Tungsten(VI) Oxide

Updated: 2026-07-24

Overview

Tungsten trioxide (WO3) microparticles are a technologically significant transition metal oxide with a particle size typically ranging from 1 to 10 micrometers. As an n-type semiconductor, it exhibits unique electronic and optical properties that make it valuable in advanced industrial applications. The compound occurs naturally as the mineral tungstite but is more commonly produced synthetically for controlled purity and particle characteristics. Industrial production involves calcination of ammonium paratungstate or acid digestion of tungsten ores. Micron-scale WO3 is preferred for many applications due to its balanced surface area and handling properties, offering improved processability compared to nanopowders while maintaining functional performance. The material is commercially available in various grades tailored to specific end uses.

Physical and Chemical Properties

Tungsten trioxide microparticles exhibit a monoclinic crystal structure at room temperature, transitioning to orthorhombic and tetragonal phases at higher temperatures. The material shows excellent thermal stability up to 1,400°C and has a bandgap of approximately 2.6-2.8 eV, making it photosensitive in the visible light spectrum. Chemically, WO3 is amphoteric, dissolving in strong bases to form tungstate salts while resisting most acids except hydrofluoric acid. Its electrical conductivity increases significantly with temperature, displaying typical semiconductor behavior. The yellow coloration results from light absorption in the blue region of the spectrum due to electronic transitions between the O 2p and W 5d orbitals.

Main Applications

In electrochromic devices, WO3 microparticles serve as the active layer in smart windows and displays, reversibly changing color under applied voltage. The automotive and construction industries utilize this property for energy-saving glazing systems. As a gas sensing material, WO3's conductivity changes in response to reducing gases like hydrogen sulfide or nitrogen oxides, enabling environmental monitoring applications. The photocatalytic properties make it effective in air purification systems and self-cleaning surfaces when combined with UV light. Additional uses include fire-retardant additives, corrosion inhibitors for metals, and as a precursor for tungsten metal and carbide production. In ceramics, it functions as a yellow pigment and flux agent.

Safety and Storage

While tungsten trioxide is generally considered low toxicity, inhalation of dust particles should be prevented through proper ventilation and respiratory protection. The material is not flammable but may release irritating tungsten oxides if involved in fires. Storage requires dry conditions in sealed containers to prevent moisture absorption and contamination. Spills should be contained and cleaned up with appropriate dust suppression methods. Disposal must comply with local regulations for heavy metal compounds. Material Safety Data Sheets (MSDS) should be consulted for specific handling procedures, particularly concerning dust explosion hazards in large-scale operations.

B2B Procurement Guide

Industrial buyers should specify particle size distribution (typically D50 value), purity level, and crystalline phase requirements. Technical grade (99.9%) suffices for most applications, while optoelectronic uses may require 99.99% purity. Packaging options range from 1kg bottles to 25kg drums or bulk containers for large consumers. Key suppliers include specialized chemical manufacturers in China, the United States, and Germany. Lead times vary from stock availability to 4-6 weeks for custom particle sizes. Quality certifications like ISO 9001 and batch analysis reports are important for consistent performance. Consider requesting samples for performance testing before large orders.