This document reports on research into improving the energy product of the rare-earth free magnetic material Fe3Se4 by doping it with manganese. Fe3Se4 has good magnetic properties like high coercivity but a low saturation magnetization limits its energy product. The researchers synthesized nanorods of Fe3-xMnxSe4 with x ranging from 0.01 to 0.2. They found that doping with 0.03 manganese increased the saturation magnetization by over 50% from 4.84 to 7.54 emu/g. This corresponded to an increase in energy product of over 130%. At low temperature the energy product showed a two order of magnitude increase, making the material promising for applications requiring magnet
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Heat treatment of BFO film deposited on Si (111): Spectroscopic studyiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis of Cobalt ferrite by Solid Reaction Methodsank_sanjay
Cobalt ferrite nano-crystalline powder was synthesized from the powder mixture of cobalt carbonate and iron oxide by mixed oxide ceramic method. The effects of temperature of calcination as well as molar ratio of CoCO3/Fe2O3 on the phase structure, morphology and magnetic properties of the products were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) techniques, respectively. The samples calcined at 800 and 900˚C consisted of cobalt ferrite, iron oxide and cobalt oxide. In the sample calcined at 1000˚C, the reaction was completed and single phase CoFe2O4 with a mean crystallite and particle sizes of 49 and 300 nm, respectively was obtained.
Structural, Electrical and Magnetotransport properties of La0.7Ca0.2Sr0.1MnO3...IOSR Journals
The sample of manganite perovskite oxide La0.7Ca0.2Sr0.1MnO3 has been prepared by solution combustion synthesis. The synthesized sample has been pelletized and further sintered at 8000C for 8 hours. The XRD pattern reveals that the samples are of single phase nature with orthorhombic structure and the diffraction patterns can be indexed with the pbnm space groups. The crystallite sizes calculated from broadening of XRD peaks using Scherrer’s formula were about 18 nm. Resistivity measurements were performed in the temperature range 2K under 3, 5, 10 and 14 T field using PPMS. Magnetoresistance shows a shift in metal-insulator transition temperature from ~213 K at zero field to ~250 K at 14T. MR value decreases as the temperature increases and at 300 K maximum value of MR is found to be ~ 22% for an applied field of 14 T. MR of ~ 28% is observed at 230 K. MR of ~ 35% is observed at 150 K in an applied field of 14 T and MR has negative sign
A study of micro structural, magnetic and electrical properties of La-Co-Sm n...IJECEIAES
A Lanthanum (La 3+ ) doped Samarium-Cobalt nanoferrites (La_x,Co_0.2,Sm_0.2,Fe_(2-x) O_4, where x=0.0,0.5,1.0) have been synthesized by sol-gel method in citrate media. Obtained spinal ferrites micro structure properties have been investigated by XRD, FTIR, SEM-EDX, and TEM-SAED techniques. All the samples are nano in size with significant hysteresis. Micro structural analysis by XRD confirms the obtained samples showing the single phase cubic spinal structures with an average crystal size found from 12 nm to 25 nm, while the average particles sizes identified from TEM analysis are ranging from 21.5nm-26.8 nm (~23.4nm) and from 20.5 nm to 28(~26.4nm) nm for x=0.5,1.0. The lattice parameter found to be a= 8.402, 8.423, 8.467Å for the respective values of x= 0.0, 0.05, and 1.0. Electrical properties show increase in dc resistivity with increase in La ion concentration. Finally, it was concluded that the doping of Lanthanum ion (La 3+ ) in the ferrites structure is found to influencing the structural and electrical properties without scarifying the ferromagnetic character.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Heat treatment of BFO film deposited on Si (111): Spectroscopic studyiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis of Cobalt ferrite by Solid Reaction Methodsank_sanjay
Cobalt ferrite nano-crystalline powder was synthesized from the powder mixture of cobalt carbonate and iron oxide by mixed oxide ceramic method. The effects of temperature of calcination as well as molar ratio of CoCO3/Fe2O3 on the phase structure, morphology and magnetic properties of the products were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) techniques, respectively. The samples calcined at 800 and 900˚C consisted of cobalt ferrite, iron oxide and cobalt oxide. In the sample calcined at 1000˚C, the reaction was completed and single phase CoFe2O4 with a mean crystallite and particle sizes of 49 and 300 nm, respectively was obtained.
