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CONTENTS
Volume 3, Number 3, September 2015
 

Abstract
The unintentionally doped and bismuth (Bi) doped zinc oxide (ZnO) films were prepared by spray pyrolysis at 450oC with zinc acetate and bismuth nitrate precursor. The n-type conduction with concentration 6.13x1016cm-3 can be observed for the unintentionally doped ZnO. With the increasing of bismuth nitrate concentration in precursor, the p-type conduction can be observed. The p-type concentration 4.44

Key Words
zinc oxide, bismuth doping, photocatalytic, spray pyrolysis

Address
Tzu-Yang Lin: Department of Electrical Engineering, National University of Kaohsiung 811, Taiwan
Yu-Ting Hsu: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan
Wen-How Lan: Department of Electrical Engineering, National University of Kaohsiung 811, Taiwan
Chien-Jung Huang: Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan
Lung-Chien Chen: Department of Electro-Optical Engineering, National Taipei University of Technology, Taipei 106, Taiwan
Yu-Hsuan Huang: Department of Electrical Engineering, National University of Kaohsiung 811, Taiwan
Jia-Ching Lin: Materials and Electro-Optics Research Division, National Chung-Shan Institute of Science and Technology, Taoyuan 325, Taiwan
Kuo-Jen Chang: Materials and Electro-Optics Research Division, National Chung-Shan Institute of Science and Technology, Taoyuan 325, Taiwan
Wen-Jen Lin: Materials and Electro-Optics Research Division, National Chung-Shan Institute of Science and Technology, Taoyuan 325, Taiwan
Kai-Feng Huang: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan

Abstract
Influence of Ag nanoparticles on optical and photovoltaic properties of, silicon substrates, silicon solar cells and glass have been investigated. Silver nanoparticles have been fabricated by evaporation of thin Ag layers followed by the thermal annealing. The surface plasmon resonance peak was observed in the absorbance spectrum at 470 nm of glass with deposited silver nanoparticles. It is demonstrated that deposition of silver nanoparticles on silicon substrates was accompanied with a significant decrease in reflectance at the wavelength 360-1100 nm and increase of the absorption at wavelengths close to the band gap for Si substrates. We studied influence of Ag nanoparticles on photovoltaic characteristics of silicon solar cells without and with common use antireflection coating (ARC). It is shown that silver nanoparticles deposited onto the front surface of the solar cells without ARC led to increase in the photocurrent density by 39% comparing to cells without Ag nanoparticles. Contrary to this, solar cells with Ag nanoparticles deposited on front surface with ARC discovered decrease in photocurrent density. The improved performance of investigated cells was attributed to Ag-plasmonic excitations that reduce the reflectance from the silicon surface and ultimately leads to the enhanced light absorption in the cell. This study showed possibility of application of Ag nanoparticles for the improvement of the conversion efficiency of wafer-based silicon solar cells instead of usual ARC.

Key Words
silver nanoparticles; plasmonic resonance; reflectance; silicon solar cells; efficiency

Address
Tayyar D. Dzhafarov, Shakir S. Aslanov and Shirin H. Ragimov: Institute of Physics, Azerbaijan National Academy of Sciences, Javid Str. 33, AZ-1143 Baku, Azerbaijan
Arif M. Pashaev, Bahadur G. Tagiev and Akper A. Aliev: National Aviation Academy of Azerbaijan Airlines, Bina 25-km, AZ-1045 Baku, Azerbaijan

Abstract
Initiation of crack and its growth simulation requires accurate model of traction – separation law. Accurate modeling of traction-separation law remains always a great challenge. Atomistic simulations based prediction has great potential in arriving at accurate traction-separation law. The present paper is aimed at establishing a method to address the above problem. A method for traction-separation law prediction via utilizing atomistic simulations data has been proposed. In this direction, firstly, a simpler approach of common neighbor analysis (CNA) for the prediction of crack growth has been proposed and results have been compared with previously used approach of threshold potential energy. Next, a scheme for prediction of crack speed has been demonstrated based on the stable crack growth criteria. Also, an algorithm has been proposed that utilizes a variable relaxation time period for the computation of crack growth, accurate stress behavior, and traction-separation atomistic law. An understanding has been established for the generation of smoother traction-separation law (including the effect of free surface) from a huge amount of raw atomistic data. A new curve fit has also been proposed for predicting traction-separation data generated from the molecular dynamics simulations. The proposed traction-separation law has also been compared with the polynomial and exponential model used earlier for the prediction of traction-separation law for the bulk materials.

Key Words
molecular dynamics simulations; single crystal; crack growth; stresses; traction-separation law

Address
Vijay Kumar Sutrakar: Aeronautical Development Establishment, Defence Research and Development Organization, New Thipasandara Post, Bangalore, 560075, India; Presently at Aeronautical Development Agency, Post Box No. 1718, Vimanapura Post, Bangalore, 560017,
India
N. Subramanya: Aeronautical Development Establishment, Defence Research and Development Organization, New Thipasandara Post, Bangalore, 560075, India; Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012, India
D. Roy Mahapatra: Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012, India

Abstract
Iron nanoparticles were made by using the modified coprecipitation technique. Usually the characteristics of synthesised particles depend upon the process parameters such as the ratio of the iron ions, the pH of the solution, the molar concentration of base used, type of reactants and temperature. A modified coprecipitation method was adopted in this study. A magnetic stirrer was used for mixing and the morphology and nature of particles were observed after synthesis. Nanoparticles were characterised through XRD. Obtained nanoparticles showed the formation of magnetite and maghemite under citric acid and oxalic acid as stabilisers respectively. The size of nanoparticle was greatly affected by the use of different types of stabilisers. Results show that citric acid greatly reduced the obtained particle size. Particle size as small as 13 nm was obtained in this study. The effects of different kinds of nucleating agents were also observed and two different types of nucleating agents were used i.e. potassium hydroxide (KOH) and copper chloride (CuCl2). Results show that the use of nucleating agent in general pushes the growth phase of nanoparticles towards the end of coprecipitation reaction. The particles obtained after addition of nucleating agent were greater in size than particles obtained by not utilising any nucleating agent. These particles have found widespread use in medical sciences, energy conservation and electronic sensing technology.

Key Words
nanoparticles; iron oxide; maghemite; magnetite; X-ray diffraction; nucleating agents; stabilisers

Address
Faaz A. Butt and Syed M. Mohsin Jafri: Department of Materials Engineering, NED University of Engineering and Technology, main University Road, Karachi-75270, Pakistan



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