The growth of crystals of erbium hydride

Crystals of the rare-earth hydride ErH2 have been produced with face areas greater than a square millimetre and corresponding volumes exceeding those of earlier crystals by orders of magnitude. The hydride, which was produced in bulk polycrystalline form by hydriding erbium metal at 950° C, has been examined by optical and X-ray techniques. For material of composition ErH2 and ErH1.8 the size of the grains and their degree of strain appears to depend more on oxygen contamination during formation and on the subsequent cooling procedure, than on the size of erbium metal crystals in the starting material.