A proportion used in determining the dimensional relationship of a representation to that which it represents: a world map with a scale of 1:4,560,000. b. A calibrated line, as on a map or an architectural plan, indicating such a proportion.
Yttria (yttrium oxide, Y 2 O 3), was discovered by Johann Gadolin in 1794 in a mineral called gadolinite from Ytterby. Ytterby is the site of a quarry in Sweden which contains many unusual minerals containing erbium, terbium, and ytterbium as well as yttrium.
Although metallic yttrium is not widely used, several of its compounds are. Yttrium oxide (Y 2 O 3) and yttrium orthovanadate (YVO 4) are both combined with europium to produce the red phosphor used in color televisions.lthough metallic yttrium is not widely used, several of its compounds are. Yttrium oxide (Y 2 O 3) and yttrium orthovanadate (YVO 4) are both combined with europium to produce the red phosphor used in color televisions.