2. The realm of mortal existence; the temporal world.
Latin: Tellus (goddess)
Latin: Trivia (goddess, whose name means “of the three ways” because, like Hecate, she was worshipped at crossroads)
2. Etymology: from the 14th century via Old French fumeterre from medieval Latin fumus terrae, "smoke of the earth"; because of its grayish foliage.
The "smoky" or "fumy" origin of its name is also said to come from the translucent color of its flowers, giving them the appearance of smoke or of hanging in smoke, as well as the slightly gray-blue haze color of its foliage, which was thought to resemble smoke coming from the ground.
Mischmetal is an alloy consisting of a crude mixture of cerium, lanthanum, and other rare-earth metals obtained by electrolysis of the mixed chlorides of the metals dissolved in fused sodium chloride.
They are used in making aluminum alloys, in some steels and irons, and in coating the cathodes of glow-type voltage regulator tubes.
Although they are generally unfamiliar, the rare-earth elements are essential for many hundreds of applications.
The versatility and specificity of the rare-earth elements have given them a level of technological, environmental, and economic importance considerably greater than might have been expected from their relative obscurity.
As technological applications of rare-earth elements have multiplied over the past several decades, demand for several of the less abundant (and formerly quite obscure) REE has increased dramatically.
Some of the Applications of the Rare-Earth Elements
- Color cathode-ray tubes and liquid-crystal displays used in computer monitors and televisions employ europium as the red phosphor and no substitute is currently known.
- Fiber-optic telecommunication cables provide much greater bandwidth than the copper wires and cables they have largely replaced.
- Fiber-optic cables can transmit signals over long distances because they incorporate periodically spaced lengths of erbium-doped fiber that function as laser amplifiers because it alone possesses the required optical properties.
- Permanent magnet technology has been revolutionized by alloys containing neodymium, samarium, gadolinium, dysprosium, or praseodymium.
- Small, lightweight, high-strength rare-earth element magnets have allowed miniaturization of numerous electrical and electronic components used in appliances, audio and video equipment, computers, automobiles, communications systems, and military gear.
- Several rare-earth elements are essential constituents of both petroleum fluid cracking catalysts and automotive pollution-control catalytic converters.
- Although more expensive, lanthanum-nickel-hydride batteries offer greater energy density, better charge-discharge characteristics, and fewer environmental problems when they are recycled or disposed of.
- The rare earth elements are essential for a diverse and expanding array of high-technology applications, which constitute an important part of the industrial economy of the United States.
- Long-term shortages or unavailability of rare-earth elements would force significant changes in many technological aspects of American life.
- State-run Chinese firms sharply expanded production and slashed prices of rare earths in the 1990's, forcing producers in the United States (previously the world’s leading producer and exporter) and elsewhere out of the market which no doubt will change now that China has restricted its exports of rare-earth minerals.
It can have as much as ten times more coercive force than a typical magnet.
- 57 La, Lanthanum
- 58 Ce, Cerium
- 59 Pr, Praseodymium
- 60 Nd, Neodymium
- 61 Pm, Promethium
- 62 Sm, Samarium
- 63 Eu, Europium
- 64 Gd, Gadolinium
- 65 Tb, Terbium
- 66 Dy, Dysprosium
- 67 Ho, Holmium
- 68 Er, Erbium
- 69 Tm, Thulium
- 70 Yb, Ytterbium
- 71 Lu, Lutetium
The group consists of the following elements which are not earths and are not literally rare; however, they are called "rare earth minerals" because they were associated with more familiar substances known as "common earth".
This Lanthanide series is shown with their atomic numbers, their symbols, and their names with links to much more detailed information about the history, who and where they were discovered, terms in four other languages, etc. for each of the listed elements as shown in the Periodic Table of Chemical Elements:
The elements range in crustal abundance (igneous crust or outer layer of the earth) from cerium, the 25th most abundant element of the 78 common elements in the earth's crust at 60 parts per million, to thulium and lutetium, the least abundant rare-earth elements at about 0.5 part per million.
Seventeen rare-earth minerals are used in a wide variety of commercial and military applications ranging from precision guided smart bombs, to efficient light bulbs, car batteries, sophisticated radar systems, mobile phones, clean energy technology, DVDs, very large wind turbines, phosphors for monitors, televisions, lighting, catalytic converters, glass polishing, petroleum refining; plus other modern applications.
Rare-earth minerals are also used in computer display screens, motherboards, hard drives, chips, and other-related elements in computers; rare metals like indium is used in liquid-crystal display screens, antimony is used in silicon wafers for semiconductors, neodymium is a vital element in industrial batteries which are used in electric motors and it is found in parts used in the speakers of cellphones, and dysprosium is used in laser materials.
Cerium is needed in such high-profile and sensitive applications as optical sensors used in F-15 fighter aircraft, and the windows and domes at the National Ignition Facility (NIF) which explores the world of high-energy-density physics.
Over 50 pounds of rare earth metal can be found in each Toyota Prius automobile and Japan is the world’s largest importer of rare earths for such products.
Hybrid vehicles use a special neodym magnet made with neodymium to help produce the energy they require to offset their usage of gas and oil.
On April 20, 2010, neodymium was priced at about $46.50 a kilogram (2.20 pounds). Since China made export rules and regulations in July, 2010, prices went up to $92 a kilogram (2.20 pounds).
Rare earth production outside of China by other countries has been limited by higher costs of mining (compared to those of China) and by concerns regarding environmental pollutions from mining wastes by other nations.
The United States previously produced all stages of the rare earth material supply chain, but now most rare earth materials processing is performed in China, giving it a dominant position that can affect the worldwide supply and prices of rare earth minerals.
According to the United States Geological Survey (USGS), the name “rare” earth elements is an “historical misnomer”, reflecting the elements’ unfamiliarity, rather than their true rarity.
Even the most scarce of rare earths, lutetium and thulium, are 200 times more abundant than gold in the earth’s crust.
China has about fifty-seven percent of the world’s known reserves, according to the United States Geological Survey. The United States has nine percent of global reserves, Australia has four percent, and Russia has fourteen percent.
Also, according to figures from the U.S. Geological Survey published earlier this year, production from Chinese mines accounted for 120,000 of the 124,000 tons of rare-earth oxides produced globally in 2009; which is more than 97 percent of the available supply; while India, Brazil, and Malaysia made up the rest of the supply or just three percent of the total.
Molycorp, the United States company that owns the Mountain Pass mine in the Mojave Desert of California, announced its intention to raise rare-earths production to meet about a sixth of global demand by 2012, and the company indicated that it would double that output if circumstances justify such an increase of production.
These screens make it possible for lower radiation doses to be used while producing acceptable film densities.
The term attenuation refers to the reduction with distance from the source of the intensity of an electromagnetic signal propagating through the atmosphere caused by the interaction of the signal with gaseous constituents of the atmosphere, aerosols, or hydrometeors.
It also includes the reduction of intensity of a radiation as it passes through a medium and it includes reductions due to both absorption and scattering.
When these elements are combined with oxygen or water, they form compounds with a basic pH.
Alkaline earth metals are not very electronegative. They have just two valence electrons, and will lose them to become positively charged ions or cations.