Holmium (Ho, atomic number 67).The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announce the existence of an “Element X”. Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is name is therefore name after Cleve’s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite and in other rare earth minerals. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. Pure holmium has a metallic to bright silver luster. It is relatively soft and malleable, it is able to stay dry in room temperature, but it rapidly oxidizes in moist air and at elevated temperatures. Holmium metal has unusual magnetic properties. It has the highest magnetic moment of any known element in the periodic table. It has the greatest number of impaired electrons and impaired electrons are what give rise to magnetism. Therefore, Holmium has many uses in magnetic materials. Very few other uses have been found for the element. Like some other rare earths Holmium seems to have a low acute toxic rating.

                  

Some known uses for Holmium are as follows:
Magnets
Ceramics
Lasers


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Europium (Eu, atomic number 63) was discovered in the form of spectral lines that were not accounted for by samarium or gadolinium concentrates in 1890 by Boisbaudran. The official discovery of europium is generally credited to Demarcay who separated the rare earth in reasonably pure form in 1901. The pure metal was not isolated until recent years. Europium is now prepared by mixing Eu203 with a 10% excess of lanthanum metal and heating the mixture in a tantalum crucible under high vacuum. The element is collected as a silvery white metallic deposit on the walls of the crucible. As with other rare earth metals (with the exception of lanthanum), europium ignites in air at about 150 to 180 degrees Celsius. Europium is about as hard as lead and is quite ductile. It is the most reactive of the rare earth metals, it quickly oxidizes in air. It resembles calcium in its reaction to water. Bastnasite and monazite are the principal ores containing europium. Europium has been identified spectroscopy in the sun and certain stars.

                  

Some known uses for Europium are as follows:
Television screens- europium oxide is now widely used as a phosphor activator and europium activated yttrium vanadate.
Laser material- europium doped plastic is used as laser material.
Ceramics
Nuclear applications.


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Gadolinium (Gd, atomic number 64) rare earth metal is obtained from the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by Merignac in 1880 and Lecoq de Boisbaudran independently isolated it from Mosasander’s yttria in 1886. Gadolinium is found in several other minerals, including monazite and bastnasite. With the development of ion-exchange and solvent extraction techniques, the availability and the prices of gadolinium and the other rare earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium. Gadolinium is silvery white, has a metallic luster and is malleable and ductile (like other related rare earth metals). At room temperature gadolinium crystallizes in the hexagonal, close packed alpha form. Upon heating to 1235 degrees Celsius, alpha gadolinium transforms into the beta form (which has a body centered cubic structure). The metal is relatively stable in dry air but tarnishes in moist air. It forms a loosely adhering oxide film which falls off and exposes more surface to oxidation. The metal reacts slowly with water and is soluble in dilute acid. Gadolinium has the highest thermal neutron capture cross-section of any known element (49,000 barns).

                  

Some known uses for Gadolinium are as follows:
MRI tests- gadolinium changes the way water molecules react in your body when scanned allowing the contrast between healthy and non healthy tissue to be seen.
Microwaves- gadolinium yttrium garnets are used in microwave applications.
Color Television_ gadolinium compounds are used as phosphors in color televisions.
The unusual superconductive properties improve the workability and resistance of iron and chromium and related alloys to high temperatures and oxidation (as little as 1% gadolinium is needed).
Duplicating performance of amplifiers such as the maser- gadolinium ethyl sulfate ahs extremely low noise characteristics and may find use in duplicating the performance.
Magnetic component that can sense hot and cold- gadolinium metal is ferromagnetic. It is unique for its high magnetic movement and for its special Curie temperature (above which ferromagnetism vanishes) lying at room temperature. Therefore it can be used as a magnetic component that can sense hot and cold.


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Erbium (Er, atomic number 68) is found in minerals that dysprosium is found in (xenotime, fergusonite, gadolinite, euxenite, polycrase and blomstrandine). In 1842, Mosander separated “yttria”, found in the mineral gadolinite, into three fractions. He called these three fractions: yttria, erbia and terbia. After 1877, the earlier known erbia became terbia. The erbia of this period was later shown to consist of five oxides, now known as: erbia, Scandia, holmia, thulia and ytterbia. By 1905 Urbain and James independently succeeded in isolating fairly pure Er2O3. Klemm and Bommer first produced reasonable pure erbium metal in 1934 by reducing the anhydrous chloride with potassium vapor. The pure metal is soft and malleable and has a bright, silvery, metallic luster. As with other rare earth metals, it’s properties depend, to a certain extent, on the impurities present. The metal is fairly stable in air and does not oxidize as rapidly as some of the other metals.

                  

Some known uses for erbium are as follows:
A photographic filter and a nuclear poison – it will kill any nuclear fission process. Compounds of it are often pink when dissolved in solution.
Amplifier of light (optical fibers) used to transmit signals for the internet.
Erbium tri-chloride is used in jewelry and sunglasses.
Erbium salts are used in welding goggles in conjunction with other rare earths.


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