Synthesis of Ruddlesden-Popper LaSrFe1-xCrxO4 phases (x = 0.0, 0.2, 0.4, 0.6) by glycine-nitrate combustion process: Effect of Cr doping on magnetic, optical and photocatalytic properties

This work presents the study of new Ruddlesden-Popper phases, LaSrFe1- xCrxO4 (x = 0.0, 0.2, 0.4 and 0.6), synthesized by glycine-nitrate combustion method. In this research, we are for the first time reporting on a complete Ruddlesden-Popper series (n=1) for the photocatalytic degradation of a dye. The effect of Cr3+ doping on the crystal structure, optical and magnetic properties of the LaSrFeO4 phase has also been systematically explored via different characterization techniques. Rietveld refinement of PXRD data indicates the formation of single phase compounds with tetragonal symmetry in the space group I4/mmm. The results show a decrease in the lattice parameters a and c, as well as the unit cell volume V, with increase in Cr3+ doping. The energy band gap (Eg) values calculated using the DRS spectra decreases with increase in Cr concentration. The magnetic measurements revealed dominant anti-ferromagnetic (AFM) interactions in all the phases and the appearance of weak ferromagnetic (FM) interactions with Cr3+ doping. The results are discussed by considering the increase in Fe3+―O―Cr3+ FM interaction in addition to the Fe3+―O―Fe3+ and Cr3+―O―Cr3+ AFM super-exchange interactions induced due to random distribution of Fe3+ and Cr3+ ions at the octahedral site. Rhodamine B, as a dye pollutant model, was used for evaluation of photocatalytic activity of the prepared phases. Enhanced photocatalytic activity was observed with the addition of Cr3+ substitution. The results show ~99% degradation for x = 0.6 while only ~76% degradation is shown for x = 0.0 sample in 40min under visible light irradiation. [Display omitted] •New RP-type LaSrFe1-xCrxO4 phases synthesized by glycine-nitrate combustion method.•Eg values decreased with increase in Cr concentration.•Dominant AFM interactions in all the phases and the appearance of weak FM interactions with Cr doping.•Enhanced photocatalytic activity was observed by Cr doping.