• A K GANGULI

Articles written in Bulletin of Materials Science

• Chemical stability of the high-Tcsuperconductor YBa2Cu3O7−δ+

YBa2Cu3 O7−δ samples stored in different environments have been studied over a period of 30 days employing TGA, electrical resistivity and X-ray diffraction measurements. Oxygen content andTcdo not change significantly in samples stored in the normal laboratory environment, in a sealed tube or in a vacuum desiccator. Superconductivity is lost only in samples stored in a very humid atmosphere around 320 K.

• Thermal expansion studies of substituted CTP derivatives

Several new Na, Y and Zr substituted derivatives of Ca0·5Ti2(PO4)3 (CTP) have been synthesized. These derivatives retain the hexagonal structure of the parent (CTP) compound with minor changes in lattice parameters. Linear thermal expansion coefficients(α) have been obtained using a high sensitivity dilatometer.

• High-pressure studies of superconductivity in BiO$_{0.75}$F$_{0.25}$BiS$_2$

BiO$_{0.75}$F$_{0.25}$BiS$_2$ crystallizes in tetragonal CeOBiS$_2$ structure (S. G. P4/nmm). We have investigated the effect of pressure on magnetization measurements. Our studies suggest improved superconducting properties in polycrystalline samples of BiO$_{0.75}$F$_{0.25}$BiS$_2$. The Tc in our sample is 5.3 K, at ambient pressure, which is marginal but definite enhancementover $T_c$ reported earlier ($=$5.1 K). The upper critical field Hc2(0) is greater than 3 T, which is higher than earlier report onthis material. As determined from the M–H curve, both H$_{c2}$ and H$_{c1}$ decrease under external pressure $P$ ($0 \leq P \leq 1$ GPa). We observe a decrease in critical current density and transition temperature on applying pressure in BiO$_{0.75}$F$_{0.25}$BiS$_2$.

• # Bulletin of Materials Science

Volume 43, 2020
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Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019