JoyZhong

I once tried to clean a piece of neodymium. The metal is easily etched with diluted HNO3, and the surface is cleaned with water, and dried with acetone. Immediately after, I polished the surface with polishing compunds, resulting in a mirrorlike surface finish. But there the luck stopped.

I immersed the shiny metal under paraffinum oil, but the metal corroded heavily within years. Nothing could stop the corrosion on depth. Even sodium behaves (and is preserved) better than Nd for a long time immersed under paraffinum oil!

 

When I purchased the lanthanide metals from David Hamric (eBay, "rare earth metals set"), I observed the same problem within a year. Finally, I solved that problem by simply purchasing La,Ce,Pr,Nd and Eu as metal pieces in sealed glass ampoules under argon gas (most of these also from Hamric).

 

My experience is that the reactive lanthanides should be kept under Ar in sealed glass ampoules. These metals should NOT be kept under paraffinum oil, at least not for an element collection.

The heavier lanthanides (from 66 Dy up to 71 Lu) does not corrode in air.

Sm corrodes slowly, and the commercial metal is often oxidized on the surface.

Gd also (and to some extent Tb), but much slower.

Hi just want to ask, I've bought Nd ingot also ,but they come in small pieces (5mm-10mm) and was previously immerse in certain kind of mineral oil. so there's a dark surface on the metal, is there any chemical that can wash away this dark surface without hurting Nd metal itself too severely? I've thought about diluted HNO3, but just afraid the Nd will react with it and won't left me anything behind, cause my Nd ingots are quite small.