Monitoring the carburization of molybdenum bimetallic nitrides and oxynitrides with CH₄/H₂/Ar mixtures: identification of a new carbonitride

Abstract

A new carbonitride Ni2Mo3(CxNy) has been synthesized by temperature-programmed carburization of the Ni2Mo3N precursor with a CH4/H2/Ar gas mixture at 923 K. This compound has been characterized by X-ray diffraction, elemental analysis, Auger electron spectroscopy, laser Raman spectroscopy, thermogravimetric analysis and field-emission scanning electron microscopy. Ni2Mo3(CxNy) crystallizes in the cubic space group P4(1)32, with a lattice parameter of a=6.64575(3) A, corresponding to the unusual filled beta-Mn structure. Its formation occurs by partial substitution of N by C via a topotactic and pseudomorphic reaction and its stability in air is higher that of Ni2Mo3N. A two-phase mixture with a cubic structure has always been obtained by the same synthetic method applied to the V2Mo(OxNy) precursor. One of these would be of carbidic nature formed at 1153 K following a reaction similar to that proposed for Ni2Mo3(CxNy).

The role of preparation route upon the ambient pressure ammonia synthesis activity of Ni2Mo3N

“…However, reactivity of lattice N within Ni 2 Mo 3 N has been observed under some circumstances. For example, topotactic replacement of lattice nitrogen by carbon to yield nickel molybdenum carbonitrides using a CH 4 /H 2 /Ar gas mixture at 650 • C has been reported [27]. To investigate the reactivity of the lattice N in greater detail, and to discern its possible implication in ammonia synthesis, preliminary heterolytic isotopic exchange studies were undertaken.…”

Compressibility and structural stability of ultra-incompressible bimetallic interstitial carbides and nitrides

“…At ambient pressure, the obtained diffraction patters for Pd 2 Mo 3 N, Ni 2 Mo 3 C 0.52 N 0.48 (space group P4 1 32) 5 , Co 3 Mo 3 C 0.62 N 0.38 , and Fe 3 Mo 3 C (space group Fd 3 m, -carbide structure) 9 correspond to the known cubic structures, which are shown in Fig. 1.…”

“…6 In this work we extend the study of the compressibility and structural properties Fe 3 Mo 3 C were synthesized by carburization of the corresponding nitrides. [7][8][9] The nitrides were heated at 10 K/min up to 923 K under flowing of a carburizing mixture of gases (360 cm 3 /min, 4.4% CH 4 , 1.1%, 94.5% Ar). The temperature was hold for 2 h (Fe 3 and Co compounds) and 4 h (Ni compound).…”

“…Pd 2 Mo 3 N was synthesized by ammonolysis of a crystalline precursor following the procedure described by El-Himri et al 3 Co 3 Mo 3 C 0.62 N 0.38 , Ni 2 Mo 3 C 0.52 N 0.48, and Fe 3 Mo 3 C were synthesized by carburization of the corresponding nitrides. [7][8][9] The nitrides were heated at 10 K/min up to 923 K under flowing of a carburizing mixture of gases (360 cm 3 /min, 4.4% CH 4 , 1.1%, 94.5% Ar). The temperature was held for 2 h (Fe 3 and Co compounds) and 4 h (Ni compound).…”

Interstitial nitrides revisited – A simple synthesis of M Mo3N (M = Fe, Co, Ni)

“…The compound Ni2Mo3(N/C) has been produced from the parent nitride and contains a random mixture of nitrogen and carbon interstitials. [7] Recently, the mineral Pd3Ag2S, named Coldwellite, has been reported to crystallise with the filled β-Mn structure. [8] Interstitial borides with the filled β-Mn structure have been shown to display superconductivity below 5K.…”