The effect of pH on X-ray-radiolysis-induced synthesis of nickel nanoparticles on lithium niobate substrates

Abstract

Photochemical reactions in aqueous media induced by X-ray irradiation have been shown to enable the synthesis of functional structures ranging from nanometer to millimeter scales. Herein, we demonstrate the synthesis and immobilization of nanoscale/microscale Ni particles onto lithium niobate (LiNbO3) substrates directly by X-ray irradiation of nickel sulfate (NiSO4) solutions with pHs from 1 to 9 using a synchrotron radiation facility. We found that the size and composition of the synthesized particles strongly depends on the pH of the solution; as pH increases, oxidation is accelerated and particle size increases. The synthesized particles exhibit magnetic hysteresis and are found to have ferromagnetic properties. Our investigation reveals that pH regulation is essential for controlling the synthesis of particles and providing characteristic functionalities to the materials. The X-ray radiolysis technique enables a state-of-the-art nanoscale/microscale three-dimensional manufacturing process that can create functional structures comprising composite constituents such as metallic and plastic materials.