Structural, Electrical and Magnetotransport properties of La0.7Ca0.2Sr0.1MnO3...IOSR Journals
The sample of manganite perovskite oxide La0.7Ca0.2Sr0.1MnO3 has been prepared by solution combustion synthesis. The synthesized sample has been pelletized and further sintered at 8000C for 8 hours. The XRD pattern reveals that the samples are of single phase nature with orthorhombic structure and the diffraction patterns can be indexed with the pbnm space groups. The crystallite sizes calculated from broadening of XRD peaks using Scherrer’s formula were about 18 nm. Resistivity measurements were performed in the temperature range 2K under 3, 5, 10 and 14 T field using PPMS. Magnetoresistance shows a shift in metal-insulator transition temperature from ~213 K at zero field to ~250 K at 14T. MR value decreases as the temperature increases and at 300 K maximum value of MR is found to be ~ 22% for an applied field of 14 T. MR of ~ 28% is observed at 230 K. MR of ~ 35% is observed at 150 K in an applied field of 14 T and MR has negative sign
A study of micro structural, magnetic and electrical properties of La-Co-Sm n...IJECEIAES
A Lanthanum (La 3+ ) doped Samarium-Cobalt nanoferrites (La_x,Co_0.2,Sm_0.2,Fe_(2-x) O_4, where x=0.0,0.5,1.0) have been synthesized by sol-gel method in citrate media. Obtained spinal ferrites micro structure properties have been investigated by XRD, FTIR, SEM-EDX, and TEM-SAED techniques. All the samples are nano in size with significant hysteresis. Micro structural analysis by XRD confirms the obtained samples showing the single phase cubic spinal structures with an average crystal size found from 12 nm to 25 nm, while the average particles sizes identified from TEM analysis are ranging from 21.5nm-26.8 nm (~23.4nm) and from 20.5 nm to 28(~26.4nm) nm for x=0.5,1.0. The lattice parameter found to be a= 8.402, 8.423, 8.467Å for the respective values of x= 0.0, 0.05, and 1.0. Electrical properties show increase in dc resistivity with increase in La ion concentration. Finally, it was concluded that the doping of Lanthanum ion (La 3+ ) in the ferrites structure is found to influencing the structural and electrical properties without scarifying the ferromagnetic character.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Studies on Electrical and Sensing Properties of Polyaniline / Iron Oxide (-F...IJERA Editor
Polyaniline iron oxide nanocomposites were prepared by in-situ polymerization method. These
nanocomposites were characterized by employing Fourier Transform Infrared (FT-IR), Scanning Electron
Microscope (SEM),Thermal study by (TGA).The dc conductivity of prepared nanocomposites was measured as
a function of temperature which shows the strong interaction between Polyaniline and iron oxide nanoparticles
and exhibits semiconducting behavior.Finally, the sensing properties of these nanocomposites are also studied at
room temperature.
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported that proceeds via the reduction of iron (III) oxide under hydrogen atmosphere. The ensuing magnetic catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm and Mössbauer spectroscopy and explored for a simple yetbut efficient transfer hydrogenation reduction of a variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine hydrate. . The catalyst could be easily separated at the end of reaction using an external magnet and can be recycled up to 10 times without any loss in catalytic activity.
The single crystal of MoSe2 grown by
chemical vapour transport (CVT)technique are used for the
fabrication of Photoelectro chemical (PEC) solar cells. The
effect of the illumination intensity on the conversion efficiency
of the fabricated PEC solar cell is studied.
Zno and znopbs heterojunction photo electrochemical cellseSAT Journals
Abstract Photo Electrochemical Cell (PEC) can also be used for splitting of water into hydrogen and Oxygen. Here, ZnO nanorod PEC has been prepared in hydrothermal method and ZnO/PbS quantum dot PEC has been prepared by hydrothermal method and chemical bath deposition method. UV-Visible spectroscopy has been observed. Flat band voltage, bandwidth and majority charge carriers have been calculated from Mott-Schottky. Impedance variation at semiconductor and electrolyte junction has been observed with Electrochemical Impedance Spectroscopy (EIS). Keywords: Hydrothermal, Chemical bath, ZnO/PbS, UV-Vis, Mott-Schottky, EIS.
Our GraphenX products are comprised of single layers of graphene oxide. It is a product of oxidation of graphite through a modified Hummers’ method. In contrast to commercially available graphene oxide sheets which possess lateral size generally less than 5μm, GraphenX are monolayers of oxidized graphene with outstandingly high lateral size (up to 0.1mm), rendering these products as an excellent candidate for diverse applications such as electronics, composite materials, energy and etc. GraphenX is a polar and functionalized material bearing several types of oxygen groups and is available in polar solvents (Water, NMP, DMF and Ethanol).
Effect of calcination on the electrical properties and quantum confinement of...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Effect of calcination on the electrical properties and quantum confinement of...eSAT Journals
Abstract Fe2O3 nanoparticles have been prepared by a simple solvothermal method using a domestic microwave oven. X-ray powder diffraction measurement indicates the amorphous nature of the as-prepared sample. Calcined samples were obtained by annealing the as-prepared sample at different temperatures, viz. 400, 500, 600 and 700oC. Transmission electron microscopic images indicate that all the five samples are spherical in shape. AC electrical measurements were carried out on pelletized samples by the parallel plate capacitor method at various temperatures ranging from 40-130oC and frequencies ranging from 100 Hz -1 MHz. Results indicate low AC electrical conductivities and consequently show the occurrence of nano confined states. The exciton Bohr radii obtained from the dielectric constant values at 40oC temperature and 1 kHz frequency are 41.8, 54.8, 55.3, 56.3 and 27.0 respectively for the as-prepared sample and samples calcined at 400, 500, 600 and 700oC which indicate a strong quantum confinement effect. The impedance spectra observed exhibit non-ideal behavior. Keywords: Semiconductors, Magnetic materials, Nanoparticles, Electrical properties
This is our final presentation for the entrepreneurial class for engineers and scientists. Watch this !
http://prezi.com/celjp-e47umm/water-treatment-space/
My presentation for a Lean Program Engineering Class in which we reduced the cost and weight of individual parts of a vehicle using lean product development techniques
This is our final presentation for the class in enterpreneurship for Engineers & Scientists. Watch this !
http://prezi.com/celjp-e47umm/water-treatment-space/
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Studies on Electrical and Sensing Properties of Polyaniline / Iron Oxide (-F...IJERA Editor
Polyaniline iron oxide nanocomposites were prepared by in-situ polymerization method. These
nanocomposites were characterized by employing Fourier Transform Infrared (FT-IR), Scanning Electron
Microscope (SEM),Thermal study by (TGA).The dc conductivity of prepared nanocomposites was measured as
a function of temperature which shows the strong interaction between Polyaniline and iron oxide nanoparticles
and exhibits semiconducting behavior.Finally, the sensing properties of these nanocomposites are also studied at
room temperature.
