Electrical transport studies of MBE grown InGaN/Si isotype heterojunctions

Mahesh Kumar,Basanta Roul,Mohana K. Rajpalke,Thirumaleshwara N. Bhat,A.T. Kalghatgi,S.B. Krupanidhi 한국물리학회 2013 Current Applied Physics Vol.13 No.1

The temperature dependent electrical transport behavior of nen InGaN/Si heterostructures grown by plasma-assisted MBE was studied. Structural characteristics of the as-grown InGaN epilayers were evaluated high resolution X-ray diffraction and composition of InGaN was estimated from photoluminescence spectra using standard Vegard’s law. Current densityevoltage plots (JeVeT) revealed that the ideality factor (h) and Schottky barrier height (SBH) (Fb) are temperature dependent and the incorrect values of the Richardson’s constant (A**) produced, suggests an inhomogeneous barrier at the heterostructure interface. The higher value of the ideality factor compared to the ideal value and its temperature dependence suggest that the current transport is mainly dominated by thermionic field emission.

Substantially enhanced front illumination photocurrent in porous SnO₂ nanorods/networked BiVO₄ heterojunction photoanodes

Bhat, Swetha S. M.,Suh, Jun Min,Choi, Seokhoon,Hong, Seung-Pyo,Lee, Sol A.,Kim, Changyeon,Moon, Cheon Woo,Lee, Mi Gyoung,Jang, Ho Won The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.30

<P>BiVO4 is a promising photoanode for photoelectrochemical applications owing to its suitable band edge position for oxygen evolving reactions. High photocurrent under front illumination is very much essential to design tandem structures with a wireless configuration. However, the performance of BiVO4 under front illumination is limited due to poor charge transport properties. Here, we show that network-like BiVO4 coupled with porous SnO2 nanorods (NRs) is a promising model to enhance the front illumination performance. A very high photocurrent density of 5.6 mA cm<SUP>−2</SUP> and 5.5 mA cm<SUP>−2</SUP> has been obtained from the front and back illumination at 1.23 V <I>vs.</I> the reversible hydrogen electrode, respectively. We demonstrate that the appropriate nanostructuring of SnO2 NRs/BiVO4 is the underlying technology to tune the performance under directional illumination. The SnO2 NRs/BiVO4 exhibits a maximum incident photon to current efficiency of ∼80% under front and back illumination. A systematic study reveals that the optimized network like BiVO4 coated on porous SnO2 NRs synergistically boosts both the charge separation and transfer efficiencies of the photoanode resulting in a significantly high photocurrent for illumination on either side. This work provides a direction to achieve enhanced photocurrent during front and back side illumination in order to realize a wireless tandem configuration.</P>

Structural performance of timber frame joints - Full scale tests and numerical validation

S.A. Aejaz,A.R. Dar,J.A. Bhat 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.4

The force resisting ability of a connection has direct implications on the overall response of a timber framed structure to various actions, thereby governing the integrity and safety of such constructions. The behavior of timber framed structures has been studied by many researchers by testing full-scale-connections in timber frames so as to establish consistent design provisions on the same. However, much emphasis in this approach has been unidirectional, that has focused on a particular connection configuration, with no research output stressing on the refinement of the existing connection details in order to optimize their performance. In this regard, addition of adhesive to dowelled timber connections is an economically effective technique that has a potential to improve their performance. Therefore, a comparative study to evaluate the performance of various full-scale timber frame Nailed connections (Bridled Tenon, Cross Halved, Dovetail Halved and Mortise Tenon) supplemented by adhesive with respect to Nailed-Only counterparts under tensile loading has been investigated in this paper. The load-deformation values measured have been used to calculate stiffness, load capacity and ductility in both the connection forms (with and without adhesion) which in turn have been compared to other configurations along with the observed failure modes. The observed load capacity of the tested models has also been compared to the design strengths predicted by National Design Specifications (NDS-2018) for timber construction. Additionally, the experimental behavior was validated by developing non-linear finite element models in ABAQUS. All the results showed incorporation of adhesive to be an efficient and an economical technique in significantly enhancing the performance of various timber nailed connections under tensile action. Thus, this research is novel in a sense that it not only explores the tensile behavior of different nailed joint configurations common in timber construction but also stresses on improvising the same in a logical manner hence making it distinctive in its approach.

