Evaluation of La_1−xSr_xMnO₃ (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−x Sr x MnO 3 -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 0.65 Sr 0.35 MnO 3 , 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.CrystEngComm This journal is

Synthesis, characterisation and study of magnetocaloric effects (enhanced and reduced) in manganate perovskites

“…In the mild hyperthermia range, cancerous tissue will be selectively damaged over healthy tissue. LSMO has already been investigated as a suitable potential mediator for MFH, [5][6][7][8] but to the knowledge of the authors, little consideration has been given to other perovskite manganates.…”

“…9 This change in Tc with structure meant that LSMO at a variety of dopant levels exhibited enhanced magnetic heating properties compared with the parent compound. 8 Figure 1(a) and (c) show the effect of substituting the A-site cation, La 3+ (cationic radii of 1.36 Å) with smaller (Ca 2+ ) or larger (Sr 2+ or Ba 2+ ) cations (cationic radii of 1.34, 1.44 or 1.61 Å respectively) 10 on the structure of the parent perovskite unit cell (1b).…”

“…compositions. [5][6][7][8] In this instance, La 3+ or Sr 2+ ions occupy the A-site and either Mn 3+ or Mn 4+ occupies the B-site. As found in a previous work by this group, an increase of the relative weight percentage of the orthorhombic (Pnma) crystalline phase is observed by increasing the strontium dopant in the LSMO synthesised using a modified peroxide sol-gel method.…”

“…As found in a previous work by this group, an increase of the relative weight percentage of the orthorhombic (Pnma) crystalline phase is observed by increasing the strontium dopant in the LSMO synthesised using a modified peroxide sol-gel method. 8 This structural change upon doping can cause a huge variation of the Curie temperature (Tc). For example, increasing the dopant from x = 0.1 to 0.2 increases the Tc from -13 °C to 77 °C.…”

“…In our previous work 8 and La1-xBaxMnO3 (LBMO) were prepared via a modified peroxide sol-gel synthesis. [15][16][17] This method has not been employed in the synthesis of LCMO or LBMO before.…”