Neodymium – History, Properties and Applications

Chemical Formula

Topics Covered

Lighter Flints and Steel Making

Background

Mossander separated a previously unidentified rose coloured oxide from cerite in 1841. He believed that the oxide contained a new element which he names didymium, as it was the inseparable twin brother of lanthanum.

Although, von Welsbach successfully separated didymium into two elemental components, neodymia and praseodymia in 1885, it was not until 1925, when neodymium was separated into a raltively pure form.

Occurrence

Neodymium is found in misch metal for which it comprises about 18%. It is also found in minerals such as monazite and bastnasite, which are the most common sources for rare earth metals.

Refining

It can be refined by separating neodymium salts from other rare earths by ion-exchange or solvent extraction. Alternatively it can be obtained by the reduction of anhydrous halides such as NdF₃ using calcium metal, while other separation methods are also available.

Key Properties

Characteristic properties of neodymium include:

· Bright silvery metallic lustre

· It is one of the more reactive rare earth metals

· It tarnishes in air, forming an oxide layer that spalls off, exposing more metal to oxidation. For this reason, neodymium should be stored under a light mineral oil or sealed in plastic

· It has two allotropes and transforms from double hexagonal to body centred cubic structure at 860°C

· Natural neodymium consists of seven different isotopes, while a further seven radioactive isotopes are recognised

Applications

Glasses and Ceramics

Perhaps the main use for neodymium is as a colourant for glasses. When added to glass it can produce colours ranging from pure violet to wine red through to warm grey. It is also added to glass to remove the green colour induced by the presence or iron. Neodymium containing glasses can be used for astronomical work to sharp bands for the calibration of spectral lines, filter for infrared radiation and as an alternative to ruby in lasers for producing coherent light. Similarly didymium is used for making the glass that goes into welders goggles and neodymium is used as a colourant for enamels.

Magnets

Neodymium is also used in magnets. Such magnets are used in items such as computer disk drives.

Lighter Flints and Steel Making

Misch metal which contains metallic neodymium is used in lighter flints due to its pyrophoric nature and steel making.