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Effect of exhaust gas recirculation and ethyl hexyl nitrate additive on biodiesel fuelled diesel engine for the reduction of NOx emissions

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Frontiers in Energy 2012年第3期6卷 304-310页

作者： k. VENk.TESWARLU B. S. R. MURTHY V. V. SUBBARAO k. vijaya kumar Mechanical Engineering Department K.L University Guntur 522502India Mechanical Engineering Department Q.I.S College of Engineering and Technology Ongole 523272 India Mechanical Engineering Department J.N.T.U Kakinada Kakinada533033 India

Cetane improvers reduce the ignition delay, which in turn reduces the combustion temperatures thereby reduce NOx emissions. Exhaust gas recirculation （EGR） proved to be an effective way to reduce the NOx emissions. In this present experimental work. a combination of exhaust gas recirculation and cetane improver ethyl hexyl nitrate （EHN） is used to investigate the performance and exhaust emissions of a single cylinder four strok. naturally aspirated direct injection and air cooled diesel engine. Test results show that the brak. thermal efficiency increases with the increase in the percentage of EGR which is accompanied by a reduction in brak. specific fuel consumption and exhaust gas temperatures, and that bio- diesel with cetane improver under 20% EGR reduces NOx emissions by 33% when compared to baseline fuel without EGR. However carbon monoxide （CO）, hydro carbon （HC） and smok. emissions increase with an increase in percentage of EGR.

关键词： additive exhaust gas recirculation (EGR),emissions ethyl hexyl nitrate (EHN) performance

Structural and Electrical Conductivity Studies in Nick.l-Zinc Ferrite

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Advances in Materials Physics and Chemistry 2012年第3期2卷 185-191页

作者： k. Rama k.ishna k. vijaya kumar Dachepalli Ravinder Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Hyderabad India Department of Physics Malla Reddy College of Engineering & Technology Secunderabad India Department of Physics Osmania University Hyderabad India

The magnetic particles of nick.l-zinc ferrite with chemical composition Ni1-xZnxFe2O4 were synthesized successfully by citrate precursor auto-combustion method using high purity nitrates and citric acid as chelating agent. The prepared powder of nick.l-zinc ferrites was sintered at 1000℃ for 1 hr to obtain good crystalline phase and was used for further study. The X-ray diffraction technique was employed to confirm the single phase formation of nick.l ferrite. The X-ray diffraction pattern shows the Bragg’s peak.which belongs to cubic spinel structure. The values of lattice constant, X-ray density, bulk.density, and porosity were calculated. The temperature dependence of the electrical conductivity plot shows the k.nk. which can be attributed to ferromagnetic-paramagnetic transition. The activation energy obtained from resistivity plots in paramagnetic region is found to be more than that in ferrimagnetic region. The conduction mechanism in nick.l-zinc ferrite particles has been discussed on the basis of hopping of electrons.

关键词： Nick.l –Zinc Ferrite Lattice Parameter X-Ray Density Bulk Density Porosity Electrical Conductivity

Effect of Annealing Temperature on the Structural and Magnetic Properties of NiFe2O4Nanoferrites

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Advances in Materials Physics and Chemistry 2017年第2期7卷 19-27页

作者： A. Sangeetha k. vijaya kumar G. Nanda kumar Department of Physics Indur Institute of Engineering and Technology Siddipet India Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Nachupally (Kondagattu) Karimnagar-Dist. Telangana India Department of Geo-Physics Osmania University Hyderabad India

Nanocrystalline NiFe2O4 spinel ferrites were synthesized by sol-gel method. The structural and magnetic properties were investigated using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). Annealing temperature showed prominent effect on the grain size. The average grain size of NiFe2O4 was observed to increase from 31 nm to 54 nm as the annealing increased from 500℃ to 1000℃. The IR spectra showed the absorption bands corresponding to stretching of tetrahedral and octahedral bands. The magnetic properties were observed to depend strongly on the annealing temperature.

