ABSTRACT
La0.7 Sr0.3 MnO3 (LSMO) nanoparticles have been obtained via solution combustion synthesis (SCS) using urea and glycine as fuels. Also, La0.7 Sr0.27 Ca0.03 MnO3 (LSCMO) nanoparticles have been synthesized through solution combustion using urea as fuel. In this paper, the combustion process was carried out with a fuel to oxidant ratio giving fuel deficient conditions ( ). The thermal analysis (TGA) indicate that the organic residues from the urea-nitrates gel mixture are eliminated above 600 °C and the post-synthesis heat treatment yields the formation of the desired phase without impurities. The obtained phases were analyzed using X-ray diffraction. The infrared analysis confirms the purity of the samples obtained using urea. However, the sample obtained using glycine confirms the formation of SrCO3. The morphology was analyzed using a FE-SEM microscope, and it was found that the particles present a spherical shape with a mean size of around 45 nm in the selected samples. The samples' energy dispersive X-ray spectra show that the desired elements (La, Sr, Ca, Mn and O) are present in the nanoparticles. The measured zero field cooled (ZFC) and field cooled (FC) magnetizations were recorded from 4.5 to 380 K at 105 A/m to obtain their blocking and Curie temperatures. Moreover, the hysteresis loops measured at room temperature confirm the superparamagnetic behavior of the elaborated samples. According to the results obtained, these nanoparticles have interesting properties that make them candidates to explore not only for their potential in biomedical applications but also in refrigeration and magnetic storage devices.
Subject(s)
Calcium Compounds , Lanthanum/chemistry , Manganese/chemistry , Oxides , Titanium , Urea/chemistry , Calcium Compounds/chemical synthesis , Calcium Compounds/chemistry , Chemistry Techniques, Synthetic/methods , Hot Temperature , Magnetite Nanoparticles/chemistry , Oxides/chemical synthesis , Oxides/chemistry , Strontium/chemistry , Titanium/chemistryABSTRACT
Resumen: Las nanopartículas magnéticas se proponen como mediadores de calor en tratamientos de hipertermia. En este trabajo se desarrollaron tres materiales tipo núcleo-coraza de diferente composición y anisotropía magnética para determinar evaluar sus propiedades como tamaño de cristal, magnetización de saturación y efectuar su recubrimiento con moléculas orgánicas. El núcleo magnético de estos materiales se elaboró por medio de la reacción de coprecipitación, siguiendo la relación estequiométrica X+2Fe2 +3O4 donde x es Fe, Co o Ni para cada material. A partir de los patrones de difracción de rayos x se determinó el tamaño de cristal de cada material, éstos fueron de 10.39 nm, 7.27 nm y 3.86 nm; además la magnetización fue de 55.84 emu/g, 36.56 emu/g y 16.21 emu/g para la magnetita, la ferrita de cobalto y de níquel respectivamente. Cada material se recubrió con aminosilano y mediante FTIR se identificaron los modos vibracionales de los enlaces C-N, N-H, C-H y Si-O involucrados en el recubrimiento.
Abstract: Magnetic nanoparticles are proposed as heat mediators in hyperthermia treatments. In this work, three core-shell materials of different composition and magnetic anisotropy were developed to determine their properties as crystal size, saturation magnetization and their coating with organic molecules. The magnetic core of these materials was made by means of the coprecipitation reaction, following the stoichiometric ratio X+2Fe2 +3O4 where X is Fe, Co or Ni for each material. From the X-ray diffraction patterns the crystal size of each material was determined, these were 10.39 nm, 7.27 nm y 3.86 nm. In addition, magnetization was 55.84 emu/g, 36.56 emu/g y 16.21 emu/g for magnetite, cobalt ferrite and nickel respectively. Each material was coated with aminosilane and by FTIR the vibrational modes of the C-N, N-H, C-H and Si-O bonds involved in the coating were identified.
