Composition and morphology of the thermal decomposition products of 3Mg(OH)2·MgCl2·8H2O nanowires--颗粒学报PARTICUOLOGY

Yu, B., & Xiang, L. (2017). Composition and morphology of the thermal decomposition products of 3Mg(OH)2·MgCl2·8H2O nanowires. Particuology, 30, 129-134. https://doi.org/10.1016/j.partic.2016.02.006

Composition and morphology of the thermal decomposition products of 3Mg(OH)₂·MgCl₂·8H₂O nanowires

Bo Yu, Lan Xiang ^*

Department of Chemical Engineering, Tsinghua University, Beijing 100084, China

10.1016/j.partic.2016.02.006

Volume 30, February 2017, Pages 129-134

Received 15 December 2015, Revised 12 February 2016, Accepted 27 February 2016, Available online 8 August 2016, Version of Record 27 January 2017.

E-mail: xianglan@mail.tsinghua.edu.cn

Highlights

• Effect of heating rate on thermal decomposition of 318MHCH was investigated.

• Physically adsorbed and crystalline water were separated from DTG curve by curve fitting method.

• Immediate collapse of 1D nanowires was identified and discussed upon heating up to 420 °C.

• Double chains model was proposed to explain the immediate collapse.

Abstract

The thermal decomposition of 3Mg(OH)₂·MgCl₂·8H₂O (318MHCH) nanowires synthesized from agglomerated Mg(OH)₂ microspheres was investigated. The influence of heating rate and temperature on the composition and morphology of the products was investigated. Thermogravimetric-differential scanning calorimetry, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction showed that increasing the heating rate from 1 to 20 °C/min promoted the escape of crystalline water from the 318MHCH nanowires. 318MHCH nanowires were dehydrated stepwise to 310MHCH porous nanowires from room temperature to 320 °C, and then to MgO cubic nanoparticles from 420 to 700 °C. The nanowires retained their one-dimensional morphology, until the phase changed to MgO. The immediate collapse of the one-dimensional structure was attributed to the presence of Mg–O/Cl chains.

Graphical abstract

Keywords

Magnesium hydroxide chloride hydrates; Thermal decomposition; Nanowires; Immediate collapse; Mg–O/Cl chains

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