Transformation of the Chromium Coordination Environment in LaCrAsO Induced by Hydride Doping: Formation of La 2 Cr 2 As 2 O y H x

We report the synthesis of La Cr As O H (0.1 < y < 1.6) oxyhydride solid solutions using a solid-state reaction under high pressure with a solid-state hydrogen source and exhibit an example of how H doping can also promote structural changes: H doping in LaCrAsO results in the formation of La Cr As O H with the La Fe Se O -type layered structure. Remarkably, this transformation includes a change of the coordination number of Cr from 4 to 6, with the some of the H being accommodated in new sites within the CrAs layers. In this way, H not only serves as a conventional electron dopant by the substitution of O but also makes new bonds to the transition metals.