Nickel submicron particles synthesized via solvothermal approach in the presence of organic bases: Formation mechanism and magnetic properties

Solvothermal synthesis offers an important approach to prepare nickel particles with high crystallinity and low agglomeration. In this study, submicron nickel particles are prepared by a solvothermal approach involving alcohol reduction with the assistance of different types of organic bases. The influences of the types of organic bases and solvents, and the amount of organic bases on the particle size and morphology of nickel are studied. It is found that an organic base with a stronger alkalinity is able to generate nickel particles with smaller size. Smaller nickel particles are also prone to be obtained from solvents with a stronger reducing ability. Moreover, the formation mechanism of nickel particles is investigated. It is found that the nickel precursor and OH− form nickel layered hydroxide salts at the initial stage, and then the nickel layered hydroxide salts gradually dissolve to form nickel particles. Magnetic measurement reveals the morphology-dependent magnetic properties. Although the sample which has the smallest size exhibits a relatively high coercivity, samples which have a rather large particle size but consist of smaller primary nanoparticles also show relatively high coercivity values.