Preparation of Li2CO3 powder nanoparticles by vacuum freeze drying

Abstract

Decreasing the particle size of Li2CO3 powder is beneficial for advancing its applications in the manufacturing of different materials and drug delivery. Therefore, in this study, a novel bottom-up process based on freezing is proposed for the production of nanoparticles. Herein, two methods of explosive nucleation were used: addition of an anti-solvent and rapid freezing. Explosive nucleation of Li2CO3 occurred during the initial stage of anti-solvent addition; in contrast, in the freezing method, it occurred at a stage when the solute, which had not migrated, was extruded to the solid–liquid interface. Li2CO3 concentration had an effect on both the crystal grain and particle size. The controlled preparation of Li2CO3 nanoparticles was achieved within a certain range of A/B ratio; when the ratio decreased from 10/0 to 10/20 v/v, the controlled synthesis of Li2CO3 nanoparticles was achieved. A lower concentration of Li2CO3 decreased the size of the crystal grain and increased the size of the particles, as observed via transmission electron microscopy and dynamic light scattering. When the A/B ratio (where A is saturated Li2CO3 solution and B is deionised water) was decreased below 10/20 v/v, the crystal grain size of Li2CO3 did not reduce significantly. To further understand the nucleation, freezing was carried out at two temperatures, i.e. 223 ± 2 K and 267 ± 2 K. The lower freezing temperature resulted in a smaller crystal grain size and more concentrated distribution.