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Showing 7 results for Krishna

M. Krishna, R. Nandini, A.v. Suresh, K. Narasimha Rao ,
Volume 15, Issue 2 (June 2018)
Abstract

An efficient solid-state approach was established to synthesize (K0.5Na0.5) NbO3 ceramics using calcination kinetics and microwave assisted sintering. Milling of carbonate and oxide raw materials were carried out for 15h to obtain homogeneous nano particles. The crystallite size of 5.30 nm was obtained for the KNN system after calcination through optimized parameters and observed to be stoichiometric in nature. The obtained nano particles showed phase transition from orthorhombic to tetragonal crystal structure without any secondary phases. The high relative density and tetragonality ratio of KNN ceramics obtained through optimized sintering parameters yielded with significant piezoelectric and ferroelectric properties.
 

R.s Krishna, J. Mishra, A. Adeniji, Sh. Das, S. Mohammed Mustakim,
Volume 17, Issue 4 (December 2020)
Abstract

The field of nanomaterial has greatly advanced in the last decade following a wider range of applications in the fields of electronics, automobiles, construction, and healthcare due to its extraordinary and ever-evolving properties. Synthesis of the nanomaterial plays a crucial role in redefining the current engineering and science field. At the same time, procuring an environment-friendly end product through eco-friendly solutions and sustainable processes is the key to many global problems. Green synthesis of nanomaterials like graphene and its derivatives involves mild reaction conditions and nontoxic precursors because it is simple, cost-effective, relatively reproducible, and often results in more stable materials. This paper primarily focuses on the green synthesis of graphene and its derivatives (graphene oxide & reduced graphene oxide) and geopolymers; a green technology for preparing graphene reinforced geopolymer composites. Various methods used globally for green synthesis of graphene and geopolymer are briefly discussed and this paper tries to integrate these two areas for a green end product. Possible applications of these green composites are also discussed to provide insights on the current growth and developments. 
S. Das, R. Ghadai, A. Krishna, A. Trivedi, R. Bhujel, S. Rai, Sh. Ishwer, K. Kalita,
Volume 17, Issue 4 (December 2020)
Abstract

Graphene oxide (GO) and reduced graphene oxide (rGO) is a semiconductor device which finds its many applications in the various electronic devices. In the present study GO and rGO thin sheets have been grown over Si wafers using Hummer’s and modified Hummer’s method and a comparison in the properties of the coatings have been carried out. The morphology of the sheets characterized by SEM revealed similar transparent sheet like structure for both the chemical synthesis. The diffraction pattern of GO and rGO prepared with modified Hummer’s method showed peak shift to lower diffraction angle from 9.96 o to 9.63 o and 26.4 o to 26.3 o respectively. The diffraction peaks were observed at diffraction phase of 001 and 002 crystal plane. FTIR spectra revealed presence of oxygen functional groups in GO thin sheets whereas peaks for oxygen functionalities are absent in rGO. The polarization curve indicated similar corrosion resistance of GO and rGO thin sheets grown under Hummer’s and modified Hummer’s. Capacitive property of rGO is better than GO as observed by the electrochemical analysis of GO and rGO..Graphene oxide (GO) and reduced graphene oxide (rGO) is a semiconductor device which finds its many applications in the various electronic devices. In the present study GO and rGO thin sheets have been grown over Si wafers using Hummer’s and modified Hummer’s method and a comparison in the properties of the coatings have been carried out. The morphology of the sheets characterized by SEM revealed similar transparent sheet like structure for both the chemical synthesis. The diffraction pattern of GO and rGO prepared with modified Hummer’s method showed peak shift to lower diffraction angle from 9.96 o to 9.63 o and 26.4 o to 26.3 o respectively. The diffraction peaks were observed at diffraction phase of 001 and 002 crystal plane. FTIR spectra revealed presence of oxygen functional groups in GO thin sheets whereas peaks for oxygen functionalities are absent in rGO. The polarization curve indicated similar corrosion resistance of GO and rGO thin sheets grown under Hummer’s and modified Hummer’s. Capacitive property of rGO is better than GO as observed by the electrochemical analysis of GO and rGO.
Umarfarooq Maktedar Abdulkhadar, Patil Somalinganagouda Shivakumargouda, Gonal Basavaraja Veeresh Kumar, Krishnaraja Govinda Kodancha,
Volume 18, Issue 3 (September 2021)
Abstract

