Structural and Magnetic Properties of Cobal Ferrite - Barium Titanate Nanotube Arrays

2011 ◽  
Vol 1368 ◽  
Author(s):  
Dario Bueno-Baques ◽  
Veronica Corral-Flores ◽  
Norma A. Morales-Carrillo ◽  
Alejandro Torres ◽  
Hector Camacho-Montes ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Barium Titanate ◽  
Composite Structures ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Nanotube Arrays ◽  
Ferromagnetic Behavior ◽  
Titanate Nanotube ◽  
Average Grain Size ◽  
Composite Nanotubes

ABSTRACTCobalt Ferrite/Barium Titanate nanotube arrays were obtained in anodic aluminum oxide templates (AAO) of 100 nm pore diameter by a two step sol-gel process. Each phase was grown in several wetting – drying cycles starting from the cobalt ferrite layers with the barium titanate on top. As-dried composite structures were sintered at 700 C. The composite nanotubes showed a fine polycrystalline microstructure with an average grain size of 5 nm. The formation of both spinel and perovskite structures was verified by High Resolution Transmission Electron Microscopy (HR-TEM) on isolated nanotubes. The growing rate by layer was found to be lower for the BaTiO3 on top of CoFe2O4 than the later on top of the AAO. Wall sizes were estimated by Z-contrast as 9.8 nm for one layer of CoFe2O4 and 6.6 nm for six layers of BaTiO3. Magnetic properties were studied by VSM. Samples showed ferromagnetic behavior with low coercive values. By means of a finite element model the deformation and stress on the piezoelectric phase was estimated and used to simulate the magnetization reversal under stress in the composite nanotubes, using an updated micromagnetic framework to include the magnetostriction effect. Simulation results showed that a curling mode is expected with opposite vortex states at the end of the nanotubes. The change in the vortex domain structure under voltage driven applied stress is presented and discussed.

scholarly journals Enhanced Magnetic Properties of BiFeO3 Thin Films by Doping: Analysis of Structure and Morphology

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 711 ◽  
Author(s):  
Yilin Zhang ◽  
Yuhan Wang ◽  
Ji Qi ◽  
Yu Tian ◽  
Mingjie Sun ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Sol Gel ◽  
Exchange Interactions ◽  
Ferromagnetic Behavior ◽  
Ferromagnetic Properties ◽  
Structure And Morphology ◽  
Related Diversification ◽  
Lattice Distortions ◽  
Mn Doped

The improvement of ferromagnetic properties is critical for the practical application of multiferroic materials, to be exact, BiFeO3 (BFO). Herein, we have investigated the evolution in the structure and morphology of Ho or/and Mn-doped thin films and the related diversification in ferromagnetic behavior. BFO, Bi0.95Ho0.05FeO3 (BHFO), BiFe0.95Mn0.05O3 (BFMO) and Bi0.95Ho0.05Fe0.95Mn0.05O3 (BHFMO) thin films are synthesized via the conventional sol-gel method. Density, size and phase structure are crucial to optimize the ferromagnetic properties. Specifically, under the applied magnetic field of 10 kOe, BHFO and BFMO thin films can produce obvious magnetic properties during magnetization and, additionally, doping with Ho and Mn (BHFMO) can achieve better magnetic properties. This enhancement is attributed to the lattice distortions caused by the ionic sizes difference between the doping agent and the host, the generation of the new exchange interactions and the inhibition of the antiferromagnetic spiral modulated spin structure. This study provides key insights of understanding the tunable ferromagnetic properties of co-doped BFO.

scholarly journals The Influence of Annealing Temperature on the Structure and Magnetic Properties of Nanocrystalline BiFeO3 Prepared by Sol–Gel Method

2021 ◽  
Author(s):  
T. Pikula ◽  
T. Szumiata ◽  
K. Siedliska ◽  
V. I. Mitsiuk ◽  
R. Panek ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Weak Ferromagnetism ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Average Grain Size ◽  
Spin Cycloid

AbstractIn this work, BiFeO3 powders were synthesized by a sol–gel method. The influence of annealing temperature on the structure and magnetic properties of the samples has been discussed. X-ray diffraction studies showed that the purest phase was formed in the temperature range of 400 °C to 550 °C and the samples annealed at a temperature below 550 °C were of nanocrystalline character. Mössbauer spectroscopy and magnetization measurements were used as complementary methods to investigate the magnetic state of the samples. In particular, the appearance of weak ferromagnetic properties, significant growth of magnetization, and spin-glass-like behavior were observed along with the drop of average grain size. Mössbauer spectra were fitted by the model assuming cycloidal modulation of spins arrangement and properties of the spin cycloid were determined and analyzed. Most importantly, it was proved that the spin cycloid does not disappear even in the case of the samples with a particle size well below the cycloid modulation period λ = 62 nm. Furthermore, the cycloid becomes more anharmonic as the grain size decreases. The possible origination of weak ferromagnetism of the nanocrystalline samples has also been discussed.

