Wet chemical synthesis strategies to develop aluminum manganese nanoparticles for high density magnetic recording
As the technology era grows rapidly, there is always a need for quick access to stored data. Magnetic tape is one type of recording media used of information storage. Its main use in computer applications is for archival storage and mass storage systems. Magnetic tape is a multi-component material consisting of a base film with a top layer of magnetic particles. Particles that are used for magnetic recording devices must exhibit good magnetic properties including large coercivity and saturation magnetization. As the need for tape performance and storage capacity increases, new types of particulate media are needed to meet these demands. One candidate of particles for future magnetic tape is ferromagnetic AlMn nanoparticles. AlMn has a ferromagnetic tetragonal L10 phase which is exhibited by a class of transition metal alloy systems such as FePt, CoPt, FePd, MnPt, etc. This phase in the AlMn binary system is labeled as the τ phase and has a large anisotropy value of approximately 107 ergs/cc which translates to good magnetic properties suitable for use in magnetic tape. The advantages of producing AlMn nanoparticles for magnetic recording are the low cost and abundance of precursor materials. This dissertation investigated strategies of a solution phase chemical synthesis to produce AlMn nanoparticles. Metal nanoparticle systems are synthesized primarily by the reduction of metal salt precursors with a reducing agent in the presence of stabilizing agents in an organic solvent. Systems of metal nanoparticles with the tetragonal L10 phase characterized by high anisotropy values such as FePt and MnPt are produced via this route, and these techniques are considered as a foundation to make AlMn nanoparticles. Cyclic voltammetry experiments give the reduction potentials of Al and Mn precursors to determine suitable reducing agents. The results of the AlMn nanoparticle synthesis attempts are chronicled by the reducing agent that was used in the reaction. Different combinations of precursors, surfactants, and solvents are used in coordination with the following reducing agents: superhydride (C6H16BLi), potassium (K), hydrogen (H2), lithium aluminum hydride (LiAlH4), and sodium (Na). Also, synthesis attempts of AlMn(X) tertiary nanoparticles and core-shell AlMn nanoparticles are presented.