This document describes a study on the structural and magnetic characterization of Co2+ substituted nanostructured copper-zinc spinel ferrites. Nano particles of Cu0.61-xCoxZn0.39Fe2O4 were synthesized using a sol-gel auto combustion method. Various characterization techniques were used to analyze the effect of Co2+ substitution on properties like particle size, lattice constant, density, cation distribution, and magnetic properties. It was found that lattice parameter and particle size increased with Co2+ content while density decreased. Cation distribution analysis showed a preference of Co2+ and Cu2+ for octahedral sites and Zn2+ for tetrahedral sites. Magnetic properties like saturation magnetization and coerc
The document discusses thermodynamic activities in the Pb(Zr1-XTiX)O3 solid solution at 1373 K. It describes how tie-line compositions were determined for intercrystalline ion exchange equilibria between Pb(Zr1-XTiX)O3 solid solution and (Zr1-YTiY)O2 solid solutions. Using this information along with known activities in the (Zr1-YTiY)O2 solutions, activities of PbTiO3 and PbZrO3 in the Pb(Zr1-XTiX)O3 solution were derived. The results showed significant positive deviation from ideality for PbTiO3-rich compositions
1. Precipitation is an easy and cost-effective process to produce nano-sized particles using inexpensive source materials like inorganic chemicals.
2. Precipitation often results in hard aggregation of primary particles during washing, filtration, and drying which must be addressed.
3. Methods to prevent aggregation include controlling crystal growth, maintaining a constant pH washing solution to encourage electrostatic repulsion, and ball milling dried aggregates with less polar solvents.
1) The document examines the high temperature oxidation behavior of a nickel-based superalloy produced by mechanical alloying. Samples were mechanically alloyed, sintered, hot-deformed, and underwent secondary recrystallization.
2) Isothermal oxidation tests were conducted on the samples at 1000°C for up to 100 hours. SEM and XRD analysis found that a protective chromium oxide (Cr2O3) film formed on the surfaces. Weight change results indicated the samples gained a small amount of weight over time, exhibiting sub-parabolic oxidation behavior.
3) XRD analysis identified the primary oxide as Cr2O3. The intensity of Cr2O3 peaks in XRD
The document discusses barium perovskites as potential humidity sensing materials. Three key points:
1) Samples of BaMO3 (M=Ti, Zr, Hf, Sn) were prepared via wet chemical synthesis or solid state reaction and tested for their electrical response to humidity.
2) All samples showed an increase in capacitance and conductivity with increasing humidity, indicating interaction between water vapor and the crystal surfaces. Sensitivity was highest at low frequencies and decreased with increasing humidity.
3) Time response to humidity changes was typically 10-100 seconds for intermediate humidity levels. Response time was influenced by the amount of mesopores in the material, with shorter response times associated with less mesoporous
Biopolymer based nanomaterials as potential biosorbents for toxic metal ionsAlexander Decker
This document summarizes a research study on the use of ternary nanoparticles composed of chitosan, yeast, and gelatin for removing toxic copper ions from water. The nanoparticles were characterized using FTIR and TEM analysis. FTIR showed the presence of functional groups from the three biopolymers and shifts upon copper ion adsorption. TEM revealed nanoparticle sizes ranging from 50-150 nm. Batch experiments showed over 90% copper ion removal, with adsorption fitting well to the Langmuir isotherm model. The effects of biopolymer composition, metal ion concentration, pH, and temperature on adsorption capacity were also examined.
This document summarizes a study on using an aqueous extract of Tridax Procumbens (TP) to inhibit corrosion of carbon steel in an aqueous solution containing chloride ions. Weight loss experiments showed that a formulation of 1 ml of TP extract and 150 ppm of Zn2+ inhibited corrosion by 96%. Polarization studies indicated that the TP-Zn2+ system functions as a cathodic inhibitor. AC impedance spectra revealed that a protective film formed on the steel surface. FTIR analysis showed the protective film consists of Fe2+-TP and Zn(OH)2. Adsorption of the inhibitor onto the steel surface followed the Langmuir isotherm model better than the Freundlich model. The
Synthesis and Study on Structural, Morphological and Magnetic properties of n...Editor IJCATR
Mn3O4 nanoparticles were prepared by co-precipitation method followed by annealing of samples at 300 °C for 2 hours. The
samples were characterized to find the structural, functional, optical, morphological, compositional and magnetic properties by PXRD,
FTIR, Micro-Raman, HRSEM, TEM, XPS, EDX and VSM respectively. Structural studies by PXRD indicate that the annealing has
strongly influenced the phase transition showing two coexisting phases of Mn2O3 and Mn3O4. Micro-Raman spectra showed the
presence of A1g mode of vibration corresponding to Mn3O4 phase. Magnetic studies of the as synthesized Mn3O4 nanoparticles depict
paramagnetic behavior at room temperature.
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.
Fabrication and characterization of conducting polymer compositeijoejournal
The document summarizes research on fabricating and characterizing a conducting polymer composite of polyvinylpyrrolidone (PVP) and potassium hydroxide (KOH). Specifically:
1. PVP and KOH were mixed using a solution casting method to prepare polymer composite specimens.
2. Tests found that the composite's conductivity and microhardness increased with higher KOH concentrations. The highest conductivity was 4×10-4 S/cm at 35 wt% KOH.
3. Microstructure analysis using an optical microscope showed even KOH distribution throughout the composite at 35 wt% KOH, the concentration with highest conductivity.
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 and analysis of electrical properties of Lead free Ba3Sr2LaTi3V7O30...inventy
This document summarizes research on the synthesis and analysis of electrical properties of a lead-free vanadate compound with the formula Ba3Sr2LaTi3V7O30. The compound was synthesized through solid-state sintering and characterized through X-ray diffraction and impedance spectroscopy. XRD analysis confirmed the formation of a single-phase orthorhombic structure. Impedance spectroscopy revealed the electrical response was mainly due to grain effects and identified two relaxation processes corresponding to grain boundaries and bulk effects. Conductivity increased with temperature, showing negative temperature coefficient behavior.
