PROPERTIES OF UNCONVENTIONAL LITHIUM BISMUTHATE GLASSES

Unconventional bismuthate glasses containing lithium oxide have been p repared by a conventional melt-quench technique. X-ray diffraction, sc anning electron microscopy, and differential thermal analysis show tha t stable binary glasses of composition xLi(2)O-(100-x)Bi2O3 can be ach ieved for x = 20-35 mol%. Systematic variation of the glass-transition temperature, density, and molar volume observed in these glasses indi cates no significant structural change with composition. Differential thermal analysis and optical studies show that the strength of the gla ss network decreases with the increase of Li2O content in the glass ma trix with a small deviation for the extra stable 30Li(2)O-70Bi(2)O(3) glass composition. Studies of Raman spectra and molar volume ensure th at all glasses are built up of [BiO6] octahedral units, while the infl uence of Li+ ions in the glass matrix is also confirmed from optical, Raman, and electrical studies. Wide transmitting window in the optical region having sharp cutoffs in both ultraviolet-visible and infrared regimes may make these glasses useful in spectral devices. High dielec tric values in these glasses compared to glasses formed with conventio nal glass former can be attributed to the influence of the high polari zability of the unconventional network forming cations, Bi3+.