Residual stress measurement is of utmost importance for the safety and reliability of engineering components and has been an active area of scientific research. Relaxation techniques such as hole drilling, slitting and ring core method are widely applied semi destructive techniques for residual stress measurements in polymer composites. This article reviews the recent literature on the measurement of residual stress in polymer composite by employing the above-mentioned relaxation techniques. This article summarizes the categories of residual stresses, causes of formation, techniques of measurements and also briefly outlines the chronological developments of the Hole drilling and slitting method. The article also provides a comparative summary of these relaxation methods.
Usha Vengatakrishnan, Kalyanaraman Subramanian, Vettumperumal Rajapand, Dhineshbabu Nattanmai Raman,
Volume 18, Issue 3 (September 2021)
Abstract

Copper oxide (CuO) nanostructure particles were prepared using KOH/NaOH catalyst by low cost precipitation method and characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM) and energy dispersive X-ray spectra (EDX) analysis. The photocatalytic dye degradation study of pure CuO nanostructure particles are analysed against two azo dyes (Direct black 38 (Black-E) and Congo red) under ultraviolet (UV) and solar irradiation. The release of major active species (*OH) in the photocatalytic degradation by as prepared CuO nanostructure particles were investigated by photoluminescence (PL) spectra with two different excitation wavelength (325and 355nm). The band gap of CuO nanostructure particles was calculated from diffuse reflectance spectra. The photocatalytic effect of CuO nanostructure particles is confirmed from the UV – Vis and photoluminescence spectra and also, further confirmed from the kinetic studies under UV and solar radiations. The photocatalytic degradation results revealed that 16.35% and 7.5% of black E and Congo red dye was degraded under UV, while it was 47.2% and 17.6% under solar light. The influence of pH on the photodegradation and change in the reaction temperature under solar irradiation were also analysed
Parasuraman Dhanasekaran, Ramakrishnan Marimuthu,
Volume 20, Issue 1 (March 2023)
Abstract

Fossil fuels served as the main source of energy throughout the 1800s when the industrial revolution got underway. Countries started aiming for carbon-neutral footprints and lowered emissions as environmental degradation became more apparent. Numerous research projects have been undertaken to discover a photovoltaic device that can replace conventional silicon (Si)-based solar cells. Dye-sensitized solar cells (DSSCs) have undergone extensive research during the past three decades. Due to their straightforward preparation process, low cost, ease of production, and low toxicity, DSSCs have seen extensive use. The reader will be able to comprehend the numerous types of TCO layers, physical methods for depositing metal oxide on TCO thin films, materials for fabricating the various DSSC layers, and the various types of dyes included in DSSC as well as their components and structures. The reader's ability to construct the DSSC, gain a general understanding of how it operates, and increase the effectiveness of these devices' potential growth and development paths are all aided by this review. For these technologies to be debated and shown to be appropriate for a breakthrough in consumer electronics on the market, manufacturing, stability, and efficiency improvements must also be addressed in the future. An overview of current DSSC prototype development and products from major firms is presented.
 
Rakhesh V, Sreedev P, Ananthakrishnan A,
Volume 21, Issue 2 (June 2024)
Abstract

Organic and Perovskite solar cells have attracted a lot of attention recently since they can be used with flexible substrates and have lower manufacturing costs. The configuration and materials employed in their construction, including the Electron Transport Layer (ETL), active layer, electrode contact, and hole transport layer greatly influence the stability and performance of these solar cells. This research focuses on the simulation of solar cells, specifically utilizing zinc oxide (ZnO) as the electron transport layer. A 0.1 molar ZnO thin film was prepared from Zinc acetate salt and was deposited on a glass substrate using the cost effective Successive Ionic Layer Adsorption and Reaction (SILAR) method. In-depth investigations were carried out on several factors, including structural, surface, optical and numerical analysis. The obtained parameters were utilized in the General-Purpose Photovoltaic Device Model (GPVDM) software to perform numerical simulations of the organic solar cell and Perovskite solar cell. Both Organic solar cells and Perovskite solar cells were designed numerically and through careful observations, electrical parameters like Open circuit Voltage (Voc), Short circuit current (Jsc), Fill Factor (FF), and Power Conversion Efficiency (PCE) were identified. The studies indicate the promising performance of simulated solar cells with SILAR-synthesized ZnO thin film as the ETL.
 

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