Article ID Journal Published Year Pages File Type
1481042 Journal of Non-Crystalline Solids 2014 7 Pages PDF
Abstract

•A transparent glass (88SiO2–2Li2O–10Fe2O3, mol%) was well prepared by sol-gel;•Precipitation of LiFe5O8 crystallites gives rise to a ferrimagnetic glass ceramic.•Paramagnetic behavior at RT condition was observed;•Superparamagnetism of α-Fe2O3 due to crystallites with size < 10 nm was detected;•With annealing, a hyperfine field arises and a relaxation is observed.

The glass with the molar composition 88SiO2–2Li2O–10Fe2O3 (mole %) was prepared by the sol-gel route and after heat-treated at temperatures between 250 and 1000 °C under oxidizing conditions. Crystalline phases (LiFe5O8, SiO2, Fe2O3 and LiFe(Si2O6)) were observed by X-ray powder diffraction in the glasses treated at temperatures above 800 °C. Scanning electron micrographs reveal the presence of particles in the samples heat-treated up to 800 °C, which are essentially amorphous or with an incipient crystallization. The increase of the heat-treatment temperature promotes the coarsening of particles.The magnetic characteristics of the prepared glasses and glass ceramics were performed using a vibrating sample magnetometer in function of the magnetic field amplitude (− 10 T ≤ B ≤ 10 T) and in function of temperature (5 K–300 K). The samples heat-treated at 900 and 1000 °C present a ferrimagnetic behavior accompanied by the appearance of peaks corresponding to the lithium ferrite phase (LiFe5O8). A curious aspect is the saturation magnetization of the sample heat-treated at 800 °C is the highest of all samples, indicating the highest amount of LiFe5O8 crystals. The Mossbauer results are in accordance with the magnetization and magnetic susceptibility measurements.

Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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