were confirmed by X-ray diffraction (XRD) patterns. Cr doping into Zn–Ni–O could not alter the hexagonal structure. The steady decrease of crystallite size by Cr substitution revealed the proper substitution of Cr3+ instead of Zn2+ in ZnO lattice with dissimilar ionic radii. The diminishing energy gap by Cr addition is due to the s–d and p–d exchange interactions among the localized d electrons of the Cr ions. The presence of Cr in Zn–Ni–O lattice was confirmed by Fourier transform infra-red (FTIR) analysis through structural bonding. The significant modulation in photoluminescence (PL) intensity, position of different PL bands, and the increase of PL emissions by Cr doping is discussed based on electron concentration, zinc interstitial, and zinc vacancies. Room temperature ferromagnetic (RTFM) nature in the derived samples is the collective consequence of intrinsic defects and exchange interaction and not by any other magnetic or Ni/Cr oxide phases.