Desenvolvimento e caracterização de vidros aluminosilicato de cálcio dopados com Nd³+

Abstract

In this work several different compositions of CaO:Al2O3:SiO2 were prepared under vacuum to study the glass forming ability of this system as a function of the SiO2 content. The samples were prepared with SiO2 concentrations between 7 to 40wt%, in order to obtain stable glasses which presented a good combination of physical properties, for use as active medium in solid state lasers. The LSCAS composition was used as reference to prepare the samples. The concentration of SiO2 was increased until 40wt%, keeping the CaO/Al2O3 ratio constant. Among 12 prepared samples, five presented total vitrification and were therefore the ones analyzed in this work. The obtained glasses are colorless, highly transparent, without visible crystallites. The influence of the silica content and of non-bridging oxygen (NBO) was discussed in terms of properties such as density, refraction index, optical transmittance, optical scattering, glass transition temperature, glass crystallization temperature, hardness, elastic moduli, specific heat, thermal diffusivity, thermal conductivity and temperature coefficient of the optical path length (dS/dT)I. The samples which presented the best combination of results were chosen for doping with Nd³+. The Nd³+ ion has been one of the most studied rare earth element and also one the most efficient candidates for photonic devices. In order to study how the Nd2O3 doping affects the properties of CAS glass, two series of CAS glass, doped with Nd2O3 up to 5wt%, were prepared under vacuum. Besides the physical properties studied for undoped samples, the coefficient of optical absorption, thermal expansion coefficient, temperature coefficient of refraction index (dn/dT), thermal coefficient of electronic polarizability, self-focusing effects (Thermal Lens), fluorescence quantum efficiency, photoluminescence and fluorescence lifetime were studied. The influence of the temperature and Nd2O3 content were discussed for the results. Overall, this work has determined physical parameters which support the idea that the obtained CAS glasses are strong materials having a useful working range temperature, a good combination of thermal, mechanical and optical properties that could be exploited in many optical applications, in particular, for the use as laser host materials.