• Ankur Jain

Articles written in Bulletin of Materials Science

• Structural, electrical and thermodynamical aspects of hydrogenated La–Ni–Si alloy

The structural, electrical and thermodynamic properties of a La–Ni–Si [La = 28.9%, Ni = 67.5%, Si = 3.6%] alloy have been investigated. Powder XRD results show that the lattice constants and unit cell volume of the alloy increase after hydrogen storage. It was also found that the resistance of the alloy increased with dissolved hydrogen concentration. Hydrogen absorption pressure composition isotherms have also been investigated which show the presence of two single 𝛼 and 𝛽 regions and one mixed (𝛼 + 𝛽) phase. The thermodynamic parameters viz. the relative partial molar enthalpy (𝛥 𝐻) and relative partial molar entropy (𝛥 𝑆) of dissolved hydrogen, are found to be in the range 8–18 kJ (mol H)-1 and 25–63 JK-1 (mol H)-1. From the dependence of 𝛥 𝐻 on the hydrogen concentration, 𝑋, the different phases [𝛼, 𝛼+ 𝛽, 𝛽] and phase boundaries of the alloy-𝐻 system are identified. Thermal conductivity and diffusivity of La–Ni–Si and its hydride have been measured at room temperature by using TPS technique. Thermal conductivity was found to decrease due to absorbed hydrogen in the alloy.

• Structural and electrical properties of swift heavy ion beam irradiated Co/Si interface

Synthesis of swift heavy ion induced metal silicide is a new advancement in materials science research. We have investigated the mixing at Co/Si interface by swift heavy ion beam induced irradiation in the electronic stopping power regime. Irradiations were undertaken at room temperature using 120 MeV Au ions at the Co/Si interface for investigation of ion beam mixing at various doses: 8 × 1012, 5 × 1013 and 1 × 1014 cm-2. Formation of different phases of cobalt silicide is identified by the grazing incidence X-ray diffraction (GIXRD) technique, which shows enhancement of intermixing and silicide formation as a result of irradiation. 𝐼–𝑉 characteristics at Co/Si interface were undertaken to understand the irradiation effect on conduction mechanism at the interface.

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

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.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
Continuous Article Publishing mode

• # 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