Variable thermal loading analysis on (111) plane of single crystal gold

Murugavel Rathinam 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.11

The temperature response on the properties of single crystal gold (111) plane at elevated temperatures was considered in this work. The ability to perform nanoindentation experiments at elevated temperatures opens up significant new possibilities in nanotechnology. The experiments are performed at various temperatures of 373 K, 473 K and 573 K with tailor made Berkovitch tip of radius 100 nm to study the behavior of single crystal gold. The new phenomenon of material bouncing back under the indenter at the end of unloading was clearly noted, due to the accumulation of high energy. The results for different temperatures were compared. Our experiments clearly show the onset of the first burst of dislocation glide, which is indicated by a sudden increase of displacement with no increase of loading,the onset of plastic deformation in connection with the periodic bursts, and the strain hardening, softening and release effects. Pile up was also observed. The complete elastic range was found. There was significant drop in the hardness, elastic modulus and the increase in depth with increasing temperature. The elastic recovery was reduced at higher temperatures.

Nanoindentation of aluminum (100) at various temperatures

Murugavel Rathinam,Ramesh Thillaigovindan,Prema Paramasivam 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.10

High temperatures generally affect materials in some form. In this regard, the capability to perform nanoscale measurements at elevated temperatures opens up new possibilities for investigating the temperature dependence of materials’ mechanical properties. Particularly, the responses of aluminum’s different mechanical properties to indentation at various temperatures have been studied experimentally. In this paper, aluminum response to different room temperatures was examined. The behaviors of a single crystal aluminum during loading and unloading were observed. Nanoindentation experiments on a single crystal aluminum (100) sample at temperatures of 265 K and 388 K were performed with different loading conditions. At the start of the first burst of the dislocation glide, which was indicated by a sudden increase in displacement with no increase in loading, evidence of plastic properties and softening effects on aluminum was identified. The ductile to brittle transition was observed at temperatures below 273 K. Generally, there was a significant increase in the penetration depth and a decrease in hardness, elastic modulus, and elastic recovery as the testing temperature increased.

Metal-organic and porous organic framework in electrocatalytic water splitting

Sivalingam Gopi,Murugavel Kathiresan,Kyusik Yun 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

The use of hydrogen as a clean and sustainable energy carrier is a desirable alternative to the use of fossilfuels. It is strongly anticipated that the development of superior electrocatalysts for boosting these processeswill reduce their overpotentials and increase the accessibility of their practical applications. Metalorganicframeworks (MOFs) and Porous organic polymers (POPs) are gaining popularity as nonpreciousalternatives to drive global water splitting due to their adaptable compositions, exceptional porosities,and ultrahigh surface areas. The use of metal–organic frameworks (MOFs) for electrochemical watersplitting has advanced rapidly in recent years. This article highlights the most significant findings fromrecent studies on designing advanced MOFs for enhancing electrochemical water splitting. Electrocatalysts based on metal–organic frameworks (MOFs) and Porous organic polymers (POPs) getspecial consideration with regard to their structure–property relationships, production methods, anddesign principles. We anticipate that this study will be a valuable tool for advancing the developmentof MOF and POP-based electrocatalysts towards usable water splitting and will also offer insights intopotential future energy technologies beyond water electrolysis.

Epitaxial Stabilization of a New Multiferroic Hexagonal Phase of TbMnO₃ Thin Films

Lee, J.-H.,Murugavel, P.,Ryu, H.,Lee, D.,Jo, J. Y.,Kim, J. W.,Kim, H. J.,Kim, K. H.,Jo, Y.,Jung, M.-H.,Oh, Y. H.,Kim, Y.-W.,Yoon, J.-G.,Chung, J.-S.,Noh, T. W. WILEY-VCH Verlag 2006 Advanced Materials Vol.18 No.23

<B>Graphic Abstract</B> <P>Multiferroic hexagonal TbMnO<SUB>3</SUB> thin films have been epitaxially stabilized on substrates with hexagonal in-plane symmetry by pulsed laser deposition. The hexagonal TbMnO<SUB>3</SUB> films show ferroelectricity below ca. 60 K with a remnant polarization 20 times larger compared to its orthorhombic bulk phase. In addition, these samples show an electric-field-induced antiferroelectric-to-ferroelectric phase transition. <img src='wiley_img/09359648-2006-18-23-ADMA200601621-content.gif' alt='wiley_img/09359648-2006-18-23-ADMA200601621-content'> </P>

육방정계 란탄계 망간산화물 RMnO₃ (R=Dy, Tb, and Gd) 박막의 에피안정화와 그 물성 연구

노태원,이정혁,이대수,장승엽,Murugavel,조영훈,정명화 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Synthesis and Properties of Few Polyphosphonate Derivatives Containing Photosensitive Unsaturated Keto Group in the Main Chain

Kalichamy Kaniappan,Salem Chandrasekaran Murugavel,Thangaian Daniel Thangadurai 한국고분자학회 2013 Macromolecular Research Vol.21 No.10

