Influence of Sr²⁺ doping on the structural, magnetic, and photocatalytic behavior of Pr_0.9-xSr_xPd_0.1Mn_0.9O₃ manganite for enhanced methylene blue degradation

We report the synthesis and characterization of two doped rare-earth manganites, Pr_0.9Pd_0.1Mn_0.9O₃ and Pr_0.8Sr_0.1Pd_0.1Mn_0.9O₃, via a conventional solid-state route, to investigate their potential for photocatalytic degradation of organic dyes under visible light. X-ray diffraction confirms that both compounds crystallize in an orthorhombic Pnma structure. Crystallite size was estimated as ∼30 nm (XRD) and ∼27 nm (SEM), confirming irregularly agglomerated quasi-spherical nanoparticles. Magnetic measurements indicate complex behavior involving superparamagnetic, spin-glass, and ferromagnetic–paramagnetic transitions. Modified Arrott plots analysis confirms that both compounds fall within the 3D-XY universality class, with critical exponents β = 0.345 and γ = 1.316 for Sr0.10. UV–visible spectroscopy revealed bandgap tuning from 2.48 eV (Sr0.00) to 2.36 eV (Sr0.10), improving light absorption and charge separation. Photocatalytic experiments using methylene blue dye under visible light show that Sr doping enhances degradation performance, achieving up to 86 % degradation in 6 min at a catalyst loading of 0.006 g/L. These results highlight the role of Sr²⁺ and Pd²⁺ co-doping in modifying the electronic structure and enhancing photocatalytic efficiency, positioning these perovskites as promising candidates for visible-light-driven environmental remediation.