Tungsten chemicals · WO₃ / WO₂.₉
Tungsten Trioxide (WO₃) — Blue and Yellow Oxide
The calcination intermediates between APT and metal powder, supplied as blue sub-stoichiometric oxide or yellow stoichiometric WO₃ depending on your reduction route.
About Tungsten oxide
Blue and yellow tungsten oxide are the same element at two different oxidation states, and the choice between them is a process decision rather than a quality one. Yellow oxide (YTO) is stoichiometric WO₃, produced by calcining APT in air. Blue oxide (BTO) is the sub-stoichiometric form, approximately WO₂.₇₂ to WO₂.₉, produced by calcining under a reducing or oxygen-deficient atmosphere.
BTO is already partially reduced, so less hydrogen and less time are needed to take it to metal. It also tends to give a finer, more uniform metal powder because the partially reduced lattice nucleates differently. Producers targeting fine grain sizes generally prefer it, and accept that it is more reactive and less forgiving in storage.
YTO is the more stable material, easier to store and handle, and the usual choice for chemical and catalyst uses where the oxide is the product rather than an intermediate. Both grades run approximately 79% tungsten and are supplied as calcined oxide powder with purity stated per order.
Specifications
| BTO appearance | Blue-grey fine powder |
|---|---|
| YTO / WO₃ appearance | Yellow fine powder |
| Tungsten content (approx.) | ~79 % |
| BTO stoichiometry (approx.) | WO₂.₇₂ – WO₂.₉ |
| YTO stoichiometry | WO₃ |
| Form | Calcined oxide powder |
| Purity | Per order, stated on CoA |
Specifications can be tailored to order. Confirm your target values with us before placing an order and we will state honestly whether they are achievable.
Blue or yellow oxide?
The decision turns on whether the oxide is an intermediate you will reduce or a product you will use as an oxide, and on how much you value fine grain size against storage stability.
Blue oxide (BTO)
Hydrogen reduction to metal powder, particularly for fine grain-size targets. Shorter reduction cycle, lower hydrogen consumption.
Yellow oxide (YTO / WO₃)
Catalyst precursors, electrochromic and pigment applications, and reduction routes where storage stability is worth more than cycle time.
Applications
Tungsten metal powder production
Hydrogen reduction of oxide is the standard industrial route to metallic tungsten. Oxide choice and reduction schedule together set the grain size of the finished powder.
Catalyst precursors
WO₃ appears in hydrotreating, selective oxidation and NOx reduction catalysts, usually supported on alumina or titania. Yellow oxide is normal here for its stability and defined stoichiometry.
Electrochromic devices
WO₃ films colour reversibly under an applied voltage, which is the basis of switchable glazing. These applications are demanding on purity and particle uniformity.
Specialty ceramic pigments
Tungsten oxides are used in ceramic colourants and specialty glass where their thermal stability at firing temperature matters.
Quality control
- Tungsten content assay
- Appearance and colour verification against the BTO or YTO standard
- Purity determination against the agreed order specification
- Certificate of analysis with every shipment
- Third-party test certificates available on request
Manufactured under an ISO 9001:2015 certified quality management system.
Packaging and export
Packed in lined drums or bags with moisture barrier, palletised for container shipment. BTO is the more reactive of the two and is packed to limit air exposure during transit and storage.
Commercial invoice, packing list, certificate of analysis and certificate of origin are supplied as standard with every export shipment.
Tungsten oxide — frequently asked questions
What is the difference between blue and yellow tungsten oxide?
Yellow oxide is stoichiometric WO₃, calcined from APT in air. Blue oxide is sub-stoichiometric, roughly WO₂.₇₂ to WO₂.₉, calcined under a reducing or oxygen-deficient atmosphere. Blue is already partially reduced; yellow is more stable in storage.
Which should I use for making tungsten metal powder?
Blue oxide, in most cases. Being partially reduced it needs less hydrogen and less time to reach metal, and it tends to give a finer, more uniform powder. Yellow oxide is the choice where storage stability outweighs reduction cycle time.
What tungsten content do the oxides carry?
Approximately 79% tungsten for both grades. Purity is set per order and stated on the certificate of analysis.
Can you supply oxide for catalyst applications?
Yes. Yellow oxide is normally specified for catalyst precursor work because of its defined stoichiometry and storage stability. Share your purity requirement and we will confirm against it before quoting.
Tungsten oxide export destinations
Country-specific specifications, logistics and compliance notes for this product: