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1.
Wenxu Zhang Bin Peng Shengqiang Zhou 《Journal of magnetism and magnetic materials》2010,322(13):1859-8980
Hexagonal barium ferrites were deposited onto sapphire substrates by radio frequency magnetron sputtering. The composition, microstructure, and magnetic properties of these isotropic thin films were investigated with Rutherford backscattering spectroscopy, X-ray diffraction, atomic force microscopy, magnetic force microscopy and SQUID magnetometry. The intrinsic coercivity of the films reaches about 11.5 kOe at room temperature. The mechanism of the coercivity is proposed to be nucleation in the decoupled single domain nanometer particles as shown by the characteristics of the magnetic domains and the virgin magnetization curves. 相似文献
2.
C.D. Lokhande S.S. Kulkarni R.S. Mane Sung-Hwan Han 《Journal of magnetism and magnetic materials》2007
A single-step electrosynthesis of copper ferrite thin films from aqueous bath (which avoids anodization step for an incorporation of oxygen species into deposit) has been carried out at room temperature. Observed tetrahedral structured nanocrystalline copper ferrite thin films showed smooth, uniform and compact surface morphology. After annealing, increase in dielectric constant and reduced dielectric loss were observed. The saturation magnetization for annealed films was 292 emu/cm3 comparable to that of other reported ferrites. 相似文献
3.
Influence of citric acid on the morphology and magnetic properties of barium ferrite thin films 总被引:1,自引:0,他引:1
Wanli Zhang 《Applied Surface Science》2010,257(1):176-6964
Hexagonal barium ferrite (BaFe12O19) thin films were fabricated by spin coating of precursors from sol-gel methods. Different amount of citric acid was added. Weight loss and changes of chemical bonds during the heat treatment below 500 °C were recorded by thermogravity analyzer and Fourier transform infrared spectroscopy, respectively. The morphology of the films, i.e. the amount of acicular crystallites in the film, was controlled by adjusting the quantity of citric acid. The X-ray diffraction shows that the films are c-axis oriented, but the crystallization is less perfect with the increase of the citric acid. With the increase of the citric acid, the percentage of the acicular crystallites increased. At the same time, the coercivity force increased. The acicular crystallites were not exchange-coupled to the platelet crystallites. The citric acid was understood to form complex with iron ions and accelerate the exothermal auto-combustion. The c-axis oriented growth of the film was thus deteriorated. 相似文献
4.
A.T. Raghavender Nguyen Hoa Hong Chulkwon Park Myung-Hwa Jung Kyu Joon Lee Daesu Lee 《Journal of magnetism and magnetic materials》2012
The effect of annealing conditions on structural and magnetic properties of copper ferrite thin films on (100) Si substrates was examined in detail. After deposition, the ferrite thin films were post-annealed in vacuum and in oxygen atmosphere for several hours. It is found that the crystal structure of CuFe2O4 thin films changed drastically depending on different heating process. A maximum magnetization was achieved in the film that was vacuum annealed and it decreased remarkably after oxygen annealing. 相似文献
5.
Cubic copper ferrite thin films, obtained by rf sputtering on quartz and subsequent post-annealing and quenching, show a large coercivity of about 300–600 Oe. Stress measurements using X-ray diffraction show high value of stress of about 400–1000 MPa. Both the stress and coercivity are found to increase with the decrease of the thickness of the films. There appears to be a contribution of the stress to the coercivity of the films, in the in-plane M–H loops. 相似文献
6.
