Synthesis and Characterization of ZnO Nanowire–CdO Composite Nanostructures

Senthil, Karuppanan,Tak, Youngjo,Seol, Minsu,Yong, Kijung Springer 2009 NANOSCALE RESEARCH LETTERS Vol.4 No.11

<P>ZnO nanowire–CdO composite nanostructures were fabricated by a simple two-step process involving ammonia solution method and thermal evaporation. First, ZnO nanowires (NWs) were grown on Si substrate by aqueous ammonia solution method and then CdO was deposited on these ZnO NWs by thermal evaporation of cadmium chloride powder. The surface morphology and structure of the synthesized composite structures were analyzed by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The optical absorbance spectrum showed that ZnO NW–CdO composites can absorb light up to 550 nm. The photoluminescence spectrum of the composite structure does not show any CdO-related emission peak and also there was no band gap modification of ZnO due to CdO. The photocurrent measurements showed that ZnO NW–CdO composite structures have better photocurrent when compared with the bare ZnO NWs.</P>

Growth and characterization of stoichiometric tungsten oxide nanorods by thermal evaporation and subsequent annealing

Senthil, Karuppanan,Yong, Kijung IOP Pub 2007 Nanotechnology Vol.18 No.39

<P>Stoichiometric tungsten oxide (WO<SUB>3</SUB>) nanorods are synthesized on tungsten (W) substrates by a high-temperature, catalyst-free, physical deposition process and by subsequent annealing in oxygen atmosphere. Tungsten oxide nanorods are grown by thermal evaporation of WO<SUB>3</SUB> powder at elevated temperature in a tube furnace. XRD, TEM and XPS analysis shows that the as-grown nanorods are single crystalline and non-stoichiometric (WO<SUB><I>x</I></SUB>). Annealing of WO<SUB><I>x</I></SUB> nanorods at 700 °C under oxygen atmosphere has led to the formation of stoichiometric WO<SUB>3</SUB> as evidenced by XRD, XPS and Raman analysis. </P>

Optimized sequencing of CNC milling toolpath segments using metaheuristic algorithms

B. Raja Chinna Karuppanan,M. Saravanan 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

Intelligent selection of a short toolpath is made possible by reducing machining cycle time. Each metal cutting layer in a workpiece is composed of several entities, such as lines and arcs, which form the different cutting segments of a cutting plan. During machining, the cutter moves at controlled feed rates along various segments at a high speed in a single cutting pass. The end of a segment is bridged to the start point of the next segment by the non-cutting movement of the tool. Any two consecutive segments can be connected in eight different ways. Finding the shortest tool path at polynomial time is impossible because toolpaths are constructed in millions of ways by sequencing the segments. This paper presents an effective method that uses heuristic optimization techniques to solve this NP-hard problem, which is known as the traveling salesman problem, for segments. The proposed method adopts particle swarm optimization (PSO) and the genetic algorithm (GA) because of their capability to generate quality solutions for optimization problems. GA and PSO are implemented in the MATLABR2016b computing environment because of the platform’s flexibility and simple coding method. The optimization procedure is validated by comparing its results with those of two industry standard CAM systems, namely, Autodesk Inventor HSM and Mastercam. Using the proposed optimization method saves up to 40 % of the tool’s airtime during machining.

Paper : Influence of Angle Ply Orientation on the Flexural Strength of Basalt and Carbon Fiber Reinforced Hybrid Composites

( Ali Nawaz Mengal ),( Saravanan Karuppanan ) 한국복합재료학회 2015 Composites research Vol.28 No.1

In this paper the influence of fiber orientation of basalt and carbon inter-ply fabrics on the flexural properties of hybrid composite laminates was experimentally investigated. Four types of basalt/carbon/epoxy inter-ply hybrid composite laminates with varying angle ply orientation of reinforced basalt fiber and fixed orientation of carbon fiber were fabricated using hand lay-up technique. Three point bending test was performed according to ASTM 7264. The fracture surface analysis was carried out by scanning electron microscope (SEM). The results obtained from the four laminates were compared. Lay-up pattern of [0B/+30B/-30B/0C]S exhibits the best properties in terms of flexural strength and flexural modulus. Scanning electron microscopy results on the fracture surface showed that the interfacial de-bonding between the fibers and epoxy resin is a dominant fracture mode for all fiber lay-up schemes.

