Preparation and characterization of sprayed In₂O₃:Mo films

Prathap, P.,Gowri Devi, G.,Subbaiah, Y. P. V.,Ganesan, V.,Ramakrishna Reddy, K. T.,Yi, J. WILEY-VCH Verlag 2008 Physica status solidi. PSS. A, Applications and ma Vol.205 No.8

<P>Transparent conducting oxides (TCO) play a major role in the area of thin film photovoltaics, flat panel displays, organic light emitting diodes and other optoelectronic devices. In order to improve the performance of a device, the TCO should have good optical transmittance as well as conductivity. In the present study, In<SUB>2</SUB>O<SUB>3</SUB>:Mo films have been grown by an economic and simple spray pyrolysis method with different molybdenum doping concentrations that vary in the range, 0–12 at% at a substrate temperature of 400 °C. The structural and morphological, electrical and optical behaviour of the as-grown layers were studied. All the deposited layers showed a body-centered cubic structure with a strong (222) orientation. In<SUB>2</SUB>O<SUB>3</SUB>:Mo films grown with Mo-concentration of 6.0 at% had the maximum grain size of 90 nm. The average optical transmittance of the films was >85% in the visible region. The change of grain size, electrical resistivity, carrier mobility and density, optical band gap and figure of merit with doping concentration was reported and discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>

Growth and characterization of indium oxide films

P. Prathap,G. Gowri Devi,Y.P.V. Subbaiah,K.T. Ramakrishna Reddy,V. Ganesan 한국물리학회 2008 Current Applied Physics Vol.8 No.2

In2O3 250450.C. The structural and morphological properties of the as-deposited lms were studied using X-ray diractometer and scanningelectron microscope as well as atomic force microscope, respectively. The lms formed at a temperature of 400.C showed body-centeredcubic structure with a strong (22) orientation. The structural parameters such as the crystallite size, lattice strain and texture coecientof the lms were also calculated. The lms deposited at a temperature of 400.C showed an optical transmittance of >85% in the visibleregion. The change of resistivity, mobility, carrier concentration and activation energies with the deposition temperature was studied.The highest gure of merit for the layers grown at 400℃ was 1.09x10-³Ω-¹.

Promotional role of Ceria in CeO2/MgAl2O4 spinel catalysts in CO2 assisted selective oxidative dehydrogenation of ethylbenzene to styrene

Ch. Prathap,V. V. Ramana Kumar,M. Venkata Rao,P. Nagaiah,S. Rama Rao K.,B. David Raju 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-

With the aim of understanding the influence of CeO2 on MgO, Al2O3 and MgAl2O4 in CO2 assistedoxidative dehydrogenation of ethylbenzene to styrene was attempted and the results conveyed that theMgAl2O4 spinel supported CeO2 (CeO2/MgAl2O4) catalyst exhibited superior activity with 80% yield ofstyrene and in apart activity consistency up to 50 h of time-on-stream, revealing the establishment ofsynergism in CeO2/MgAl2O4, ascertained from XRD, BET Surface area, FT-IR, H2-TPR, UV–vis DRS, XPS, TPDand HRTEM techniques, acid-base characteristics of MgAl2O4, smaller particle size of CeO2 and its highdispersion are responsible for elevated activity, stability and regenarable capability.

Effect of balanced and unbalanced magnetron sputtering processes on the properties of SnO2 thin films

Gauri Shanker,P. Prathap,K.M.K. Srivatsa,Preetam Singh 한국물리학회 2019 Current Applied Physics Vol.19 No.6

A comparative study has been carried on the role of balanced magnetron (BM) and unbalanced magnetron (UBM) sputtering processes on the properties of SnO2 thin films. The oxygen partial pressure, substrate temperature and deposition pressure were kept 20%, 700 °C and 30 mTorr, respectively and the applied RF power varied in the range of 150–250 W. It is observed that the UBM deposition causes significant effect on the structural, electrical and optical properties of SnO2 thin films than BM as evidenced by X-ray diffraction, C-V, Spectroscopic Ellipsometer and Photoluminescence measurements. The value of band gap (Eg) of the films deposited at 150W in UBM is found as Eg=3.83 eV which is much higher than the value of Eg=3.69 eV as observed in BM sputtering indicating that UBM sputtering results in good crystalline quality. Further, the C-V measurements of SnO2 thin films deposited using UBM at high power 250W show hysteresis with large flat band shift indicating that these thin films can be used for the fabrication of memory device. The observed results have been attributed to different mechanisms which exist simultaneously under unbalanced magnetron sputtering due to ion bombardment of growing SnO2 thin film by energetic Ar+ ions.

Al-doped ZnS layers synthesized by solution growth method

K. Nagamani,N. Revathi,P. Prathap,Y. Lingappa,K.T. Ramakrishna Reddy 한국물리학회 2012 Current Applied Physics Vol.12 No.2

ZnS is one of the potential candidates as a window/buffer layer for solar photovoltaic applications. Aldoped ZnS nanocrystalline films were grown by a simple and economic process, chemical solution growth method. The layers were prepared for different Al-dopant concentrations that vary in the range, 0e10 at. %. The effect of Al-doping on the composition, structure, optical, electrical and photoluminescence properties of the synthesized layers was determined using appropriate techniques. The elemental composition of a typical sample with 6 at. % ‘Al’ in ZnS was Zn ¼ 44.9 at. %, S ¼ 49.8 at. % and Al ¼ 5.3 at. %. The films were nanocrystalline in nature and showed (111) plane of ZnS as the preferred orientation for all the doping concentrations. The layers with 6 at. % of Al showed a crystallite size of w9 nm. The FTIR studies confirmed the presence of ZnS in the layers. The layers showed an average transmittance of w75% in the visible region. The change of photoluminescence behaviour with dopant concentration was also studied. The electrical resistivity was considerably decreased from 107 Ucm to 103 Ucm with Al-doping. The detailed analysis of results will be presented and discussed.