Y.Q. LiY. Huang S.H. QiF.F. Niu L. Niu 《Journal of magnetism and magnetic materials》2011,323(16):2224-2232
SrLaxFe12−xO19 films (x=0-1.0) with large magneto-crystalline anisotropy were synthesized on SiO2 substrate by sol-gel and self-propagating high-temperature synthesis technique. The films were characterized by various experimental techniques including X-ray diffraction analysis, Field Emission Scanning Electron Microscope, Atomic Force Microscopy, Vibrating Sample Magnetometry and vector network analyzer. The results show that La ions completely enter into strontium ferrite lattice without changing the ferrite appearance; its grain size is approximately 40-80 nm, its length is 100 nm; the magnetoplumbite structure is proved through testing a concertina form of the crystal grain; the maximum coercivity is 5986 Oe at x=0.2; La-doped films possess a wider microwave absorption frequency range with better gross loss angle tangent (tan δ>0.1), from 9 to 10.5 GHz at x=0.2, where the maximum value of tan δ reaches 0.2709. The La-doped films reach smaller nanometer size, better magnetic properties and microwave absorption properties with the doping of lanthanum. 相似文献
7.
Ali Ghasemi Azadeh Ashrafizadeh Carla Fabiana Cerqueira Machado Xiaoxi Liu 《Journal of magnetism and magnetic materials》2010,322(20):3064-3071
In this study CuxMg0.5−xZn0.5Fe2O4 (x=0-0.5) nanoparticles and thin films were prepared by sol-gel processing. The morphologies of nanoparticles were observed by transmission electron microscope (TEM). The Mössbauer spectroscopy (MS) was employed to determine the site preference of the constitutive elements. Magnetic dynamics of the nanoparticles was studied by the measurement of AC magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between interacting or non-interacting system. Results exhibited that there is strong interaction between fine particles. X-ray diffraction (XRD) patterns of the thin films indicate the formation of single-phase cubic spinel structure. Atomic force microscope (AFM) was employed to evaluate the surface morphologies of the prepared thin films. Vibrating sample magnetometer (VSM) was employed to probe magnetic properties of samples. It was found that with an increase in the amount of copper, the saturation of magnetization and initial permeability increase. 相似文献
8.
Perpendicularly oriented barium ferrite thin films with low microwave loss,prepared by pulsed laser deposition
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Barium ferrite(Ba M) thin films are deposited on platinum coated silicon wafers by pulsed laser deposition(PLD).The effects of deposition substrate temperature on the microstructure,magnetic and microwave properties of Ba M thin films are investigated in detail.It is found that microstructure,magnetic and microwave properties of Ba M thin film are very sensitive to deposition substrate temperature,and excellent Ba M thin film is obtained when deposition temperature is 910℃ and oxygen pressure is 300 m Torr(1 Torr = 1.3332×10~2Pa).X-ray diffraction patterns and atomic force microscopy images show that the best thin film has perpendicular orientation and hexagonal morphology,and the crystallographic alignment degree can be calculated to be 0.94.Hysteresis loops reveal that the squareness ratio(M_r/M_s) is as high as 0.93,the saturated magnetization is 4004 Gs(1 Gs = 10~4T),and the anisotropy field is 16.5 kOe(1 Oe = 79.5775 A·m~(-1)).Ferromagnetic resonance measurements reveal that the gyromagnetic ratio is 2.8 GHz/kOe,and the ferromagnetic resonance linewith is108 Oe at 50 GHz,which means that this thin film has low microwave loss.These properties make the Ba M thin films have potential applications in microwave devices. 相似文献
9.
Synthesis and characterization of hard magnetic composites—Hollow microsphere/titania/barium ferrite
Hard magnetic composites—hollow microsphere (core)/titania (intermediate layer)/barium ferrite (magnetic shell) (M/T/B) were prepared by wet-chemical method. Barium ferrite nanoparticles were directly coated on the rutile titania-coated hollow microsphere forming light hard magnetic composites using sol-gel technique. The prepared composites were characterized with FESEM, EDS, XRD and vibrating sample magnetometry. The composites are composed of barium ferrite, hematite, titania and mullite. For the samples with 40 wt.% barium ferrite, its specific saturation magnetization with titania is increased to 17.88 emu/g in comparison with 9.6 emu/g without titania. The function of titania in the composites is also discussed. 相似文献
10.
