Preparation and Characterization of Magnesium Hydroxide Sulfate Hydrate Whiskers

• DOI: 10.1021/cm000249f
• Publication Date: 2002-07-26T05:54:00Z
• Authors: Yi Ding; Guangtao Zhang; Shuyuan Zhang; Xinming Huang; Weichao Yu; Yitai Qian
• Keywords: Superstructure; Orthorhombic crystal system; Selected area diffraction; Stoichiometry

Reaction of magnesium sulfate with aqueous ammonia in a hydrothermal condition (150−180 °C) produced fibrous hydroxide hydrate (MHSH) composition corresponding to stoichiometry 4.34Mg(OH)2·MgSO4·xH2O. Chemical analysis showed that the quantity x was more likely be 2 rather than well-known 3. The MHSH whiskers were about 0.3−2 μm diameter and 40−100 length, an aspect ratio no less 100. Selected area electron diffraction (SAED) X-ray patterns (XRD) well-crystallized orthorhombic structure. An interesting superlattice observed from ED but this superstructure unstable under radiation high-energy beam especially HREM conditions. Several techniques such as XRD, TEM, EDS, HREM, XPS, TGA-DTA, FTIR, etc. used characterize structural features thermal behavior experimental products. Our sample found lose two hydration waters at 330 °C, further decompose higher treatment temperature, transform finally into MgO near 1000 °C.