Synthesis crystallization kinetic and optical properties of europium doped tellurite nano-glass

Tellurite glass of composition (80-x) TeO2 – 5 Na2O – 15 MgO – (x) Eu2O3, with the concentration region of 0 = x = 2.5 mol% was prepared using conventional melt-quenching technique. The transition temperature, Tg, crystallization temperature, Tc and melting temperature, Tm were determined using Differential Thermal Analysis (DTA). The glass with nano-crystalline particle was prepared by heating the as-cast glass at temperature 15 - 20 oC above the Tc. The X-Ray Diffraction (XRD) technique with the Scherrer equation was used to determine the size of nano- crystalline particle of the samples while the Scanning Electron Microscopy (SEM) technique was used to identify the formation of nano-crystalline phase. The crystallization kinetics was investigated by using DTA at various heating rate while the glass density and hardness was determined by Precisa Densitometer and Vickers microhardness, respectively. Meanwhile, the emission characteristic was evaluated using the Photoluminescence Spectroscopy (PL). The thermal analysis showed that the Tg and Tc increased with the increasing of Eu3+ content while Tm showed a break in linearity as the Eu3+ increased. The result also showed that the glass stability up to 109.29. XRD spectra confirmed the presence of nano particles with an average diameter around 68.7 nm. Meanwhile the SEM studies revealed the existence nano-crystalline morphology which was associated with the existence of crystallized phase. The influence of Eu3+ content on crystallization kinetics showed a shift of crystallization temperature peak towards a higher temperature with the increasing of heating rate as described by Kissinger and Ozawa method. The activation energy (Ea) was found to decrease from 306.9 eV to 48.9 eV with an increasing of dopant concentration. The density was found to be in the range of 5.234 to 5.334 g cm-3 while the Vickers microhardness was found to vary from 2.59 to 2.84 GPa depending on the dopant concentration. A detailed study on the luminescence spectra showed that all emission peaks for 5D0 - 7F0, 5D0 - 7F1, 5D0 - 7F2, 5D0 - 7F3 and 5D0 - 7F4 transitions were found to be around 568 nm, 600 nm, 628 nm, 664 nm and 712 nm, respectively. It was also found that the heat-treated glass and the inverse quality factor decreased with increasing Eu3+ dopant concentration

Study of crystallization kinetics of Teo2-Na2O-Mgo glass using Ozawa method: influence of europium

The study of the crystallization kinetics of rare-earth doped glass stimulated much interest especially for crystallization process. In this work transparent Eu2O3 doped glasses with composition TeO2 - Na2O - MgO were prepared using conventional melt-quenching technique. The amorphous nature of glass was confirmed using X-ray diffraction method. The influence of Eu3+ content on the crystallization kinetics of the glass such as activation energy (E-a) was thoroughly evaluated under non-isothermal conditions using DTA. The crystallization kinetic at different heating rate from 5 degrees C min(-1) to 25 degrees C min(-1) at different crystallization temperature (T-p) were examined and verified using Ozawa method. The result showed that the activation energy (E-a) was decreased with the increasing of the dopant concentration from 319.8 eV to 93.5 eV

Epidemiological and medico-social aspects of primary glaucoma

Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Efficient optical enhancement of Er3+ doped lead-tellurite glass embedded with gold nanoparticles: role of heat-treatment

Enhancing the optical response of rare earth doped glasses for miscellaneous optical applications is challenging in materials science and technology. Influences of heat treatments in modifying the spectral features of melt-quench synthesized gold nanoparticles embedded Er3 +-doped lead–tellurite glasses are investigated. Time of heat treatment is varied from 1 to 24 h. Modifications in physical, optical and structural parameters are ascribed to the alteration of non-bridging oxygen due to heat treatments. X-ray Diffraction patterns of all glass samples confirm their amorphous nature in the presence of crystalline peak at 28.66°. Transmission Electron Microscopic images reveal the nucleation of gold nanoparticles having average diameter in the range 1.24–8.40 nm for the heat-treated samples. The ultraviolet–visible-near-infrared spectra exhibit seven absorption bands centered at 490, 526, 551, 652, 800, 979 and 1520 nm corresponding to 4f–4f transitions of Er3 + ions. The up-conversion emissions peaks centered at 520, 550 and 660 nm are assigned to 2H11/2–4I15/2,4S3/2–4I15/2 and 4F9/2–4I15/2 transitions, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of gold NPs. The intensity parameters related to the radiative transitions within 4fn configuration of Er3 + ion are determined and analyzed using Judd–Ofelt theory

Physical, structural, and Raman spectroscopic traits of neodymium-doped lead Oxyfluoride zinc phosphate glass

Nd3+ with composition of (60 - x) P2O5 - 10ZnO - 30PbF2 - (x) Nd2O3 where (0.0 ≤ x ≤ 2.0 mol %) was prepared using a melt-quenching approach to the development of transparent glasses. These glasses have been confirmed to be an amorphous structure through XRD analysis. The glass density, molar volume and ionic packing density were obtained in the range of 3.978- 4.157 g cm-3, 41.949 - 41.073 cm3 mol-1 and 0.614-0.624, respectively. Using Fourier Transform Infrared (FTIR) and Raman Spectroscopy, the chemical functional groups and biomolecules of samples were characterised. The FTIR spectra revealed six main bands assigned to P-O, P-O-P, P=O, (PO3)2- and hydroxyl groups (O-H), while Raman shift detected five symmetric and asymmetric bands attributed to P-O-P bonds in Q1 units, (PO4)3- bonds in Q0 units, (PO3)2- bonds in Q1 units, (PO2)- bonds in Q2 units and P=O bonds in Q3 units. It is believed that the proposed oxyfluoride glasses may be useful and suitable applicant to lasing materials and sensors sensitivity