Estudo de vidros cálcio boroaluminato dopados com Eu2O3

Abstract

Calcium Boroaluminate (CaBAl) glass is an important family of optical materials, which has been studied due to the good combination of chemical, thermal, mechanical, optical and spectroscopic properties. In this work Eu2O3 doped CaBAl glasses were prepared and thermal, structural, optical and spectroscopic properties were discussed in terms of rare earth content. Results of density, glass transition temperature, crystallization temperature, specific heat, refractive index, optical absorption coefficient, luminescence and lifetime measures were analyzed. Molar volume, thermal conductivity, electronic polarizability, ion concentration per cubic centimeter and interionic distance were calculated. X-ray diffraction, Raman and FT-IR were also carried out to obtain structural information of these glasses. The results show that europium doping, when replacing CaO, induced changes in various properties of the glass studied. The X-ray data showed the amorphous nature of all samples. Raman and FT-IR data confirmed the structural change, which showed that Eu2O3 addition cause the simultaneous increase in the bands corresponding to the presence of structural units of the type BO3, BO4 and non-bridging oxygens (NBO). The thermal and structural results shows that the incorporation of Eu2O3 lead to an increase in density, glass transition temperature, decrease in crystallization onset temperature and a consequent reduction in the thermal stability of the glass. The glass doping didn’t affect significantly the specific heat and the thermal conductivity, within the errors. The results of refractive index show an increase with Eu2O3 content. The absorption spectrum of glass matrix shows that it is transparent from 370nm to 2400nm. The absorption coefficient at 394nm showed a linear increase with the Eu2O3 concentration. The luminescence results indicate two emission bands centered at 614nm and 700nm. The emission intensity for these peaks increase with dopant concentration and no luminescence quenching was observed for the studied compositions. The emission lifetime results at 614nm shows a exponential decrease with doping concentration due to, probably, ion-ion interaction . The data analysis shows that the europium acts as network modifier. The results show that glasses studied in this work have a good combination of properties, making these glasses, potential candidate for use in photonic devices.