Novel superstructure in the high-concentrated hydrogen solid solutions ZrV 2D x>4

Abstract

A novel hydrogen superstructure with k = 0 is found to form in the hydrogen solid solutions ZrV 2D x in the concentration range 4 < x < 4.5. According to the neutron-diffraction investigation performed, it has tetragonal symmetry ( a = 5.517 Å, c = 7.921 Å for ZrV 2D 4.32 at T = 10 K) and belongs to the space group I4 1/ a. Four hydrogen atoms are arranged just as in the known superstructure ZrV 2D x<4 , in the 2Zr + 2V tetrahedral interstices. The surplus hydrogen atoms, exceeding x = 4, locate in the uncommon 4V tetrahedral interstices. Distances between all hydrogen atoms exceed 2 Å.