Microwave-Assisted Synthesis of Magnetic Ni Wire from a Metal−Organic Precursor Containing Ni(II) and Triethanolamine

A novel approach is proposed to synthesize Ni wire by microwave (MW) heating of the preorganized rod microstructure of crystal consisting of Ni2+ ions and triethanolamine (TEA). Field emission scanning electron microscopy (FESEM) studies of the Ni-TEA crystal reveal that TEA molecules lead to the formation of sub-micrometer-sized needle bundles that appear as a sheaf of straw tied in the middle. The organized structure stems from the hydrogen bonding, which is evident from single crystal X-ray diffraction and infrared spectroscopic (IR) studies. Microscopic studies using scanning electron microscopy, transmission electron microscopy, and atomic force microscopy show that nanoparticles of 12 nm are connected to each other and build the equilibrium wire structure. Thermogravimetric analysis-differential thermal analysis experiments in association with X-ray diffraction studies provide direct evidence that microwave irradiation plays a crucial role in stabilizing the pure Ni phase. The high blocking temperature, TB 300 K, with a remnant magnetic moment (MR) of 12 emu/g of the Ni wire is observed, allowing for room temperature magnetic applications. The observation of high blocking temperature is due to the interparticle interaction and high magnetocrystalline anisotropic constant, K = 19.2 × 105 erg cm−3 of the Ni nanoparticles. The advantages of the proposed method are, no need to use external template and reducing agent, and second sample can be prepared in air and aqueous medium.