Synthesis and formation mechanism of micro/nano flower-like MgCO_3·5H_2O

• Published in: 矿物冶金与材料学报：英文版 2014, Vol.21 (3), p.304-310
• Main Author: Wan-zhong Yin Yu-lian Wang Qiang-dong Ji Jin Yao Ying Hou Lei Wang Wen-xing Zhong
• Format: Article
• Language: English
• Subjects: 傅里叶变换红外光谱; 合成; 差示扫描量热法; 形成机理; 扫描电子显微镜; 碳酸镁; 磷酸二氢钾; 纳米颗粒
• ISSN: 1674-4799; 1869-103X

Micro/nano magnesium carbonate pentahydrate（MgCO3 ·5H2 O） with flower-like morphology was synthesized using magnesite as a substrate and potassium dihydrogen phosphate as an additive. The synthesized samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The influence of pyrolysis time on crystal morphology was explored. The formation mechanism was investigated on the basis of the characterized results and the crystal structure of MgCO3 ·5H2 O. The results showed that the flower-like MgCO3 ·5H2 O was 1.5-3.0 μm in length and 100-500 nm in diameter and was successfully obtained with a pyrolysis time of 30 min. The formation mechanism of flower-like MgCO3 ·5H2 O is suggested to be the selective adsorption of potassium dihydrogen phosphate on the surface. The process of flower-like crystal growth is as follows： amorphous nanoparticles formation, acicular and rod monocrystal formation, flower-like monocrystal formation, and flower-like polymers（MgCO3 ·5H2 O） crystallization. In the MgCO3 ·5H2 O crystal, the magnesium ion presents two different octahedral coordinations corresponding to2 26 Mg（H O）＋and2 2 2 4 23 [Mg（H O）（CO） ]--, and the chemical formula of the crystal is2 2 6 2 4 23 Mg（H O） Mg（H O）（CO）2.