Synthesis, morphological, structural, and magnetic studies of Gd_1-xPr_xCrO₃ nanoparticles

A series of nanocrystalline compounds, Gd_1-xPr_xCrO₃ (where 0 ≤ x ≤ 1 and Gd: Gadolinium, Pr: Praseodymium, Cr: Chromium and O: oxygen), was synthesized by the auto-combustion route followed by annealing at 700 °C. XRD revealed that all samples in the series are perovskites with a distorted orthorhombic structure and crystallized into the Pbnm space group. The average particle size for the samples annealed at 700 °C for 4 h was in the range of (50–91) nm. There was an agreement between Rietveld fitting results and the TEM results for the average particle size. It is noted that with the rise in the Pr concentration due to the reduction of Gd concentration in the compounds, the magnetization for field cooling/zero-field cooling (FC/ZFC) modes decreases. The compounds in the series exhibit the magnetization reversal (MR) phenomenon at ZFC mode. In contrast, the parent compound displays negative magnetization behavior at FC mode with a minimum magnetization value at 14 K. The Néel transition temperature (T_N) is found to increase linearly with increasing Pr concentration as well. Moreover, as the Pr concentration in the Gd_1-xPr_xCrO₃ series increases, the compensation temperature (T_comp2) increases while the spin flipping temperature (T_SF) decreases. All samples under investigation showed magnetic switching, which makes them useful for magnetic switching applications. At different temperatures, the magnetization as a function of a magnetic field was measured. Weak ferromagnetism was observed just below (T_N), and notable magnetic features at lower temperatures. Above (T_N), the compounds are paramagnetic. The exchange bias (EB) phenomenon was studied for all the samples in the series without applying a cooling, magnetic field (ZFC-EB) and under different cooling, magnetic fields (FC-EB) at (1 T, 2 T, and 3 T). From the measurements of ZFC-EB, it is found that H_EB increases by 600% with increasing the dopant concentration from x = 0 to x = 1 with a further increase by 200% with field cooling as small as 1 T. That means the compounds can be used in the applications of EB-based magnetic devices. It is observed that H_EB, M_max, and H_c of the compounds depend on the temperature at different applied cooling fields.