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About Praseodymium

Praseodymium Bohr

In 1841, Carl Gustav Mosander obtained a novel oxide from his experiments with rare-earth containing minerals. He believed this compound to be an oxide of a new rare earth element that he called didymium, and this element was included on an early version of Dmitri Mendeleev’s periodic table. Later experiments by Austrian chemist Carl Auer Welsbach in 1885 showed that this oxide was actually a mixture of salts of two new elements, which were subsequently named praseodymium and neodymium. Praseodymium salts are yellow-green in solution, leading to the naming of the compound from the greek word prasinos, meaning green, and the previously chosen root didymos, meaning twin.

Like many of the rare earth elements, praseodymium is used primarily in small amounts to “dope” other materials, as its presence even in small concentrations imparts useful properties. In many cases, praseodymium is used to alter optical properties or in light production or detection applications. Praseodymium is one of the rare earth elements found in didymium glass, which is used in safety goggles that block potentially harmful intense ultraviolet, infrared, and yellow light produced by during some types of welding and glassworking. Fluoride glass doped with praseodymium can be used as a fiber optical amplifier for use with light around a wavelength of 1300nm. Praseodymium-doped crystals are used as gain media in solid-state lasers. Praseodymium is one of several rare earths used to produce extremely bright carbon arc lights, though these are becoming much more rarely used in their primary application in the motion picture industry. Praseodymium compounds can be used yield either a yellow or yellow-green coloring, depending on the application; in glass and enamel, praseodymium is used for yellow coloring. Adding praseodymium to cubic zirconia produces a yellow-green stone which mimics the mineral peridot. Modern medical computed tomography (CT) scanners often use praseodymium-doped scintillator crystals in their X-ray detecting sensors.

Additionally, praseodymium is used as a dopant in alloying applications, catalysts, and other novel materials. Small amounts of praseodymium alloyed with magnesium produce high-strength metals used in demanding applications such as jet engines. Praseodymium-nickelalloys exhibit an extremely strong magnetocaloric effect and have been used in refrigeration devices to attain extremely low temperatures. Praseodymium is used in small amounts in neodymium magnets, which are the strongest permanent magnets commercially available. Praseodymium-doped ceria can be used to catalyze a variety of reactions. Praseodymium-doped thin films are being investigated due to a variety of potentially useful properties including photoluminescence. Praseodymium-doped yttrium silicate crystals are used in quantum computing research.

Praseodymium nickelates, praseodymium doped ceria, and praseodymium barium copper oxide are all being researched as cathode materials for solid oxide fuel cells. Historically, the rare-earth alloy mischmetal was used in lighter flints, and modern flints still contain small amounts of praseodymium along with other rare earths. Finally, praseodymium oxide thin-film surface coatings provide antireflective properties and durability.

Praseodymium is one of the light rare earths and is typically sourced, along with other elements from that group, from the minerals monazite and bastnasite.

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High Purity (99.999%) Praseodymium Oxide (Pr2O3) Powder Praseodymium is highly valued in glass and ceramic production as a bright yellow pigment. Much research is being done on its optical properties for use in amplification of telecommunication systems, including as a doping agent in fluoride fibers. High Purity (99.999%) Praseodymium (Pr) Sputtering TargetPraseodymium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Metallic forms include pellets, rod, wire, and granules for evaporation source material purposes. Praseodymium oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Praseodymium is also available in soluble forms including praseodymium chloride, praseodymium nitrate, and praseodymium acetate. These compounds can be manufactured as solutions at specified stoichiometries.

Praseodymium Properties

Praseodymium (Pr) atomic and molecular weight, atomic number and elemental symbol Praseodymium is a Block F, Group 3, Period 6 element. The number of electrons in each of praseodymium's shells is 2, 8, 18, 21, 8, 2 and its electronic configuration is [Xe]4f3 6s2. Praseodymium Bohr ModelThe praseodymium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-10-0, praseodymium has a grayish white appearance. Elemental PraseodymiumIt resembles the typical trivalent rare earths, however, it will exhibit a +4 state when stabilized in a zirconia host. Unlike other rare earth metals, which show antiferromagnetic and / or ferromagnetic ordering at low temperatures, praseodymium is paramagnetic at any temperature above 1 K. Praseodymium is found in the minerals monazite and bastnasite. Praseodymium was discovered by Carl Auer von Welsbach in 1885. The origin of the element name comes from the Greek words 'prasios didymos' meaning green twin.

