1. Appearance and Structure
Color: Orange-yellow to reddish-brown crystalline solid.
Form: Typically exists as a fine powder or layered crystalline structure.
Crystal System: Orthorhombic crystal lattice (at room temperature).
2. Density
Density: 3.357 g/cm³ (at 25°C).
3. Thermal Properties
Melting Point:
Decomposes at ~690°C (does not melt intact; breaks down into vanadium(IV) oxide (VO₂) and oxygen gas).
Phase Transitions:
Undergoes reversible structural changes upon heating (e.g., layered → disordered phases).
4. Electrical and Optical Properties
Electrical Conductivity:
Acts as a semiconductor (n-type) with conductivity dependent on temperature and oxygen vacancies.
Optical Behavior:
Exhibits strong absorption in the ultraviolet (UV) and visible light ranges.
Used in photochromic and electrochromic applications due to light-induced redox activity.
5. Magnetic Properties
Magnetism:
Paramagnetic at room temperature (weak attraction to magnetic fields).
6. Mechanical Properties
Hardness: Relatively brittle solid.
Thermal Expansion: Low thermal expansion coefficient.
7. Solubility
In Water: Slightly soluble (~0.8 g/L at 20°C).
In Acids/Bases:
Dissolves in strong acids (e.g., H₂SO₄) to form yellow vanadyl ions (VO²⁺).
Reacts with alkalis (e.g., NaOH) to produce vanadate salts (e.g., NaVO₃).
8. Hygroscopicity
Moisture Interaction: Non-hygroscopic (does not absorb water significantly under normal conditions).
