Transport properties of Li2O-MnO2-B2O 3 glasses

Lithium borate containing MnO2 glasses have been synthesized by melt quenching technique over a wide composition range. Frequency and temperature dependent conductivity measurements have been carried out in the range of 10 Hz to 13 MHz and at a temperature range of 298 K-523 K respectively. The impedance plots show only one semicircle indicating the presence of one type of conduction mechanism. The analysis of dc conductivity show that the conductivity is dominated by Li+ ions and the presence of MnO 2 has negligible effect. The ac conductivity data has been analysed by fitting the data into Almond-West type power law behaviour Ï = Ï(o) + AÏs. The power law exponent s is also determined and it is found to decrease with increase of temperature. We have also carried out the scaling behaviour of the ac conductivity and it is seen that all the curves coalesce on to a master curve suggesting that the ion transport mechanism remains unaffected at all temperatures. The results are discussed in the light of the structure of borate glass network. © 2005 Elsevier B.V. All rights reserved

Electrical conductivity studies of AgI-​Ag2O-​B2O3-​TeO2 glasses

The Ag ion conducting borotellurite glasses were prepd. by melt quenching technique. The cond. and dielec. measurements were carried out on these glasses as a function of frequency from 10 Hz to 10 MHz between 298-​328 K. The anal. of cond. measurement shows that the Ag ions are the main charge carriers, which are considered to be the predominant factor playing the role of enhancing the cond. The power law exponent s and stretched exponent β are found to be insensitive to both temp. and compns. A.c. cond. and dielec. relaxation behavior of these glasses were also studied and the results are discussed in view of the structure of borate and tellurite network

Elastic properties and spectroscopic studies of Na2O-ZnO-B2O3 glass system

Elastic properties, 11B MAS-NMR and IR spectroscopic studies have been employed to study the structure of Na2O-ZnO-B2O3 glasses. Sound velocities and elastic moduli such as longitudinal, Young's bulk and shear modulus have been measured at a frequency of 10 MHz as a function of ZnO concentration. Both sound velocities and elastic moduli increase with increasing ZnO concentration. Poisson's ratio and Debye temperature were also found to increase with ZnO concentration. 11B MAS-NMR and IR spectra show characteristic features of borate network and compositional dependence trends as a function of Na2O/ZnO concentration. The results are discussed in view of borate network and dual structural role of Zn2+ ion into the network. The results indicate that the Zn2+ ions are likely to occupy network forming positions in this glass system

Elastic properties and spectroscopic studies of lithium lead borate glasses

Elastic properties of xLi2O - 20PbO - (80-x)B2O 3 glasses have been measured at a frequency of 10 MHz using X-cut and Y-cut quartz transducers. The trends in the variation of elastic moduli, Poisson's ratio and Debye temperature have been studied. The elastic moduli namely longitudinal and young's modulus show strong linear dependence while bulk and shear modulus vary marginally as a function of Li2O concentration. The Poisson's ratio is found to be almost constant and Debye temperature increases with the increase of Li2O concentration. IR, MAS-NMR and glass transition temperature studies have been also carried out. Glass transition temperature is found to increase with increase of Li 2O concentration. IR and MAS-NMR spectra show characteristic features of borate network and systematic change as a function of Li 2O concentration. The variation in the elastic properties and structural features of IR and MAS-NMR indicate that Pb2+ ions are likely to occupy network forming positions in this glass system

Elastic properties of fast ion conducting lithium based borate glasses

Elastic properties of Li2O-PbO-B2O3 glasses have been investigated using sound velocity measurements at 10 MHz. Four series of glasses have been investigated with different concentrations of Li2O, PbO and B2O3. The variations of molar volume have been examined for the influences of Li2O and PbO. The elastic moduli reveal trends in their compositional dependence. The bulk and shear modulus increases monotonically with increase in the concentration of tetrahedral boron which increases network dimensionality. The variation of bulk moduli has also been correlated to the variation in energy densities. The Poisson's ratio found to be insensitive to the concentration of tetrahedral boron in the structure. The experimental Debye temperatures are in good agreement with the expected theoretical values. Experimental observations have been examined in view, the presence of borate network and the possibility of non-negligible participation of lead in network formation. © 2005 Elsevier B.V. All rights reserved

Thermal physical, and infrared spectroscopic studies on glasses prepared by microwave route

This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of BO 4/2 - and B 2V 2O 9 2-) groups are confirmed by Infrared Spectroscopy of investigated glasses. © 2011 American Institute of Physics

EPR study of vanadium ion in zinc-boro-vanadate glasses

This paper describes EPR studies on x V 2O 5-(40-x)ZnO- 60B 2O 3 (where x=5, 10, 15 and 20 mol %) glass system. These studies indicate a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The EPR spectra show a distinct hyperfine structure of 51V. Spectral analysis shows that the vanadium is present in the glass as vanadyl ion [VO] 2+ at tetragonally distorted octahedral site. The decrease of A ∥ and A ⊥ with increase of V 2O 5 concentration suggests an increase in the covalence between the central atom and the surrounding oxygen ligands. © 2011 American Institute of Physics