Symbol: Pr
Atomic Number: 59
Atomic Weight: 140.9077
Element Category: Lanthanide
Group, Period, Block: n/a, 6, f
Color: silvery white, yellowish tinge
Other Names: Praseodym, Praséodyme
Melting Point: 931°C, 1707.8°F, 1204.15 K
Boiling Point: 3520°C, 6368°F, 3793.15 K
Density: 6779  kg·m3
Liquid Density @ Melting Point: 6.50 g·cm3
Density @ 20°C: 6.77 g/cm3
Density of Solid: 6640 kg·m3
Specific Heat: 0.046 Cal/g/K @ 25°C
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 11.3
Heat of Vaporization (kJ·mol-1): 357
Heat of Atomization (kJ·mol-1): 356.69
Thermal Conductivity: 0.125 W/cm/K @ 298.2 K
Thermal Expansion: (r.t.) (poly) 6.7 µm/(m·K)
Electrical Resistivity: 68 nΩ-cm @ 25°C
Tensile Strength: N/A
Molar Heat Capacity: 27.20 J·mol-1·K-1
Young's Modulus: ( form) 37.3 GPa
Shear Modulus: ( form) 14.8 GPa
Bulk Modulus: ( form) 28.8 GPa
Poisson Ratio: ( form) 0.281
Mohs Hardness: N/A
Vickers Hardness: 400 MPa
Brinell Hardness: 481 MPa
Speed of Sound: (20 °C) 2280 m·s-1
Pauling Electronegativity: 1.13
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.07
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.87
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 59
Protons: 59
Neutrons: 82
Electron Configuration: [Xe]4f3 6s2
Atomic Radius: 182 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 203±7 pm
Covalent Radius (Å): 1.9
Van der Waals Radius: 239 pm
Oxidation States: 4, 3, 2 (mildly basic oxide)
Phase: Solid
Crystal Structure: Hexagonal
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 92.786
1st Ionization Energy: 527 kJ·mol-1
2nd Ionization Energy: 1020 kJ·mol-1
3rd Ionization Energy: 2086 kJ·mol-1
CAS Number: 7440-10-0
EC Number: 231-120-3
MDL Number: MFCD00011174
Beilstein Number: N/A
SMILES Identifier: [Pr]
InChI Identifier: InChI=1S/Pr
PubChem CID: 23942
ChemSpider ID: 22384
Earth - Total: 129 ppb
Mercury - Total: 99 ppb
Venus - Total: 135 ppb
Earth - Seawater (Oceans), ppb by weight: 0.0006
Earth - Seawater (Oceans), ppb by atoms: 0.000026
Earth - Crust (Crustal Rocks), ppb by weight: 8700
Earth - Crust (Crustal Rocks), ppb by atoms: 1300
Sun - Total, ppb by weight: 1
Sun - Total, ppb by atoms: 0.005
Stream, ppb by weight: 0.03
Stream, ppb by atoms: 0.0002
Meterorite (Carbonaceous), ppb by weight: 100
Meterorite (Carbonaceous), ppb by atoms: 10
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 2
Universe, ppb by atom: 0.02
Discovered By: Carl Auer von Welsbach
Discovery Date: 1885
First Isolation: N/A

Health, Safety & Transportation Information for Praseodymium

Praseodymium is somewhat toxic. Safety data for Praseodymium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) praseodymium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Warning
Hazard Statements H250
Hazard Codes F
Risk Codes 17
Safety Precautions N/A
RTECS Number N/A
Transport Information UN 3208 4.3/PG 1
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)

