Structural investigation of fluorophosphate glasses by 19F, 31P MAS-​NMR and IR spectroscopy

International audienceA series of glass samples of compn. [(x)​MnF2-​(x-​80)​NaPO3-​(20)​ZnF2] where x = 0, 10, 20, 30 and 40, has been prepd. IR and NMR spectroscopy have been performed, esp. 19F MAS and 31P MAS NMR. On the basis of these measurements, glass structure may be described as a hybrid network of ZnF6 and MnF6 octahedra sharing corners and edges and also connected to tetrahedral fluorophosphate groups (PX)​4 where X = O-​ or F-​. Sodium cations fill vacancies of this network

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

International audienceBioactive 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 (T g, T c, and T f). 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

Effect of Eu substitution on the crystallographic and magnetic properties of the BiMn2O5 oxide obtained by urea combustion

International audiencePolycrystalline oxide materials with nominal compositions BiMn2O5 and Bi0.9Eu0.1Mn2O5 were obtained by urea combustion. Crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for both compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam (Z=4). Replacement of Bi+3 by Eu+3 promoted a slight distortion and a unit cell contraction due to a decrease of the c-parameter for Bi0.9Eu0.1Mn2O5. The SEM/EDX techniques confirmed the formation of single-phase materials with excellent mapping distribution. Magnetic measurements showed different behaviors: BiMn2O5 is an antiferromagnet (AFM) with a Néel temperature (TN) of 41 K and a Curie–Weiss temperature ΘCW of −277 K, while Bi0.9Eu0.1Mn2O5 displayed a ferrimagnetic behavior with a TC of 44 K and ΘCW of −270 K. The role of Eu+3 and the mechanisms responsible for the magnetic transition are discussed on the basis of chemical bonds and exchange interactions

SrSnO3:N – nitridation and evaluation of photocatalytic activity

International audienceThe SrSnO3 was prepared in powders form by a conventional method of solid state reaction and submitted to thermal treatment under NH3 in order to obtain the oxynitride and then promote photocatalytic activity at the visible region. Three different nitridation conditions were tested. The results showed that when the SrSnO3 is subjected to nitridation at moderate conditions (600 °C and 650 °C) oxynitide is formed preserving the perovskite structure. On the other hand, when the nitridation occurs at more severe conditions (750 °C), it is possible to observe the decomposition of the structure instead of the incorporation of N. Samples in which oxynitride is formed, SrSnO3:N, showed high potential photocatalysis under visible light, showing to be about 4 times more active than SrSnO3 or TiO2 at the same condition

Preparation of niobium based oxynitride nanosheets by exfoliation of Ruddlesden-Popper phase precursor.

International audienceA new oxynitride Ruddlesden-Popper phase K1.6Ca2Nb3O9.4N0.6 .1.1H2 O was synthesized by the topochemical ammonolysis reaction at 700 °C from the oxide Dion-Jacobson phase KCa2Nb3O10 in the presence of K2CO3. The oxynitride showed good stability with a little loss of nitrogen, even after a few months of exposure to air. Its crystal structure was solved by Rietveld refinement of X-ray powder diffraction data in space group P4/mmm and considering a two-phase mixture, due to the difference in the degree of hydration, with a = 3.894(2) Å and c = 17.90(8) Å for the most hydrated phase and a = 3.927(6) and c = 17.09(2) for the less one. Optical band gaps were measured by diffuse reflectance UV-Vis indicating a red shift of Eg to the visible region. The oxynitride layered perovskite was then protonated and exfoliated into nanosheets. TEM images and SAED patterns of the nanosheets proved that exfoliation was successful, showing lattice parameters quite compatible with the Rietveld refinement

Valorisation du calcin en mousse de verre

National audienc

From waste CRT glasses to foam glass

International audienc

Glass Recycling

International audienceThe main objective of this chapter is to give the reader a general overview of glass recycling activity. Industrial and academic results are presented, which are useful to open new possibilities of economic activities using glass waste for environmental benefits for the society. The greatest answer to master the environmental effect of glass wastes is to reuse them. Recycling of these wastes principally from glass bottles and flat glasses will benefit in safeguarding the earth's natural resources, diminishing landfill places, and saving energy and money. With a number of TV sets and computers attaining their end-of-life, electronic production is also challenged with the main difficulty of dealing with used devices. © 2019, Springer Nature Switzerland AG

From waste CRT glasses to foam glass

International audienc

Valorisation du calcin en mousse de verre

International audienc