Terbium thermal properties

The rare earth oxides have a number of distinguishing properties important in catalytic applications. The oxides are basic O) compared to alumina, lanthanum oxide (La203) being the most basic. The oxides also have good thermal stability, a valuable characteristic in most industrial applications. Some rare earths including cerium, praseodymium, and terbium form non-stoichiomet-ric oxides ( ), an important property shared by many good oxidation catalysts. These mixed valence state compounds are typically polymorphic. 

Similar to the europium complexes, the terbium complexes used as good emitters in OLEDs also need to have high photoluminescent efficiencies, good carrier transporting properties, and sufficiently good thermal stability for small molecule materials to form a film by thermal evaporation in vacuum. 

The only study of the temperature dependence of the mechanical properties of terbium was compression tests by Sokolov et al. (1970) who reported the purity of their metal to be 98.88 percent, but no analysis of non-metallics was made. Although fig. 8.33 shows only one compression flow stress (20% strain) versus temperature curve, Sokolov et al. did furnish curves for two additional strain rates. These additional curves were parallel to the flow stress curve reproduced in fig. 8.33 and the peak in the flow stress shown at 500 K shifted to higher temperatures with higher strain rates in the manner characteristic of strain aging or some other thermally-activated process. The dip in the maximum compression strain tends to support a strain aging phenomenon. No obvious manifestation of the a(h.c.p.) to a (orthorhombic) phase change at about 220 K is evident in the mechanical properties. More data in the critical region are needed to determine whether the transformation produces an effect. 

---