159-tir11
Bronze medal, France.
Minted in 1938, beautiful patina, some minor defects, some traces of oxidation.Engraver / Artist : N. Aronson.
Dimension : 60 mm by 80 mm.
Weight : approximately 200 g.
Metal : Bronze.
Mark on the edge : triangle + bronze.
Quick and neat delivery.
The support is not for sale.
The stand is not for sale.
Rare earths are a group of metals with similar properties including scandium 21Sc, yttrium 39Y and the fifteen lanthanides.
These metals are, contrary to what their name suggests, quite widespread in the earth's crust, like certain common metals. The abundance of cerium is thus around 48 ppm1, while that of thulium and lutetium is only 0.5 ppm. In elemental form, rare earths have a metallic appearance and are quite soft, malleable and ductile. These elements are chemically quite reactive, especially at high temperatures or when finely divided.
Their electromagnetic properties come from their electronic configuration with progressive filling of the 4f sublayer, at the origin of the phenomenon called lanthanide contraction.
It was not until the Manhattan Project in the 1940s that rare earths were purified at an industrial level, and the 1970s that one of them, yttrium, found mass application in the manufacture of phosphors of cathode ray tubes used in color television. From the point of view of the global economy, rare earths are now part of strategic raw materials.
The following table gives the atomic number, symbol, name, etymology and uses of the 17 rare earths.
The name of a rare earth derives depending on the case:
from the place name of the discovery (Ytterby, Scandinavia);
named after a discoverer (Gadolin, Samarski);
mythology (Ceres, Prometheus, Thule);
of the circumstances of the discovery (see La, Pr, Nd, Dy).
Z Symbol Name Etymology Uses2,3,4,5
21 Sc Scandium from Latin Scandia (Scandinavia). Light aluminum-scandium alloys: military aeronautics; additive (ScI2) in metal halide lamps; 46Sc: radioactive tracer in refineries.
39 Y Yttrium from the village of Ytterby, Sweden, where the first rare earth mineral was discovered. Lasers: Yttrium aluminum garnet (YAG) doped with lanthanides6 (Nd, Ho, Er, Tm, Yb); vanadate YVO4 doped with Eu: red phosphors (TV), doped with Nd: lasers, doped with Ce3+: GaN LED; compact fluorescent bulbs; mixed barium, copper, and yttrium oxide (YBCO): high-temperature superconductors; yttrium-stabilized cubic zirconia (YSZ): refractory conductive ceramics; yttrium iron garnet (YIG): microwave filters; spark plugs; 90Y: cancer treatment.
57 Lanthanum from the Greek λανθάνειν, “hidden”. Nickel-metal hydride batteries; high refractive index and low dispersion glasses; laser (YLaF); fluoride glasses; hydrogen storage.
58 This Cerium from the dwarf planet Ceres, named after the Roman goddess of agriculture. Oxidizing chemical agent; glass polishing powder (CeO2); yellow coloring of glasses and ceramics; glass discoloration; catalysts: self-cleaning furnace liners, hydrocarbon cracking, exhaust pipes; YAG doped with Ce: yellow-green phosphor for light-emitting diodes; Incandescent sleeves.
59 Pr Praseodymium from the Greek πράσινος, “pale green”, and δίδυμος, “twin”. Permanent magnets (alloyed with Nd); Fiber amplifiers; dyes for glasses (green) and ceramics (yellow); welder's goggles (allied to Nd).
60 Nd Neodymium from the Greek νεο-, “new” and δίδυμος, “twin”. Permanent magnets (wind turbines; small hydropower plants; hybrid cars); YAG lasers; purple coloring of glasses and ceramics; ceramic capacitors; welder's goggles (allied to Pr).
61 Pm Promethium of the Titan Prometheus, who brought fire to mortals. Potential applications of 147Pm: luminous paints, nuclear batteries, energy source for space probes.
62 Sm Samarium of the Russian mining engineer Vasily Samarsky-Bykhovets. Permanent magnets (SmCo5); X-ray lasers7; catalysts; neutron capture; masers; 153Sm: radiotherapy.
63 Eu Europium from the continent of Europe. Red (Eu3+) and blue (Eu2+) luminophores: compact fluorescent lamps, intensifying screens for X-rays, TV; lasers; crypts: biological probes by energy transfer between fluorescent molecules; control rods (nuclear reactors).
64 Gd Gadolinium by Johan Gadolin, discoverer of yttrium in 1794. Lasers; neutron capture: nuclear reactors; contrast agent in MRI8; Green luminophores; intensifying screens for X-rays; steel additive.
65 Tb Terbium from the village of Ytterby, Sweden. Green luminophores: compact fluorescent lamps, intensifying screens for X-rays, TV; lasers; cryptates (see Eu); Terfenol-D (Tb0.3Dy0.7Fe1.9): magnetostriction, transducers.
66 Dy Dysprosium from Greek δυσπρόσιτος, “difficult to obtain”. Permanent magnets; metal halide lamps; HDDs ; lasers; Terfenol-D (see Tb).
67 Ho Holmium from Latin Holmia (latinized form
These metals are, contrary to what their name suggests, quite widespread in the earth's crust, like certain common metals. The abundance of cerium is thus around 48 ppm1, while that of thulium and lutetium is only 0.5 ppm. In elemental form, rare earths have a metallic appearance and are quite soft, malleable and ductile. These elements are chemically quite reactive, especially at high temperatures or when finely divided.
