Element

Gadolinium Element Properties and Information

September 8, 2022

Gadolinium Element Properties and Information

Gadolinium is 64^th element on the periodic table. Elements are arranged in the periodic table on the basis of the atomic number. Atomic number is the number of protons in the nucleus of the atom. Gadolinium has an atomic number of 64. It is located in the Group ‘Lanthanides’ and Period 6 of the periodic table of elements. It is denoted by ‘Gd’. It is named after mineral Gadolinite which is itself named after Johan Gadolin, a French chemist.

Lanthanides have a complex history separation. First cerium was discovered in 1803, the separated sample in and of itself was found to be impure. Two elements were separated from it in 1839; lanthanum and didymium. The didymium itself turned out to be a mixture of elements and they were separated as praseodymium and neodymium in 1879. It still harbored more elements and a sample of rare-earth samarium was extracted. The sample of samarium itself was not totally pure and contained more elements. Gadolinium was discovered in it in 1886 by Jean Charles Galissard de Marignac.

Gadolinium is found in nature only in combined form because it is quite reactive. Although gadolinium is named after gadolinite mineral, it is present in it only in trace amounts. Gadolinium’s concentration in Earth’s crust is 6.2 ppm. Like all other lanthanides it is obtained from the minerals bastnaesite and monazite.

Physical Properties

Gadolinium is soft, ductile silvery-white metal which is only slightly available.
The atomic mass of gadolinium is 157.25.
The melting point of gadolinium is 1313°C.
The boiling point of gadolinium is 3266°C.
The density of gadolinium is 7900 in S.I. units at 20°C.
Gadolinium crystallizes in a hexagonally-closed-packed structure at room temperature. It transforms to body-centered-cubic at 1235°C.
Gadolinium is ferromagnetic below 20°C and strongly paramagnetic above it.
Naturally occurring gadolinium is composed of 6 stable isotopes; gadolinium-154, Gadolinium-155, gadolinium-156, gadolinium-157, gadolinium-158, and gadolinium-160.

Chemical Properties

Gadolinium is quite reactive, it combines with most elements to form Gd(III) derivatives.
Gadolinium combines with carbon, nitrogen, sulfur, boron, phosphorus, selenium, silicon, and arsenic at elevated temperatures to form binary compounds.
Gadolinium is relatively stable in dry-air when compared to other lanthanides. It tarnishes easily when exposed to moist air.
Gadolinium is quite a strong reducing agent; it reduces many metallic oxides to their corresponding elements.
Gadolinium is quite electropositive in nature. It reacts slowly with cold-water and faster with hot-water.
Gadolinium reacts with all the halogens to form corresponding trihalides at 200°C.

Methods of Production

From Bastnaesite or Monazite: The ore is first subjected to electrostatic separation multiple times to separate its magnetic properties. After separation it is treated with hot-concentrated sulphuric acid to get dissolved sulfates of lanthanides. The acid filter is neutralized using sodium hydroxide at pH 3-4, during this process; the thorium gets removed as a hydroxide. The solution is then treated with ammonium oxalates to get lanthanide oxalates. The oxalates are converted to oxides by annealing. The oxides are then dissolved in nitric acid solution wherein cerium gets removed because of its insolubility. The solution is then treated with magnesium nitrate to produce a crystrallized mixture of double salts of lanthanides. The salts are separated using ion exchange chromatography. The gadolinium salts are reduced to gadolinium using calcium.
Reduction: Calcium can be used in argon atmosphere to reduce gadolinium salt or gadolinium oxide to gadolinium at temperature of 1450°C. Calcium metal can also be used to reduce anhydrous gadolinium fluoride to obtain gadolinium.

Relevance in Chemical and Related Industries

Alloys: Gadolinium possesses unusual metallurgical properties. Addition of even 1% of gadolinium to iron, chromium, and related alloys, immensely improves the workability and resistance to high temperatures and oxidation.

Relevance in Other Industries

Medicine: Gadolinium-157 is used to target tumors in neutron therapy. It has high neutron capture cross-section.
Imaging: Gadolinium is used in Magnetic Resonance Angiography, X-ray imaging, and nuclear-medicine imaging system.