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported that proceeds via the reduction of iron (III) oxide under hydrogen atmosphere. The ensuing magnetic catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm and Mössbauer spectroscopy and explored for a simple yetbut efficient transfer hydrogenation reduction of a variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine hydrate. . The catalyst could be easily separated at the end of reaction using an external magnet and can be recycled up to 10 times without any loss in catalytic activity.
The single crystal of MoSe2 grown by
chemical vapour transport (CVT)technique are used for the
fabrication of Photoelectro chemical (PEC) solar cells. The
effect of the illumination intensity on the conversion efficiency
of the fabricated PEC solar cell is studied.
Zno and znopbs heterojunction photo electrochemical cellseSAT Journals
Abstract Photo Electrochemical Cell (PEC) can also be used for splitting of water into hydrogen and Oxygen. Here, ZnO nanorod PEC has been prepared in hydrothermal method and ZnO/PbS quantum dot PEC has been prepared by hydrothermal method and chemical bath deposition method. UV-Visible spectroscopy has been observed. Flat band voltage, bandwidth and majority charge carriers have been calculated from Mott-Schottky. Impedance variation at semiconductor and electrolyte junction has been observed with Electrochemical Impedance Spectroscopy (EIS). Keywords: Hydrothermal, Chemical bath, ZnO/PbS, UV-Vis, Mott-Schottky, EIS.
Our GraphenX products are comprised of single layers of graphene oxide. It is a product of oxidation of graphite through a modified Hummers’ method. In contrast to commercially available graphene oxide sheets which possess lateral size generally less than 5μm, GraphenX are monolayers of oxidized graphene with outstandingly high lateral size (up to 0.1mm), rendering these products as an excellent candidate for diverse applications such as electronics, composite materials, energy and etc. GraphenX is a polar and functionalized material bearing several types of oxygen groups and is available in polar solvents (Water, NMP, DMF and Ethanol).
Effect of calcination on the electrical properties and quantum confinement of...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Effect of calcination on the electrical properties and quantum confinement of...eSAT Journals
Abstract Fe2O3 nanoparticles have been prepared by a simple solvothermal method using a domestic microwave oven. X-ray powder diffraction measurement indicates the amorphous nature of the as-prepared sample. Calcined samples were obtained by annealing the as-prepared sample at different temperatures, viz. 400, 500, 600 and 700oC. Transmission electron microscopic images indicate that all the five samples are spherical in shape. AC electrical measurements were carried out on pelletized samples by the parallel plate capacitor method at various temperatures ranging from 40-130oC and frequencies ranging from 100 Hz -1 MHz. Results indicate low AC electrical conductivities and consequently show the occurrence of nano confined states. The exciton Bohr radii obtained from the dielectric constant values at 40oC temperature and 1 kHz frequency are 41.8, 54.8, 55.3, 56.3 and 27.0 respectively for the as-prepared sample and samples calcined at 400, 500, 600 and 700oC which indicate a strong quantum confinement effect. The impedance spectra observed exhibit non-ideal behavior. Keywords: Semiconductors, Magnetic materials, Nanoparticles, Electrical properties
This is our final presentation for the entrepreneurial class for engineers and scientists. Watch this !
http://prezi.com/celjp-e47umm/water-treatment-space/
My presentation for a Lean Program Engineering Class in which we reduced the cost and weight of individual parts of a vehicle using lean product development techniques
This is our final presentation for the class in enterpreneurship for Engineers & Scientists. Watch this !
http://prezi.com/celjp-e47umm/water-treatment-space/
A project based on the book Factory Physics, written by Prof Hopp of the University of Michigan's Ross School of Business, which focuses on manufacturing and inventory based problems
I prodotti vernicianti e i sistemi tintometriciFilippo Busolo
I prodotti vernicianti e i sistemi tintometrici. Slide del corso di formazione tenuto il 18/11/2016 presso l'Ordine Interprovinciale dei Chimici del Veneto.
Study of magnetic and structural and optical properties of Zn doped Fe3O4 nan...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes synthesizing of magnetic nanocomposite with co-precipitation
method.
Materials and Methods:
Magnetic ZnxFe3-xO4 nanoparticles with 0-14% zinc doping (x=0, 0.025, 0.05, 0.075, 0.1 and 0.125) were successfully synthesized by co-precipitation method. The prepared zinc-doped Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and UV-Vis spectroscopy.
Results:
results obtained from X-ray diffraction pattern have revealed the formation of single phase nanoparticles with cubic inverse spinal structures which size varies from 11.13 to 12.81 nm. The prepared nanoparticles have also possessed superparamagnetic properties at room temperature and high level of saturation magnetization with the maximum level of 74.60 emu/g for x=0.075. Ms changing in pure magnetite nanoparticles after impurities addition were explained based on two factors of “particles size” and “exchange interactions”. Optical studies results revealed that band gaps in all Zn-doped NPs are higher than pure Fe3O4. As doping percent increases, band gap value decreases from 1.26 eV to 0.43 eV.
Conclusion:
These magnetic nanocomposite structures since having superparamagnetic property
offer a high potential for biosensing and biomedical application.
