Elastic moduli of ternary tellurite glasses at room temperature

Longitudinal and shear ultrasonic velocities in the ternary tellurite glasses have been measured at room temperature with different percentages of the third component. The ternary tellurite glasses have the form (composition in mol%): 70 TeO2 - (30-x) V2O5 - xAnOm, where ΑnΟm is CeO2 or ZnO, and x = 3, 5, 7, 10 mol%. The elastic properties, longitudinal, shear, bulk and Young's modulus, have been calculated together with Poisson's ratio and Debye temperature. Α qualitative analysis has been carried out after calculating the ring diameter of the glass network, Quantitatively, the estimated bulk modulus and Poisson's ratio of the ternary TeO2-V2O5-CeO2 system have been calculated, using the bond compression model and according to the cation-anion bond of each oxide present in the glass, in order to analyze the room-temperature elastic moduli data. Information about the structure of the glass can be deduced after calculating the number of network bonds per unit volume, the average stretching force constant, the average ring size and the mean cross link density

Elastic properties of tellurite glasses

Elastic properties of binary and ternary tellurite glass systems of the composition (in mol%) (100-x) TeO2 - x Nb2O5, and (100-x) TeO2 - 0.5x (Nb2O5 + Li2O) were calculated from the measured densities as well as from longitudinal and shear ultrasonic velocities at room temperature. Ultrasonic velocity measurements were taken at 4 MHz ultrasonic frequency using the pulse echo technique. Elastic moduli, and Debye temperature calculated from experimental data and calculated theoretically using the bond compression model were used to obtain quantitative details about the structure of these glasses. The effect of adding either Nb2O5 alone or Nb2O5 and Li2 on the elastic moduli was investigated in terms of the number of network bonds of the glass systems. The average atomic ring size of the network was also calculated and it was found that it depends on the concentration of the modifiers. The obtained results show that these glasses become more stable and compact when modified with Nb2O5 or with Nb2O5 and Li2O, which increases the elastic moduli in the two systems

Relaxation of ultrasonic waves in ternary TeO2-V2O5-Sm2O3 glasses

Studies were carried out on the attenuation of longitudinal ultrasonic waves in tellurite glasses containing vanadium and samarium oxides with different concentrations, using the pulse echo technique. Glass samples were prepared in the form (composition in mol%): 65 TeO2 - (35 - x) V2O5 - x Sm2O3, where x = 0.1, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%. The temperature dependence of the attenuation at ultrasonic frequencies of 2, 4, 6, and 10 MHz in the temperature range 150 to 280 Κ was proved. The shape of the loss peaks, i.e. the relaxation spectra, showed the presence of well-defined peaks at various temperatures depending upon glass composition and operating frequency. It was observed that these loss peaks shift to higher temperatures with increasing frequency suggesting some kind of relaxation process. Activation energies of the relaxation process, and deformation potential were calculated. Results showed that activation energies are strongly dependent on the samarium oxide content. Deformation potential is also frequency- and composition-dependent. Discussion of the results obtained in this study is reported

Synthesis and investigations on tellurium myconanoparticles

Tellurium has attracted the attention of many researchers and manufacturers due to its unique properties. Through the current work, six fungal isolates have been screened for their ability to reduce potassium tellurite (K2TeO3) into elemental tellurium nanoparticles (TeNPs). The most promising fungal isolate was identified as Aspergillus welwitschiae and given the accession number (KY766958) based on molecular basis and has been used for biogenic (enzymatic) production of TeNPs. The produced TeNPs have been characterized using DLS, TEM and FTIR. Data showed that, the particle size is 60.80 d.nm with oval to spherical shape. The produced TeNPs have been evaluated for antimicrobial activity at 25 mg/ml. Data revealed antibacterial activity against E. coli and Staphylococcus aureus (MRSA). Evaluation of the effect of γ-irradiation on TeNPs production showed that, the productivity was improved at 1 kGy and suppressed gradually at higher doses