Studies on Rare Earth doped Germanium Tellwrite Glasses

Abstract

newline samples of the composition, (1-x)TeO2 - xGeO2, with x= 0.10, 0.20, 0.25 and 0.30 mol% and those with samarium oxide and praseodymium oxide doping were prepared by conventional melt quenching method. The compositions with x = 0.2 and 0.3 mol% only formed the transparent glasses and were labeled as GT1 and GT2 glasses, respectively. Sm2O3 and Pr6O11 rare earths were doped separately in GT1 composition and were labeled as GT1S and GT1P glasses respectively, then both the rare earths were doped together in GT1 composition and labeled as GT1SP. The characterization was done using XRD, DSC, FTIR and Raman spectroscopy. Density, optical absorption, AC and DC conductivity measurements were also carried out. The work reports the effects of addition of GeO2 and rare earth oxides (Sm2O3 and Pr6O11) on the physical, structural, electrical and optical properties of the host glass matrix. The glass compositions, GT1, GT2 and GT1S resulted in transparent yellow glasses, GT1P in green color and GT1SP in yellowish green color. The amorphous nature of the glasses was confirmed by XRD. The density and molar volume of the glasses showed direct proportional behavior depending upon their molar mass and atomic radius, respectively. The thermal parameters like glass transition temperature and onset crystallization temperature were analyzed and the stability parameters like thermal stability and Hruby factor were calculated. The value of glass transition temperature of undoped glasses is almost twice to that of rare earth doped glasses. The glasses, GT1 and GT1S, exhibited higher stability to devitrification. FTIR and Raman analyses of the glasses indicated the progressive conversion of TeO4 units into TeO3/ TeO3+1 units and confirmed that GeO2 act as a network modifier in the undoped glasses. Both the analyses also confirmed the presence of TeO4, TeO3/TeO3+1 and GeO4 structural units in the glass network. Absorption coefficient, optical energy gap, Urbach energy, refractive index, molar refractivity, polarizability and met