• A Das

      Articles written in Bulletin of Materials Science

    • History effects in low-field magnetoresistance of BPSSCO polycrystals

      A Das A Banerjee R Srinivasan

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      Low-field (H<40 G) magnetoresistance measurements have been made on Bi1·6Pb0·4Sr2Ca2Cu3O10 polycrystals at several temperatures between 80 and 105 K. Considerable hysteresis in ρ(H) is found in a zero-field-cooled sample when the applied field is increased from 0 to a maximum value and then lowered back to 0 at all temperatures. The observation of hysteresis is taken as an evidence for field trapping in the grains. We show that the hysteresis in ρ(H) occurs for applied fields much lower than that at whichdρ(H)/dH exhibits a discontinuity. In addition, we find that when the applied magnetic field (Ha) is lowered from a maximum field, the effective intergranular field,Heff, becomes zero forHc>0, which gives rise to a minimum in ρ(H).

    • CuBO$_2$ nanonetwork: a novel and significant candidate for photocatalytic dye degradation

      S SANTRA A DAS N S DAS K K CHATTOPADHYAY

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      CuBO$_2$ is a novel material in the research field of transparent conducting oxide. In this study, CuBO$_2$ nanostructures have been synthesized via sol–gel method. The phase formation is confirmed using an X-ray diffractometer. Detailedmorphological analysis is performed by field emission scanning electron microscopy and transmission electron microscopy. Anovel uniform nanonetwork-like structure is obtained and its band gap is found to be 4.24 eV. In ultraviolet light irradiation, this as-synthesized sample shows efficient photocatalytic activity for degradation of organic dye Rhodamine B. The degradation efficiency and the rate constant were calculated as $\sim$70% and $1.32 \times 10^{−3}$ min$^{−1}$, respectively. This nanonetwork-like structure can be a potential candidate as the base material to attach various metals and metal oxide nanostructures to get highly efficient future photocatalysts. As a result, this study opens up a new gateway to fabricate novel environment-friendly nanocatalysts with high performance.

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