Magnetic properties of LaFe1-xCrxO3 and Fe2-2xCr2xO3 mixed oxides

Mixed oxides with formula L a F e 1-x C r x O 3 and F e 2-2x C r 2x O 3 , where 0≤x≤1, are studied. The samples have been prepared using solid state reaction technique in air. The X-ray diffraction spectra indicated that the samples crystallize in a corundum phase with space group ( R3c ) for F e 2-2x C r 2x O 3 and in the perovskite structure for L a F e 1-x C r x O 3 . Many techniques have been used to explore the magnetic properties of the systems. High field, ZFC and FC magnetization vs. temperature, d.c. susceptibility and Mossbauer spectroscopy were carried out. High temperature magnetic susceptibility measurements and high field magnetic magnetization (H ≤ 20 T) show that the behavior of the susceptibility and the magnetization are complex. Mossbauer spectra of the solid solutions have been measured at 4.2 K and in the temperature range 77 K to 300 K. The shapes of spectra are unusual, showing strong relaxation phenomena in a wide temperature range as recently observed for many frustrated systems. The results are discussed by establishing the existence of various magnetic structures, inducing intermediate magnetic phases between the antiferromagnetic and the paramagnetic states. Preliminary magnetic phase diagrams of the systems have been established.