- Nanoparticles NiFe2-xTbxO4 (x=0.00, 0.04, 0.08,
0.12) ferrite was prepared by solgel combution method. The
samples were characterized with X-ray diffraction and TEM
measurements. The effect of Tb3+ cations substitution on
structure of prepared nanoparticles was investigated. From the
analysis, the system was found to be inverse spinel cubic
structure. The lattice parameter (a) changes increases with Tb
doping content. Room temperature DC electrical resistivity
decreases. Dielectric properties have been studied in the
frequency range of 1 kHz to 5 MHz. Permittivity and tangent
loss (tanδ) decreases with the substitution of Tb3+ in parent
crystal structure.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Physical and Magnetic Properties of Manganese Ferrite NanoparticlesIJERA Editor
In this paper, manganese ferrite (MnFe2O4) nanoparticles were synthesized using chemical bath deposition (CBD) method and characterized by XRD and TEM to determine different properties of nanoparticles. The results obtained showed the formation of manganese ferrite nanoparticles with an average particle size are in good agreement with previous reported experimental results and displayed good magnetic properties. Magnetic properties was determined using Vibrating Sample Magnetometer(VSM). Due to simplicity and low cost of this process, it could be used for synthesis of ferrites nanoparticles. These materials may be used in drug delivery systems, electronic devices and water remediation.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect of Ytterbium Substitution on the Structural and Magnetic Properties of...ijtsrd
A series of ytterbium substituted Zinc ferrites Zn YbxFe1 x 2O4 with x=0.0000, 0.0125, 0.0250, 0.0375, 0.0500 was synthesized by the solid state method. The structural characterizations of all the prepared samples were done by using X ray diffraction XRD . These studies confirmed the formation of single phase structure in all compositions. The increase in the value of lattice parameter with increase in ytterbium concentration suggests the expansion of unit cell. Crystallinity and the crystallite size are observed to increase with the concentration of Ytterbium. The substitution of ytterbium strongly influences the magnetic characteristics and this is confirmed from the magnetization measurements at room temperature. Zar Zar Myint Aung "Effect of Ytterbium Substitution on the Structural and Magnetic Properties of Nanocrystalline Zinc Ferrite" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27826.pdf Paper URL: https://www.ijtsrd.com/physics/other/27826/effect-of-ytterbium-substitution-on-the-structural-and-magnetic-properties-of-nanocrystalline-zinc-ferrite/zar-zar-myint-aung
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
Optimization of structure-property relationships in nickel ferrite.pdfProximaCentauri15
In this report, a detail analysis of the impact of annealing temperature on the structural, elastic, morphological,
optical, and magnetic behavior of NiFe2O4 nanoparticles prepared by the citrate sol-gel method is presented.
Analyzing the XRD patterns by the Rietveld method confirms that all the annealed samples have been crystallized
to cubic spinel structure belonging to Fd3 m space group with a single phase. Rietveld analysis demonstrates the
change in structural and microstructural parameters and movement of cations from tetrahedral to octahedral
sites and vice-versa upon annealing. The quantitative estimation of Ni2+ & Ni3+ and Fe2+ & Fe3+ has been carried
out using XPS analysis. Decreases in peak broadening and shift of five Raman active peaks towards higher frequency
upon annealing have been analyzed using the phonon confinement model. The variation in elastic parameters
with annealing temperature has been assessed by FTIR analysis. The UV analysis reveals the increase of
the optical energy band gap and the decrease of Urbach energy with annealing temperature enhancement. A
noticeable sharp absorption band at 748 nm in UV spectra is attributed to 3A2g(3F)→3T1g(3F) electronic transition.
Room temperature magnetic hysteresis loops exhibit an increase of saturation magnetization upon
annealing which is discussed with reference to finite size effects and disorderly surface spins. The estimated value
of magnetocrystalline anisotropy constant by Law of Approach to saturation (LAS) theory as well as coercivity
value elucidates the annealing effect in changing the magnetic single domain state of the particle to a multidomain
state. Analysis of ZFC and FC magnetization curve measured at 100 Oe in the temperature range 400
K–60 K reveals the significant impact of annealing temperature on magnetic anisotropy, inter-particle interaction,
and blocking temperature. Exploring the magnetic hysteresis loop measured in the temperature range
60–400 K over field strength of ± 3 T demonstrates the significant role of annealing on magnetic exchange
interaction. Temperature dependent behavior of saturation magnetization and coercivity has been analyzed
using modified Bloch’s law and Kneller’s relation. The magnetic heating efficiency examined by the induction
heating system reveals that the sample has enough potential for hyperthermia application.
Dielectric, Electric and Thermal Behavior of La3+ doped Co-Zn NanoferriteIOSRJAP
Dielectric, Electric and Thermal properties of rare earth La3+ material doped in Co0.5Zn0.5 Lax Fe(2- x)O4 (where x=0.025, 0.050, 0.075, 0.100, 0.125) reaction nanocrystalline ferrites were synthesized by sol-gel auto combustion method. The electric, dielectric constant and Thermal properties were investigated. The dielectric constants and dielectric loss of the samples was observed between the 100Hz and 5 MHz. The resistivities of the prepared samples were measured from 0 Volt to 550 Volts at the constant temperature 2000C using the Two Probe method. The Thermal properties were characterized by Thermo Gravimetric and Differential Thermal Analysis (TGDTA).
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study of Microstructural, Electrical and Dielectric Properties of La0.9Pb0.1M...Scientific Review SR
The present work studies the microstructural and electrical properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 ceramics synthesized by solid-state route method. Microstructure and elemental analysis of both samples were carried out by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) method, respectively. Phase analysis by X-ray diffraction (XRD) indicated formation of single phase distorted structure. The XRD data were further analyzed by Rietveld refinement technique. Raman analysis reveals that Y atom substitutes La site into the LPMO with shifting of phonon modes. The temperature variation of resistivity of undoped and Y-doped La0.9Pb0.1MnO3 samples have been investigated. The electrical resistivity as a function of temperature showed that all samples undergo an metal-insulator (M-I) transition having a peak at transition temperature TMI. Y-doping increases the resistivity and the metal-insulator transition temperature (TMI) shifts to lower temperature. The temperature-dependent resistivity for temperatures less than metal-insulator transition is explained in terms the quadratic temperature dependence and for T > TMI, thermally activated conduction (TAC) is appropriate. Variation of frequency dispersion in permittivity and loss pattern due to La-site substitution in LPMO was observed in the dielectric response curve.
