Preparation, structural, photoluminescence and magnetic studies of Cu doped ZnO nanoparticles co-doped with Ni by sol–gel method

• Published in: Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2015-11, Vol.74, p.93-100
• Main Authors: Theyvaraju, D., Muthukumaran, S.
• Format: Article
• Language: English
• Subjects: Energy gap; Magnetic property; Photoluminescence; X-ray diffraction
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2015.06.012

Zn0.96−xNi0.04CuxO nanoparticles have been synthesized by varying different Cu concentrations between 0% and 4% using simple sol–gel method. X-ray diffraction studies confirmed the hexagonal structure of the prepared samples. The formation of secondary phases, CuO (111) and Zn (101) at higher Cu content is due un-reacted Cu2+ and Zn2+ ions present in the solution which reduces the interaction between precursor ions and surfaces of ZnO. Well agglomerated and rod-like structure noticed at Cu=4% greatly de-generate and enhanced the particle size. The nominal elemental composition of Zn, Cu, Ni and O was confirmed by energy dispersive X-ray analysis. Even though energy gap was increased (blue-shift) from Cu=0–2% by quantum size effect, the s–d and p–d exchange interactions between the band electrons of ZnO and localized d electrons of Cu and Ni led to decrease (red-shift) the energy gap at Cu=4%. Presence of Zn–Ni–Cu–O bond was confirmed by Fourier transform infrared analysis. Ultraviolet emission by band to band electronic transition and defect related blue emission were discussed by photoluminescence spectra. The observed optical properties concluded that the doping of Cu in the present system is useful to tune the emission wavelength and hence acting as the important candidates for the optoelectronic device applications. Ferromagnetic ordering of Cu=2% sample was enhanced by charge carrier concentration where as the antiferromagnetic interaction between neighboring Cu–Cu ions suppressed the ferromagnetism at higher doping concentrations of Cu. Secondary phases, CuO and Zn were noticed at higher Cu content. Tuning of energy gap and PL emission band were discussed based on defect formation. [Display omitted] •Ni, Cu co-doped ZnO nanoparticles were successfully synthesized by sol–gel method.•Secondary phases, CuO (111) and Zn (101) were noticed at higher Cu content.•Energy gap was tuned by Cu content.•UV and visible emission band were discussed based on defect formation.