Enhancement of physical properties of Zn1-xNixO pellets synthesized by novel TVA technique for device applications

Abstract

Ni-doped ZnO (Zn1-xNixO, x = 0.03, 0.05, 0.06) pellet samples were chemically synthesized by pyrophoric method, followed by annealing at 800 °C for 4 h. To reduce the coherently diffracted domains or the particle size of the synthesized pellets, a novel thermo-vibrational annealing (TVA) technique was used, which was based on the principle of applying a constant source of vibrational mechanical energy at the time of annealing, also followed by vibrational dry quenching. The complete setup was designed and fabricated in-house. Using this setup, two optimized concentrations of Zn0.95Ni0.05O samples were prepared, one processed with calibrated vibration at a speed of 360 rpm and the other processed without vibration. From X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) studies, it was found that the particle size of the sample annealed with vibration was reduced to nano compared to the sample annealed without vibration. The corresponding grain size reduction was observed by scanning electron microscopy (SEM) studies. The semiconducting nature of both the samples with n-type charge carriers was confirmed by Hall Effect measurements. The low field positive magnetoresistance was observed for both the samples at room temperature (RT). Magnetization measurements (SQUID) showed that the room temperature ferromagnetic behavior in the sample can be improved by annealing in the presence of vibrational mechanical energy. Therefore, the novelty of the synthesis method in achieving smaller particles and grains are noteworthy, which can be used as a promising candidate for various spintronics device as well as sensing applications.