Reaction of LiH and BeH2

Abstract Lithium hydride (LiH) and beryllium hydride (BeH 2 ) powder have been mixed and heated. The BeH 2 is from a unique cache of the material made twenty years ago by an organometallic synthesis. In the hydride reaction, one atom of hydrogen comes off at 500 to 600 K and almost two atoms at 675 K. X-ray diffraction shows the formation of Li 2 BeH 4 plus an unknown lithium-beryllium hydride at temperatures as low as 343 K. The yield of these compounds decreases with increasing temperature and is as high as 60 to 100% at 350 to 400 K. Identical behavior is seen with crystalline and noncrystalline BeH 2 . The LiH-BeH 2 reaction is thought to create enough heat to temporarily melt the products. Released hydrogen gas or organic vapors then push the material into a foam at 440 to 470 K.