Studies of the Atomic and Crystalline Characteristics of Ceramic Oxide Nano P...albertdivis
In the present study, some transition metal oxides (Zinc oxide, iron oxide and copper oxide) which are widely used in the fabrication of electronic devices were selected and subjected to biofield treatment.
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.
Preparation, Structure, and Characterization of Nd2mo2o9 fast Oxide Ion Condu...IJARIIT
The structure and ion conductivity of Nd2Mo2O9powders were synthesized by using Nd(NO2)3, MoO3, and aspartic acid (fuel) in assisted combustion method with heating at 550˚C for 6 hours. The thermal decomposition, phase identification, morphology, ionic conductivity of the samples were studied by TGA/DTA, XRD and SEM four probe D.C. method respectively. The formation of Nd2Mo2O9 was confirmed by FTIR studies. The synthesis and crystallization were followed by thermochemical techniques (TGA/DTA) studies. The synthesized materials showed reasonable ionic conductivity. These results indicate that assisted combustion method is a promising method to prepare nanocrystalline Nd2Mo2O9 for solid oxide fuel cell.
Ferrites: Ferrites are mixed metal oxides of magnetic nature in which iron is the main component.
In general, ferrites show four different types of crystal structures namely,
1] Ferrospinel Structure.
2] Hexagonal Structure.
3] Garnet Structure.
4] Orthoferrite structure.
We are going to discuss about spinel structure as Co Ni ferrite is a spinel ferrite.
Ferrospinel Structure.
They have the general formula MeFe2O4, where Me is divalent metal ion or a mixture of ions having average valence of two. The unit cell is cubic. The oxygen ions forms a nearly close-packed face centered cubic structure and the metal ions are distributed over tetrahedral and octahedral holes.
Normal ferrites:In which all-divalent metal ions occupy A sites and all the Fe3+ occupy B sites.
e.x. Zn 2+ [Fe23+] O4
Zn 2+ ions have a very low octahedral preference; therefore they enter the A-sites of the lattice, resulting in normal ferrites.
Inverse ferrites:In which all divalent metal ions and half the Fe3+ ions occupy B sites while remaining Fe3+ occupy A sites.
e.x. Fe3+[ Fe3+ Ni2+] O4
Mixed ferrites:In which all divalent metal ions and Fe3+ ions are uniformly distributed over the tetrahedral and octahedral sites.
Co - Ni ferrite is a mixed spinel ferrite, which has general formulae
AII x BII 1-x Fe2O4
This document summarizes the synthesis and characterization of lithium substituted copper-manganese ferrite nanoparticles. Four samples of lithium ferrite nanoparticles with varying lithium content were prepared using an auto-combustion technique. Magnetic characterization using vibrating sample magnetometry showed that magnetization increased from 5.08 emu/g to 45.35 emu/g with increasing lithium content. Field emission scanning electron microscopy revealed that grain size also increased from 96 nm to 112 nm with higher lithium substitution levels. In conclusion, lithium substituted copper-manganese ferrite nanoparticles were successfully synthesized and exhibited ferromagnetic behavior and tunable properties based on the lithium content.
This document summarizes a presentation given by Miss. Sarita Kumbhar on her research synthesizing and characterizing nickel-zinc ferrite thin films under the guidance of Prof. C. H. Bhosale. The presentation covered the methodology using spray pyrolysis, results from XRD, SEM, AC conductivity, and dielectric property measurements. Key findings included that the nickel-zinc ferrite thin films had a polycrystalline spinel cubic structure, smooth and uniform surface morphology, AC conductivity dependent on frequency, and decreasing dielectric constant with increasing frequency. Impedance spectroscopy also provided insight into grain boundary behavior.
This document summarizes a seminar on magnetic nanocomposites. It discusses how nanocomposites have particles mixed at the nanoscale, including magnetic nanocomposites containing ferromagnetic particles. The history of magnetic nanocomposites is reviewed, from early amorphous alloys to developments in the 1980s-1990s of alloys like FINEMET, NANOPERM, and HITPERM. Recent developments discussed include core-shell nanoparticles, colloidal crystals, mesoporous nanocomposites, and functional polymers. Applications mentioned are using magnetic fields to destroy tumor cells, transformers, and DC-DC power converters. Challenges remaining are controlled synthesis, understanding mechanisms, cost, toxicity
This document summarizes a research paper that analyzes unsteady magnetohydrodynamic (MHD) free convection heat and mass transfer flow through a non-homogeneous porous medium bounded by an infinite porous vertical plate. The flow considers effects of radiation, chemical reaction, temperature gradient dependent heat source, and exponentially decreasing permeability and suction velocity. Governing equations are derived and solved approximately using perturbation techniques. Results are discussed for cooling of the plate, showing effects of parameters on velocity, skin friction, and heat/mass transfer rates through graphs and tables.
Combining both Plug-in Vehicles and Renewable Energy Resources for Unit Commi...IOSR Journals
This document presents a study that combines plug-in electric vehicles with vehicle-to-grid technology (V2G), renewable energy resources like wind and solar, and existing power plants, to optimize unit commitment in smart grids. The goal is to minimize total costs and emissions. A genetic algorithm is used to optimize scheduling of generation units, V2G vehicles providing spinning reserves, and time-varying renewable sources over a 24-hour period to meet load demand at lowest cost while satisfying constraints. Simulation results validate that integrating V2G and renewable energy sources can effectively reduce costs and emissions for the smart grid.
