Evaluation of La1−xSrxMnO3 (0 ≤ x < 0.4) synthesised via a modified sol–gel method as mediators for magnetic fluid hyperthermia

Abstract

A range of lanthanum strontium manganates (La_1−xSr_xMnO₃–LSMO) where 0 ≤ x < 0.4 were prepared using a modified peroxide sol–gel synthesis method. The magnetic nanoparticle (MNP) clusters obtained for each of the materials were characterised using scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and infra-red (IR) spectroscopy in order to confirm the crystalline phases, crystallite size and cluster morphology. The magnetic properties of the materials were assessed using the Superconducting quantum interference device (SQUID) to evaluate the magnetic susceptibility, Curie temperature (T_c) and static hysteretic losses. Induction heating experiments also provided an insight into the magnetocaloric effect for each material. The specific absorption rate (SAR) of the materials was evaluated experimentally and via numerical simulations. The magnetic properties and heating data were linked with the crystalline structure to make predictions with respect to the best LSMO composition for mild hyperthermia (41 °C ≤ T ≤ 46 °C). La_0.65Sr_0.35MnO₃, with crystallite diameter of 82.4 nm, (agglomerate size of ∼10 μm), T_c of 89 °C and SAR of 56 W g_Mn⁻¹ at a concentration 10 mg mL⁻¹ gave the optimal induction heating results (T_max of 46.7 °C) and was therefore deemed as most suitable for the purposes of mild hyperthermia, vide infra.