Compact nanoarchitectures of lead selenide via successive ionic layer adsorption and reaction towards optoelectronic devices

Bhat, T. S.,Vanalakar, S. A.,Devan, R. S.,Mali, S. S.,Pawar, S. A.,Ma, Y. R.,Hong, C. K.,Kim, J. H.,Patil, P. S. Springer Science + Business Media 2016 Journal of materials science Materials in electron Vol.27 No.5

<P>Thin films of Lead Selenide (PbSe) having compact nanoarchitectures were synthesized by a facile and cost-efficient successive ionic layer adsorption and reaction (SILAR) technique. The structural, morphological, optical and compositional properties were studied using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), UV-vis spectrophotometer, and X-ray photoelectron spectroscopy (XPS) techniques. Moreover, the effect of SILAR cycles on the morphology of PbSe thin films was investigated. XRD patterns revealed the formation of crystalline PbSe with the cubic crystal structure. FESEM images show shape evolution from nanoparticulate to merged pyramidal-like structure with variation in size from similar to 200 to 430 nm. The optical direct band gap energy of PbSe were varies from 1.32 to 1.20 eV with the increase in deposition cycles. The HRTEM and SAED results show the crystalline nature of the sample which is in good agreement with the XRD. The electrical characterizations were performed in order to obtain the ohmic behavior in the metal-semiconductor interface. The deposited thin films show a good ohmic behavior.</P>

Photochemical and biochemical responses of heliconia (Heliconia stricta ‘Iris’) to different light intensities in a humid coastal environment

K Nihad,Mukesh K. Berwal,K. Balachandra Hebbar,Ravi Bhat,A. Abdul Haris,S. V. Ramesh 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.6

A field experiment was conducted to evaluate the performance of heliconia (Heliconia stricta ‘Iris’) grown under four levels of photosynthetically active radiation (PAR) in a randomized block design. Photochemical and biochemical parameters were recorded to assess the physiological and biochemical changes in heliconia that accompany varying light intensities. The plants grown under the lowest PAR (30 to 35% of open condition) showed enhanced growth with a higher biomass accumulation, plant height, suckering habit, emergence of flowering shoots, inflorescence yield, and light use efficiency. The leaves exposed to high PAR (open condition) recorded reduction in chlorophyll content (60.8%), chlorophyll index (43.9%), and Fv/Fm (21.4%) compared to values for the leaves exposed to the lowest PAR (30 to 35%). Plant soluble sugars were reduced with the increasing PAR, whereas reducing sugar content was high under fully irradiated conditions but showed a decreasing trend with a reduction in PAR. Total phenolic content and malondialdehyde were lower at 30 to 35% PAR with a reduction in magnitude of 58.4% and 34.8%, respectively, compared to the open condition. Similarly, super oxide dismutase, peroxidase, and polyphenol oxidase activities in the leaf decreased 36.2%, 28.7%, and 23.3%, respectively, from the highest PAR (or open condition) in this range. Improved photochemical and biochemical activities of plants grown under lower light intensities resulted in production of quality inflorescences. Hence, Heliconia stricta ‘Iris’ can be recommended as an intercrop on coconut plantations where the light intensity is low (30 to 35%) for improving the livelihood of farmers.