Luminescence and structural properties of self-assembled Y(V,P)O4:Eu3+@amorphous-K-VO3 core/shell nanophosphors

SU JO, Deok,SENTHIL, Karuppanan,TAKAKI, Masaki,YOON, Dae Ho Ceramic Society of Japan 2013 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.121 No.1414

<P>A Liquid-Phase Precursor method followed by a 5% KOH solution treatment was employed for the facile synthesis of Y(V,P)O-4:Eu3+@amorphous-K-VO3 core/shell nanophosphors with non-stoichiometric composition Y-x(V0.44P0.56)O-4:Eu-0.1 (x = 0.855, 0.875, 0.90 and 0.965). It was observed that this non-stoichiometric composition approach leads to the control of the size, shape and unit cell parameters depending upon the Y concentration. The shell layer of 2-7 nm formed by alkaline solution treatment at room-temperature was observed by Transmission Electron Microscope (TEM). The particle size grew up by 20-50 nm and the luminescence properties were enhanced by 9-31% after the KOH solution treatment. In contrast, the micro-sized Y(V,P)O-4:Eu3+ phosphors treated by the KOH solution did not show any change in their luminescence properties. This KOH solution treatment opens new possibilities to facilely synthesize Y(V,P)O-4:Eu3+@amorphous-K-VO3 core/shell nanophosphors with highly stable properties and improved luminescence. (C) 2013 The Ceramic Society of Japan. All rights reserved.</P>

Synthesis of Novel Double-Layer Nanostructures of SiC–WO _<i>x</i> by a Two Step Thermal Evaporation Process

Kim, Hyeyoung,Senthil, Karuppanan,Yong, Kijung Springer 2009 NANOSCALE RESEARCH LETTERS Vol.4 No.8

<P>A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W<SUB>18</SUB>O<SUB>49</SUB>nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W<SUB>18</SUB>O<SUB>49</SUB>nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters.</P>

Semitransparent all-oxide p-NiO/n-ZnO nanowire ultraviolet photosensors

Lee, Ki Ryong,Jung, Byung Oh,Cho, Sung Woon,Senthil, Karuppanan,Cho, Hyung Koun Cambridge University Press (Materials Research Soc 2013 Journal of materials research Vol.28 No.18

<▼1><B>Abstract</B><P/></▼1><▼2><P>All-oxide ultraviolet (UV) photosensors based on NiO/ZnO nanowire heterostructure were fabricated on corning glass substrates. The p-type NiO layers were directly deposited on the ZnO nanowire arrays grown on the AZO bottom electrode/glass for the formation of a p-n diode, followed by the growth of the ITO top electrode layer for the electrical interconnection of nanostructures. The fabricated device structure showed a transmittance value of about 60% in the visible region, resulting in semitransparent properties. The current-voltage (<I>I</I>-<I>V</I>) characteristics of the fabricated p-n heterostructure showed a typical rectifying behavior with a current rise at about 4 V and an <I>I</I>(forward)/<I>I</I>(reverse) ratio of about 11.3 at 8 V. In addition, the ITO/p-NiO/n-ZnO/AZO structure responded at a wave-length position of 370 nm in reverse bias, together with weak photoresponse in the visible region. An UV sensor based on the all-oxide ZnO nanowire absorber exhibited improved photoresponse compared to the device based on a ZnO thin film.</P></▼2>

Invasion potential of Kappaphycus alvarezii on corals at Kurusadai Island, Gulf of Mannar, India

Mandal, Subir Kumar,Mantri, Vaibhav A.,Haldar, Soumya,Eswaran, Karuppanan,Ganesan, Meenakshisundaram The Korean Society of Phycology 2010 ALGAE Vol.25 No.4

The marine red alga Kappaphycus alvarezii is a major source of $\kappa$-carrageenan. It has been introduced in 20 countries including India. Recently, several reports have expressed concerns about Kappaphycus invasion on Acropora corals at Kurusadai Island in the Gulf of Mannar, India, which is part of a marine bioreserve. To understand the extent of the Kappaphycus invasion, 27 randomly selected locations around Kurusadai Island and the mainland coast were surveyed during May-August 2008 and July 2009. Our rigorous sampling revealed that K. alvarezii was confined to two different patches of 105 m $\times$ 55 m and 8 m $\times$ 9 m located at the southeastern part of Kurusadai Island. The actual extent of the K. alvarezii canopy coverage was 76.7 $m^2$, accounting for less than 0.0035% of the total coral reef area. The daily growth rate of the K. alvarezii at Kurusadai was 0.7%. K. alvarezii was not observed in the coral reef area of the adjoining Pullivasal and Poomarichan Islands or the Palk Bay area cultivation sites. The lack of functional reproductive cycle, low spore viability, and the absence of microscopic phases in the life cycle of this alga coupled with the abundance presence of herbivores may restrict the further spread of this alga, so its invasive potential at Kurusadai Island is considered remote.

