Molybdenum-doped La_0.7Sr_0.3MnO₃ nanoparticles: tuning magnetic and heating properties for magnetic hyperthermia

Self-limited magnetic hyperthermia offers a promising approach for cancer therapy by exploiting materials whose Curie temperature (T _C) intrinsically constrains overheating during treatment. In this work, ultrafine La_0.7Sr_0.3Mn_1-x Mo _x O₃ (x = 0.10, 0.15, 0.20) nanoparticles were synthesized via the glycine-nitrate process. All samples crystallized in a rhombohedral (R3̄c) structure, with particle size decreasing from ∼230 nm to ∼105 nm as Mo content increased. Magnetic measurements revealed ferromagnetic-paramagnetic transitions with decreasing T _C. The substitution of Mo⁶⁺ for Mn³⁺/Mn⁴⁺ disrupted double-exchange interactions and altered the Mn³⁺/Mn⁴⁺ balance, leading to reduced magnetization and a progressive decrease in T _C (from 350 to 290 K). Under an alternating magnetic field, the nanoparticles exhibited rapid initial heating followed by a plateau near T _C, demonstrating self-limited heating behavior. Specific absorption rate values were moderate (∼14-16 W g^-1 for intermediate doping and ∼7 W g^-1 at the highest doping), consistent with magnetic dilution and surface spin effects. These results show that La_0.7Sr_0.3Mn_1-x Mo _x O₃ nanoparticles possess intrinsically self-limited heating suggesting their promise for magnetic hyperthermia. Further fine-tuning Mo doping, particle size, and surface properties could more precisely adjust the Curie temperature and enhance heating efficiency, advancing these nanoparticles toward safe and effective hyperthermia applications.