Effect of Annealing Temperatures in Oxygen on the Structure and Magnetic Properties of Yttrium Iron Garnet (Y3Fe5O12) Films Prepared by a Sol-Gel Method Followed by a Spin Coating Technique

2016 ◽  
Vol 846 ◽  
pp. 626-634 ◽  
Author(s):  
Noor Baayah Ibrahim ◽  
Ftema W. Aldbea ◽  
Akmal Zaini Arsad ◽  
Noorhasniyah Md Rodee
Keyword(s):  
Magnetic Properties ◽  
Yttrium Iron Garnet ◽  
Sol Gel ◽  
Soft Magnetic Materials ◽  
Yttrium Iron ◽  
Gel Method ◽  
Sol Gel Method ◽  
Average Value ◽  
Average Grain Size ◽  
Iron Garnet

Yttrium iron garnet (Y3Fe5O12) films were prepared by a sol-gel method followed by an annealing process at 500,600,700,800, and 900°C in oxygen atmosphere for 2 hours. The microstructure characterization carried out by an X-ray diffractometer showed that the film started to crystalline into YIG phase at 700°C. The average grain size of the films measured using a field emission scanning electron microscope gave the average value of 20 to 70 nm. The magnetic properties measured by a vibrating sample magnetometer showed that all of the films were soft magnetic materials. The saturation magnetization values increased with the increment of annealing temperature. However, the coercivity values were independence with temperatures.Keywords:Thinfilms;Crystalline;Sol-gelmethod;

Structural, morphological and magnetic properties of Mn2+ ions substituted nanosized nickel–copper–cobalt ferrites through sol–gel auto-combustion method

2019 ◽  
Vol 34 (01) ◽  
pp. 2050002
Author(s):  
Wei Zhang ◽  
Aimin Sun ◽  
Xiqian Zhao ◽  
Xiaoguang Pan ◽  
Yingqiang Han
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Spinel Structure ◽  
Remanent Magnetization ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Combustion Method ◽  
Magnetic Data ◽  
Nickel Copper ◽  
Auto Combustion

Manganese substituted nickel–copper–cobalt ferrite nanoparticles having the basic composition [Formula: see text] (x = 0.0, 0.1, 0.2, 0.3 and 0.4) were synthesized by sol–gel auto-combustion method. X-ray diffraction (XRD) was used to estimate phase purity and lattice symmetry. All the prepared samples show the single-phase cubic spinel structure. Fourier transform infrared (FTIR) measurements also confirm the cubic spinel structure of the ferrite that is formed. The preparation of samples show these nearly spherical particles by Transmission electron microscopy (TEM). The magnetic properties of Mn[Formula: see text] ion substituted in nickel–copper–cobalt ferrite were studied by Vibrating sample magnetometer (VSM). The saturation magnetization ([Formula: see text]), remanent magnetization [Formula: see text], coercivity [Formula: see text], magnetic moment [Formula: see text] and anisotropy constant [Formula: see text] first increase and then decrease with the increase of [Formula: see text] ions content. They had better magnetism than pure sample and other substituted samples when the substitution amount of [Formula: see text] ions was [Formula: see text]. At [Formula: see text], the maximum values of remanent magnetization [Formula: see text], saturation magnetization [Formula: see text] and coercivity [Formula: see text] are 25.58 emu/g, 61.95 emu/g and 689.76 Oe, respectively. This indicates that the magnetism of ferrite can improve by substituting with the appropriate amount of manganese. However, due to the excess [Formula: see text] ions instead, ferrite magnetism is weakened. This means that these materials can be used in magnetic data storage and recording media.

scholarly journals Structural and Magnetic Properties of Mn Doped BiFeO3 Nanomaterials

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
V. Srinivas ◽  
A. T. Raghavender ◽  
K. Vijaya Kumar
Keyword(s):  
Magnetic Properties ◽  
Doping Concentration ◽  
Structural Changes ◽  
Sol Gel ◽  
Rietveld Analysis ◽  
Ferromagnetic Behavior ◽  
Structural Formation ◽  
Mn Doping ◽  
Structural And Magnetic Properties ◽  
Mn Doped

Nanocrystalline Bi1-xMnxFeO3  (0≤x≤0.3) materials were synthesized using sol-gel technique. The structural and magnetic properties were investigated in detail. Rietveld analysis from XRD revealed the structural formation of BiFeO3. As the Mn doping concentration was increased, the structure of BiFeO3 changed from rhombohedral to tetragonal. All the M-H loops showed the ferromagnetic behavior in the prepared samples. Magnetization was observed to enhance as the Mn doping concentration was increased. The enhanced magnetization may be due to the collapse of the space modulated spin structure as observed from the structural changes.

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