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Structure, Thermal Stability, and Magnetism of Ni 4 N Thin Films
Author(s) -
Pandey Nidhi,
Gupta Mukul,
Stahn Jochen
Publication year - 2020
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202000294
Subject(s) - tetragonal crystal system , materials science , analytical chemistry (journal) , magnetization , thin film , ferromagnetism , enthalpy , lattice constant , magnetism , diffraction , crystallography , crystal structure , condensed matter physics , thermodynamics , chemistry , nanotechnology , magnetic field , physics , chromatography , quantum mechanics , optics
Herein, the synthesis, structure, thermal stability, and magnetic properties of Ni 4 N thin films are studied. Ni 4 N is difficult to synthesize in the correct chemical order and stoichiometry due to unfavorable thermodynamics. During the synthesis of Ni–N thin films, it is found that the substrate temperature ( T s ) is a critical parameter affecting the growth of a Ni 4 N phase. The Ni 4 N phase transforms into an amalgamation of [Ni+Ni 3 N] phases even if the T s rises just above 300 K. These results elucidate a correlation between atomic diffusion and T s . N self‐diffusion measurements carried out using secondary‐ion mass spectroscopy indicate that substantial N self‐diffusion is occurring at low T s . A comparison of N self‐diffusion coefficients in Fe–N, Co–N, and Ni–N indicates that N self‐diffusion in Ni–N lies between that of Fe–N and Co–N and exhibits a greater correlation with the enthalpy of formation. A transformation from the cubic–to‐tetragonal deformation in the Ni 4 N crystal lattice as a function of increasing N concentration is evident from the X‐ray diffraction and X‐ray absorption near‐edge spectroscopy measurements. Magnetization measurements confirm a nonferromagnetic state of Ni 4 N at 300 K, which transforms into a ferromagnetic state at 15 K.