Yttrium general properties

Table 1. General properties of ions of scandium, yttrium, lanthanum and lanthanoids. 

Rare earth elements, such as yttrium, cerium and samarium, are well known to stabilize tetragonal Zr02 at lower temperatures, although the tetragonal Zr02 is generally stable at and above 1373 K. In the present study the effect of rare earth element addition on the catalytic properties of the amorphous Ni-Zr alloy-derived catalysts has been examined in order to improve the catalytic activity of the catalysts. 

Here, the so-called heavy lanthanides include the elements from samarium to-lutetium, except for ytterbium and europium which behave like bivalent metals and have unique properties. For these heavy-lanthanide-carbon systems, no complete phase diagram was found, only some information about the formation and the crystal structure of the carbides is available. On the basis of these data the general characteristics of the phase diagrams of the heavy-rare-earth-carbon systems can be summarized. In this case the yttrium-carbon phase diagram may be regarded as the best prototype available for compounds of the heavy lanthanide systems with carbon. 

Scandium, yttrium, and the lanthanide mettils comprise 17 elements for which systematically-determined mechanical property data are sparse. Pioneering work on the mechanical properties of rare earth metals was done in the mid to late 1950 s and was conducted almost exclusively by three groups B. Love and associates at Research Chemicals, Inc. C.R. Simmons and associates at General Electric Co. and E.M. Savitskiy and associates in the USSR. Since that time the number of investigations has increased and the property values have changed considerably with improvements in metal purification methods. 

Simmons, C.R., 1959, The Mechanical Properties of Yttrium, Scandium and the Rare Earth Metals, AECU-4423, General Electric Co., Aircraft Nuclear Propulsion Dept., Cincinnati, Ohio. 

Generally, aluminate phosphors with high luminescence efficiency and excellent thermal stabilities have attracted increasing attention. Typically, Ce -doped yttrium aluminum garnet Y3Al50i2 Ce (YAG Ce ) yellow-emitting phosphor has excellent properties and is widely used to generate w-LEDs. 

In general, the ionic radii give an indication of the expected coordination number in a rare earth complex, though this is more apparent in aqueous solutions than in the solid state, where bulky ligands and different coordination modes may result in unexpected CNs. Scandium with its smaller ionic size has a significantly lower average coordination number than the other rare earths. The properties of scandium and yttrium, which are partly due to the ionic radii, are discussed in relation to those of the lanthanides in section 1.3.4. 

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