TerbiumIII

Terbium(III) refers to the trivalent oxidation state of the element terbium, typically denoted Tb3+. In most compounds, terbium is present as Tb3+. Terbium is a lanthanide with atomic number 65 and is relatively scarce, occurring in minerals such as monazite and xenotime as part of the rare earth elements. The Tb3+ ion is small and highly charged, with a preference for high coordination numbers (typically 6–9), and forms a wide range of salts and oxides. A common oxide is terbium(III) oxide, Tb2O3, which is used as a pigment and as a precursor for other Tb3+ compounds. Other Tb3+ compounds include terbium(III) chloride (TbCl3), terbium(III) fluoride (TbF3), and various nitrates and organic salts.

Properties: In aqueous solution, Tb3+ is generally colorless. A notable feature of Tb3+ is its luminescence: when incorporated into suitable host materials, Tb3+ emits green light with a strong emission near 545 nm, arising from the 5D4 → 7F5 transition. The f-electron transitions are sharp and characteristic, and luminescence can be quenched by high concentrations of Tb3+ or by non-radiative pathways in certain hosts.

Applications: Tb3+-containing materials are widely used as green phosphors in displays, lighting, and fluorescent lamps, as well as dopants in ceramics, glass, and lasers to impart green optical properties. They are also studied for specialized phosphor and upconversion applications.

Safety and handling: Compounds of terbium are considered to have moderate toxicity; standard laboratory precautions are advised to minimize ingestion or inhalation and to prevent environmental release.