Synthesis, structure and magnetic properties of multipod-shaped cobalt ferrite nanocrystals

2019 ◽  
Vol 43 (26) ◽  
pp. 10259-10269 ◽  
Author(s):  
Mohammed Hennous ◽  
E. Venkata Ramana ◽  
David M. Tobaldi ◽  
Benilde F. O. Costa ◽  
M. A. Valente ◽  
...  

A non-aqueous sol–gel route followed by oriented attachment to make multi-pod CoFe2O4 nanocrystals showing large room temperature saturation magnetization.

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qing Lin ◽  
Jinpei Lin ◽  
Yun He ◽  
Ruijun Wang ◽  
Jianghui Dong

Gadolinium substituted cobalt ferrite CoGdxFe2−xO4(x= 0, 0.04, 0.08) powders have been prepared by a sol-gel autocombustion method. XRD results indicate the production of a single cubic phase of ferrites. The lattice parameter increases and the average crystallite size decreases with the substitution of Gd3+ions. SEM shows that the ferrite powers are nanoparticles. Room temperature Mössbauer spectra of CoGdxFe22−xO4are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization decreases and the coercivity increases by the Gd3+ions.


2019 ◽  
Vol 34 (01) ◽  
pp. 2050002
Author(s):  
Wei Zhang ◽  
Aimin Sun ◽  
Xiqian Zhao ◽  
Xiaoguang Pan ◽  
Yingqiang Han

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.


2020 ◽  
Vol 34 (03) ◽  
pp. 2050041
Author(s):  
Xiqian Zhao ◽  
Aimin Sun ◽  
Wei Zhang ◽  
Lichao Yu ◽  
Zhuo Zuo ◽  
...  

In order to study the effect of sintering temperature on the structure and magnetic properties of nickel-magnesium-cobalt ferrite, [Formula: see text] spinel ferrite with different sintering temperatures (500[Formula: see text]C, 600[Formula: see text]C, 700[Formula: see text]C, 800[Formula: see text]C, 900[Formula: see text]C and 1000[Formula: see text]C) was prepared by sol–gel method. The magnetic properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Vibrating sample magnetometer (VSM). The results show that the sintering temperature has a significant effect on the structure and magnetic properties of nickel-magnesium-cobalt ferrite. Analysis of the XRD pattern confirmed that all samples showed a single-phase cubic spinel structure. The particle size of the prepared sample determined by the Scherrer equation was 51 nm to 135 nm. As the sintering temperature increases from 500[Formula: see text]C to 1000[Formula: see text]C, the intensity of all peaks gradually increases, the crystallinity and particle size of the sample increase significantly, but the coercive force decreases, the saturation magnetization, the residual magnetization and the squareness [Formula: see text] increase first and then decrease. Compared with other samples, the 800[Formula: see text]C sintered samples had the highest saturation magnetization (59.03 emu/g), remanent magnetization (30.65 emu/g) and squareness (0.519). The increasing peak height of [Formula: see text] at [Formula: see text] indicates that the cubic spinel structure samples have good crystallinity and magnetic stability.


2016 ◽  
Vol 19 (3) ◽  
pp. 123-128
Author(s):  
Minh Truong Xuan Nguyen ◽  
Oanh Le Kieu Pham ◽  
Ha Ky Phuong Huynh ◽  
Vien Minh Le

Nano ferrites have received considerable attentions due to their various applications such as magnetic or catalyst materials. In this work, nickel-cobalt ferrite (Co1-xNixFe2O4) was synthesized by sol-gel method using stearic acid. The effects of calcination temperature and nickel/cobalt ratios on the formation of structure were also investigated. XRD results show that all samples which were calcined from 6000C to higher temperature for 1 hour were in single cubic spinel phases. The magnetic properties include saturation magnetization (Ms) and coercivity (Hc) have been also investigated by using vibrating sample magnetometer (VSM). The saturation magnetization and coercivity of CoFe2O4 calcined at 6000C for 1hour is 74.4 emu/g and 1519.13 Oe, respectively. The saturation magnetization and coercivety of substituted materials decrease with increasing Ni content.


2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.


2012 ◽  
Vol 501 ◽  
pp. 236-241 ◽  
Author(s):  
Ftema W. Aldbea ◽  
Noor Bahyah Ibrahim ◽  
Mustafa Hj. Abdullah ◽  
Ramadan E. Shaiboub

Thin films nanoparticles TbxY3-xFe5O12 (x=0.0, 1.0, 2.0) were prepared by the sol-gel process followed by annealing process at various annealing temperatures of 700° C, 800° C and 900° C in air for 2 h. The results obtained from X-ray diffractometer (XRD) show that the films annealed below 900°C exhibit peaks of garnet mixed with small amounts of YFeO3 and Fe2O3. Pure garnet phase has been detected in the films annealed at 900°C. Before annealing the films show amorphous structures. The particles sizes measurement using the field emission scanning electron microscope (FE-SEM) showed that the particles sizes increased as the annealing temperature increased. The magnetic properties were measured at room temperature using the vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of the films also increased with the annealing temperature. However, different behavior of coercivity (Hc) has been observed as the annealing temperature was increased.


2013 ◽  
Vol 690-693 ◽  
pp. 1702-1706 ◽  
Author(s):  
Shuang Jun Nie ◽  
Hao Geng ◽  
Jun Bao Wang ◽  
Lai Sen Wang ◽  
Zhen Wei Wang ◽  
...  

NiZn-ferrite thin films were deposited onto silicon and glass substrates by radio frequency magnetron sputtering at room temperature. The effects of the relative oxygen flow ratio on the structure and magnetic properties of the thin films were investigated. The study results reveal that the films deposited under higher relative oxygen flow ratio show a better crystallinity. Static magnetic measurement results indicated that the saturation magnetization of the films was greatly affected by the crystallinity, grain dimension, and cation distribution in the NiZn-ferrite films. The NiZn-ferrite thin films with a maximum saturation magnetization of 151 emucm-3, which is about 40% of the bulk NiZn ferrite, was obtained under relative oxygen flow ratio of 60%.


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