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Influence of bath temperature on microstructure and NH3 sensing properties of chemically synthesized CdO thin films

Sharma A. K., Potdar S. S., Yewale M. A., Shirgaonkar Deepak B., Pakhare K. S., Sargar B. M., Rokade M. V., Patil U. M.

Materials Science Poland

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2019

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Vol. 37, No. 1

25--32

EN

Cadmium oxide (CdO) thin films were synthesized using chemical bath deposition (CBD) method from aqueous cadmium nitrate solution. The bath temperatures were maintained at room temperature (25 °C) and at higher temperature (80 °C). The structural studies revealed that the films showed mixed phases of CdO and Cd(OH)2 with hexagonal/monoclinic crystal structure. Annealing treatment removed the hydroxide phase and the films converted into pure CdO with cubic, face centered crystal structure. SEM micrographs of as-deposited films revealed nanowire-like morphology for room temperature deposited films while nanorod-like morphology for high temperature deposited films. However, cube-like morphology was observed after air annealing. Elemental composition was confirmed by EDAX analysis. Band gap energies of the as-deposited films varied over the range of 3 eV to 3.5 eV, whereas the annealed films showed band gap energy variation in the range of 2.2 eV to 2.4 eV. The annealed films were successfully investigated for NH3 sensing at different operating temperatures and at different gas concentrations. The room temperature synthesized film showed a response of 17.3 %, whereas high temperature synthesized film showed a response of 13.5 % at 623 K upon exposure to 24 ppm of NH3.

2

Study on harmonic analysis of functionally graded plates using FEM

Sharma A. K., Sharma P., Chauhan P. S., Bhadoria S. S.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 4

941--961

EN

This paper presents the harmonic and vibration analysis of functionally graded plates using the finite element method. Initially, the plates are assumed isotropic and the material properties of it are assumed to vary continuously through their thickness direction according to a power-law distribution of the volume fractions of the plate constituents. The four noded shell element is used to analyse the functionally graded plates. Four functionally graded plates-Al/Al2O3, Al/ZrO2, Ti–6Al–4V/Aluminium oxide, and SUS304/Si3N4 are considered in the study, and their results are obtained so that the right choice can be made in applications in high temperature environment and in reducing the vibration amplitudes in applications such as aircrafts, rockets, missiles, etc. Numerical results for the natural frequency and harmonic response amplitude are presented. Results are compared and validated with available results in the literature. Effects of boundary conditions, material and damping on natural frequency and harmonic response of the functionally graded plates are also investigated.

3

Propagation of torsional surface waves in a nonhomogeneous half-space with circular irregularity in free surface

Sethi M., Sharma A. K., Sharma A.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 4

929--939

EN

The present paper studies the effect of circular regularity on propagation of torsional surface waves in an elastic non-homogeneous half-space. Both rigidity and density of the half-space are assumed to vary inversely linearly with depth. Separation of variable method has been used to get the analytical solutions for the dispersion equation of the torsional surface waves. Also, the effects of non-homogeneity and irregularity on the phase velocity of torsional surface waves have shown graphically.

4

Stabilization of fly ash and lime sludge composites: Assessment of its performance as base course material

Sahu V., Srivastava A., Misra A. K., Sharma A. K.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 3

475--485

EN

In the present study, two potential industrial waste materials, such as, fly ash (FA) and lime sludge (LS) that are generated in bulk quantities and poses environmental hazards were mixed and stabilized using lime (CL) and gypsum (G) in order to make them suitable for use in Civil Engineering construction applications. Different mix proportion of FA and LS stabilized with different % of CL and G were studied and tested for unconfined compressive strength (UCS), split tensile strength test (STS) and California bearing ratio (CBR) to check the suitability of prepared composite for construction industries. It is noted that the optimal composition consisted of FA and LS in 1:1 ratio, 12% CL and 1% G content. The composite was also found to be durable with no leaching of heavy metals. Further, the selected composite was further studied for the microstructural development through scanning electron microscopy (SEM) and X-ray diffraction (XRD) to understand the phenomenon of chemical process or reaction and reason for strength gain. The developed composite (50FA + 50LS + 12CL + 1G) is suggested for application as base course layer material in flexible pavements due to its good requisite strength and durability. It is further highlighted that issues of uncertainty in strength and stiffness characteristics of pavement layer materials and its implications on analysis and design of flexible pavements can be studied through reliability based approach in combination with numerical analysis and Monte Carlo simulations.

5

Electrochemical synthesis of nanoplatelets-like CuS0.2Se0.8) thin film for photoluminescence applications

Sharma A. K., Yewale M. A., Chavan G. A., Kambale D. B., Potdar S.

Materials Science Poland

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2015

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Vol. 33, No. 2

397--401

EN

Copper sulfide-selenide (CuS0.2Se0.8) thin films were deposited on FTO coated glass substrate (fluorine doped tin oxide) and stainless steel substrates using electrodeposition technique. Deposited thin films were characterized using different characterization techniques viz. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, photoluminescence spectroscopy and surface wettability. XRD study showed polycrystalline nature with cubic phase of the films. Scanning electron microscopy showed that the surface area of the substrate was covered by the nanoplatelets structure of a thickness of 140 to 150 nm and optical study showed that the direct band gap was similar to 1.90 eV. Surface wettability showed hydrophobic nature of the CuS0.2Se0.8 thin films.

6

Generalized weighted composition operators on the Bergman space

Sharma A. K.

Demonstratio Mathematica

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2011

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Vol. 44, nr 2

359--372

EN

Let φ and ψ be holomorphic maps on the open unit disk D such that φ (D) ⊂ D and H (D) be the space of holomorphic functions on D. For a non-negative integer n, define a linear operator (…), f ∈ H (D). In this paper, we characterize boundedness and compactness of (…) on the Bergman space A². We also compute the upper and lower bounds of essential norm of this operator on the Bergman space.