Study of spinel-type ZnNixCo2−xO4 nano-particles, synthesised by thermal decomposition of ternary metal nitrate solutions

• Low temperature synthesis of spinel-type ZnNixCo2-xO4 nano-particles.
• Ni/Co site selective physiochemical properties.
• Superparamagnetic like behaviour.
• Dc conductivity at 30 °C is 0.03 S/cm for ZnNi0.6Co1.4O4 nanocrystals.

We report the structural, magnetic and electrical properties of new composition of spinel-type ZnNixCo2−xO4 (0.1 ≤ x ≤ 0.6) nano-particles. The X-ray diffraction and Fourier transform infrared spectroscopy studies reveal that the ZnNixCo2−xO4 nano-crystals show pure cubic spinal for all compositions wherein Co ions are systematically replaced by Ni ions. The electron microscopic studies reveal the nanoparticle sizes are of well-defined spherical shape and the magnetometry studies show superparamagnetic like behaviour with smaller values of coercive fields. The maximum dc conductivity at 30 °C is found to be 0.03 S/cm for ZnNi0.6Co1.4O4. Activation energies of dc conductivity obtained from Arrhenius plots are within the range of 0.12–0.35 eV for extrinsic and 0.13–0.78 eV for intrinsic regions and are affected by Ni concentration. Overall results suggest that these nano-particles are of high crystalline quality and electrical properties are dominated by holes as major charge carriers.

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