Ronan Lebullenger

Systematic substitutions in ZBLA and ZBLAN glasses

Starting from ZBLA and ZBLAN glasses, the following substitutions were implemented: CdF 2 /BaF 2 , KF/BaF 2 in ZBLA, KF/NaF and RbF/NaF in ZBLAN 14, PbF 2 /BaF 2 in ZBLAN 20. Basic glass compositions are: 57ZrF 4 -34BaF 2 -5LaF 3 -4AlF 2 , 54ZrF 4 -24BaF 2 -4LaF 3 -4lF 3 -14NaF and 52ZrF 3 -20BaF 2 -4LaF 3 -4AlF 3 -20NaF. The evolution of physical properties versus composition is reported. Some non-linear evolutions were observed

Excess entropy and thermal behavior of Cu- and Ti-doped bioactive glasses

Bioactive glasses belong to the ceramic family. They are good materials for implantation due to their excellent capacities to create an intimate bond with bones. Copper is known for its anti-inflammatory, antibacterial, and antifungal properties. Titanium is biocompatible and resistant to corrosion. These chemical elements can be introduced in bioactive glasses to provide a wide variety of uses and to enhance the physiological properties of implanted biomaterials. In this work, bioactive glasses doped with different contents of copper and titanium were synthesized by the melting method. The purpose is to study the effect of doping metal element on the thermal characteristics (Tg, Tc, and Tf). The results revealed that the increase of the content of copper and titanium in the glass matrix decreases the melting temperature and induces an increase of the thermal stability. The excess entropies of pure and doped glasses were calculated. Obtained results highlighted the decrease of the excess entropy with the increase of metal elements contents.

Thermal and elastic characterization of Sb2O3–Na2O–ZnO glasses

New glasses were investigated in the ternary system Sb2O3?Na2O?ZnO. The glass transition temperature, Tg, and the onset of the crystallization Tx range from 278 to 304??C and from 370 to 450??C, respectively. The thermal stability factor (Tx?Tg) lies between 109 and 155??C. Ultrasonic velocities were measured by using the pulse echo method to determine the elastic parameters (E, G, K and L) and other related parameters (Poissons ratio, acoustic impedance and Debye temperature). Other physical properties were also measured, such as density and microhardness. The different measured properties are analyzed in the light of the structural role of ZnO in these glasses.

Synthesis of high purity fluorides by wet chemistry

The synthesis of high purity for the preparation of optical glasses requires that the residual concentration in transition metals and anionic oxygen is very low. Various synthesis processes in aqueous solutions have been investigated. Purification steps may be included in these processes. Dehydration conditions depend on cationic nature. ZrF4 and AlF3 require fluorinating atmosphere while alkali and earth alkali cations are not hydrolyzed when the temperature increases. This review concerns ZrF4, AlF3, NaF, LiF, MgF2, CaF2, SrF2 and BaF2. Hydrates or complex fluorides NaHF2 and BaHF3 may be formed as intermediate compounds.