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Physical properties of unconventional binary sodium bismuthate glasses
Author(s) -
AlAssiri M. S.,
Tashtoush N. M.,
Ragab H. S.,
ElDesoky M. M.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200723456
Subject(s) - amorphous solid , molar volume , materials science , differential scanning calorimetry , scanning electron microscope , analytical chemistry (journal) , octahedron , conductivity , microstructure , glass transition , infrared spectroscopy , mineralogy , crystallography , chemistry , crystal structure , thermodynamics , metallurgy , composite material , physics , organic chemistry , chromatography , polymer
Abstract Unconventional binary glasses in the system Na 2 O–Bi 2 O 3 have prepared by a conventional press‐quenching technique. X‐ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), infrared (IR) spectra, density ( ρ ) and, molar volume ( V m ) and dc conductivity ( σ ) of these glasses were reported. The overall features of XRD curves confirm the amorphous nature of the present glasses. SEM investigation shows a surface without any microstructure, which is a characteristic of the amorphous phase. Systematic variation of the glass transition temperature ( T g ), density and IR spectra observed in these glasses indicates significant structural change with composition. Their variation with the composition has been explained by taking into consideration the structure of these glasses. From IR spectra, we conclude the presence of BiO 3 pyramidal and BiO 6 octahedral units in the glass structure. From the density ( ρ ) and molar volume ( V m ), the BiO 6 octahedral units are transformed into BiO 3 pyramidal units because Na +1 are introduced within the network of the glass as a modifier and consequently change the structural units into a more open structure. T g was observed to decrease with an increase in Na 2 O content and to lie between 330 °C and 366 °C. The dc conductivity has been explained in terms of the structure of bismuthate glasses. At lower compositions of Na 2 O, the small variation in conductivity and activation energy has been attributed to the occupancy of Na + ions at the interstices of BiO 6 octahedra, acting as a charge compensator, while at higher concentrations of Na 2 O, the conductivity increases rapidly due to the formation of weak nonbridging oxygen (NBO) sodium ionic bond. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)