Name | Tungsten(IV) oxide |
Synonyms | WO2 dioxotungsten TUNGSTEN OXIDE TUNGSTEN DIOXIDE Tungsten dioxide oxygen(-2) anion Wolfram(IV)dioxide Tungsten(IV) oxide tungsten(+4) cation Tungsten oxide (WO2) |
CAS | 12036-22-5 |
EINECS | 234-842-7 |
InChI | InChI=1/2O.W/q2*-2;+4 |
Molecular Formula | O2W |
Molar Mass | 215.84 |
Density | 12,11 g/cm3 |
Melting Point | 1500-1600°C |
Boling Point | 1730℃[at 101 325 Pa] |
Water Solubility | Soluble in acid and potassium hydroxide. Insoluble in water. |
Appearance | Brown to purple to black powder |
Specific Gravity | 12.11 |
Color | brown |
Exposure Limit | ACGIH: TWA 3 mg/m3NIOSH: TWA 5 mg/m3; STEL 10 mg/m3 |
Storage Condition | RT, argon filled storage |
MDL | MFCD00049709 |
Hazard Symbols | Xi - Irritant |
Risk Codes | 37 - Irritating to the respiratory system |
Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36 - Wear suitable protective clothing. |
WGK Germany | 3 |
TSCA | Yes |
EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
Introduction | Tungsten dioxide (WO2) is a material with metal conductivity. The oxygen vacancy defect in the tungsten dioxide lattice and the strong metal-metal bond inside the crystal, therefore, tungsten dioxide (WO2) has metal conductivity (electronic conductivity is about 3.5 × 102 S/cm). |
application | tungsten dioxide can be used as a raw material intermediate, mainly as a tungsten trioxide/tungsten dioxide composite material for lithium ion battery negative electrode. |
production method | 1. tungsten dioxide produced by hydrogen reduction method of tungsten trioxide can stably exist in an atmosphere of 900 ℃, 40% ~ 55% hydrogen and 45% ~ 60% water vapor, so this compound can be manufactured by the following method: hydrogen purified by silica gel passes through a flask filled with water, it becomes hydrogen saturated with water vapor. At this time, the temperature of the water in the flask should be accurately kept at 85 ℃. The flask to the reaction tube is connected with a connecting tube, and an electric heating wire is wrapped on the connecting tube and heated to about 100 ℃. Do not condense water vapor. A mixed gas of hydrogen and water vapor is introduced into the quartz reaction tube. Put the disk with tungsten trioxide in the reaction tube, and raise the temperature of the reaction tube to 800~900 ℃. The reduction reaction ends in about 2 hours. It is then cooled in a nitrogen stream without oxygen. 2. Metal tungsten reduction method of tungsten trioxide. According to the molar ratio of 1: 2, the metal tungsten powder and tungsten trioxide are accurately weighed and fully mixed. Put the mixture into a sealed quartz tube at one end and exhaust the container thoroughly. When the temperature is raised to 950 ℃ in vacuum and kept for 40h, brown crystalline tungsten dioxide powder is obtained. 3. Using ferrous sulfate as a reducing agent, the reducing agent is added to the sodium tungstate aqueous solution, and tungsten dioxide is precipitated. |