M. Rami Reddy

Acoustic investigations on PbO-Al2O3-B2O3 glasses doped with certain rare earth ions

Elastic moduli (Y, η), Poisson’s ratio (σ), microhardness (H) and some thermodynamical parameters such as Debye temperature (θD), diffusion constant (Di),latent heat of melting (ΔHm) etc of PbO-Al2O3-B2O3 glasses doped with rare earth ions viz. Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Yb3+, are studied as functions of temperatures (in the temperature range 30–200°C) by ultrasonic techniques. All these parameters are found to increase with increasing atomic numberZ of the rare earth ions and found to decrease with increasing temperature of measurement. From these results (together with IR spectra of these glasses), an attempt is made to throw some light on the mechanical strength of these glasses.

Optical and structural investigation of Dy3+–Nd3+ co-doped in magnesium lead borosilicate glasses

MgO-PbO-B2O3-SiO2-Nd2O3-Dy2O3 glasses are prepared by melt-quenching technique. The samples are characterized by X-ray diffraction (XRD), optical absorption, luminescence and Fourier transform infrared (FT-IR) spectral studied. XRD analysis evidently indicates that the prepared samples are fully amorphous nature. From the optical absorption spectra, the bonding environment surrounding the Dy(3+) and their energy level scheme in glass network is analyzed. Enhancement of Dy(3+) emission by non-radiative energy transfers from Nd(3+) has been observed here. The samples emits intensive bluish yellow color from the (4)F9/2→(6)H15/2, (6)H13/2 transition of Dy(3+) ions in these glasses which are nearer to white light and it is also supported by the chromaticity color coordinates. The FT-IR spectra reveal that network connectivity is increased with replacement of bonds B-O-B, Si-O-Si by more resistant B-O-Si bonds with gradually increasing the content of Dy(3+) ions in the glass network. Along with spectroscopic parameters some physical parameters like density, refractive index etc. are measured for the glasses.

The Spectroscopic Properties of Mo5+ in ZnO-ZnF2-B2O3 Glasses

The system of glass samples ZnO-ZnF2-B2O3 containing different concentrations of MoO3 (ranging from 1.0-7.0 mol%) were prepared. The glasses were characterized by optical absorption, ESR, FTIR and Raman spectral studies. The analyses of the results of the optical absorption and ESR studies indicated that the molybdenum ions coexisted in Mo5+ state with Mo6+ state in these glasses, whereas the results of the FTIR and Raman spectral studies indicated that there was an increasing degree of disorder in the glass network with increase in the concentration of MoO3.