Terbium(III,IV) oxide, occasionally called tetraterbium heptaoxide, has the formula Tb4O7, though some texts refer to it as TbO1.75. There is some debate as to whether it is a discrete compound, or simply one phase in an interstitial oxide system.
Molar mass： 747.6972 g/mol
Appearance： Dark brown-black
Density： 7.3 g/cm3
Melting point： Decomposes to Tb2O3
Solubility in water：Insoluble
It acts as a precursor for the preparation of other terbium compounds. It is used as a redox catalyst in reactions involving oxygen. At high temperatures, it can liberate oxygen. It finds applications in the manufacture of glass, optic and ceramic. Nanoparticles of terbium oxide are used as analytical reagents for the determination of drugs in food.