Praseodymium Isotopes

Naturally occurring praseodymium (Pr) has one stable isotope: 141Pr.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
121Pr 120.95536(75)# 600(300) ms p to 120Ce; ß+ to 121Ce; ß+ + p to 120La (3/2-) N/A 957.9 -
122Pr 121.95181(54)# 500# ms ß+ to 122Ce N/A N/A 965.98 -
123Pr 122.94596(64)# 800# ms ß+ to 123Ce 3/2+# N/A 983.38 -
124Pr 123.94296(64)# 1.2(2) s ß+ to 124Ce N/A N/A 991.46 -
125Pr 124.93783(43)# 3.3(7) s ß+ to 125Ce 3/2+# N/A 1008.85 -
126Pr 125.93531(21)# 3.12(18) s ß+ to 126Ce (4,5,6) N/A 1016.93 -
127Pr 126.93083(21)# 4.2(3) s ß+ to 127Ce 3/2+# N/A 1025.01 -
128Pr 127.92879(3) 2.84(9) s ß+ to 128Ce (3+) N/A 1042.4 -
129Pr 128.92510(3) 32(3) s ß+ to 129Ce (11/2-) N/A 1050.48 -
130Pr 129.92359(7) 40.0(4) s ß+ to 130Ce (6,7)(+#) N/A 1058.56 -
131Pr 130.92026(6) 1.50(3) min ß+ to 131Ce (3/2+) N/A 1066.64 -
132Pr 131.91926(6) 1.49(11) min ß+ to 132Ce (2+) N/A 1084.03 -
133Pr 132.916331(13) 6.5(3) min ß+ to 133Ce (3/2+) N/A 1092.11 -
134Pr 133.91571(4) ~11 min ß+ to 134Ce (5-) N/A 1100.19 -
135Pr 134.913112(13) 24(2) min ß+ to 135Ce 3/2(+) N/A 1108.27 -
136Pr 135.912692(13) 13.1(1) min ß+ to 136Ce 2+ N/A 1116.35 -
137Pr 136.910705(13) 1.28(3) h EC to 137Ce 5/2+ N/A 1124.43 -
138Pr 137.910755(15) 1.45(5) min EC to 138Ce 1+ N/A 1132.51 -
139Pr 138.908938(8) 4.41(4) h EC to 139Ce 5/2+ N/A 1149.9 -
140Pr 139.909076(7) 3.39(1) min EC to 140Ce 1+ N/A 1157.98 -
141Pr 140.9076528(26) STABLE - 5/2+ 4.136 1166.06 100
142Pr 141.9100448(26) 19.12(4) h EC to 142Ce; ß- to 142Nd 2- N/A 1164.82 -
143Pr 142.9108169(28) 13.57(2) d ß- to 143Nd 7/2+ 0.234 1172.9 -
144Pr 143.913305(4) 17.28(5) min ß- to 144Nd 0- 2.7 1180.98 -
145Pr 144.914512(8) 5.984(10) h ß- to 145Nd 7/2+ N/A 1189.06 -
146Pr 145.91764(7) 24.15(18) min ß- to 146Nd (2)- N/A 1197.14 -
147Pr 146.918996(25) 13.4(4) min ß- to 147Nd (3/2+) N/A 1205.21 -
148Pr 147.922135(28) 2.29(2) min ß- to 148Nd 1- N/A 1203.98 -
149Pr 148.92372(9) 2.26(7) min ß- to 149Nd (5/2+) N/A 1212.06 -
150Pr 149.926673(28) 6.19(16) s ß- to 150Nd (1)- N/A 1220.13 -
151Pr 150.928319(25) 18.90(7) s ß- to 151Nd (3/2)(-#) N/A 1228.21 -
152Pr 151.93150(13) 3.63(12) s ß- to 152Nd 4+ N/A 1226.98 -
153Pr 152.93384(11) 4.28(11) s ß- to 153Nd 5/2-# N/A 1235.05 -
154Pr 153.93752(16) 2.3(1) s ß- to 154Nd (3+,2+) N/A 1243.13 -
155Pr 154.94012(32)# 1# s [>300 ns] ß- to 155Nd 5/2-# N/A 1241.9 -
156Pr 155.94427(43)# 500# ms [>300 ns] ß- to 156Nd N/A N/A 1249.97 -
157Pr 156.94743(43)# 300# ms ß- to 157Nd 5/2-# N/A 1258.05 -
158Pr 157.95198(64)# 200# ms ß- to 158Nd N/A N/A 1256.82 -
159Pr 158.95550(75)# 100# ms ß- to 159Nd 5/2-# N/A 1264.89 -