The picture is extracted from a Scanning Electron Microscope (SEM) observing a Ni-BaH2 powder catalyst, which I am researching on for the application of ammonia production using metal hydrides catalysts. The image shows a spherical agglomeration of Ni nanoparticles. This was unexpected as it is desired that the Ni nanoparticles are fixed on the particles of BaH2. In that case, the sample was most definitely not ground long enough, leading to some Ni nanoparticles to form a cluster with each other.