Molybdenum Oxide Nitrides of the Mo₂(O,N,□)₅ Type: On the Way to Mo₂O₅

Abstract

Blue-colored molybdenum oxide nitrides of the Mo(O,N,□) type were synthesized by direct nitridation of commercially available molybdenum trioxide with a mixture of gaseous ammonia and oxygen. Chemical composition, crystal structure, and stability of the obtained and hitherto unknown compounds are studied extensively. The average oxidation state of +5 for molybdenum is proven by Mo K near-edge X-ray absorption spectroscopy; the magnetic behavior is in agreement with compounds exhibiting MoO units. The new materials are stable up to ∼773 K in an inert gas atmosphere. At higher temperatures, decomposition is observed. X-ray and neutron powder diffraction, electron diffraction, and high-resolution transmission electron microscopy reveal the structure to be related to VNbO-type phases, however, with severe disorder hampering full structure determination. Still, the results demonstrate the possibility of a future synthesis of the potential binary oxide MoO. On the basis of these findings, a tentative suggestion on the crystal structure of the potential compound MoO, backed by electronic-structure and phonon calculations from first principles, is given.

3D Electron Diffraction: The Nanocrystallography Revolution

“…The 3D ED ability of analyzing single components in a nanocrystalline mixture was also applied for the study of HP syntheses , and metallic alloys . 3D ED is also a powerful instrument for the characterization of intermediate synthetic snapshots, to follow a specific reaction pathway. , …”

“…51 3D ED is also a powerful instrument for the characterization of intermediate synthetic snapshots, to follow a specific reaction pathway. 128,129 4.2. Minerals.…”

Structure analysis of materials at the order–disorder borderline using three-dimensional electron diffraction

“…The structure of these materials can generally be broken up in hard blocks which are kept together by relatively weaker connections. Three examples can be found in the synthetic complex oxides NaTi 3 O 6 (OH)Á2H 2 O (Andrusenko et al, 2011), KLa 5 O 5 (VO 4 ) (Colmont et al, 2016) and Mo 2 (O,N,&) 5 (Weber et al, 2017). The structures of the former two oxides consist of rigid bands interconnected by loosely bonded alkali atoms and possibly water.…”