关键词： Sol-Gel Nick.l Ferrite Crystallite Size Structural Properties Magnetic Properties

Synthesis and Characterization of Copper Substituted Nick.l Nano-Ferrites by Citrate-Gel Technique

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Advances in Materials Physics and Chemistry 2012年第3期2卷 192-199页

作者： R. Sridhar Dachepalli Ravinder k. vijaya kumar Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Hyderabad India Department of Physics Osmania University Hyderabad India Vignan’s Institute of Technology & Aeronautical Engineering College Deshmukhi India

Mixed Copper substituted Nick.l nano-ferrites having the chemical formula Ni1-xCuxFe2O4 (where x = 0, 0.2, 0.4, 0.6, 0.8, 0.9 and 1.0) were synthesized by citrate gel technique. The crystal structure characterization and morphology were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). An elemental composition of the samples were studied by energy dispersive X-ray Spectroscopy (EDS). Lattice parameter, X-ray density, Volume of the Unit Cell and The values of the hopping length for octahedral (dB) and tetrahedral (dA) sites were calculated. The observed results can be explained on the basis of composition.

关键词： Ferrites Nano-Materials X-Ray Diffraction SEM EDS

Magnetic Properties of Ni-Zn Ferrites by Citrate Gel Method

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Advances in Materials Physics and Chemistry 2012年第3期2卷 149-154页

作者： k. Rama k.ishna k. vijaya kumar C. Ravindernathgupta Dachepalli Ravinder Department of Physics Government Polytechnic Nizamabad India Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Hyderabad India Department of Physics Malla Reddy College of Engineering & Technology Secunderabad India Department of Physics Osmania University Hyderabad India

Ni-Zn ferrite with a nominal composition of Ni1-xZnxFe2O4 (x = 0, 0.2, 0.6, 0.8, 0.9) are prepared by citrate gel method and characterized by X-ray diffraction. Magnetic properties of all samples are obtained by using VSM (Vibrating Sample Magnetometer) in the range of 10 k.e. The saturation magnetization values of the samples are carried out from the B-H loop. The effect of composition on saturation magnetization and magnetic moment are studied in this paper. The results showed that Saturation magnetization and magnetic moment values increases gradually as Zn2+ composition increases, it reaches maximum value 70.28 emu/gm for (x = 0.6) and decreases further with increasing Zn2+ composition.

关键词： Ni-Zn Ferrites Citrate Gel Method: Vibrating Sample Magneto Meter Saturation Magnetization Magnetic Moment

Structural and Elastic Behavior of Chromium Doped Pr0.5Sr0.5MnO3System

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Advances in Nanoparticles 2021年第1期10卷 26-35页

作者： Ashok.kumar k.suma Elle Sagar G. Sreeram Reddy k. vijaya kumar Department of Physics JNTU Hyderabad Hyderabad India B V Raju Institute of Technology Narsapur India Vidya Jyothi Institute of Technology Hyderabad India

A series of colossal magneto resistance (CMR) materials with compositional formula Pr0.5Sr0.5Mn1-xCrxO3 (x = 0, 0.1, 0.2, 0.3, 0.4) were prepared by sol-gel technique using pure metal nitrates as the starting materials. These samples were characterized structurally by X-ray diffraction, FTIR and SEM. All the samples exhibit orthorhombic structure without any detectable impurities. The bulk densities for all the compositions were measured from the pellets. The Young’s and Rigidity moduli, Poisson’s ratio and Debye temperature of all the compositions were calculated with the experimentally measured ultrasonic longitudinal and shear velocities at room temperature using pulse transmission technique. As the materials are porous, zero porous elastic moduli have also been calculated using a well-known Hasselmann and Fulrath model. The observed variation of elastic moduli with varying chromium doping concentration has been studied qualitatively.

