Seker, O. F.Izgi, T.Kolat, V. S.Bayri, N.Gencer, H.Pektas Kolat, M.Atalay, S.2026-04-042026-04-0420260022-22911573-7357https://doi.org/10.1007/s10909-026-03378-8https://hdl.handle.net/11616/109844A comprehensive investigation of the structural, magnetic, and magnetocaloric properties of polycrystalline La0.67-xGdxCa0.33MnO3 (x = 0, 0.05, 0.1, 0.15, and 0.2), synthesized by the solid-state method, has been carried out. X-ray diffraction confirmed that all compositions crystallize in a single-phase orthorhombic Pbnm structure. A systematic decrease in the Curie temperature, from 257 K (x = 0) to 61 K (x = 0.2), was observed and attributed to the suppression of double-exchange interactions and the emergence of magnetic inhomogeneity. Most notably, the substitution of Gd led to a pronounced enhancement in the magnetic entropy change (|Delta SM|), reaching a maximum of 11.24 J/kg K under a 5 T field for the x = 0.2 composition, which stands as one of the highest values reported for manganites. In addition, a secondary anomaly in the entropy change curves, particularly at elevated fields, was associated with a field-induced metamagnetic transition arising from the coexistence of paramagnetic and antiferromagnetic states above TC. Critical behavior analysis based on Arrott plots further revealed that all samples exhibit a first-order magnetic phase transition. These simultaneous observations of exceptionally large Delta SM values and metamagnetic features highlight the potential of these rare-earth-modified manganites for high-performance magnetocaloric applications.eninfo:eu-repo/semantics/closedAccessMagnetocaloric effectPerovskite manganiteGd substitutionMagnetic entropyArticle222210.1007/s10909-026-03378-82-s2.0-105029812769Q3WOS:001686972300001Q40000-0003-0424-4865