Crystal Structures of Molybdenum Nitride(Mo3N5) with Anisotropic Compressibility

Takuya Sasaki et al. published a research paper related to molybdenum nitride^[1]. In this paper, a novel high-pressure molybdenum nitride phase, Mo3N5, was synthesized at above 45 GPa via a nitridation reaction of molybdenum with nitrogen under high pressure using a laser-heated diamond anvil cell. 

Figure 1. Crystal Structure of Molybdenum Nitride^[1].

Molybdenum nitride(Mo3N5), having an N–N dimer and 7-coordinated Mo sites, crystallizes in an orthorhombic structure with a space group of Cmcm (No. 63) without other prototype structures. The refined lattice parameters for Mo3N5 were a = 2.86201(2) Å, b = 7.07401(6) Å, and c = 14.59687(13) Å. The DFT enthalpy calculation suggested that Mo3N5 is a high-pressure stable phase, which is also consistent with an increasing coordination number compared to ambient- and low-pressure phases. The zero-pressure bulk modulus of Mo3N5 was determined to be K0 = 328(4) GPa with K′0 = 10.1(6) by the fitting for the compression curve, which is almost consistent with the theoretical E–V curve and elastic stiffness constants. The compressibility of molybdenum nitride has axial anisotropy corresponding to the N–N dimer direction in the crystal structure.

Reference

[1] High-pressure synthesis and crystal structures of molybdenum nitride Mo3N5 with anisotropic compressibility by a nitrogen dimer. doi:10.1039/D2DT03433F