Effects of ammonia on the microstructure and crystallinity of nickel-based carbonate materials†

Abstract

In this work, we focus on interpreting the effects of ammonia on the crystallization route of Ni-based metal carbonates, Ni_xCo_yMn_zCO₃ (0 < x, y, z < 1, x : y : z = 8 :1 : 1, MCO₃). The nucleation and crystal growth processes of MCO₃ are effectively decoupled by carrying out explosive nucleation in a microreactor, followed by hydrothermal crystallization in sequence. During the hydrothermal crystallization process, the presence and content of ammonia significantly affect the crystal structure, composition and morphology of MCO₃ particles, which play a key role in the transformation process of crystals. Meanwhile, ammonia can regulate the precipitation–complexation balance through the interaction of hydrogen bonds and the formation of metal complexes and improve the formation of a nanocubic microstructure. The recognition of the growth mechanism may further help in the modification research on carbonate materials.