What Is Tantalum Oxide?
Tantalum oxide, a white to almost white inorganic compound, is recognized by its chemical formula Ta2O5, with a molecular weight of 441.89, and a CAS registration number of 1314-61-0. Notable for its high decomposition temperature of 1,470℃, it is almost insoluble in water.
It is regulated under the Safety and Health Law, specifically designated in the Hazardous and Noxious Substances to be labeled.
Uses of Tantalum Oxide
Due to its high refractive index and superior film stability in ion-assisted deposition (IAD) processes, tantalum oxide is a key material in optical lens manufacturing. It also serves as a raw material for antireflective coatings and interference filters in various applications, including computer displays and automobile windshields. Additionally, its high dielectric constant makes it vital in the production of electronic ceramics, such as dielectrics for electrolytic capacitors.
Properties of Tantalum Oxide
This oxide is an inert material characterized by its high refractive index and low absorption, insoluble in all solvents but corrosive to strong bases and hydrofluoric acid. While it shows resistance to reactions with HCl or HBr, it dissolves in hydrofluoric acid and reacts with potassium hydrofluoride and HF.
Structure of Tantalum Oxide
Also known as tantalum (V) oxide or tantalum pentoxide, its structure is predominantly disordered, being either amorphous or polycrystalline. Due to the challenges in growing single crystals, structural information is mainly derived from powder X-ray diffraction techniques. The densities for β-Ta2O5 and α-Ta2O5 are 8.18 g/cm3 and 8.37 g/cm3, respectively.
Other Information on Tantalum Oxide
1. Occurrence of Tantalum Oxide
Tantalum is primarily found in the minerals columbite and tantalite within igneous pegmatites, with notable occurrences in Sweden and Finland. While pure tantalum oxide is rare in nature, these minerals contain significant amounts of tantalum, making them key sources of the metal.
2. Purification of Tantalum Oxide
The purification process involves leaching, extraction, and firing stages. Initially, tantalum ores are treated with hydrofluoric and sulfuric acids, producing water-soluble hydrogen fluoride. Following liquid-liquid extraction using organic solvents, tantalum and niobium are separated, and the pure tantalum fluoride solution is neutralized and calcined to produce tantalum oxide.
3. Synthesis of Tantalum Oxide
For electronics applications, tantalum oxide is synthesized through methods like metalorganic vapor deposition (MOCVD), leveraging the hydrolysis of volatile halides and alkoxides to create thin films essential for various electronic devices.