A direct-doping method was tested to design new composite-glasses by incorporating lanthanum niobate nanocrystals (NC) in tellurite glasses. NC powder were grinding with glass powder before heating-quenching, with the main investigation approached of best parameters for NC suitable homogenization but limited dissolution. Thermal analysis signalizes that prior heat-treatment of NC promotes higher transparency and limits NC dissolution. These materials with visually detectable NC aggregates exhibited glass transition temperatures close to the starting glass. LaNbO4 phase was hardly detected by X-ray diffraction because of the low weight ratio and partial dissolution but the monoclinic polymorph could be identified for lower time. UV-visible-NIR transmission spectra also related progressive lower transparency with light scattering of NC aggregates. Photoluminescence suggest that lower times allowed to ensure the NC environment with lower crystallinity around Eu3+-ions in final composite-glass. These results pave the way for designing new materials containing NC not achievable by conventional nucleation-growth methods. directdoping direct doping compositeglasses composite glasses (NC heatingquenching, heatingquenching heating quenching, quenching heating-quenching heattreatment heat treatment LaNbO Xray X ray time UVvisibleNIR UV visible NIR Eu3+ions Eu3ions Euions Eu3+ ions Eu3 Eu compositeglass. compositeglass composite-glass nucleationgrowth nucleation growth methods

Abstract Whilst the optical and structural properties of the glasses containing tantalum oxide have been considerably investigated, research into their mechanical properties is not substantially established. This work reports on the mechanical characterization of transparent germanate glass samples, obtained via the melt-quenching technique, with a molar content of Ta2O5 ranging from 0% to 20%. The introduction of Ta2O5 in the samples is related to significant improvements in the mechanical properties. The transition from glass to transparent glass-ceramic via the controlled crystallization of Ta2O5 proved to be a tool to increase both the elastic modulus and the hardness while keeping the transparency of the material. The average elastic modulus of the studied compositions ranged from 69.2 GPa to 99.1 GPa, while the average hardness of the same samples varied from 5.10 GPa to 7.34 GPa.

The glass forming ability was investigated in the codoped Er3+/Yb3+ ternary system NaPO3-WO3-PbF2 with increasing amounts of PbF2. It has been found that glass samples can be obtained for PbF2 contents ranging from 0 mole% to 50 mole% for the codoped samples and an undoped sample containing 60% of lead fluoride could also be vitrified. Thermal properties of the most PbF2 concentrated glasses exhibit strong dependence of the composition with a decrease of the glass transition temperatures and thermal stabilities against devitrification with increasing the lead fluoride content. These glass samples were heat-treated near the crystallization peaks and the X-ray diffraction measurements pointed out that the dominant phase which precipitates from the glass samples containing 40% and 50% of PbF2 is the lead fluorophosphate phase Pb5F(PO4)3 whereas the sample containing 60% of PbF2 exhibits a preferential bulk crystallization of cubic lead fluoride β-PbF2.