TiO2-HfN Radial Nano-Heterojunction: A Hot Carrier Photoanode for Sunlight-Dr...Pawan Kumar
The lack of active, stable, earth-abundant, and visible-light absorbing materials to replace
plasmonic noble metals is a critical obstacle for researchers in developing highly efficient and costeffective photocatalytic systems. Herein, a core–shell nanotube catalyst was fabricated consisting of
atomic layer deposited HfN shell and anodic TiO2 support layer with full-visible regime photoactivity
for photoelectrochemical water splitting. The HfN active layer has two unique characteristics: (1) a
large bandgap between optical and acoustic phonon modes (2) and no electronic bandgap, which
allows a large population of long life-time hot carriers, which are used to enhance the photoelectrochemical performance. The photocurrent density (≈2.5 mA·cm−2 at 1 V vs. Ag/AgCl) obtained in
this study under AM 1.5G 1 Sun illumination is unprecedented, as it is superior to most existing
plasmonic noble metal-decorated catalysts and surprisingly indicates a photocurrent response that
extends to 730 nm. The result demonstrates the far-reaching application potential of replacing active
HER/HOR noble metals such as Au, Ag, Pt, Pd, etc. with low-cost plasmonic ceramics.
2. Among other iron based compounds, FePt is an ideal com-
pound, but the cost and availability of Pt make it unsuitable for
mass application.
A relatively cheaper but interesting compound, Fe3Se4, has
been studied since the 1950s,8,9
but its hard magnetic property
remained unattended for a long time. Fe3Se4 has a NiAs-type
structure, and the iron vacancies are arranged in an ordered
fashion.8
Single crystal studies on Fe3Se4 have shown that it has
a monoclinic unit cell of dimensions a = 6.167 Å, b = 3.537 Å,
c = 11.17 Å, and β = 92.0°.11,12
Fe3Se4 orders ferrimagnetically
below 313 K. The easy axis of magnetization is in the c plane.
However, the magnetization does not saturate even at 11 T.8
The importance of this compound lies in its large uniaxial
magnetocrystalline anisotropy. In the case of anisotropic nano-
structures the anisotropy of the system can be further enhanced.
Recently, Zhang et al. have synthesized Fe3Se4 nanostructures
by a simple solution phase method that exhibits hard mag-
netic properties.10
There are only a few reports where this
ferrimagnetic monoclinic phase of iron chalcogenide has been
studied in nano dimensions.10−14
A coercivity value as large
as 40 kOe has been achieved at 10 K.6
The temperature
dependence of magnetocrystalline anisotropy of this compound
was studied both experimentally and theoretically by Wang
et al.13
Despite possessing such a unique property, the energy
product of this compound is low because of its low satura-
tion magnetization. At room temperature, a typical reported
magnetization value at a field of 9 T is ∼5 emu/g;10
however,
smaller values of magnetization, such as 1.89 emu/g at 300 K13
and 2.2 emu/g at 293 K12
for Fe3Se4 nanostructures, are also
reported.
Figure 2. (a−h) High resolution transmission electron microscope images (a) for Fe3Se4 and (b−h) for Fe3−xMnxSe4 (x = 0.01, 0.02, 0.03, 0.04,
0.05, 0.07, 0.1) samples at 200 nm scale. (i−p) High resolution transmission electron microscope images for Fe3−xMnxSe4 (x = 0.01, 0.02, 0.03, 0.04,
0.05, 0.07, 0.1) samples at 50 nm scale.
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3. The most imperative figure of merit for the hard magnets is
the maximum energy product (BH)max. The theoretical maxi-
mum of (BH)max is given by the following equation:2
μ=BH M( )
1
4
max 0 s
2
(1)
where μ0 is the permeability of free space and Ms is the
saturation magnetization. As the saturation magnetization (Ms)
plays a very important role in deciding the energy product,
increasing the Ms value is very crucial for its application in hard
magnetic materials.
The ferrimagnetism in Fe3Se4 arises due to the ordered iron
vacancy on the alternate layers of iron.10
Substitution of some
Fe with Mn ions may have an important influence on the net
ferrimagnetic moment of the system. In this work, we report a
significant increase in the saturation magnetization of Fe3Se4
nanostructures by doping Mn ions in Fe sites, Fe3−xMnxSe4
(x = 0.01−0.2). We also report a detailed analysis of the Raman
spectra explaining the effect of manganese ion doping on the
crystal structure, which may be related to the increase in satu-
ration magnetization.
2. EXPERIMENTAL SECTION
2.1. Materials. Iron(III) 2,4-pentanedionate [Fe(acac)3]
(>97%), manganese(III) 2,4-pentanedionate [Mn(acac)3]
(technical grade), Se (powder, 99.999%), and oleylamine
(80−90%) were purchased from Sigma-Aldrich and were used
without any further purification.
2.2. Synthesis of Fe3Se4 Nanoparticles. The synthesis
was done by a high temperature organic solution phase method
as reported elsewhere.10
Briefly, 0.53 g (1.5 mmol) of Fe(acac)3
and 0.158 g (2 mmol) of Se powder were added to 15 mL of
oleylamine in a 100 mL three-neck flask under N2 atmosphere.
The mixture was heated to 120 °C and kept for 1 h. Then, the
temperature was increased to 200 °C and kept for 1 h. Finally,
the solution temperature was raised to 300 °C and kept for 1 h.
