Continuous morphology-controllable precipitation strategy for europium oxalate hydrates via microchannel reactor

A flow chemistry based continuous morphology-controllable precipitation strategy was successfully developed for synthesis of europium oxalate hydrate microparticles. The effects of flow ratio between raw materials within microchannels on the crystal structure, morphology and particle size distribution of the precipitated products were firstly studied. The results shown that both high yield and controllable morphology were achieved for Eu3+ precipitation reactions under its low concentration condition. The effects of supersaturation, mixing intensity, and reaction temperatures were also investigated in detail, which proved the continuous preparation of layered microparticles with concentrated size distribution can be achieved by this strategy. Multiple characterizations and comparison experiment synergistically reveal that the feed flow ratios of nitric acid and oxalic acid determines the morphology and particle size distribution due to affecting the mixing degree and phase composition of the precipitation reaction. In addition, the phase and morphology conversion of precipitates after calcination treatment were also studied, the as-calcined metal oxide powder exhibited a decent photoluminescence characteristic. In summary, this work demonstrates a promising precipitation strategy within micro-channels for mass controllable production of high-quality metal oxide materials.

Automated summary

A flow chemistry-based continuous morphology-controllable precipitation strategy was developed for synthesizing europium oxalate hydrate microparticles. The effects of flow ratio on the crystal structure, morphology, and particle size distribution were investigated. The study showed that high yield and controllable morphology can be achieved for Eu3+ precipitation reactions at low concentrations. Additionally, the effects of supersaturation, mixing intensity, and reaction temperatures were studied in detail, demonstrating the continuous preparation of layered microparticles. The feed flow ratios of nitric acid and oxalic acid were found to determine the morphology and particle size distribution, which in turn affected the mixing degree and phase composition of the precipitation reaction. The phase and morphology conversion of precipitates after calcination treatment were also studied, revealing decent photoluminescence characteristics in the as-calcined metal oxide powder. This work demonstrates a promising precipitation strategy within micro-channels for mass controllable production of high-quality metal oxide materials.