A series of homo and copolyphosphonate derivatives were synthesized by interfacial polycondensation reactions of 1,3-bis(4-hydroxyphenyl)propenone with phenylphosphonic dichloride and terephthaloyl chloride, and 3-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)propenone with phenylphosphonic dichloride and terephthaloyl chloride using a phase transfer catalyst at ambient temperature. The diol monomers were prepared by condensing 4-hydroxy benzaldehyde and 3-methoxy-4-hydroxybenzaldehyde with 4-hydroxy acetophenone. The structures of the synthesized monomers and polymers were confirmed using UV, IR and 1H, 13C, and 31P NMR spectroscopic techniques. The molecular weights of the polymers were determined by gel permeation chromatography. The thermal properties of the polymers were studied by thermogravimetric analysis and differential scanning calorimetry under a nitrogen atmosphere. The photosensitive property of the polymers in films and solution states was investigated by ultraviolet spectroscopy. Photocrosslinking proceeded via a 2π+2π cycloaddition reaction of α,β-unsaturated carbonyl group. The chemical and physical properties of methoxy substituted polymers were compared to those of the unsubstituted polymers. The structure-property relationships and flame retardant characteristics of the synthesized polymers were also studied.

Impedance spectroscopic analysis of the organic ferroelectric e Diisopropylammonium bromide (DIPAB)

Ch. Thirmal,P. Murugavel,V. Subramanian 한국물리학회 2014 Current Applied Physics Vol.14 No.5

We report the dielectric and ac conductivity studies on the organic molecular ferroelectric, diisopropylammonium bromide polycrystalline sample. The frequency and temperature dependant real and imaginary parts of the impedance show two relaxations in the sample. The Nyquist plots exhibit two semicircles revealing both grain and grain boundary contributions to the resistance above Curie temperature. We find that the compound shows a non-Debye type relaxation behavior and the conductivity follows the semiconducting behavior. The conduction mechanism can be explained by the barrier hopping model.

Ferroelectric Properties of Multiferroic Hexagonal ErMnO3 Thin Films

장승엽,Daesu Lee,Jung-Hyuk Lee,Pattukkannu Murugavel,정진석 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

The authors investigated the ferroelectric properties of epitaxial thin films of hexagonal ErMnO3 fabricated on Pt(111)/Al2O3(0001) substrates. The ferroelectric characteristics were observed with a reasonable remnant polarization value (3.0 μC/cm2 at 160 K). However, the films exhibited an unusual antiferroelectric-like behavior with a temperature- and an electric-field-dependence. The coercive field showed an abrupt increase below the antiferromagneitc ordering temperature, indicating the possibility of interference between ferroelectric domains and antiferromagnetic domains. The authors investigated the ferroelectric properties of epitaxial thin films of hexagonal ErMnO3 fabricated on Pt(111)/Al2O3(0001) substrates. The ferroelectric characteristics were observed with a reasonable remnant polarization value (3.0 μC/cm2 at 160 K). However, the films exhibited an unusual antiferroelectric-like behavior with a temperature- and an electric-field-dependence. The coercive field showed an abrupt increase below the antiferromagneitc ordering temperature, indicating the possibility of interference between ferroelectric domains and antiferromagnetic domains.

Zinc Chloride Modified Electronic Transport and Relaxation Studies in Barium-Tellurite Glasses

Sunil Dhankhar,R. S. Kundu,Sunita Rani,Preeti Sharma,S. Murugavel,Rajesh Punia,N. Kishore 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.5

The ac conductivity of halide based tellurium glasses havingcomposition 70 TeO2-(30-x) BaO-x ZnCl2 ; x = 5, 10, 15 , 20 and 25has been investigated in the frequency range 10-1 Hz to 105Hz and inthe temperature range 453 K to 553 K. The frequency and temperaturedependent ac conductivity show mixed behaviour with increase inhalide content and found to obey Jonscher’s universal power law. Thevalues of dc conductivity, crossover frequency and frequency exponenthave been estimated from the fitting of experimental data of acconductivity with Jonscher’s universal power law. For determining theconduction mechanism in studied glass system, frequency exponent hasbeen analyzed by various theoretical models. In presently studiedglasses, the ac conduction takes place via overlapping large polarontunneling (OLPT). The values of activation energy for dc conduction(W) and the one associated with relaxation process (ER) are found toincrease with increase in x up to glass sample with x = 15 and thereafterit decrease with increase in zinc chloride content. DC conduction takes place via variable range hopping (VRH) as proposed byMott with some modification suggested by Punia et al. The value of real part of modulus (M') is observed to decrease withincrease in temperature. The value of stretched exponent (β) obtained from fitting of M'' reveals the presence of non-Debye typeof relaxation in presently studied glass samples. Scaling spectra of ac conductivity and values of electric modulus (M' and M'')collapse into a single master curve for all the compositions and temperatures. The values of relaxation energy (ER) for all thestudied glass compositions are almost equal to W, suggesting that polarons have to overcome same barrier while relaxing andconducting. The conduction and relaxation processes in the studied glass samples are composition and temperature independent.

Formation of hexagonal phase of TbMnO₃ thin film and its multiferroic properties

Lee, J.-H.,Lee, D.,Noh, T. W.,Murugavel, P.,Kim, J. W.,Kim, K. H.,Jo, Y.,Jung, M.-H.,Yoon, J.-G.,Chung, J.-S. Published for the Materials Research Society by th 2007 Journal of materials research Vol.22 No.8