Substantially enhanced photoelectrochemical performance of TiO₂ nanorods/CdS nanocrystals heterojunction photoanode decorated with MoS₂ nanosheets

Bhat, Swetha S.M.,Pawar, Sachin A.,Potphode, Darshna,Moon, Chang-Ki,Suh, Jun Min,Kim, Changyeon,Choi, Seokhoon,Patil, Dipali S.,Kim, Jang-Joo,Shin, Jae Cheol,Jang, Ho Won Elsevier 2019 Applied Catalysis B Vol.259 No.-

<P><B>Abstract</B></P> <P>Two-dimensional (2D) MoS<SUB>2</SUB> nanosheets (NSs) modified 1D TiO<SUB>2</SUB> nanorods/0D CdS nanocrystals (NCs) heterojunction has been fabricated by all solution process as a potential anode for photoelectrochemical (PEC) water splitting applications. This heterojunction photoanode shows high photocurrent density of 3.25 mA/cm<SUP>2</SUP> at 0.9 V vs. RHE (0 V vs. Ag/AgCl) compared to the pristine TiO<SUB>2</SUB>/CdS photoanode. The influence of MoS<SUB>2</SUB> NSs on PEC performance of TiO<SUB>2</SUB>/CdS/MoS<SUB>2</SUB> heterojunction has been systematically investigated. We demonstrate that MoS<SUB>2</SUB> NSs transfer holes from CdS and facilitate further charge separation in TiO<SUB>2</SUB>/CdS. Time resolved photoluminescence measurement reveals increase in photoluminescence lifetime due to the presence of MoS<SUB>2</SUB> NSs in TiO<SUB>2</SUB>/CdS/MoS<SUB>2</SUB> resulting in enhanced PEC activity. This work suggests that 1D TiO<SUB>2</SUB>/0D CdS/2D MoS<SUB>2</SUB> heterojunction prototype is an interesting system where MoS<SUB>2</SUB> NSs can be utilized to improve charge separation in photoanodes. This study would pave the way towards designing new heterojunction functional materials for efficient PEC applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photoanodes were fabricated by all solution process. </LI> <LI> Enhanced photoelectrochemical performance of TiO<SUB>2</SUB> 1D/0D CdS/MoS<SUB>2</SUB> 2D triple heterojunction photoanode was achieved. </LI> <LI> The heterojunction photoanode shows high photocurrent density of 3.25 mA/cm<SUP>2</SUP> at 0.9 V vs. RHE (0 V vs. Ag/AgCl). </LI> <LI> Role of MoS<SUB>2</SUB> nanosheets on the improved photoelectrochemical performance has been investigated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Decoration of solution-processed MoS<SUB>2</SUB> nanosheets on TiO<SUB>2</SUB> nanorods/CdS nanocrystals photoanode substantially improves the photoelectrochemical performance. The heterojunction photoanode TiO<SUB>2</SUB>/CdS/MoS<SUB>2</SUB> with ZnS shows high photocurrent density of 3.25 mA/cm<SUP>2</SUP> at 0 V vs. Ag/AgCl (0.9 V vs. RHE).</P> <P>[DISPLAY OMISSION]</P>

A Comparison of Three-Phase High-Frequency Transformer Isolated LCC and LCL-Type DC-DC Resonant Converter Topologies

M. Almardy,A.K.S. Bhat 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

A comparison of HF transformer isolated, softs-witched 3-phase LCC-type and (LC)(L)-type dc-dc resonant converters with capacitive output filters including the effect of the HF transformer magnetizing inductances are presented. These converters are designed for the same specifications based on the approximate analysis approach. Intusoft simulation results for both designed converters are given for various input voltage and for different load conditions. The experimental verification of the designed converters performance are established by building a 300W rated power converters in the power electronics lab and the experimental results for both converters have been given. A variable frequency control with 180<SUP>0</SUP> wide gating pulses is adopted for regulating the output. Both converters operate in zero-voltage switching (ZVS) at various input voltage and different load conditions.