The document provides an overview of SAP FICO interview questions and answers related to various topics like enterprise structure, general ledger, accounts receivable, accounts payable, and invoice verification. It was published by SAPTOPJOBS, a team of SAP consultants, to help candidates clear SAP FICO interviews with 100% success. The copyright information is also provided.
Modeling of generation and propagation of cardiac action potential using frac...IOSR Journals
This document presents a model for simulating cardiac action potentials using fractional differential equations. The model builds off the existing Hund-Rudy dynamic model by replacing ordinary differential equations with fractional differential equations to more accurately model ion exchange mechanisms. The fractional model is shown to capture cardiac action potential generation and propagation with higher accuracy than ordinary differential equation models. An electrical circuit representation of the fractional model is also proposed to abstract the transmembrane ion exchange process.
Cynthia Elmore is an experienced events operations manager with nearly 15 years of experience coordinating and managing events in over 30 countries. She is currently an Events Manager at Centre for Management Technology in the Netherlands, where she project manages events from inception to completion. Prior to this role, she was a Venture Manager and Executive Assistant at Feyecon BV & Algae Biotech, where she managed multiple joint ventures and new business development. She has also held leadership roles such as General Manager of Events & Office Operations at Centre for Management Technology in Singapore.
This 3 page document from NewTek discusses trends, ideas and scenarios for their website in 2014. It focuses on new technologies and how consumers are interacting with companies online. The document also provides recommendations on how NewTek can improve their website to better engage customers and drive sales through new features and strategies.
The document discusses 5 blogs and what media techniques they use to convey information and engage consumers. It also asks which areas from the blogs would be employed in the respondent's own blog. The blogs discussed use techniques like images, videos, reviews and autobiographies to effectively engage consumers on topics like urban culture, movies, jazz music and beauty. The respondent indicates they would employ feedback links, slideshows, autobiographies and quotes in their own blog.
IOSR Journal of Business and Management (IOSR-JBM) is an open access international journal that provides rapid publication (within a month) of articles in all areas of business and managemant and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications inbusiness and management. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document describes a low power pipelined FFT processor architecture based on the Radix-4 single delay commutator (R4SDC) algorithm. It implements and compares 16, 64, and 256-point FFT architectures using conventional R4SDC, a complex multiplier, and a multiplier-less architecture based on common subexpression technique. For the 16-point FFT, an ordered R4SDC architecture is proposed that reorders coefficients and inputs to minimize switching activity and reduce power consumption compared to the conventional design. Simulation results show the area and power requirements of the different architectural implementations.
Pillows and chairs can be used for both relaxation and exercise or play. Pillows are commonly used for sleeping or leaning but can also be used for pillow fights with friends. Chairs can be sat on but also used for balancing exercises by dancing on them or testing their quality, and chairs and pillows arranged together can make a cute scene.
SIMULINK Based Model for Determination of Different Design Parameters of a Th...IOSR Journals
1) A SIMULINK model is presented to determine the design parameters of a 3-phase squirrel cage induction motor through computer simulation. The model calculates dimensions such as stator and rotor diameters, core lengths, slot sizes, conductor areas, and other parameters based on input specifications.
2) The document outlines the SIMULINK models used to calculate key motor components like the main frame, stator, conductor size, slots, core, air gap, rotor, end rings, and performance parameters. Test inputs are provided and the model outputs various motor dimensions that meet the specified ratings and design constraints.
3) The simulation results match expected values and indicate the motor slip will be around 5.8%, which is
The document discusses the learning process from a preliminary school magazine task to the full product. It notes that the preliminary version used basic typography and no photos, while the front cover had 5 fonts making it disorganized. For the final product, the author included photos on every page and learned to avoid overdesigning. The document concludes that magazines need to seem suitable for their audience and that the author gained knowledge of software to create the final product.
A Novel High Order Tree for Securing Key Management for Multicast ServicesIOSR Journals
The document proposes a novel high order tree scheme called MKE-MGKM for securing key management in multiple multicast group environments. The MKE-MGKM scheme uses asymmetric master and slave keys generated from a master key encryption algorithm. This asymmetry allows rekeying overhead to be reduced by modifying only the master key when a slave key is updated, while keeping other slave keys unchanged. Numerical analysis and simulations show the MKE-MGKM scheme can reduce the storage overhead of a key distribution center by 75% and the storage overhead of a user by up to 85%, as well as communication overhead by 60%, compared to existing schemes. The scheme aims to address limitations of existing group key management schemes for multiple co-existing multicast
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
Synthesis and Characterisation of Copper Oxide nanoparticlesIOSR Journals
Cupric oxide (CuO) nanoparticles were prepared by the chemical route by calcinations at a higher temperature from 300oC to 400 oC. For the comparison transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements were made through JCPDS. There is good agreement between data produced by spectroscopy and the microscopic measurements.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Synthesis and charaterization of la1 x srxmno3 perovskite nanoparticlesMai Trần
In recent times perovskite materials are extensively studied and have attracted much attention because they exhibit interesting the properties, showing potential applications in commercial, technical and biomedical. In Vietnam, perovskite materials be of interest research and applications are strong but with major research direction is to go deep into the electrical properties and the magnetic properties. The Lanthanum Strontium manganite is a perovskite-based crystal-structured ceramic material with the formula of La1-xSrxMnO3, where x describes the doping ratio. It has attracted much attention due to its good magnetic, electrical, and catalytic properties and is becoming an attractive possibility material in several biomedical applications, particularly with nano-size. In industry, this material is commonly used in as a cathode material in commercially produced solid oxide fuel cells. In this thesis, we present the Perovskite nanoparticles La1-xSrxMnO3 were successfully synthesized of the nanosize La1-xSrxMnO3 at x = 0; 0.1; 0.2; 0.3 and 0.4 which prepared by a modified sol-gel method. Structure and magnetic properties of them were systematically investigated in dependence on doped Sr ratio x. The structure was investigated by XRD and show slightly changed but magnetic properties varied strongly with changing the doping ratio x. Magnetic properties of samples were studied by Vibrating Sample Mode of Physical Properties Measurement System show at the room temperature, the samples show superparamagnetic properties with high saturated magnetization MS of 57 emu/g which strongly dependents on the doped Sr ratio x.
