• Kamlendra Awasthi

      Articles written in Bulletin of Materials Science

    • Transport through track etched polymeric blend membrane

      Kamlendra Awasthi Vaibhav Kulshreshtha B Tripathi N K Acharya M Singh Y K Vijay

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      Polymer blends of polycarbonate (PC) and polysulphone (PSF) having thickness, 27 𝜇m, are prepared by solution cast method. The transport properties of pores in a blend membrane are examined. The pores were produced in this membrane by a track etching technique. For this purpose, a thin polymer membrane was penetrated by a single heavy ion of Ni7+ of 100 MeV, followed by preferential chemical etching of the ion track. Ion permeation measurements show that pores in polymeric membrane are charged or neutralized, which depends upon the variation in concentration of the solvent. The 𝑉–𝐼 curve at concentration, N/10, shows that the pores are negatively charged, whereas at concentration, N/20, the linear nature of 𝑉–𝐼 curve indicates that the pores approach towards neutralized state and on further concentration, N/40, the pores become fully neutralized, consequently the rectifier behaviour of pores has been omitted.

      The gas permeability of hydrogen and carbon dioxide of this membrane was measured with increasing etching time. The permeability was measured from both the sides. Permeability at the front was larger than the permeability at the back which shows asymmetric behaviour of membranes.

    • The fascinating world of Soft Materials

      KAMLENDRA AWASTHI RABIBRATA MUKHERJEE S KRISHNA PRASAD

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    • Effect of Cu ion implantation on the structural and electrical properties of BiSbTe$_3$ single crystals

      NISHA YADAV M D ANOOP JYOTI YADAV RINI SINGH NABARUN BERA SANDEEP RAVAJI PATEL ANKUR JAIN TAKAYUKI ICHIKAWA FOURAN SINGH KAMLENDRA AWASTHI MANOJ KUMAR

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      Invoking defects with ion implantation is an attractive means to modify the physical parameters of materials. In the present work, Cu ions at fluence (1 ${\times}$ 10$^{15}$ ions cm$^{-2}$) with 100 keV energy were implanted on BiSbTe$_3$ (BST) single crystals. The X-ray diffraction (XRD) measurements on pristine and Cu ion-implanted crystals demonstrate a decrease in lattice parameter (a = b) from 4.31 to 4.26 A$^º$ with an increment in ‘c’ lattice parameter from 30.47 to 30.48 A$^º$ with implantation. The peaks in XRD are shifted to lower 2${\theta}$, which are attributed to tensile strain induced in sample due to implantation. The composition of pristine BST crystal depicted from X-ray photoelectron spectroscopy is Bi:Sb:Te = 1.08:1.45:2.4. The implantation of Cu in BST single crystals is confirmed by energy dispersive X-ray technique. The resistivity measurements reveal a decrease in resistivity with implantation due to decrease in strain with Cu ion implantation. The Hall coefficient is found to be positive for both the samples signifying that the holes are the dominating charge carriers. A slight shift in Fermi level was observed with implantation. The magnetoresistance data is fitted with an equation $R(B)$ = c+b${\times}$B$^a$ using Python. The parameter c varies from ${\sim}$228 to ${\sim}$388.5 m${\Omega}$ for the pristine sample, whereas for implanted sample it varies from 5.89 to 6.66 m${\Omega}$ throughout the temperature range ${\sim}$4–300 K. This drastic reduction in c is due to the Cu ion implantation, which augments the metallic nature of the sample.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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