Effect of Co and Ni codoping on the structural, magnetic, electrical and optical properties of ZnO

• Synthesis of Co/Ni co-doped ZnO using a simple solid state reaction method.
• Structural probing using X-ray diffraction, Raman spectra and Fourier transformation.
• Systematic band gap tailoring induced by Ni doping.
• Weak ferromagnetism at room temperature potentially viable in spintronic devices.

Co and Ni codoped ZnO-based dilute magnetic semiconductors having a general formula of Zn0.9Co0.1−xNixO (x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.10) have been prepared using a simple solid-state reaction method. A single-phase hexagonal wurtzite structure, confirmed by X-ray diffraction, has been developed for Zn0.9Co0.1−xNixO (x < 0.05), while minor secondary peaks of NiO were detected in samples having x = 0.06, 0.08 and 0.10. The study of surface morphology revealed grain sizes in the range of 1.41–0.71 μm. Raman spectra in the 200–800 cm−1 range have been studied. The direct band gap energy for all the samples was found to be less than that of pure ZnO. Fourier transform infrared spectroscopy and UV–vis spectroscopy confirmed the incorporation of the Co and Ni ions into a ZnO lattice. Magnetic characterisation performed by vibrating sample magnetometer exhibited room-temperature ferromagnetism. Temperature-dependent electrical resistivity measurements were performed using a four-point probe technique.

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