This document summarizes a study that investigated three copper(II) imidazolate frameworks as photocatalysts for reducing CO2 into methanol under visible light irradiation. The frameworks were synthesized via hydrothermal or precipitation reactions and characterized using various techniques. Their photocatalytic activities for CO2 reduction and methylene blue degradation were evaluated. Results showed the orthorhombic copper(II) imidazolate framework with a band gap of 2.49 eV and green color exhibited the best photocatalytic activity for CO2 reduction, producing 1712.7 μmol/g of methanol over 5 hours. Its synergistic small band gap and crystal structure were determined to be critical factors for its performance.
Dielectric behaviour of Ni+2 substituted Cu Co Nanocrystalline Spinel Ferrite...inventionjournals
Herein, the dielectric properties such as permittivity (real part ε’ and imaginary part ε”) and dielectric loss tangent (tan δ) are reported for the series [Nix Cu(constant) Co0.8-x Fe2O4] where constant=0.2 with x=0.2, 0.4 and 0.6 of ferrites, prepared by Sol-Gel auto-combustion technique by using high purity metal nitrate and citric acid as a catalyst. The variation in the real part (ε’) of dielectric constant , imaginary part ( ε”) of dielectric constant and dielectric loss tangent (tan δ) are studied at room temperature in the frequency range of 100 Hz to 5 MHz. Structural characterization of the annealed samples was done with the help of X-ray diffraction method. The particle size and single phase formation of NiCuCoFe2O4 ferrite was confirmed by Xray diffraction analysis and TEM. The particle size of prepared sample was confirmed by Scherer’s formula. The effect on Particle size (t) and lattice constant (Å) is observed due to substitution of Ni2+ in Cu Co. The digital LCR meter is used to obtain the magnetic properties of prepared pallets. The variations in the structural and dielectric properties of the prepared ferrite material are discussed.
Dielectric behaviour of Ni+2 substituted Cu Co Nanocrystalline Spinel Ferrite...inventionjournals
Herein, the dielectric properties such as permittivity (real part ε’ and imaginary part ε”) and dielectric loss tangent (tan δ) are reported for the series [Nix Cu(constant) Co0.8-x Fe2O4] where constant=0.2 with x=0.2, 0.4 and 0.6 of ferrites, prepared by Sol-Gel auto-combustion technique by using high purity metal nitrate and citric acid as a catalyst. The variation in the real part (ε’) of dielectric constant , imaginary part ( ε”) of dielectric constant and dielectric loss tangent (tan δ) are studied at room temperature in the frequency range of 100 Hz to 5 MHz. Structural characterization of the annealed samples was done with the help of X-ray diffraction method. The particle size and single phase formation of NiCuCoFe2O4 ferrite was confirmed by Xray diffraction analysis and TEM. The particle size of prepared sample was confirmed by Scherer’s formula. The effect on Particle size (t) and lattice constant (Å) is observed due to substitution of Ni2+ in Cu Co. The digital LCR meter is used to obtain the magnetic properties of prepared pallets. The variations in the structural and dielectric properties of the prepared ferrite material are discussed
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.
final accept-Optical and structural properties of TiO2 nanopowders with Co-Ce...nasrollah najibi ilkhchy
This document discusses a study on the optical and structural properties of TiO2 nanopowders doped with 2 mol% cerium and 4 mol% cobalt. X-ray diffraction analysis showed that cerium doping inhibited the formation of the rutile phase of titanium dioxide and promoted retention of the anatase phase at higher calcination temperatures. Optical absorption spectroscopy indicated that doping reduced the band gap of titanium dioxide from 3.21 eV to 3.14-3.20 eV. The crystallite size decreased with doping while the surface area increased compared to undoped titanium dioxide.
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
Studies On The Cobalt(II) And Copper(II) Complexes Of 2,5-Substituted 1,3,4-T...IOSR Journals
1. New metal complexes of Co(II) and Cu(II) were synthesized by reacting solutions of the metal salts with 2,5-substituted 1,3,4-triazole ligands in an alcoholic medium.
2. The complexes were characterized through techniques such as elemental analysis, magnetic susceptibility, molar conductance, and IR spectroscopy.
3. Based on analytical data and characterization, the complexes were determined to have a 1:2 metal to ligand ratio and the ligand was found to act as a bidentate ligand coordinating through nitrogen atoms in the ring.
This document summarizes research on nanocrystalline titania powders doped with copper. Key findings include:
- Copper doping affected the phase stability of titania, promoting the rutile phase at higher temperatures.
- The 5% copper-doped titania sample had the largest degradation of methylene orange dye under visible light, indicating better photocatalytic activity than pure titania.
- UV-Vis spectroscopy estimated the band gap of the copper-doped titania to be 1.9-2 eV, lower than pure titania and allowing absorption of visible light.
Structure, microstructure and dielectric study of (ba0.6 sr0.4)(zr0.6ti0.4)o3...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.
Synthesis, characterization and electrocatalytic activity of silver nanorods ...tshankar20134
This document describes the synthesis of silver nanorods using a polyol process. Silver nitrate and polyvinylpyrrolidone (PVP) are reduced by propylene glycol at high temperature, allowing control over the diameter and length of the nanorods. Characterization with SEM, TEM, XRD and UV-vis spectroscopy confirms the formation of crystalline silver nanorods. Electrochemical testing shows that a glassy carbon electrode coated with silver nanorods exhibits high catalytic activity for the reduction of benzyl chloride, with a more positive reduction potential than bulk silver or plain glassy carbon electrodes. The extraordinary catalytic effect of the silver nanorods is likely due to their morphology and high affinity for chloride ions.
