Fabrication of Magnesium Diboride Thin Films by Aerosol Deposition

Sinha, B.B.,Chung, K.C.,Jang, S.H.,Hahn, B.D.,Park, D.S.,Wang, X.L.,Dou, S.X. The Korean Superconductivity Society 2011 Progress in superconductivity Vol.13 No.2

Superconducting $MgB_2$ thin films were fabricated by using a novel aerosol deposition technique wherein the pre-reacted powder is directly transformed into respective thin film. The formed thin films were characterized by X-ray diffraction technique and FE-SEM to understand its structure and morphology and the superconducting behavior has been characterized with the four probe resistivity measurement. The as-deposited thin films were formed into the frustrated amorphous structure, which were relaxed on the further heat treatment at $900^{\circ}C$ for 3 hrs. The relaxed amorphous $MgB_2$ thin films showed a comparatively high superconducting onset at about 38 K.

Collective effect of hydrogen in argon and Mg as ambiance for the heat treatment on MgB₂

Sinha, B.B.,Jang, S.H.,Chung, K.C. The Korea Institute of Applied Superconductivity a 2014 한국초전도저온공학회논문지 Vol.16 No.2

Magnesium diboride superconductor is still of considerable interest because of its appealing characteristics towards application mainly at around 20 K. Unlike Nb-based superconductors, $MgB_2$ can be operated by cryogen-free cooler which provides a cost effective alternative at low field of around 2-5 T. To explore this operating field region considerable efforts are necessary to marginally improve the superconducting properties of $MgB_2$. Under this situation, even the heat treatment environment during the synthesis is considered as an important factor. The addition of $H_2$ gas in small amount with Ar as a mixed gas during annealing has an adverse effect on the superconducting properties of $MgB_2$. It is although interesting to find that the presence of Mg vapor along with hydrogen during heat treatment results in the appreciable improvement in the flux pinning and the overall response of the critical current density for the ex-situ $MgB_2$ samples.

Mg과 B 혼합분말을 이용하여 분말압연 공정으로 제조된 $MgB_2$ 초전도 판재연구

정국채,장세훈,김정호,Chung, K.C.,Chang, S.H.,Sinha, B.B.,Kim, J.H.,Dou, S.X. 한국초전도학회 2012 Progress in superconductivity Vol.13 No.3

$MgB_2$ superconducting sheets have been fabricated by powder rolling method using mixture of Mg and B powders. Sheet-type $MgB_2$ bulk samples of ~10 mm width and 50-100 mm long were squeezed out after compacted by two rotating rolls of 130 mm diameter with gap distance of 0.5 mm and speed of ~40 cm/min (~1 rpm). The nominal composition of Mg, which is ductile metal, was added up to 30% to facilitate forming the $MgB_2$ sheets. The annealed samples at $900^{\circ}C$ and 3 hrs showed superconducting transition temperature of ~32 K and critical current densities at zero fields were ${\sim}10^5A/cm^2$ at 5 K and ${\sim}5{\times}10^4A/cm^2$ at 20 K.

A safe and cost-effective PMMA carbon source for MgB₂

Ranot, Mahipal,Jang, S.H.,Shinde, K.P.,Sinha, B.B.,Bhardwaj, A.,Oh, Y.S.,Kang, S.H.,Chung, K.C. The Korea Institute of Applied Superconductivity a 2017 한국초전도저온공학회논문지 Vol.19 No.1

Carbon is proven to be very effective in pinning the magnetic vortices and improving the superconducting performance of $MgB_2$ at high fields. In this work, we have used polymethyl methacrylate (PMMA) polymer as a safe and cost effective carbon source. The effects of molecular weight of PMMA on crystal structure, microstructure as well as on superconducting properties of $MgB_2$ were studied. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for $MgB_2$ doped with different molecular weights of PMMA. This indicates that carbon could be substituted in the boron honeycomb layers without affecting the interlayer interactions. As compared to undoped $MgB_2$, substantial enhancement in $J_c(H)$ properties was obtained for PMMA-doped $MgB_2$ samples both at 5 K and 20 K. The enhancement could be attributed to the effective carbon substitution for boron and the refinement of crystallite size by PMMA doping.

Bi-spectrum for identifying crack and misalignment in shaft of a rotating machine

Sinha, Jyoti K. Techno-Press 2006 Smart Structures and Systems, An International Jou Vol.2 No.1

Bi-spectrum is a tool in the signal processing for identification of non-linear dynamic behvaiour in systems, and well-known for stationary system where components are non-linearly interacting. Breathing of a crack during shaft rotation is also exhibits a non-linear behaviour. The crack is known to generate 2X (twice the machine RPM) and higher harmonics in addition to 1X component in the shaft response during its rotation. Misaligned shaft also shows similar such feature as a crack in a shaft. The bi-spectrum method has now been applied on a small rotating rig to observe its features. The bi-spectrum results are found to be encouraging to distinguish these faults based on few experiments conducted on a small rig. The results are presented here.

Seismic qualification using the updated finite element model of structures

Sinha, Jyoti K.,Rao, A. Rama,Sinha, R.K. Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.1

The standard practice is to seismically qualify the safety related equipment and structural components used in the nuclear power plants. Among several qualification approaches the qualification by the analysis using finite element (FE) method is the most common approach used in practice. However the predictions by the FE model for a structure is known to show significant deviations from the dynamic behaviour of 'as installed' structure in many cases. Considering such limitation, few researchers have advocated re-qualification of such structures after installation at site to enhance the confidence in qualification vis-$\grave{a}$-vis plant safety. For such an exercise the validation of FE model with experimental modal data is important. A validated FE model can be obtained by the Model Updating methods in conjugation with the in-situ experimental modal data. Such a model can then be used for qualification. Seismic analysis using the updated FE model and its advantage has been presented through an example of an in-core component - a perforated horizontal tube of a nuclear reactor.