After 1 h, the heat source was removed and the solution was
allowed to cool naturally to room temperature. The Fe3Se4
nanoparticles were precipitated by the addition of 20 mL of
2-propanol. The precipitate was then centrifuged and washed
with a solution containing hexane and 2-propanol in a 3:2 ratio.
2.3. Synthesis of Mn-Doped Fe3Se4 Nanoparticles.
[Fe(acac)3] and [Mn(acac)3] were mixed in a certain ratio (total
1.5 mmol) to synthesize Mn doped iron selenide nanoparticles
(Fe3−xMnxSe4) with x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.07, 0.1,
or 0.2.
2.4. Characterization Methods. Powder X-ray diffraction
(XRD) patterns were collected with the use of a PANalytical
X’PERT PRO instrument using iron filtered Cu Kα radiation
(λ = 1.5406 Å) in the 2θ range of 20−70° with a step size of
0.02°. The size and morphology of the prepared particles were
obtained with the use of an FEI Technai F30 high resolution
transmission electron microscope (HRTEM) equipped with
a supertwin lens (s-twin) operated at 300 keV accelerating vol-
tage with a Schottky field emitter source with a maximum beam
current (>100 nA) and small energy spread (0.8 eV or less).
The point-to-point resolution of the microscope is 0.20 nm
with a spherical aberration of 1.2 mm and a chromatic aberration
of 1.4 mm with a 70 μm objective aperture size. The powders
obtained were dispersed in hexane and then drop-cast on a
carbon-coated copper TEM grid with 200 mesh and loaded to a
single tilt sample holder.
Raman spectra were recorded on an HR-800 Raman spec-
trophotometer (Jobin Yvon-Horiba, France) using monochro-
matic radiation (achromatic Czerny−Turner type monochro-
mator with silver treated mirrors) emitted by a He−Ne laser
(633 nm), operating at 20 mW and with accuracy in the range
between 450 and 850 nm ± 1 cm−1
, equipped with a ther-
moelectrically cooled (with Peltier junctions), multichannel,
spectroscopic grade CCD detector (1024 × 256 pixels of
26 μm) with dark current lower than 0.002 electron pixel−1
s−1
.
An objective of 50× LD magnification was used both to focus
and to collect the signal from the powder sample dispersed on
the glass slide.
Static magnetic property measurements of Fe3Se4 nano-
particles were performed using a physical property measure-
ment system (PPMS) from Quantum Design Inc., San Diego,
CA, equipped with a 9 T superconducting magnet. We per-
formed dc magnetization vs temperature (M−T) and magnetic
field vs magnetization hysteresis (M−H) measurements using a
vibrating sample magnetometer (VSM) attachment. For dc
magnetic measurements, the samples were precisely weighed
and packed inside a plastic sample holder which fit into a brass
sample holder provided by Quantum Design Inc. with neg-
ligible contribution in the overall magnetic signal. We collected
M−H loops at a rate of 50 Oe/s in a field sweep from −85 to
85kOe at the vibrating frequency of 40 Hz. The M−T mea-
surements were also carried out in the temperature range from
Figure 3. (A) Raman spectra of Fe3−xMnxSe4 (x = 0−0.2) nanorods.
(B) Zoomed-in view of the encircled region in (A).
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4. 3 to 350 K at 100 Oe. The cooling and heating rates were kept
constant at 2 K/min for all the measurements. First, at 350 K,
the desired field was applied and the system was cooled to 3 K
and data were recorded while the sample was heated from 3 to
350 K. The curve obtained was designated as field cooled (FC)
cooling and field cooled heating, respectively. For zero field
cooled (ZFC) measurements, the sample was first cooled from
350 to 3 K in zero magnetic field and data were collected in
heating mode once the field was applied at 3 K.
3. RESULTS AND DISCUSSION
3.1. X-ray Diffraction. The crystal structure of Fe3Se4 was
characterized from the powder X-ray diffraction patterns. The
XRD peaks of the pure Fe3Se4 nanostructures are in good
agreement with bulk Fe3Se4 (JCPDS Card No. 657252), which
has monoclinic structure with a space group I2/m (12) and unit
cell lattice parameters a = 12.73, b = 3.493, and c = 6.159 Å (see
Supporting Information, Figure S1). The strongest line in the
pattern corresponds to the (111) plane. No significant changes
in the peak positions were observed in the XRD patterns of
Mn-doped samples compared with undoped Fe3Se4 (Figure 1).
Some peak broadening was observed for the (311) and (6̅02)
doublet peak with increasing doping concentration. The peak
broadening might be due to increase in lattice strain after
doping with Mn. Moreover, the X-ray form factors for Fe and
Mn are 15.6 and 14.9, respectively, and ionic radii for Fe3+
and
Mn3+
are 55 and 65 pm, respectively. Therefore, it is difficult
to interpret the intensity profile from Fe and Mn using a
lab source X-ray diffractometer. For the highly doped samples
(x = 0.1 and 0.2), the intensity of the (1̅12) and (6̅02) peaks
decreases slightly compared to other lightly doped samples.
The reason for this decrease of intensity of the (1̅12) and (6̅02)
peaks is not clear to us yet.
3.2. Electron Microscopy Imaging and Diffraction
Study. The HRTEM study of the Fe3Se4 nanostructures and
Mn-doped nanostructures shows that the rod-shaped nano-
structures are highly aggregated for all the samples (Figure 2)
due to their ferrimagnetic nature at room temperature.
Moreover, the image quality for magnetic particles is also
affected due to the strong Lorentz interaction of electrons with
oriented spins inside the particles. The diameter of the nano-
rods is in the range 30−50 nm. From high resolution images
(see Supporting Information, Figure S2), the lattice fringe with
interplanar distance d111 = 0.27 nm is clearly visible (which is
slightly larger than the point resolution of our microscope in
Scherzer defocus condition and atoms are visible as dark spots).