The document summarizes the synthesis and characterization of a novel square-grid complex with the formula [Cu16L18](dmf)3 (1). The complex was formed through self-assembly of a 2,6-pyridinedicarbaldehyde bis(hydrazone) ligand (H4L1) and Cu2+ salt. X-ray crystallography revealed a [4x4] square grid structure consisting of 16 Cu2+ ions in a mixed coordination environment bridged by the ligand. Magnetic measurements showed both ferro- and antiferromagnetic spin exchanges occurring, with antiferromagnetic coupling dominating at low temperatures.
This document summarizes research on the optical and structural properties of tenorite (CuO) nanopowders doped with silicon (Si) and zirconium (Zr). Nanopowders were synthesized using a sol-gel method and calcined at temperatures from 400-700°C. X-ray diffraction analysis showed the samples crystallized in a tenorite structure and doping affected crystallinity and particle size. Optical absorption spectroscopy indicated undoped CuO has a direct bandgap of 1.78eV, while doped CuO (15% Si, 15% Zr) has a wider bandgap of 3.75-3.95eV. Scanning electron microscopy and other characterization techniques
1 Packing of spheres: Unit cell and description of crystal structure, close
packing of spheres, holes in closed-packed structures.
2 Structure of Metals: Polytypism, structures that are not closed packed, polymorphism of metals, atomic radii of metals, alloys.
3 Ionic solids: Characteristic structures of ionic solids, the rationalization of structures, the energetics of ionic bonding, consequences of lattice enthalpy.
Studies of the Atomic and Crystalline Characteristics of Ceramic Oxide Nano P...Mahendra Kumar Trivedi
In the present study, some transition metal oxides (Zinc oxide, iron oxide and copper oxide) which are widely used in the fabrication of electronic devices were selected and subjected to biofield treatment.
Application of Fe3O4 Sphere Doped with Zn for Enhanced Sonocatalytic Removal ...ijtsrd
The document describes research on using Fe3O4 spheres doped with zinc (Zn) as a sonocatalyst for removing hexavalent chromium (Cr(VI)) from aqueous solutions. Fe3O4 spheres doped with Zn were synthesized using a simple solvothermal method. Characterization showed the Zn was successfully doped into the crystal structure of Fe3O4 spheres. Testing found the doped spheres had high sonocatalytic activity for degrading Cr(VI) under visible light, with 95.8% removal efficiency. The enhanced activity is attributed to the uniform sphere structure and metal doping effect.
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
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F0363341
1. IOSR Journal of Applied Physics (IOSR-JAP)
e-ISSN: 2278-4861.Volume 3, Issue 6 (May. - Jun. 2013), PP 33-41
www.iosrjournals.org
www.iosrjournals.org 33 | Page
Structural and magnetic characterization of Co2+
substituted
nano structured Copper-Zinc spinel ferrite
Sindhu S1
, D. D. Birajdar2
1
GND Engineering College, Bidar, Karnataka State, India
2
B.S.S. Arts,Science and Commerce college Makani, Osmanabad (M.S.), India
Abstract : Nano particles of Cu0.61-xCoxZn0.39Fe2O4 (0 ≤ x ≤ 0.5) synthesized through sol-gel auto combustion
method. Nitrates of elements and citric acid are used as starting materials. X-ray Diffraction, Thermo
Gravimetric Analysis and Vibrating Sample Magnetometer are used to analyze the properties. Effect of
variation in the Co substitution and its impact on particle size, lattice constant, density, cation distribution,
ferritization temperature, associated water content, magnetic properties like saturation magnetization(MS),
coercivity(HC) and remanent magnetization(Mr) is observed. Lattice parameter increases with increasing Co+2
concentration whereas X-ray density, bulk density decreases with the Co+2
content. In Cation distribution the
Co and Cu ion show preference towards octahedral B-site, Zn occupy A site whereas Fe occupy both A and B
site. Cation redistribution takes place for x > 0.3. Saturation magnetization increases from (x ≤ 0.3). For x >
0.3, Ms decreases suggesting that significant canting exists at B site. However, coercivity, magnetocrystalline
anisotropy and remanant magnetization increases with the Co2+
substitution.
Keywords: Coercivity(HC), Remanent and Saturation Magnetization , Sol-gel synthesis, Thermo Gravimetric
Analysis and Vibrating Sample Magnetometer, X-ray Diffraction.
I. Introduction
Co2+
substituted Cu0.61-xCoxZn0.39Fe2O4 ferrites are commercially important magnetic materials and play
an important role in the production of magnetic recording media.The cation distribution in CuFe2O4 copper
ferrite can be represented by formula (Cu2+
x+Fe3+
1-x)A
[Cu2+
1-x+Fe3+
1+x]B
O4. The parameter of inversion is (0 ≤ x
≤ 0.5). When the spinel is synthesized using classical ceramic technologies (high temperature treatment of the
initial oxides of the metal cations) with strict stoichiometry (x = 1), it has tetragonal structure with crystal cell
parameters a = 8.20 and c = 8.60; c/a = 1.05 [1]. The c/a ratio can be changed via decreasing the copper
concentration, or alternatively, by temperature treatments. Yokoyama et al. [2] observed changes in the crystal
structure of nanosized CuFe2O4 powders obtained by co-precipitation and subsequent annealing. According to
some other authors [3] a = 8.24, c = 8.68, but c/a is again 1.05. The structure of CuFe2O4 is considered as that of
a tetragonally deformed spinel stretched along the (0 1 1) direction. They proved that the copper spinel is cubic
at temperatures below 300°C and tetrahedral over 400°C. Further Co ferrite shows good magnetostrictive
properties, magnetocrystalline anisotropy, high coercivity and moderate saturation magnetization among all the
ferrite family [10]. Therefore, by keeping this composition in our mind, we have proposed the studies on
structural analysis, cation distribution and magnetic properties of nano-size Cu0.61-xCoxZn0.39Fe2O4 (0 ≤ x ≤ 0.5)
by sol-gel method.
