MSE PRO Bismuth (III) Oxide (Bi₂O₃) Powder, 99.999% (5N) (Metal Basis)

Formula: Bi₂O₃

Formula Weight: 465.96 g/mol

Form: Yellow powder

Melting point: 817°C

Density: 8.9 g/cm³

Solubility in water: insoluble
Solubility: soluble in most acids

Bi₂O₃ is used in solid-oxide fuel cells (SOFCs) as well as a raw material is making optical materials.  Interest has centered on δ- Bi₂O₃ as it is principally an ionic conductor. In addition to electrical properties, thermal expansion properties are very important when considering possible applications for solid electrolytes. High thermal expansion coefficients represent large dimensional variations under heating and cooling, which would limit the performance of an electrolyte. The transition from the high-temperature δ- Bi₂O₃ to the intermediate β- Bi₂O₃ is accompanied by a large volume change and consequently, a deterioration of the mechanical properties of the material. This, combined with the very narrow stability range of the δ-phase (727–824 °C), has led to studies on its stabilization to room temperature.

Bi₂O₃ easily forms solid solutions with many other metal oxides. These doped systems exhibit a complex array of structures and properties dependent on the type of dopant, the dopant concentration and the thermal history of the sample. The most widely studied systems are those involving rare earth metal oxides, Ln₂O₃, including yttria, Y₂O₃. Rare earth metal cations are generally very stable, have similar chemical properties to one another and are similar in size to Bi³⁺, which has a radius of 1.03 Å, making them all excellent dopants. Furthermore, their ionic radii decrease fairly uniformly from La³⁺ (1.032 Å), through Nd³⁺, (0.983 Å), Gd³⁺, (0.938 Å), Dy³⁺, (0.912 Å) and Er³⁺, (0.89 Å), to Lu³⁺, (0.861 Å) (known as the ‘lanthanide contraction’), making them useful to study the effect of dopant size on the stability of the Bi₂O₃  phases.

Bi₂O₃  has also been used as sintering additive in the Sc₂O₃ – doped zirconia system for intermediate temperature SOFC.