Their electromagnetic properties come from their electronic configuration with progressive filling of the 4f sublayer, at the origin of the phenomenon called lanthanide contraction.
It was not until the Manhattan Project in the 1940s that rare earths were purified at an industrial level, and the 1970s that one of them, yttrium, found mass application in the manufacture of phosphors of cathode ray tubes used in color television. From the point of view of the global economy, rare earths are now part of strategic raw materials.
The following table gives the atomic number, symbol, name, etymology and uses of the 17 rare earths.
The name of a rare earth derives depending on the case:
from the place name of the discovery (Ytterby, Scandinavia);
named after a discoverer (Gadolin, Samarski);
mythology (Ceres, Prometheus, Thule);
of the circumstances of the discovery (see La, Pr, Nd, Dy).
Z Symbol Name Etymology Uses2,3,4,5
21 Sc Scandium from Latin Scandia (Scandinavia). Light aluminum-scandium alloys: military aeronautics; additive (ScI2) in metal halide lamps; 46Sc: radioactive tracer in refineries.
39 Y Yttrium from the village of Ytterby, Sweden, where the first rare earth mineral was discovered. Lasers: Yttrium aluminum garnet (YAG) doped with lanthanides6 (Nd, Ho, Er, Tm, Yb); vanadate YVO4 doped with Eu: red phosphors (TV), doped with Nd: lasers, doped with Ce3+: GaN LED; compact fluorescent bulbs; mixed barium, copper, and yttrium oxide (YBCO): high-temperature superconductors; yttrium-stabilized cubic zirconia (YSZ): refractory conductive ceramics; yttrium iron garnet (YIG): microwave filters; spark plugs; 90Y: cancer treatment.
57 Lanthanum from the Greek λανθάνειν, “hidden”. Nickel-metal hydride batteries; high refractive index and low dispersion glasses; laser (YLaF); fluoride glasses; hydrogen storage.
58 This Cerium from the dwarf planet Ceres, named after the Roman goddess of agriculture. Oxidizing chemical agent; glass polishing powder (CeO2); yellow coloring of glasses and ceramics; glass discoloration; catalysts: self-cleaning furnace liners, hydrocarbon cracking, exhaust pipes; YAG doped with Ce: yellow-green phosphor for light-emitting diodes; Incandescent sleeves.
59 Pr Praseodymium from the Greek πράσινος, “pale green”, and δίδυμος, “twin”. Permanent magnets (alloyed with Nd); Fiber amplifiers; dyes for glasses (green) and ceramics (yellow); welder's goggles (allied to Nd).
60 Nd Neodymium from the Greek νεο-, “new” and δίδυμος, “twin”. Permanent magnets (wind turbines; small hydropower plants; hybrid cars); YAG lasers; purple coloring of glasses and ceramics; ceramic capacitors; welder's goggles (allied to Pr).
61 Pm Promethium of the Titan Prometheus, who brought fire to mortals. Potential applications of 147Pm: luminous paints, nuclear batteries, energy source for space probes.
62 Sm Samarium of the Russian mining engineer Vasily Samarsky-Bykhovets. Permanent magnets (SmCo5); X-ray lasers7; catalysts; neutron capture; masers; 153Sm: radiotherapy.
63 Eu Europium from the continent of Europe. Red (Eu3+) and blue (Eu2+) luminophores: compact fluorescent lamps, intensifying screens for X-rays, TV; lasers; crypts: biological probes by energy transfer between fluorescent molecules; control rods (nuclear reactors).
64 Gd Gadolinium by Johan Gadolin, discoverer of yttrium in 1794. Lasers; neutron capture: nuclear reactors; contrast agent in MRI8; Green luminophores; intensifying screens for X-rays; steel additive.
65 Tb Terbium from the village of Ytterby, Sweden. Green luminophores: compact fluorescent lamps, intensifying screens for X-rays, TV; lasers; cryptates (see Eu); Terfenol-D (Tb0.3Dy0.7Fe1.9): magnetostriction, transducers.
66 Dy Dysprosium from Greek δυσπρόσιτος, “difficult to obtain”. Permanent magnets; metal halide lamps; HDDs ; lasers; Terfenol-D (see Tb).
67 Ho Holmium from Latin Holmia (latinized form
63 Eu Europium from the continent of Europe. Red (Eu3+) and blue (Eu2+) luminophores: compact fluorescent lamps, intensifying screens for X-rays, TV; lasers; crypts: biological probes by energy transfer between fluorescent molecules; control rods (nuclear reactors).
64 Gd Gadolinium by Johan Gadolin, discoverer of yttrium in 1794. Lasers; neutron capture: nuclear reactors; contrast agent in MRI8; Green luminophores; intensifying screens for X-rays; steel additive.
65 Tb Terbium from the village of Ytterby, Sweden. Luminophor
64 Gd Gadolinium by Johan Gadolin, discoverer of yttrium in 1794. Lasers; neutron capture: nuclear reactors; contrast agent in MRI8; Green luminophores; intensifying screens for X-rays; steel additive.
65 Tb Terbium from the village of Ytterby, Sweden. Luminophor