关键词： CMR Materials Resistivity Ultrasonic Velocity Elastic Moduli

Effect of Ba Substitution on the Structural and Magnetic Properties of BiFeO₃

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World Journal of Nano Science and Engineering 2016年第1期6卷 38-44页

作者： V. Srinivas A. T. Raghavender k. vijaya kumar Department of Physics Government Institute of Electronics Secunderabad TS India Department of Electronics and Communication Engineering Nishitha College of Engineering and Technology Hyderabad TS India Department of Physics JNTUH College of Engineering Jagtial Nachupally (Kondagattu) Karimnagar-Dist. TS India

Bi1-xBaxFeO3 (0 ≤ x ≤ 0.3) nanopowders were synthesized using sol-gel technique. The structural and magnetic properties were investigated using X-ray diffraction, SEM and VSM. As Ba2+ doping concentration was increased, the structure of the samples changed from rhombohedral to tetragonal or monoclinic. The structural change might be an important factor for achieving the ferroelectric properties in this material. The lattice parameters were observed to increase with increase in Ba2+ concentration. All the M-H loops showed the ferromagnetic behavior. Magnetization was observed to enhance with increase in Ba concentration. The enhancement in the magnetization due to Ba2+ doping may be due to the replacement of Bi3+ ions by Ba2+ which might have resulted in the suppression of spiral spin structure.

关键词： Multiferroic Material Structural Magnetic Properties

Effect of Aluminium Doping on Structural and Magnetic Properties of Ni-Zn Ferrite Nanoparticles

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World Journal of Nano Science and Engineering 2015年第3期5卷 68-77页

作者： k. vijaya kumar D. Paramesh P. Venk.t Reddy Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Nachupally (Kondagattu) Karimnagar-Dist Telangana State India Sreenidhi Institute of Science and Technology (Autonomous) Hyderabad India

Aluminium doped Ni-Zn ferrite nanoparticles of general formula of Ni0.5Zn0.5AlxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0) have been synthesized by sol-gel auto combustion method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dis-persive X-ray (EDX), Fourier transform spectroscopy (FTIR) and vibrating sample magneto meter (VSM). XRD studies confirm that all compositions show single phase cubic spinel structure. The crystallite size was calculated using the Debye-Scherrer formula and found in the range of 17 - 52 nm. The lattice parameter “a” is found to decrease with increasing Al3+ content. The SEM images clearly show the crystalline structure and EDX patterns confirm the compositional formation of the synthesized compositions. The results of FTIR analysis indicated that the functional groups of Ni-Zn spinel ferrite were formed during the sol-gel synthesis process. The IR spectra showed two main absorption bands, the high frequency band ν1 around 600 cm-1 and the low frequency band ν2 around 400 cm-1 arising from tetrahedral (A) and octahedral (B) interstitial sites in the spinel lattice. As doping is increased the magnetic behavior is found to decrease and the composition x = 2.0 ferrite appears to be exhibiting superparamagnetism as the coercive field and retentivity are found near zero.

关键词： Al-Ni-Zn Ferrite Nanoparticles XRD EDX SEM FTIR VSM

Synthesis, XRD &SEM Studies of Zinc Substitution in Nick.l Ferrites by Citrate Gel Technique

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World Journal of Condensed Matter Physics 2012年第3期2卷 153-159页

作者： k. Rama k.ishna D. Ravinder k. vijaya kumar Ch. Abraham Lincon Department of Chemistry P. G. College of Science Osmania University Hyderabad India Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Nachupally (Kondagattu) India Department of Physics Malla Reddy College of Engineering & Technology Secunderabad India Department of Physics P. G. College of Science Osmania University Hyderabad India

Ni-Zn ferrite with a nominal composition of Ni1–XZnXFe2O4 (X = 0, 0.2, 0.6, 0.8, 0.9 & 1.0) ferrite powders have been successfully prepared at a very low temperature (180℃) by a novel auto combustion process using citric acid as a coordinating agent. Phase purity of the solid solutions has been confirmed by X-ray diffraction. Morphological, elemental composition characterizations of the prepared samples were performed by high resolution scanning electron microscopy and energy dispersive spectroscopy (EDS). Magnetic properties of all samples are obtained by using VSM (Vibrating Sample Magnetometer) in the range of 10 k.oe. The saturation magnetization values of the samples are carried out from the B-H loop. The effect of composition on saturation magnetization and magnetic moment are studied in this paper. The results showed that Saturation magnetization and magnetic moment values increases gradually as Zn2+ composition increases, it reaches maximum value 70.28 emu/gm for (X = 0.6) and decreases further with increasing Zn2+ composition.

关键词： Ni-Zn Ferrite Citrate Precursor Auto Combustion Saturation Magnetization Magnetic Moment