Invasion potential of Kappaphycus alvarezii on corals at Kurusadai Island, Gulf of Mannar, India

Subir Kumar Mandal,Vaibhav A. Mantri,Soumya Haldar,Karuppanan Eswaran,Meenakshisundaram Ganesan 한국조류학회I 2010 ALGAE Vol.25 No.4

The marine red alga Kappaphycus alvarezii is a major source of κ-carrageenan. It has been introduced in 20 countries including India. Recently, several reports have expressed concerns about Kappaphycus invasion on Acropora corals at Kurusadai Island in the Gulf of Mannar, India, which is part of a marine bioreserve. To understand the extent of the Kappaphycus invasion, 27 randomly selected locations around Kurusadai Island and the mainland coast were surveyed during May-August 2008 and July 2009. Our rigorous sampling revealed that K. alvarezii was confined to two different patches of 105 m × 55 m and 8 m × 9 m located at the southeastern part of Kurusadai Island. The actual extent of the K. alvarezii canopy coverage was 76.7 m2, accounting for less than 0.0035% of the total coral reef area. The daily growth rate of the K. alvarezii at Kurusadai was 0.7%. K. alvarezii was not observed in the coral reef area of the adjoining Pullivasal and Poomarichan Islands or the Palk Bay area cultivation sites. The lack of functional reproductive cycle, low spore viability,and the absence of microscopic phases in the life cycle of this alga coupled with the abundance presence of herbivores may restrict the further spread of this alga, so its invasive potential at Kurusadai Island is considered remote.

Stabilization of cryptomelane α-MnO₂ nanowires tunnels widths for enhanced electrochemical energy storage

Selvaraj, Aravindha Raja,Rajendiran, Rajmohan,Chinnadurai, Deviprasath,Rajendra Kumar, Gunasekaran,Kim, Hee-Je,Senthil, Karuppanan,Prabakar, Kandasamy Elsevier 2018 ELECTROCHIMICA ACTA Vol.283 No.-

<P><B>Abstract</B></P> <P>One dimensional manganese oxides with tunnel structures have attracted as an effective electrochemical energy storage material because of its efficient electrolyte/cation interfacial charge transports which enables improved pseudo capacitive performance. We have reported a simple one step hydrothermal technique to incorporate K<SUP>+</SUP> ions to maintain the tunnel width of cryptomelane α-MnO<SUB>2</SUB> nanowires during cycling performance. The effects of K<SUP>+</SUP> ions on the electrochemical performance is studied by tuning the phases of α-KMnO<SUB>2</SUB> nanowires to Mn<SUB>3</SUB>O<SUB>4</SUB> through an intermediate phase of Mn<SUB>2</SUB>O<SUB>3</SUB> by subsequent calcinations at various temperatures. K<SUP>+</SUP> ions doped α-MnO<SUB>2</SUB> nanowires exhibit a highest specific capacitance of 402 Fg<SUP>-1</SUP> at a current density of 1 Ag<SUP>-1</SUP> in 1 M Na<SUB>2</SUB>SO<SUB>4</SUB> electrolyte solution compared to Mn<SUB>2</SUB>O<SUB>3</SUB> and Mn<SUB>3</SUB>O<SUB>4</SUB>. The as synthesized α-KMnO<SUB>2</SUB> nanowires have a wider tunnel widths and enriched OH radical species and hence the electrolyte cations (Na<SUP>+</SUP>) penetrate the tunnels very easily resulting the polarization enhanced intercalation pseudo capacitance. The symmetric α-KMnO<SUB>2</SUB> nanowire supercapacitor device shows very high energy density (15.83 Wh kg<SUP>−1</SUP>), power density (128.35 W kg<SUP>−1</SUP>) and excellent cyclic stability with 88% retention of the initial capacitance after 3000 cycles.</P>