No significant changes in the morphology, size, and interplanar
distance of rods are observed after Mn doping. The selected
area electron diffraction (SAED) pattern shows (see Supporting
Information, Figure S3) the ring pattern though each particle
is single crystalline in nature (see Supporting Information,
Figure S3), which is due to the random orientation of a large
collection of such particles contributing from the selected area
by the SAED aperture in the back focal plane of the electron
microscope. From the energy dispersive spectra (EDS) of as-
synthesized Fe3Se4nanostructures, the Kα emission gives the
Figure 5. (A) Comparison of magnetization versus temperature curves
(in ZFC and FC modes) for undoped and doped (x = 0.04) Fe3Se4
nanorods. (B) Zoomed-in view of M−T curve around the transition
temperature to show that the Curie temperature does not change with
doping.
Figure 4. (A) Variation of the fwhm of Raman modes of 225 and
400 cm−1
in the Raman spectra with doping concentration x. (B)
Variation of the peak shift of Raman modes of 225 and 400 cm−1
in the
Raman spectra with doping concentration x with respect to pure Fe3Se4.
The Journal of Physical Chemistry C Article
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5. ratio of the atomic percent of iron and selenium as 0.75 (see
Supporting Information, Figure S4 and Table S1).
3.3. Raman Study. Raman scattering is an excellent tool to
study the lattice strain and bond disorder. We observed that the
Raman spectra of all samples (doped and undoped) are the
same with little shift in peak position and change in the full
width at half-maximum (fwhm). We believe that this is the first
report of Raman spectra of Fe3Se4, and therefore, due to the
absence of any previous report on Raman spectra of Fe3Se4
in the literature, we compared our results with those for
β-Mg2SiO4, which crystallizes in a similar I2/m space group
symmetry.15,16
The peaks at ∼228 and 411 cm−1
in Fe3Se4
spectra can be assigned to lattice vibration (Figure 3). The shift
in Raman peak position as a function of Mn doping concen-
tration is shown in Figure 4. It was found that both Raman
peaks shift to lower cm−1
as the Mn doping concentration
increases and show a dip at x = 0.05 and then again shift to
higher cm−1
. From this observation, it can be concluded that,
for the increase in the doping until x = 0.05, the lattice strain
decreases and, for higher doping, the lattice strain increases.
The fwhm also shows the same doping concentration (x =
0.05) as a peak and higher doping concentration samples show
almost similar values of fwhm. The increase in fwhm can be due
to the increase in disorder in the lattice.
3.4. Magnetic Studies. The temperature-dependent
magnetization is measured in a 100 Oe field. From the M−T
curve, the Curie temperature of iron selenide nanoparticles is
found to be 328 K (Figure 5A). According to earlier reports of
doping with transition metals,6
the Curie temperature and the
saturation magnetization decreased with increased concen-
tration of Co ion doping and the samples become paramagnetic
at room temperature. The coercivity at room temperature was
reduced to zero with cobalt ion doping. From the zoomed-in
view of the M−T curve (Figure 5B), it is clear that the Curie
temperature does not change with Mn ion doping.
All the doped and undoped samples show hard magnetic
properties (Figure 6).The room temperature coercivity (Hc) of
Fe3Se4 is found to be 2.74 kOe. This coercivity value is com-
parable to those of the RE-based nanoparticles of SmCo5
(Hc 2−8 kOe) and Nd2Fe12B (Hc 1.2−4 kOe).17−20
The inset
of Figure 6 shows a zoomed-in view of the hysteresis curves
clearly depicting the coercive and remanence field for samples
with varying doping concentration. At lower temperature a
colossal increase in coercivity is observed and Hc reaches
27.08 kOe at 10 K (Figure 7), which is in good agreement with
the earlier reports.6,8,9
M−H data show no saturation of magne-
tization even at the field value of 8.5 T (Figure 6).This may be
due to a superparamagnetic contribution in the magnetization
which may come from some ultrafine particles;9
also, any
“ferri”magnetic system requires a higher field to align all the
spins and we may have uncompensated spin and spin disorder
at the surface of the nanorods. For Fe3Se4 the magnetization at
8.5 T is 4.8 emu/g at 300 K, which increases to 14.18 emu/g at
10 K (Figure 7). The saturation magnetization is determined
from the M versus 1/H plot at the high field range (above 6 T).
As we increase the Mn doping concentration slowly from x =
0.01 to 0.03, the magnetization value (Ms) increases from 5.76
to 7.5 emu/g; the remanence magnetization (Mr) also shows an
increase in this range. Beyond x = 0.03 (for x = 0.04, 0.05,
0.07), the Ms values decrease with increase in doping concen-
tration. As the Mn doping is further increased (x = 0.1, 0.2),
Table 1. Summary of Magnetization Parameters Calculated for Fe3−xMnxSe4 Nanorodsa
no. x Hc(300 K) (kOe) Ms (emu/g) Mr (emu/g) Mr/Ms Ha(300 K) (kOe) K(300 K) (erg/cm3
) energy product (kG Oe)
1 0 2.74 4.84 1.63 0.336 7.053 1.12 × 105
4.377
2 0.01 2.76 5.79 1.9 0.328 7.376 1.4 × 105
5.858
3 0.02 2.47 6.73 2.11 0.313 6.028 1.33 × 105
7.352
4 0.03 2.17 7.54 2.5 0.331 5.169 1.38 × 105
10.22
5 0.04 2.4 5.74 1.93 0.336 6.054 1.14 × 105
6.139
6 0.05 2.65 5.55 1.97 0.354 6.427 1.17 × 105
6.457
7 0.07 2.3 5.20 1.84 0.353 5.497 0.94 × 105
5.575
8 0.1 1.99 4.56 1.35 0.296 5.154 0.82 × 105
3.08
9 0.2 1.94 4.41 1.09 0.247 5.211 0.75 × 105
1.953
a
Hc, coercivity; Ha, anisotropy field; K, anisotropy constant.
