Тантал (V) оксид

Химические свойства

Tantalum pentoxide, Ta2O5, is a white powder existing in two thermodynamically stable modifications. The orthorombic b-phase changes at 1,360 °C (2,480 °F) into the tetragonal a-modification. The existence of an e-modification has also been reported. Tantalum pentoxide reacts slowly with hot hydrofluoric acid but is insoluble in water and in most solutions of acids and alkalies. For analytical purposes, it can be dissolved by fusion with alkali hydroxides, alkali carbonates, and potassium pyrosulfate.

Физические свойства

White orthorhombic crystal or powder; density 8.20 g/cm³; melts at 1,785°C; insoluble in water, ethanol and practically all acids; soluble in hydrofluoric acid; solubilized by fusion with caustic potash or potassium hydrogen sulfate.

Физические свойства

Dielectric used in film supercapacitors. Tantalum oxide is a high-refractiveindex, low-absorption material used in making optical coatings in the near-UV (350 nm) to IR (8 μm). Insoluble in most chemicals except HF, HF-HNO₃ mixtures, oleum, fused alkali hydroxides (e.g., NaOH, KOH), and molten pyrosulfates.

Использование

Tantalum pentoxide is used in making high refractive index optical glass; as a dielectric film on tantalum for its use as a capacitor component and rectifier; and for preparing tantalum metal, its carbide, and many other tantalum compounds.

Подготовка

Tantalum pentoxide is obtained as an intermediate in extracting tantalum from the columbite-tantalite series of minerals. Also, the oxide can be made by heating Ta metal in oxygen or air at elevated temperatures.

Общее описание

Tantalum pentoxide is dielectric in nature making it useful for making capacitors in the electronics industry.

Опасность

TLV: 5 mg/m3.

Профиль безопасности

Mildly toxic by ingestion. Incompatible with ClF3, BrF3, Li. See also TANTALUM.