Construction of core@shell nanostructured NiFe2O4@TiO2 ferrite NAND logic gate using fluorescence quenching mechanism for TiO2

This study reports on the construction of nano nickel ferrite NAND logic gate utilizing the concept of fluorescence quenching mechanism due to its possible applications for the TiO2 sensor. Sol-gel auto combustion route and two-step synthesis procedures were adopted for synthesis and characterization of NiO, NiTiO3, NiFe2O4, and novel magnetic core-shell NiFe2O4@TiO2. The high crystalline phase formation, surface morphology and identical particle size formation (23-32 nm) were confirmed from XRD, SEM and W-H plot respectively. The TEM micrographs of core-shell NiFe2O4@TiO2 revels the inhomogeneous cages of TiO2 and unsymmetrical boundary around the magnetic NiFe2O4 core. The optical band gap (determined from UV-DRS spectra using Kubelka-Munk equation) decreases significantly from NiO(3.94 eV) to NiFe2O4@TiO2(1.84 eV) indicates enhanced semiconducting nature. The FTIR-ATR spectra spotlighted on the relaxation of the intrinsic metallic [Ni-(octa/tetra)-O] stretching vibrations from NiO to NiFe2O4@TiO2 core-shell. The quenching intensity of photoluminescence (PL) spectra in core@shell nanostructured materials inspires us to design an analogical nano ferrite NAND logic gate. The threshold value of logic gate response was established on 0.5 for the desired output signal. Finally, the potential applications of the ferrite NAND logic gate have utilized for TiO2 sensing. The saturation magnetization was lessened in magnetic core-shell NiFe2O4@TiO2 (7.13 emu/gm.) due to TiO2 shell. (C) 2018 Published by Elsevier B.V.