Low Temperature reduction of oxynitrides by metal hydride

Abstract

Oxynitrides have attracted a great deal of interest, particularly for photocatalysis, but it is hard to optimize the O/N ratio precisely. Using the reducing agent CaH₂ on oxynitrides is expected to remove O^2- selectively, or perhaps even lead to the synthesis of mixed anion compounds with three types of anions (O^2-/H^-/N^3-). With the oxynitride perovskites La_xSr_1-xTiO_3-xN_x (0 ≤ x ≤ 1), we succeeded in preparing oxynitride-hydrides for 0 ≤ x ≤ 0.2, while the reduction reaction was not observed in 0.2 ≤ x ≤ 1. This result suggests that N^3- inhibits oxide reduction or H^- diffusion throughout the bulk.