Pareto-optimization of complex system architecture for structural complexity and modularity

Sinha, K.,Suh, E. S. SPRINGER VERLAG KG 2018 Research in engineering design Vol.29 No.1

<P>Due to ever-increasing complexity of cutting-edge engineering systems, the need for managing structural complexity and modularity of such systems is becoming important. The complexity of the overall system architecture is mostly decided during the initial concept generation stage, when configurations of major modules within the system are determined. In this paper, we present a multi-objective optimization framework for (1) minimizing the variation in complexity allocation to individual modules, while (2) maximizing for the degree of modularity. The optimization framework was applied to a case study, where a trailing bogie system for railroad train was optimized for structural complexity allocation among individual modules and overall system modularity. The modularity maximizing decomposition is shown to induce a large variation in module-level complexity distribution with a small fraction of modules sharing a disproportionately large chunk of overall system complexity, while equitable distribution of module-level complexity leads to erosion in the degree of modularity achieved for the resulting system decomposition.</P>

Foliar Application of Magnesium Sulphate and Basal Application of Calcium Carbonate: A New Dimension in Production of Tasar Crops

Sinha, Uma S.P.,Das, Susmita,Sinha, Manoj K. Korean Society of Sericultural Science 2012 International Journal of Industrial Entomology Vol.25 No.1

An experiment was carried out to boost the production of tasar crops through application of secondary nutrients. Different combinations of secondary nutrients were prepared and its effect was studied on the yield and quality of leaves of tasar food plant Terminalia tomentosa W & A with 2.4 m ${\times}$ 2.4 m spacing and cocoon characters of tasar silkworm Antheraea mylitta Drury reared on them. Among different combinations of secondary nutrients, foliar application of magnesium sulphate (2%, w/v) and basal application of 3 quintal/ha of calcium carbonate (secondary nutrient combination SM5) was found to be the best in crop improvement. It improves the quantity and quality of leaves as well as the commercial characters of cocoons. As a result, silk production improves. Under this combination, leaf yield increased by 26.55% in comparison to control. Average increase in moisture, total mineral, crude protein and total carbohydrate was 3.26%, 20.84%, 15.39% and 17.85% respectively as compared with control. Further, bio assay studies revealed that average larval weight, E.R.R., cocoon weight, shell weight and silk ratio percent increased by 11.25%, 25.71%, 20.05%, 35.14% and 12.17% respectively over control which indicates that secondary nutrient combination $SM_5$ has significant role in improving the production of tasar crops.

Atomic-layer-deposited buffer layers for thin film solar cells using earth-abundant absorber materials: A review

Sinha, Soumyadeep,Nandi, Dip K.,Kim, Soo-Hyun,Heo, Jaeyeong North-Holland 2018 Solar Energy Materials and Solar Cells Vol. No.

<P><B>Abstract</B></P> <P>Atomic layer deposition (ALD) is not just a thin film deposition technology limited to the semiconductor IC industries to grow high-<I>k</I> gate dielectric or a Cu diffusion barrier layer. In recent times, it has found plenty of applications in the field of renewable energy due to its precise thickness control up to few angstroms and its unique feature of conformal and uniform coating on any randomly shaped 3D structure. ALD has far-reaching applications in this field, including electrochemical storage, fuel cells, solar photovoltaics (PV), and catalysis for water splitting to produce H<SUB>2</SUB> as a green fuel. In solar PV technology, ALD is now being extensively used as an efficient tool to deposit surface passivation layers, absorber or sensitizer, transparent conducting oxide, and barrier and buffer layers in several kinds of solar cells. Out of all the different layers associated with a solar cell, ALD is majorly used for the development of a very thin <I>n-</I>type buffer layer. This review article presents a systematic chronological study on such ALD-grown buffer layers for thin film solar cells (TSFCs). The study is carried out in detail based on different earth-abundant absorber materials, such as Cu<SUB>2</SUB>ZnSn(S,Se)<SUB>4</SUB> (CZTSSe), Cu<SUB>2</SUB>O and SnS, for which ALD is successfully used to deposit the buffer layer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ALD buffer layers for TFSCs based on emerging absorbers are reviewed. </LI> <LI> Correlation between cell performance and ALD process parameters is investigated. </LI> <LI> Progress on the efficiency of the TFSCs based on ALD buffers is reported. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Optical and magnetic properties of Ni doped ZnO planetary ball milled nanopowder synthesized by co-precipitation

Shinde, K.P.,Pawar, R.C.,Sinha, B.B.,Kim, H.S.,Oh, S.S.,Chung, K.C. Ceramurgica ; Elsevier Science Ltd 2014 CERAMICS INTERNATIONAL Vol.40 No.10

Ni doped ZnO nanopowders have been synthesized by the co-precipitation route followed by planetary ball milling. The synthesized powder was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HR-TEM), UV-vis spectrophotometry, fluorescence spectrophotometry and Quantum Design PPMS for structural, morphological, microstructural, optical and magnetic properties measurements. All the samples show wurtzite hexagonal crystal structure. The optical absorption spectra show a shift in the position of band edge towards lower energy. The estimated band gap is found to decrease with higher nickel doping. The room temperature PL measurements illustrate UV emission centered at 390nm (3.17eV), which is ascribed to the near-band-edge (NBE) emissions of ZnO and broad green emission around 540nm. Room temperature ferromagnetism in the Ni doped ZnO nanopowders has been confirmed by magnetic property measurements.