Structural and electronic properties of Fe(AlxGa1-x)3 system.

FeGa₃ is a well known intermetallic semiconductor with a band gap, which is induced by d-p hybridization. In this work, we present the results of experimental and theoretical studies on the effect of Al substitution in FeGa₃, obtained by X-ray diffraction (XRD) study, temperature dependent resistivity measurement, room temperature Mössbauer measurement, and density functional theory based electronic structure calculations. It is observed that up to x=0.178 in Fe(Al_xGa_1-x)₃, which is the maximum range studied in this work, Al substitution reduces the lattice parameters a and c, preserving the parent tetragonal P4₂/mnm crystal structure of FeGa₃. Rietveld refinement of the XRD data shows that Al atoms replace Ga atoms located at the 8j sites in FeGa₃. A comparison of the trends of the lattice parameters and energy band gap obtained from the calculations and experimental measurements also confirms that Al atoms primarily replace the Ga atoms in the 8j site. The band gap of Fe(Al_xGa_1-x)3 for x=0.178 is reduced by ≈24% as compared to FeGa₃. The system thus has a lot of promise for applications in band gap engineering in infra-red devices. [ABSTRACT FROM AUTHOR]