II. Experimental:
2.1 Preparation method:
Sol-gel auto-combustion method is a novel method of preparing nano-materials [11] by which
nanocrystalline powder of Cu0.61-xCoxZn0.39Fe2O4 (0 ≤ x ≤ 0.5) is prepared. It can save energy and avoid
agglomeration during the calcinations at high temperature. A.R. grade citric acid (C6H8O7)·H2O, copper nitrate
(Cu(NO3)2·3H2O, zinc nitrate (Zn(NO3)2·6H2O, cobalt nitrate (Co(NO3)2·3H2O and ferric nitrate
Fe(NO3)3·9H2O were used as starting materials. The metal nitrates were dissolved in a minimum amount of
double distilled water to get a clear solution and ammonia solution was slowly added to maintain the pH. The
mixed solution was kept on to a hot plate with continuous stirring. The solution became viscous and finally
formed a very viscous brown gel. When finally all water molecules were removed from the mixture, the viscous
gel began frothing. After few minutes, the gel automatically ignited and burnt with glowing flints. The auto-
combustion was completed within a minute, yielding the brown-colored ashes termed as a precursor. The
powder which is thus prepared, then annealed at 600 0
C for 4 hours.
2.2 Structural and magnetic characterization:
The dried gels were characterized by Thermo gravimetric analysis and differential thermal analysis at a
heating rate of 100
C/min in air atmosphere. The samples were powdered for X-ray investigations. Magnetic
2. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 34 | Page
measurements were performed using the commercial PARC EG&G vibrating sample magnetometer VSM 4500.
Hysteresis curve loops were measured at room temperature with maximum applied magnetic fields. Magnetic
field sweep rate was 5 Oe/s for all measurements. Hence measurement of hysteresis loops with maximum field
of 0.7 T took about 2 hours. The samples prepared in powder form were fixed in paraffin in order to exclude the
motion of powder in a measuring cap.
III. Results and discussion:
3.1 Structural properties:
The experimental observation showed that the nitrate–citrate gels with all three molar ratios of metal
nitrates to citric acid exhibited self-propagating combustion behavior. It was also observed that the combustion
rate is associated with the ratio of nitrates of citric acid. The TGA of the mid sample x = 0.3 decomposing in air
atmosphere in the temperature range 20 to 7000
C with a heating rate of 10 0
C/min is shown in Fig. 1.
The observed weight loss below 1000
C of x = 0.3 sample for Co is attributed to the loss of physically or
chemically absorbed OH groups. The weight loss around 350 0
C, which is ascribed to the vaporization of
absorbed water. The third weight loss around 350 to 600 0
C, which is associated with the residual organic matter
including citric acid. The weight loss below 600 0
C is due to the loss of absorbed water and the decomposition
of organic derivatives. Final weight loss above 600 0
C, due to weight loss of as received powder. The end-
products after decomposition were identified as single spinel phase Cu–Co–Zn ferrite. From the analysis of
their recorded XRD patterns (Fig. 2).
This proves the simultaneous completion of decomposition process of oxalate complex and ferritization. The
XRD patterns exhibit peaks corresponding to typical Cu–Co–Zn ferrites and the absence of any other impurity
phase. Substitution of Cu by Co increases the overall crystallinity of the spinel phase and all the peaks are
3. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 35 | Page
indexed as reported on ASTM cards (cards 1-1121 and 3-0864). The variation of lattice constant with
composition x is shown in Fig. 3.
It is clear from Fig. 3 that lattice constant decreases with increase in x for x = 0.1. For x > 0.1 lattice constant
increases with composition x. Generally in a solid solution series, linear increase or decrease of lattice constant
within the miscibility range with composition is observed [12]. This may results into initial decrease in lattice
constant up to x = 0.1 beyond which it increases. This nonlinear behavior of lattice constant suggests that the
ferrite system is not completely normal or inverse. In the present series, Cu0.61-xCoxZn0.39Fe2O4 (0 ≤ x ≤ 0.5)
smaller Cu2+
(0.72Å) ions are replaced by larger Co2+
(0.745Å) [13]. Doping Co2+
ions in a spinel type structure
will induce uniform strain in the lattice as the material is elastically deformed. This effect causes the lattice
plane spacing to change and the diffraction peaks shift to a lower 2 position. Since each primitive unit cell of
the spinel structure contains eight molecules, the X-ray density, dX’ was determined according to the following
relation [14] 3
8
)(
aN
M
Ferritedx
where M is molecular weight of the particular ferrite, N is the
Avogadro’s number and a3
is the volume of the cubic unit cell and are shown in Fig.4.
From Fig. 4, it is observed that X-ray density ‘dx’ decreases with addition of Co2+
ion content, which may be
attributed to the ionic radii of constituent ions causing decrease in lattice parameter and the molecular weight of
cobalt ferrite (234.625) is lower than copper ferrite (239.23). The bulk density ‘dB’ of the specimens has been
determined by the hydro-static method. The values of the bulk density are shown in Fig. 4. The bulk density was
found to decrease with Co content x. These measurements show densities decreases with Co2+
substitution
which in accordance with the densities of pure Cu and Co ferrites, 8.95gm/cm3
and 5.29gm/cm3
, respectively.
4. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 36 | Page
The broad peaks are seen in XRD indicates the nano particle size of the ferrite formed due to sol-gel
preparation. It is also evident from the crystallite size of 25-34 nm for all samples estimated from the most
intense peak (311) using the Scherrer equation, Dhkl = 0.9λ/Bcosθ, [15] where Dhkl, λ, B, and θ are the volume-
averaged particle diameter, X-ray wavelength, full width at half maximum (FWHM), and diffraction angle,
respectively.
The present results in fig.5 depict that the increasing concentration of cobalt Co2+
decreases with the particle
size. This was probably due to the reaction condition, which favored the formation of new nuclei preventing
further growth of particles when the Co concentration was increased. This may be due to migration of small
number of Co2+
ions in the midst of Co3+
ions in B-sites. This observation is similar to that of Caltun et. al. [16]
for Co-Mn ferrite. The hopping length for tetrahedral A-site (LA) and octahedral B-sites (LB) are calculated
using the values of lattice constant. The variation of hopping lengths with Co content x is shown in Fig. 6 & 7.
It is observed from Fig. 6 & 7 that the distance between the magnetic ions (hopping length) increases as Co
content x increases. Using the experimental values of lattice constant ‘a’ and oxygen positional parameter ‘u’
and substituting it into equations discussed elsewhere [17]. Tetrahedral and octahedral bond length (dAx and dBx),
tetrahedral edge, shared and unshared octahedral edge (dAXE, dBXE and dBXEU) were calculated and the values are
given in Table 1
5. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 37 | Page
Table 1
Tetrahedral bond (dAx), Octahedral bond (dBx), Tetra edge (dAxE) and octaedge (Shared dBXE and
unshared dBXEU). The error estimates is (± 0.002 Å).
It is observed that the allied parameter increases as from its starting value with Co content x increases. This
could be related to the larger radius of Co2+
ions as compared to Cu3+
ions and the site occupancy of the
constituent ions in the present ferrite system.
3.2 Cation distribution:
The cation distribution in the present system was obtained from the analysis of X-ray diffraction
patterns. In this method the observed intensity ratios were compared with the calculated intensity ratios. In the
present study Bertaut method [18] is used to determine the cation distribution. This method selects a few pairs of
reflections according to the expression
.
'''
.
.
'''
.
Calc
lkh
Calc
hkl
Obs
lkh
Obs
hkl
I
I
I
I
(1)
where,
.Obs
hklI and
.Calc
hklI are the observed and calculated intensities for reflection (hkl), respectively. If an
agreement factor (R) is defined as in Eq. (2), the best-simulated structure which matches the actual structure of
the sample will lead to a minimum value of R and the corresponding cation distribution is obtained for each hkl
and lkh '' reflection pair considered.
.
'''
.
.
'''
.
Calc
lkh
Calc
hkl
Obs
lkh
Obs
hkl
I
I
I
I
R (2)
The intensities of these are nearly independent of the oxygen parameters. To determine the cation
distribution and its variation with composition, it is necessary to calculate for each composition the above
mentioned intensity ratios expected for given arrangements of the cations and compare them with the
experimental values.
Phklhkl LPFI
2
(3)
where, F is structure factor, P is multiplicity factor, LP the Lorentz polarization factor and
2cossin
2cos1
2
2
PL (4)
The atomic scattering factor for various ions was taken from the literature [19]. It The cation distribution for
each concentration and the site preferences of cations distributed among tetrahedral A-site and octahedral B-site
showing the fraction of Cu2+
and Fe3+
ions on either sites are listed in Table 2.
Table 2
Cation distribution of Cu0.61-xCoxZn0.39Fe2O4
X
Cation distribution
A-site B-site
0.0 (Zn0.39Fe0.61) [Cu0.61Fe1.39] O4
0.1 (Cu0.06Zn0.39Fe0.55) [Cu0.45Co0.1Fe1.45] O4
0.2 (Cu0.075Zn0.39Fe0.535) [Cu0.425Co0.2Fe1.375] O4
0.3 (Cu0.08Zn0.39Fe0.53) [Cu0.32Co0.3Fe1.38] O4
0.4 (Cu0.09Co0.05Zn0.25Fe0.61) [Cu0.21Co0.35Zn0.05Fe1.39] O4
0.5 (Cu0.1Co0.09Zn0.21Fe0.60) [Cu0.1Co0.41Zn0.09Fe1.40] O4
X
dAX
(Å)
dBX
(Å)
Tetra edge (Å) Octa edge (Å)
dAXE dBXE dBXEU
0 1.907 2.054 3.113 2.831 2.981
0.1 1.904 2.050 3.106 2.820 2.973
0.2 1.905 2.051 3.109 2.825 2.974
0.3 1.907 2.053 3.113 2.828 2.978
0.4 1.909 2.055 3.116 2.831 2.982
0.5 1.911 2.057 3.121 2.835 2.985
6. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 38 | Page
The variation of mean ionic radius of the A-site (rA) and of the B-site (rB) with Co is shown in Fig. 8 &
9. The rA increases up to x ≤ 0.3, this is due the increase in migration of larger Cu2+
(0.72 Å) ions from B site to
A site which replaces smaller Fe3+
(0.67 Å) ions at B site.
0A R3a
4
1
ur
(5)
Fig. 10 shows the increase in the theoretical value of lattice constant ath with Co cotent &Fig. 11 shows
decreasing value of oxygen positional parameter ‘u’ from 0.387 to 0.386 (Å). However, in the present work
u>0.375 may be due to anion displacement from the ideal situation so that it forms a expanded tetrahedral
interstices. The lattice disturbance is confirmed from the data for lattice constant and the oxygen positional
parameter u. The theoretical lattice parameter ‘ath’ was calculated using the values of tetrahedral and octahedral
reading (rA, rB) and is given by the following relation,
0B0Ath Rr3Rr
33
8
a (6)
where, rA and rB are radii of tetrahedral (A) site and octahedral [B] site, R0 is radius of oxygen i.e. (R0= 1.32 Å).
