Structural, Mössbauer Spectroscopy and Ab initio Calculations Investigations of gamma-Fe4N-GaN Nanocomposites

A.V. GIL REBAZA; SAJITH KURIAN; SAYAN BHATTACHARYYA; J. DESIMONI; E.L. PELTZER Y BLANCÁ; N.S. GAJBHIYE

Conferencia; XII Latin American Conference on the Applications of the Mössbauer Effect; 2010

A controlled one step ammonolysis method with three different Fe:Ga ratios (70:30, 50:50 and 30:70) was used to synthesize functional nanocomposite material consisting of 30-40 nm particles of g΄-Fe4N, Fe4-xGaxN phases in a GaN and Fe-doped GaN phase matrix. The g΄-Fe4N, Fe4-xGaxN, GaN phases is confirmed by Rietveld analysis of the X-Ray diffraction patterns, while Fe-doped GaN was established from Mössbauer spectroscopy that showed a hyperfine magnetic field distribution. Structural and hyperfine characterization are put together with the ab-initio calculations, performed using FP-LAPW method within the framework of DFT as implemented in the Wien2k code. The agreement of the lattice parameters obtained from ab-initio calculations and the experimental ones reinforce the hypothesis of the formation of Fe4-xGaxN. Even though the Mössbauer spectra at 5K shows a complex structure, existence of all the phases are confirmed by analysis of the spectra and the magnetic hyperfine fields obtained from ab-initio calculation.