Figure 6. Comparison of M−H curves for Fe3−xMnxSe4 (x = 0, 0.01,
0.02, 0.03, 0.04, 0.05, 0.07, 0.1, and 0.2) nanorods at 300 K.
Figure 7. Comparison of M−H curves for Fe3−xMnxSe4 (0, 0.1, and
0.2) nanorods at 10 and 300 K.
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6. the saturation magnetization shows a significant decrease and
drops even below that of the Fe3Se4 sample (Table 1). A similar
phenomenon of decrease in saturation magnetization at higher
doping concentration is also observed when monoclinic
zirconia is doped with manganese ions.21
The reason for this
decrease in saturation magnetization with higher Mn ion con-
centration may be attributed to the antiferromagnetic coupling
between manganese ions at higher doping concentration.23
For
Fe3Se4 the Mr/Ms value was found to be 0.336; for a heavily
doped sample (x = 0.2) this ratio drops to 0.247 (Figure 8).
The coercivity experiences a very small decrease with manga-
nese doping for low doping concentration. However, for x = 0.1
and 0.2, the coercivity reduces significantly (Table 1). The
reason for the increase in saturation magnetization initially with
manganese ion doping may be due to the net contribution of
Mn ions to the ferrimagnetic moment. At 10 K, the coercivity
of Fe3Se4 increases to 29.5 kOe, which is 10-fold greater than
the value at 300 K. The M−H loop becomes close to square at
10 K and the Mr/Ms ratio increases to 0.587.
The upper limit to coercivity is determined by the anisotropy
field of the material.4
As a general trend, the coercivity of the
material reaches nearly 25% of the anisotropy field. We have
determined the anisotropy field by extrapolating the magne-
tization graph in easy and hard axis directions.22,23
The aniso-
tropy constant (K) at 300 K was calculated from the saturation
magnetization (Ms) and anisotropy field (Ha) according to the
following equation.
=K M H
1
2
s a
(2)
At 300 K, K for Fe3Se4 is 1.12 × 105
erg/cm3
. The K value was
determined for all nine samples and is tabulated in Table 1. As
observed earlier,6
the K value for Fe3Se4 is an order of
magnitude higher than that for Fe3O4.
The energy product of all the samples was calculated from
the third quadrant of the B−H hysteresis loop at 300 K. The
third quadrant of the B−H loop for pure Fe3Se4 nanostructures
is shown in Figure 9. The area under the shaded portion repre-
sents the energy product of the sample. For Fe3Se4 the energy
product is found to be 4.38 kG Oe, which increases to 10.22 kG
Oe for Fe2.97Mn0.03Se4. At 10 K, the energy product increases
by almost 2 orders of magnitude for Fe3Se4 (∼0.12 MG Oe).
The practical energy product that we can get from a permanent
magnet depends strongly on its processing. The alignment
of easy axes in a particular direction can greatly enhance the
Mr/Ms ratio and help in increasing the energy product.
Compacting the magnetic nanoparticles with high packing
densities is very crucial for the development of permanent
magnets. This enhancement of the energy product by more
than 130% is a vital step in developing new rare-earth-free
alternatives to permanent magnets.
4. CONCLUSION
In conclusion, we have successfully synthesized manganese
doped iron selenide nanostructures in an attempt to increase
the energy product of the sample. The magnetization value in-
creased from 4.84 to 7.54 emu/g, without any change in the
Curie temperature, which is important for its application in
hard magnets. We could obtain a more than 130% increase in
the energy product value in manganese doped iron selenide
nanostructures. At lower temperatures, a 2 order of magnitude
increase in the energy product is observed. The reason for the
decrease in coercivity and saturation magnetization in highly
doped samples is not clear and is a subject of further study with
the help of neutron diffraction studies, etc.
■ ASSOCIATED CONTENT
*S Supporting Information
X-ray diffraction pattern image, selected area diffraction pattern,
high resolution images of lattice fringes, and EDX spectrum
images. This material is available free of charge via the Internet
at http://pubs.acs.org.
■ AUTHOR INFORMATION
Corresponding Author
*E-mail: p.poddar@ncl.res.in.
Author Contributions
∥
M.S.B. and R.D. contributed equally to this work.
Notes
The authors declare no competing financial interest.
■ ACKNOWLEDGMENTS
P.P. acknowledges the Centre of Excellence on Surface Science
at the National Chemical Laboratory and network project
Nano-SHE funded by the Council of Scientific and Industrial
Research (CSIR), India, and Department of Science &
Technology (DST), India (DST/INT/ISR/P-8/2011). M.S.B.
Figure 8. Variation of Ms and Mr/Ms ratio with doping concentration
(x) for Fe3−xMnxSe4 nanorods.
Figure 9. M−H plot and B−H plot for Fe3Se4 nanocrystals at 300 K.
(inset) Calculation of maximum energy product from the B−H
hysteresis loop of Fe3Se4 at 300 K.
The Journal of Physical Chemistry C Article
dx.doi.org/10.1021/jp411956q | J. Phys. Chem. C 2014, 118, 4016−40224021
7. acknowledges the Department of Science and Technology,
INSPIRE, India, for financial support. R.D. acknowledges the
Council of Scientific and Industrial Research (CSIR), India, for
providing a Senior Research Fellowship (SRF).
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