It is noticed that ath is higher than a at lower concentration of Co2+
, and becomes closer at higher Co content.
The deviation may be due to the formation of Co3+
in tetrahedral sites which has lower radius than Co2+
.
7. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 39 | Page
3.3 Magnetic properties:
Room temperature hysteresis loops with the field of 7 kOe, for all the samples are shown in Fig. 12. Fig. 12
shows the variation of saturation magnetization with Co2+
content x. These plots show that an increase in Co2+
doping yields monotonic increase in the saturation magnetization of Cu-Co-Zn ferrite (for x ≤ 0.3), which may
be due to the substitution of Cu2+
ions by Co2+
ions on the octahedral sites. The magnetic moment µB per ion for
Co2+
ions (3 µB) is more than that for Cu2+
(1 µB). Therefore, the increasing Co2+
concentration (x) on the
octahedral sites may result in an increasing magnetic moment per formula of and Cu0.61-xCoxZn0.39Fe2O4 (0 ≤ x ≤
0.5) an enhancement of magnetization .Magnetization decreases for x > 0.3 this may be due to the following
fact.
As the percentage of Co2+
increases from 0.3 to 1, the Ms value gets decreased. Similarly, an increase
of a and or b shift the magnetization value to lower side explains low Ms value for x ≤ 0.3. The net magnetic
moment (nB Cal.) is given by the sum of the magnetic moments of A and B sublattices, i.e., MS = MB-MA. For
Co2+
substituted Cu-Zn ferrite, Co+2
substitution for Cu2+
ions at B site, leading to a increase in the B site
sublattice magnetization. Moreover, the Fe3+
(5µB) ions are replaced by less magnetic Cu2+
(1µB) ions of A-site,
leading to a decrease in the A site sublattice magnetization, which leads to a increase in the net magnetization.
For example, we use the known magnetic moments for Cu2+
(1µB), Zn2+
(0µB), and Fe3+
(5µB). In this study, the
cationic distribution, Zn2+
(0µB) ions are non-magnetic and do not contribute to the sublattice magnetization.
For Cu0.61-xCoxZn0.39Fe2O4. ABS MMM = (0.7 × 5)µB- (0.7 × 1 + 1.3 × 5)µB = 3.7 µB. The observed
magnetic moment (nB Obs.) per formula unit in Bohr magneton (µB) was calculated by using the relation [30].
5585
Mwt.Mol
n S
B
where nB is the magnetic moment of the samples expressed in Bohr magneton. Ms is the saturation
magnetization. The values of (nB) are shown in Fig. 12 & 13.
8. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 40 | Page
Both of them increase up to x = 0.3 and then decrease with the increase in Co concentration. Similar reports for
saturation magnetization have been quoted by others [31].
nB = (6 + x) cos αY−K −5 (1− x) (5)
where x represents Co concentration. The values of Y–K angles are demonstrated in Fig. 10. It increases
exponentially with the increase in Co concentration for x > 0.3. This shows that in the present system of ferrites,
randomness increases as Co is substituted in these Cu ferrites and shows a significant departure from Néel
collinear model. The coercive force (Hc) is an independent parameter, which can be altered by
magnetocrystalline anisotropy, particle size, porosity, heat deformation and hence is not dependent on saturation
magnetization. In this study, the coercive forces tend to rise in increasing Co2+
substitution content, in which the
values of coercive force varied in the range 100.21- 268.83 Oe (Fig. 15 & 16)
The strong magnetocrystalline anisotropy of the octahedral Co2+
ions contributed to the strengthening of the
coercive force. There will be a dependence of anisotropy constant K on the Co2+
ion concentration x, which can
be evaluated by using the relation [37]
S
C
M
K98.0
H
For all the concentrations Co2+
ions system may be considered as isolated Because of the strong dependence of
the anisotropy on the location of cations, the measurement of coercivity is a sensitive probe for following cation
migrations after increasing Co2+
ions. Furthermore, the distortion of the unit cell, the directional order of the
octahedral Co2+
ions, and the shape anisotropy of the particles combine to render Cu0.61-xCoxZn0.39Fe2O4 ferrite
powders to become hard magnetic materials with increasing coercivities [38]. The remanent magnetization (Mr)
is also an independent parameter since it is not wholly dependent on saturation magnetization (Ms) and coercive
force (Hc). The values of remanent magnetization increases from 8.11 to 19.67 emu/gm. Our samples have
significance in magnetic recording media, because recording media requires a high saturation magnetization and
a moderately high coercivity [39].
IV. Conclusions:
The main conclusions that are derived from the obtained results are:
Copper nitrate, Cobalt nitrate, zinc nitrate and interacted with ferric nitrate at temperatures starting from
600 0
C yielding Cu0.61-xCoxZn0.39Fe2O4.
The particle size estimated showed a decreasing trend with the increase in the Co concentration though the
preparation condition was identical for all the samples.
The cation distribution suggests that Co2+
and Cu+2
both have strong preference towards octahedral B-site,
Zn2+
also occupy B site by very small amount, whereas Fe3+
occupy both A and B site.
Magnetic measurements shows an increase in Ms value for x ≤ 0.3 and for x > 0.3 shows decreasing trend
which suggests, redistribution of cations is occurred at higher Co2+
substitution, which ultimately result
preferential filling of Co and/or Cu ions in the tetrahedral site.
Samples have significance in magnetic recording media.
9. Structural and magnetic characterization of Co2+
substituted nano structured Copper-Zinc spinel
www.iosrjournals.org 41 | Page
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