Supervisor: prof. M. Liška/ Partner research institution: CSIC – Spanish National Research Council (Spain, supervised by prof. A. Durán)
Phosphate glasses are a class of special materials with a broad interest in optical applications and since they possess large emission cross sections and low non-linear refractive indices they are ideal for their use as solid state matrices for the emission of laser radiation. However, the use of glasses as laser hosts requires the production of generally large dimensions with a very high optical homogeneity and high quantum efficiencies, thus needing of very special processing conditions and a strict control of the glass composition. Additionally, the melting of phosphate glasses may also imply certain difficulties such as those regarding high volatility of their constituents, easiness of devitrification and rapid change of the viscosity with temperature due to their higher fragile character. The ability to choose the right composition as well as the adequate processing conditions for their preparation lies in the precise knowledge of the atomic structure and its influence on the glass properties.
This project proposal will be carried out within the area of Optical Materials and its main objective will be to set up the fundamentals for a model based on the relationships between the thermodynamics and the structure of the phosphate melts and glasses. The core of the proposal will employ the theoretical methodology previously developed by the group at TNUAD for phosphate glasses that uses the Shakhmatkin and Vedishcheva thermodynamic model . This approach uses structural data obtained through Nuclear Magnetic Resonance and Raman spectroscopies by which it was possible to calculate the Gibbs free energy of formation of the oxides in the glass composition . The final aim of the project will be to obtain a model that based on the relationships between the structure and thermodynamics of the phosphate melts can be able to predict the glass forming ability and the main properties of the glasses.
This PhD work will be divided into two periods: the first, of two years, at the laboratories of CSIC for the preparation and study of the structure of the glasses; and a second of one year for the evaluation of the thermodynamic model at TNUAD.
References: J.H. Campbell, J.S. Hayden, A. Marker, High power solid state lasers: a laser glass perspective, Int. J. App. Glass Sci. 2 (2011) 3-29. B. A. Shakhmatkin, N. M. Vedishcheva, M. M. Shultz, A. C. Wright, The thermodynamic properties of oxide glasses and glass-forming liquids and their chemical structure, J. Non-Cryst. Solids 177 (1994) 249-256. M. Liska, J. Machacek, M. Chromcikova, O. Gedeon, Thermodynamic model and structure of ZnO-MoO3-P2O5 glasses, Phys. Chem. Glasses: Eur. J. Glass Sci. Technol. B 56(2) (2015) 63-66.