Physical properties of Terbium

Terbium is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. And It is relatively stable in air as compared to other lanthanides. The terbium(III) cation is brilliantly fluorescent, in a bright lemon-yellow color that is the result of a strong green emission line in combination with other lines in the orange and red. Terbium easily oxidizes, and is therefore used as element only for research purpose. And Terbium has a simple ferromagnetic ordering at temperatures below 219 K. When the temperature is above 219 K, it turns into an helical antiferromagnetic state in which all of the atomic moments in a particular basal plane layer are parallel, and oriented at a fixed angle to the moments of adjacent layers.