• Basudeb Karmakar

      Articles written in Bulletin of Materials Science

    • Effects of SiO2 and TiO2 fillers on thermal and dielectric properties of eco-friendly bismuth glass microcomposites of plasma display panels

      Shiv Prakash Singh Karan Pal Anal Tarafder Mousumi Das Kalyandurg Annapurna Basudeb Karmakar

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      The effects of SiO2 (amorphous) and TiO2 (crystalline, rutile) fillers on softening point (𝑇s), glass transition temperature (𝑇g), coefficient of thermal expansion (CTE), and dielectric constant (𝜀) of zinc bismuth borate, ZnO–Bi2O3–B2O3 (ZBIB) glass microcomposites have been investigated with a view to its use as the white back (rear glass dielectric layer) of plasma display panels (PDPs). The experimentally measured properties have also been compared with those of theoretically predicted values. Both the experimental and theoretical trends of these properties with added filler contents correlate very well. The interaction of fillers with glass which occurred during sintering at 560°C has also been monitored by XRD and FTIR spectroscopic analyses. The microstructures and distribution of fillers in the glass matrix have been analyzed by SEM images. It is observed that the fillers have partially dissolved in the glass at the firing temperature leaving some unreacted filler as residue which results in ceramic–glass microcomposites. In consideration of the desired properties of white back of PDPs, the addition of TiO2 filler to ZBIB glass is found to be more preferable than SiO2 filler. The addition of 10 wt% TiO2 filler yielded 𝑇s, 𝑇g, CTE and 𝜀 values of 560°C, 480°C, 82 × 10-7/K and 14.6 which are found to meet the desired values of < 580°C, < 500°C, < 83 × 10-7/K and < 15, respectively with respect to use of PD200 glass as substrate in PDP technology.

    • Anomalous properties of chloroborosilicate glasses in the K2O–BaO–Al2O3–B2O3–SiO2–BaCl2 system

      Nilanjana Shasmal Anal Tarafder Basudeb Karmakar

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      A series of chloroborosilicate glass having composition (in mol%) (100−x)(42SiO2–30B2O3–20BaO–4K2O–4Al2O3)–xBaCl2 (where 𝑥 = 0−30) has been prepared by the melt quench technique yielding transparent monolithic glasses up to 𝑥 = 22.5. Structural investigation by infrared reflection and UV–vis–NIR absorption revealed the bridging action of Cl atom and decrease in non-bridging oxygens with the increase in BaCl2 content. Thermal properties (𝑇g, 𝑇d and 𝑇s) were measured by the dilatometry and softening point measurement. Viscosity was calculated using the Vogel–Fulcher–Tammann equation. Elastic constants were measured by the ultrasonic method. Other mechanical properties like hardness, fracture toughness were also measured. All of the thermal and mechanical properties exhibited a similar trend of anomalous variation as a function of the BaCl2 content, showing maxima at 10 mol% and a sharp increase at 25 mol% BaCl2 content. The anomaly has been explained by the structural point of view with the help of the aforementioned spectroscopic data.

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