Bismuth tellurite and bismuth borotellurite samples were synthesized and structure-property corre... more Bismuth tellurite and bismuth borotellurite samples were synthesized and structure-property correlations were carried out by density, X-ray diffraction, dielectric measurements, differential scanning calorimetry, infrared, Raman and 11 B Magic Angle Spinning Nuclear Magnetic Resonance studies. Low concentration of Bi 2 O 3 (5-mol %) forms bismuth tellurite glass while higher concentration of Bi 2 O 3 (10 and 20-mol%) produces anti-glasses on splat-quenching the melt. The short-range structure of bismuth borotellurite glasses consists of TeO 4 , TeO 3 , BO 4 and BO 3 structural units. Raman studies show that TeeO coordination (N TeeO) in bismuth tellurite glass and anti-glass samples decreases from 3.48 to 3.43 with increase in Bi 2 O 3 concentration from 5 to 20-mol%. On incorporating 20-mol% of B 2 O 3 into bismuth tellurite sample, N TeeO decreases to 3.33 and the glass forming ability enhances significantly as compared to that of bismuth tellurite system. On increasing B 2 O 3 upto 40-mol%, the BeO coordination decreases steadily. The addition of Bi 2 O 3 produces the structural transformation: TeO 4 → TeO 3 in Bi 2 O 3-TeO 2 system while B 2 O 3 produces the structural transformation: BO 4 → BO 3 in Bi 2 O 3-B 2 O 3-TeO 2 series without significantly modifying N TeeO. The glass transition temperature increases from 371 °C to 410 °C on increasing B 2 O 3 from 20 to 40-mol%, this increase is due to increase in the concentration of stronger BeO linkages at the expense of weaker TeeO bonds. Decrease in the dielectric constant from 24.1 to 19.3 with B 2 O 3 concentration is due to decrease in density while the polarizability of bismuth borotellurite series remains constant.
Bismuth tellurite and bismuth borotellurite samples were synthesized and structure-property corre... more Bismuth tellurite and bismuth borotellurite samples were synthesized and structure-property correlations were carried out by density, X-ray diffraction, dielectric measurements, differential scanning calorimetry, infrared, Raman and 11 B Magic Angle Spinning Nuclear Magnetic Resonance studies. Low concentration of Bi 2 O 3 (5-mol %) forms bismuth tellurite glass while higher concentration of Bi 2 O 3 (10 and 20-mol%) produces anti-glasses on splat-quenching the melt. The short-range structure of bismuth borotellurite glasses consists of TeO 4 , TeO 3 , BO 4 and BO 3 structural units. Raman studies show that TeeO coordination (N TeeO) in bismuth tellurite glass and anti-glass samples decreases from 3.48 to 3.43 with increase in Bi 2 O 3 concentration from 5 to 20-mol%. On incorporating 20-mol% of B 2 O 3 into bismuth tellurite sample, N TeeO decreases to 3.33 and the glass forming ability enhances significantly as compared to that of bismuth tellurite system. On increasing B 2 O 3 upto 40-mol%, the BeO coordination decreases steadily. The addition of Bi 2 O 3 produces the structural transformation: TeO 4 → TeO 3 in Bi 2 O 3-TeO 2 system while B 2 O 3 produces the structural transformation: BO 4 → BO 3 in Bi 2 O 3-B 2 O 3-TeO 2 series without significantly modifying N TeeO. The glass transition temperature increases from 371 °C to 410 °C on increasing B 2 O 3 from 20 to 40-mol%, this increase is due to increase in the concentration of stronger BeO linkages at the expense of weaker TeeO bonds. Decrease in the dielectric constant from 24.1 to 19.3 with B 2 O 3 concentration is due to decrease in density while the polarizability of bismuth borotellurite series remains constant.
Uploads
Papers by Dr. Atul K