Effect of Mist Classification on Size and Magnetic Property of Magnetic Hyperthermia Particles Synthesized by Ultrasonic Spray Pyrolysis

Abstract

Manganese perovskite La_0.75Sr_0.25MnO₃ (LSM) fine particles for magnetic hyperthermia therapy were synthesized by an ultrasonic spray pyrolysis method modified with a mist classifier installed between a sprayer and a reactor to produce particles with the size range of 50–200 nm. The mist classification suppressed the generation of particles larger than 500 nm. From an X-ray diffraction measurement, it was found that the phase of synthesized particles was La_0.75Sr_0.25MnO₃ with and without the mist classification. The crystallite size of synthesized particles decreased with decreasing the nozzle diameter of classifier. Curie temperature estimated from the magnetization measurement at various temperatures was reduced from T_C＝323 K (50°C) to T_C＝297–312 K (24–39°C) when the mist was classified. The production rates also decreased from 118 mg h^-1 to 39 - 4 mg h^-1 by using the mist classifier.