Electron irradiation effects on electrical and optical properties of sol-gel prepared ZnO films

Bhat, J. S.,Patil, A. S.,Swami, N.,Mulimani, B. G.,Gayathri, B. R.,Deshpande, N. G.,Kim, G. H.,Seo, M. S.,Lee, Y. P. American Institute of Physics 2010 JOURNAL OF APPLIED PHYSICS - Vol.108 No.4

Understanding corrosion inhibition of mild steel in acid medium by new benzonitriles: Insights from experimental and computational studies

Chaouiki, A.,Lgaz, H.,Chung, Ill-Min,Ali, I.H.,Gaonkar, S.L.,Bhat, K.S.,Salghi, R.,Oudda, H.,Khan, M.I. Elsevier 2018 Journal of molecular liquids Vol.266 No.-

<P><B>Abstract</B></P> <P>Two benzonitrile derivatives, namely 4-(isopentylamino)-3-nitrobenzonitrile (PANB) and 3-amino-4-(isopentylamino)benzonitrile(APAB) have been synthesized and evaluated as corrosion inhibitors for mild steel (MS) in 1 M HCl solution at 303 K by gravimetric, potentiodynamic polarization (PDP) curves, and electrochemical impedance spectroscopy (EIS) methods, as well as Density Functional Theory (DFT) and molecular dynamics (MD) simulations. The results suggest that tested compounds are excellent corrosion inhibitors for mild steel with PANB showing superior performance. Polarization measurements revealed that PANB and APAB behaved as mixed type inhibitors. The polarization resistance, according to EIS studies, found to be dependent on the inhibitor's concentration. The adsorption of PANB and APAB on mild steel surface obeyed Langmuir's adsorption isotherm. On the one hand, DFT and MD simulations are being used to explain the effect of the molecular structure on the corrosion inhibition efficiency and on the other hand to simulate the adsorption of benzonitrile derivatives on mild steel surface. The protection of carbon steel in 1 M HCl was confirmed by using scanning electron microscope (SEM) and Atomic Force Microscopy (AFM). Electrochemical, DFT and MD simulations results are in good agreement.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel benzonitrile derivatives have been synthesized and characterized. </LI> <LI> Potentiodynamic polarization curves reveal that tested inhibitors act as mixed type. </LI> <LI> The adsorption of two compounds obeys Langmuir adsorption isotherm. </LI> <LI> Surface morphology was examined by SEM and AFM. </LI> <LI> The experimental results were correlated with DFT and MD stimulation results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

CONTROL OF NOX FROM A DI DIESEL ENGINE WITH HOT EGR AND ETHANOL FUMIGATION: AN EXPERIMENTAL INVESTIGATION

G. S. HEBBAR,A. K. BHAT 한국자동차공학회 2013 International journal of automotive technology Vol.14 No.3

Oxides of nitrogen (NOx) are one of the major hazardous pollutants from diesel engine emission. Various control technologies exist for its control but each technique has advantages and disadvantages. At present, there is no single optimal technique that can control NOx without other side effects. Technologies available for NOx reductions either cause fuel penalty or increase other polluting emissions. Exhaust Gas Recirculation is an effective technique in controlling oxides of nitrogen in diesel engines but do not become attractive at higher loads and higher percentage of recirculated gas as combustion tends to deteriorate at higher loads leading to reduced engine thermal efficiency and increased hydrocarbon and smoke emission. Ethanol is an established alternate fuel used in diesel engine either as a blend or fumigated using a separate injector. Experiments were conducted on a single cylinder diesel engine to examine the effect of EGR temperature on NOx and other emission constituents. Hot EGR gave better results up to 30% EGR rate but EGR cooling was found better in terms of NOx reductions and efficiency. It was found that NOx reductions up to 88% was possible but at the cost of about 18% loss in thermal efficiency. This inconvenience of fuel penalty caused by Exhaust Gas Recirculation can be overcome by applying ethanol fumigation. The findings of experimental results for this combined technique are presented in this paper. With this combined technique, apart from reducing the oxides of nitrogen, engine power and efficiency approaches to that of only diesel combustion condition with improvements in smoke, hydrocarbon and carbon monoxide emissions.