Influence of substrate temperature on physical properties of sprayed Zn0.85Mn0.15O films

L. Raja Mohan Reddy,P. Prathap,K.T. Ramakrishna Reddy 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Zn1-xMnxO thin films have been synthesized by chemical spray pyrolysis at different substrate temperatures in the range, 250–450 ℃ for a manganese composition, x = 15%, on corning 7059 glass substrates. The as-grown layers were characterized to evaluate their chemical and physical behaviour with substrate temperature. The change of dopant level in ZnO films with substrate temperature was analysed using X-ray photoelectron spectroscope measurements. The X-ray diffraction studies revealed that all the films were strongly oriented along the (002) orientation that correspond to the hexagonal wurtzite structure. The crystalline quality of the layers increased with the increase of substrate temperature up to 400 ℃ and decreased thereafter. The crystallite size of the films varied in the range, 14–24 nm. The surface morphological studies were carried out using atomic force microscope and the layers showed a lower surface roughness of 4.1 nm. The optical band gap of the films was ~3.35 eV and the electrical resistivity was found to be high, ~104Ωcm. The films deposited at higher temperatures (>350 ℃) showed ferromagnetic behaviour at 10 K. Zn1-xMnxO thin films have been synthesized by chemical spray pyrolysis at different substrate temperatures in the range, 250–450 ℃ for a manganese composition, x = 15%, on corning 7059 glass substrates. The as-grown layers were characterized to evaluate their chemical and physical behaviour with substrate temperature. The change of dopant level in ZnO films with substrate temperature was analysed using X-ray photoelectron spectroscope measurements. The X-ray diffraction studies revealed that all the films were strongly oriented along the (002) orientation that correspond to the hexagonal wurtzite structure. The crystalline quality of the layers increased with the increase of substrate temperature up to 400 ℃ and decreased thereafter. The crystallite size of the films varied in the range, 14–24 nm. The surface morphological studies were carried out using atomic force microscope and the layers showed a lower surface roughness of 4.1 nm. The optical band gap of the films was ~3.35 eV and the electrical resistivity was found to be high, ~104Ωcm. The films deposited at higher temperatures (>350 ℃) showed ferromagnetic behaviour at 10 K.

Optimization of friction stir welding process parameters on AA 6063-SiC-B4C hybrid metal matrix composites by genetic algorithm

R. Srinivasan,B. Suresh Babu,P. Prathap,Ruban Whenish,R. Soundararajan,G. Chandramohan 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.1

Friction Stir Welding (FSW) is a metal joining process has its own benefits over fusion welding processes. FSW AluminiumMetal Matrix Composites (AMMC) replaced conventional metals for structural applications in aerospace, automobile andmarine sectors. In this present investigation, process parameters of FSW for joining AA 6063-SiC-B4C hybrid MMCs wereoptimized in order to achieve maximum tensile strength. Initially, AMMC was manufactured through stir casting with thematrix AA 6063 and reinforcements SiC and B4C. The hybrid MMC work pieces were subjected to FSW process by varyingthe process parameters such as tool rotation speed, welding speed and axial force using Taguchi L27 orthogonal array. Tensilestrength of hybrid composite was examined and regression analysis were done using MINITAB V17 software. GeneticAlgorithm technique was used to optimize the tensile strength with FSW parametric combinations. The optimum parametersfor FSW of AA6063-SiC-B4C hybrid composites were Tool rotational speed (TRS) – 1050 rpm; Axial Force (AF) – 10 kN andWeld Speed (WS) – 45 mm/min obtained. The optimal parameters were applied to experimental study and the results werevalidated.

Numerical and experimental study on flexural behavior of reinforced concrete beams: Digital image correlation approach

B. Murali Krishna,V. Guru Prathap Reddy,T. Tadepalli,P. Rathish Kumar,Yerra Lahir 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.6

Understanding the realistic behavior of concrete up to failure under different loading conditions within the framework of damage mechanics and plasticity would lead to an enhanced design of concrete structures. In the present investigation, QR (Quick Response) code based random speckle pattern is used as a non-contact sensor, which is an innovative approach in the field of digital image correlation (DIC). A four-point bending test was performed on RC beams of size 1800 mm x 150 mm x 200 mm. Image processing was done using an open source Ncorr algorithm for the results obtained using random speckle pattern and QR code based random speckle pattern. Load-deflection curves of RC beams were plotted for the results obtained using both contact and non-contact (DIC) sensors, and further, Moment (M)-Curvature (κ) relationship of RC beams was developed. The loading curves obtained were used as input data for material model parameters in finite element analysis. In finite element method (FEM) based software, concrete damage plasticity (CDP) constitutive model is used to predict the realistic nonlinear quasi-static flexural behavior of RC beams for monotonic loading condition. The results obtained using QR code based DIC are observed to be on par with conventional results and FEM results.