Spinel Ferrites (CoFe2O4): Synthesis, Magnetic Properties, and Electromagnetic Generator for Vibration Energy Harvesting

Cobalt ferrite bearing the chemical formula of CoFe2O4 was synthesized by a high-temperature solid-state reaction. The Rietveld refinement of the experimental XRD data shows that the synthesized material crystallizes in a cubic symmetry with a lattice parameter a = b = c = 8.391 Å. The magnetic property of CoFe2O4 reveals the maximum magnetization value of 84.17 emu/g, confirming a strong ferrimagnetic nature. Further, we have built an electromagnetic energy generator (EMG) device based on the CoFe2O4 magnetic material, copper coil, and three-dimensional (3D) printed tube-like structure. The electrical output response of the device was collected by shaking it by hand and an electric shaker. A voltage of 1.95 V and current of 4.7 mA was generated from the device while delivering a power output as high as 0.86 mW at a load resistance of 103 Ω. The electrical output remained constant over long-term device operation, confirming that the fabricated device is capable of generating a stable output for a longer duration. Powering of light-emitting diodes (LEDs) and charging of capacitors were performed by utilizing the fabricated EMG. Further, the self-powered recognition of different speeds when the device was placed upon an electric shaker confirms that it can be utilized in many real-time applications.