On the origin of the high Kerr coefficient measured in thallium zinc tellurite glasses

International audienceMeasurements of Kerr electrooptical sensitivity of several zinc-thallium-tellurite glasses are presented, and composition dependence of Kerr sensitivity is compared with the dependence of the second harmonic generation efficiency collected for optically poled TeO2-TlO0.5-ZnO glasses. These data being analyzed jointly with Raman measurements data allowed us to conclude that the high electrooptical Kerr coefficient and nonlinearity of Tl2O-ZnO-TeO2 glasses, and their sharp increase with augmenting concentration of thallium oxide TlO0.5 above 15% should be attributed to the presence of Tl+ cations having very high non-linear polarizability most likely related to their electronic lone pairs

Theoretical Third-Order Hyperpolarizability of Paratellurite from the Finite Field Perturbation Method

International audienceDensity functional theory was used to estimate the third-order hypersusceptibility (3) of the R-TeO2 paratellurite (as a model structure for TeO2 glass) and the same value for R-SiO2 cristobalite (as a model structure for glassy silica). The attempt was made to gain a physical insight into the nature of the extraordinarily high hypersusceptibility of TeO2 glass. A finite field perturbation method implemented in the CRYSTAL code with the “sawtooth” approach was employed. The (3) values calculated for R-TeO2 were found to be of the same order as that measured for TeO2 glass and much higher than the values computed for R-SiO2 which, in turn, were close to that of glassy silica

Verres tellurites de thallium dopes à l'argent

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Crystal structure and dynamical properties of a new tellurite : AgTlTeO3

International audienceThe structure of a newly synthesized AgTlTeO3 crystalline compound has been solved from single crystal X-ray diffraction data and refined to a final reliability factor R1 = 0.037. It was found having an orthorhombic Iba2 space group symmetry with unit cell parameters a = 14.708(7) A˚ , b = 10.745(6)A˚ , c = 5.166(3)A˚ , Z = 8. Its lattice is divided into separated AgTlTeO3 sheets parallel to [0 1 0] which are formed by TeO3 pyramids, TlO4 disphenoids and AgO6 octahedra sharing either corners or edges. At the same time, from the crystal chemistry point of view, it can be classified as a typical island-type compound made up from molecular-like [TeO3]2 ortho-anions weakly connected with Ag+ and Tl+ cations. The vibrational spectra and their interpretations complemented by the calculated elastic properties confirm this classification. The model-estimated piezoelectric constants allow characterizing AgTlTeO3 as a strong pyroelectric structure

New glasses within the Tl2O-Ag2O-TeO2 system : thermal characteristics, Raman spectra and structural properties

International audienceWithin the Tl2O-Ag2O-TeO2 system, a large glass-forming domain was evidenced and is presented for the fist time. Densities, glass transition (Tg) and crystallization (Tc) temperatures of the relevant glasses were measured. A structural approach of these glasses as functions of the composition was performed using Raman scattering. The Raman spectra were analysed in terms of the structural modifications induced by the Tl2O and Ag2O modifiers. It has clearly evidenced a phase separation inherent in tellurite glasses with low valence cations (as Tl+ and Ag+). The glasses would be constituted of two phases only: one of pure TeO2 and one of pure ortho-tellurite M2TeO3 (M = Ag, Tl) with the statistically mixed Ag-Tl cationic composition

Photosensitivity in glasses

A photosensitive glass containing a small amount of a photosensitive metal such as Au, Ag, or Cu, and a sensitizer of CeO2, is expressed a function of the redox reaction induced by the irradiation of ultraviolet light. In particular, a photosensitive glass is an indispensable material in the photolithography technique, which is valuable in the microprocessing of glass substrates. Here we aim to discuss the photosensitivity of glass from the perspectives of photochemical, photophysical, and photothermal mechanisms. In particular, from three different points of view (photothermal, photochemical, and photophysical interactions), various intriguing phenomena induced by ultrashort pulse lasers are addressed. Furthermore, a new type of photosensitivity exhibiting nonreciprocal characteristics is also discussed