Synthesis of Nanocrystalline Lithium Zinc Ferrites Using Polyacrylic Acid, and Their Initial Densification

Abstract

A chemical synthesis technique that uses polyacrylic acid (PAA) to prepare nanocrystalline Li0.3Zn0.4Fe2.3O4 was investigated. Phase‐pure spinel that had an average particle size of ∼13 nm was synthesized at a low temperature (450°C) for 30 min. The average particle size was dependent on the firing temperature and amounts of PAA and Bi2O3. The combustion reaction of PAA was believed to be the main reason for the low‐temperature synthesis of nanocrystalline lithium zinc (LiZn) ferrites. In addition, a chelating tendency was observed, via infrared (IR) spectroscopy, in the dried gel precipitates that were prepared at a low pH (∼2). The initial densification behavior of the nanopowder compacts was studied using linear‐shrinkage data. Densification of the nanopowder without Bi2O3 started at low temperatures (∼400°C). The addition of Bi2O3 to the nanopowder noticeably did not contribute to reducing the initial densification temperature. This result was supported by the activation‐energy calculation for the initial densification. Compared to an activation energy of 280 kJ/mol for grain‐boundary diffusion of the nanopowder without Bi2O3, a higher value (430 kJ/mol) was obtained in the case of the 3 wt% Bi2O3‐containing nanopowder.