Gadolinium (Gd)

Stable isotopes of gadolinium available from ISOFLEX

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
Gd-152  64  88  151.919789 0.20%  30.60-34.80% Oxide
Gd-154  64  90  153.920862 2.18%  52.10-64.20%  Oxide
Gd-155 64 91 154.922619 14.80% >90.00% Oxide
Gd-156 64 92 155.922120 20.47% ≥93.30% Oxide
Gd-157 64 93 156.923957 15.65% 88.40% Oxide
Gd-158 64 94 157.924101 24.84% >97.30% Oxide
Gd-160 64 96 159.927051 21.86% 98.20% Oxide

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Gadolinium was discovered by Jean de Marignac in 1880. It is named for gadolinite, one of the minerals in which it was found, which was in turn named for chemist Johan Gadolin.

A colorless or light yellow lustrous metal, gadolinium occurs in a hexagonal close-packed crystalline form, known as alpha-gadolinium, which transforms to a body-centered cubic allotropic form, beta-gadolinium, when it reaches 1262 ºC. It exhibits a high degree of magnetism, especially at lower temperatures. Its salts are colorless. It has a vapor pressure of 9.0 torr at 1800 ºC. It also has superconductive properties. It is combustible and burns in air to form the oxide. It reacts slowly in water, is soluble in dilute acid, and is insoluble in water. All of its compounds are trivalent. Although the metal is stable in air at ordinary temperatures, it burns in air when heated to 150-180 ºC. Gadolinium is a strong reducing agent. It reduces oxides of several metals such as iron, chromium, lead, manganese, tin and zirconium into their elements. It burns in halogen vapors above 200 ºC, forming gadolinium(III) halides.

The most important application of this metal is as control rod material for shielding in nuclear power reactors. Other uses are in thermoelectric generating devices, as a thermoionic emitter, in yttrium-iron garnets in microwave filters to detect low-intensity signals, as an activator in many phosphors, for deoxidation of molten titanium, and as a catalyst.

Properties of Gadolinium

Name Gadolinium 
Symbol Gd 
Atomic number 64 
Atomic weight 157.25 
Standard state Solid at 298 ºK 
CAS Registry ID 7440-54-2 
Group in periodic table N/A 
Group name Lanthanoid 
Period in periodic table 6 (Lanthanoid) 
Block in periodic table f-block 
Color Silvery white 
Classification Metallic 
Melting point 1313 °C
Boiling point 3266 °C
Vaporization point 3266 ºC
Thermal conductivity 10.5 W/(m·K) at 298.2 ºK
Electrical resistivity 134.0 µΩ·cm at 25 ºC 
Electronegativity 1.1 
Specific heat 0.230 J/g mol at 20 ºC 
Heat of vaporization 305 kJ·mol-1 at 3266 ºC
Heat of fusion 10 kJ·mol-1
Density of liquid 7.4 g/cm3 at 1313 °C 
Density of solid 7.90 g/cm3 
Electron configuration [Xe]4f75d16s2 (partially filled f orbital) 
Common oxidation state +3