Structure and crystallization of zinc and germanium oxynitrides determined by neutron diffraction

Abstract

The zinc and germanium oxynitride phases, prepared by reaction of NH 3 with Zn 2GeO 4, are semiconductors and are fit for use as selective sensors of ammonia. They present a large range of compositions. A neutron diffraction structural study using the time-of-flight method has been realized for one of these compounds. It shows an hexagonal würtzite-type unit cell with a statistical occupation of the anionic and cationic sites and a defect in the cationic site. The lines are broadened and their basis is very large. The sample is described as a mixture of two phases, one of single composition and the other of fluctuating composition. The latter explains the basis. The broadening of lines is explained by the grain-size. The structure refinement leads to the correlation factor R=0.040 with the unit cell parameters a = 3.2090 (1) Å and c=5.1927(3)Å for the well-crystallized phase.