Messi Biology states that hexagonal plate magnesium hydroxide is a typical layered inorganic material with a unique hexagonal plate-like crystal structure. Its crystal structure determines its excellent physical and chemical properties, such as high thermal stability, electrical insulation, and good flame retardant properties.
1. Basic Characteristics of the Crystal Structure
Magnesium hydroxide belongs to the layered hydrotalcite-like materials. Its crystal structure is mainly composed of magnesium ions (Mg²⁺) and hydroxide ions (OH⁻), forming a layered structure similar to aluminum hydroxide (Al(OH)₃) and nickel hydroxide (Ni(OH)₂).
- Unit Cell Parameters: Magnesium hydroxide crystals belong to the Hexagonal System, with the space group P3m1.
- Interlayer Binding Force: Hydroxide ions (OH⁻) surround magnesium ions (Mg²⁺) to form an octahedral structure. The layers are mainly bonded by hydrogen bonds and Van der Waals forces, making it easy to peel off and form nanosheet structures.
- Interlayer Spacing: The interlayer spacing of standard magnesium hydroxide is about 0.47nm, but it can be adjusted through intercalation or modification.
2. Formation Mechanism of Hexagonal Plate Morphology
The formation of hexagonal plate magnesium hydroxide is influenced by the anisotropic growth of the crystal. Its growth mechanism is mainly controlled by the Ostwald ripening process:
- In aqueous solution, Mg²⁺ combines with OH⁻ to form Mg(OH)₂ crystal nuclei.
- As the reaction time increases, the crystal preferentially grows along specific directions, eventually forming a layered structure.
- Since the (001) plane of the hexagonal crystal system has the lowest surface energy, the growth on the (001) plane is slower, while the growth in the (100) and (110) plane directions is faster, eventually forming a hexagonal sheet morphology.
3. Influence of the Crystal Structure of Hexagonal Plate Magnesium Hydroxide on Performance
Due to its unique layered structure, hexagonal plate magnesium hydroxide exhibits the following excellent properties:
- High Specific Surface Area: Enhances adsorption capacity, with potential applications in catalysis and water treatment.
- Good Dispersibility: Has better dispersibility in polymers than traditional granular magnesium hydroxide, making it suitable as an inorganic filler.
- Excellent Flame Retardant Properties: Its layered structure dehydrates to form MgO at high temperatures, which helps to insulate heat and suppress smoke.
- Enhanced Mechanical Properties: In composite materials, it can improve the toughness and heat resistance of the material.
4. Characterization Methods for Hexagonal Plate Magnesium Hydroxide
In order to confirm the crystal structure of hexagonal plate magnesium hydroxide, the following characterization methods are usually used:
- X-ray Diffraction (XRD): Determines the crystal structure and interlayer spacing.
- Scanning Electron Microscopy (SEM): Observes the plate-like morphology and size distribution.
- Transmission Electron Microscopy (TEM): Analyzes the hexagonal structure and layered characteristics of the crystal.
- Fourier Transform Infrared Spectroscopy (FTIR): Determines the presence of hydroxide groups and surface modification.