Green synthesis of Jamborite phase hexagonal nickel oxide nanoparticles (Ni3O6-NPs), structural, optical, electrical and dielectric behavior followed by seed germination

Jamborite phase hexagonal nickel oxide nanoparticles (Ni 3 O 6 -NPs) have been of great interest due to their outstanding optical, dielectric and electrical properties. NPs were synthesized by green method using Citrus jambhiri leaves extract and Nickel acetate tetra-hydrate (Ni(CH 3 CO 2 ) 2 .4H 2 O) precursor for checking their effect on the germination of Sorghum bicolor seeds. Samples were annealed at 500 ºC. Structural, optical, electrical and dielectric behavior of Ni 3 O 6 -NPs were analyzed using X-ray diffraction, UV-Visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, current-voltage (I-V) and dielectric measurement. The hexagonal closed packed structure was confirmed through XRD analysis and the range of crystallite size was found from 8.5 to 11.2 nm. The dislocation density (7.97 × 10 −3 1/nm 2 –13.8 × 10 −3 1/nm 2 ), lattice strain (7.7 × 10 −3 –9.9 × 10 −3 ) and surface area (25.375–33.724 m 2 g −1 ) were also calculated. Direct optical band gaps of prepared samples were estimated using the Tauc's relation in the range of 2.93–3.25 eV. The electrical measurements afrimed the semiconducting behavior of the NPs. The dielectric constant (131.28), dielectric loss (256.1), and loss tangent (3.62) were observed from the dielectric analysis of the samples. Photoluminescent spectra of prepared samples exhibit spectra at 445–495 nm emission bands, which confirm the existence of oxygen and nickel vacancies. Functional groups accountable for the essential synthesis and solidity of NPs were illustrated by FTIR spectroscopy. Bands at 770 cm −1 and 858 cm −1 are due to stretching vibration of metal-oxide (Ni–O) bonds. Application of NPs as bio-fertilizer showed that Ni 3 O 6 -NPs have positive effect on the germination of Sorghum bicolor seeds. The maximum germination index (GI), relative root elongation (RLE) and relative seed germination (RSG) were increased by Ni 3 O 6 -NPs mediated samples 111.2–145.7%, 55.71–72.85% and 200%, respectively as compared to control sample.