An analysis on structural and magnetic properties of La1-xRExFeO3 (x=0.0 and 0.5, RE = Nd, Sm and Gd) nanoparticles

La1-xRExFeO3 (x = 0.0 and 0.5, RE = Nd, Sm and Gd) is synthesised by sol-gel citrate combustion method. X-ray diffraction (XRD) and Raman spectra show orthorhombic phase with Pbnm symmetry, confirmed by profile fitting and Raman modes analysis for La1-xRxFeO3 samples. The estimated crystallite size and the orthorhombic strain of La1-xRExFeO3 (x = 0.0 and 0.5, RE = Nd, Sm and Gd) from XRD data illustrate the role of ionic size substitution. The temperature-and field-dependent magnetisation M(T) and M(H) were measured using vibrating sample magnetometer. The M(H) curve parameters of La1-xRExFeO3(x = 0.5, RE = Nd and Gd) exhibit a relation of Mr proportional to 1/H-c and H-ex proportional to H-C at 20, 150 and 300 K. The M (T) curve of La0.5Nd0.5FeO3 and La0.5Gd0.5FeO3 indicates the paramagnetic-like behaviour, whereas the M (H) curve reveals the antiferromagnetic signature in them. The M (H) curve of La0.5Sm0.5FeO3 shows a strong AFM pinned ferromagnetism and ferromagnetism (FM) at 150 and 20 K, respectively. Further, field-cooled (FC) and zero-field-cooled (ZFC) measurement of La0.5Sm0.5FeO3 indicates a competitive interaction of AFM-FM, which is emphasised by a broad blocking temperature at similar to 117 K in ZFC curve. The FM-like ordering of Sm3+ ions are observed below at similar to 150 K in FC curve of La0.5Sm0.5FeO3. In addition, the electron paramagnetic resonance spectra at room temperature show a high g value and a strong non-homogenous broadening for La0.5Sm0.5FeO3.