Lezhong Li Long PengYuanxun Li Xinghua Zhu 《Journal of magnetism and magnetic materials》2012,324(1):60-62
Co-substituted NiZn ferrite thin films, Ni0.5Zn0.5CoxFe2−xO4 (0≤x≤0.2), were synthesized by the sol-gel process. The structure and magnetic properties of Ni0.5Zn0.5CoxFe2−xO4 ferrite thin films have been investigated. The diffraction peak shifted towards the lower angle and the lattice parameter increased with Co substitution. There is little influence of Co substitution on the microstructure of NiZn ferrite thin films. The saturation magnetization gradually increases with the increase in Co substitution when x≤0.10, and decreases when x>0.10. Meanwhile, the coercivity initially decreases with the increase in Co substitution when x≤0.10, and increases when x>0.10. 相似文献
11.
Daming ChenYingli Liu Yuanxun LiWenguo Zhong Huaiwu Zhang 《Journal of magnetism and magnetic materials》2011,323(22):2837-2840
In this article, the influences of the BaCu(B2O5) (BCB) additive on sintering behavior, structure and magnetic properties of iron deficient M-type barium ferrite Ba(CoTi)xFe11.8−2xO19 (BaM) have been investigated. It is found that the maximum sintered densities of BaM change from 86% to 94% as the BCB content varies from 1 to 4 wt%. Single-phase BaM can be detected by the XRD analysis in the sample with 3 wt% BCB sintered at 900 °C, and the microstructure is hexagonal platelets with few intragranular pores. This is attributed to the formation of the BCB liquid phase. Meanwhile, the experimental results illuminate that the CoTi ions prefer to occupy the 4f2 and 2b sites and the magnetic properties depend on the amount of CoTi-substitution. In addition, the chemical compatibility between BaM and silver paste is also investigated; it can be seen that BaM is co-fired well with the silver paste and no other second phase is observed. Especially, the 3 wt% BCB-added Ba(CoTi)0.9Fe11O19 sintered at 900 °C has good properties with the sintered density of 4.9 g/cm3, saturation magnetization of 49.7 emu/g and coercivity of 656.6 Oe. These results indicate that it is cost effective in the production of Low Temperature Co-fired Ceramics (LTCC) multilayer devices. 相似文献
12.
M-type barium ferrite thin films were deposited onto sapphire (0 0 l) substrates by radio frequency magnetron sputtering. An ultra-thin layer about 20 nm was deposited and annealed before continuous deposition of the films up to 500 nm under different sputtering pressures: 0.2, 0.5, 0.8 and 1.0 Pa, respectively. It was found that the atomic ratios of Fe to Ba increased from 9.3 to 15.0 with the increase of the pressure. The films sputtered at all pressures have c-axis normal to the film plane by a four circle X-ray diffractometer, which is an improvement of the films directly sputtered on the substrate. Needle-like grains were formed on the surface of the films under higher sputter pressure with bubble domains, which is originated from high magnetocrystalline anisotropy of the film. Magnetic hysteresis loops recorded by vibrating sample magnetometer agree with them, where in-plane and out-of-plane loops of the samples prepared under high sputtering pressures are quite different, while they are almost identical of the samples under low pressures. The influence of the sputtering pressure was understood by that with the increase of the pressure, resputtering of the films was increased. Nucleation with c-axis normal to the film plane was deteriorated. Thus samples prepared under high pressure have more needle-like crystallites which have c-axis parallel to the film plane. 相似文献
13.
Genevès T Domenichini B Imhoff L Potin V Heintz O Peterlé PM Bourgeois S 《Micron (Oxford, England : 1993)》2008,39(8):1145-1148
Room temperature depositions of barium on a thermal silicon oxide layer were performed in ultra high vacuum (UHV). In-situ X-ray photoelectron spectroscopy (XPS) analyses were carried out as well after exposure to air as after subsequent annealings. These analyses were ex-situ completed by secondary ion mass spectrometry (SIMS) profiles and transmission electron microscopy (TEM) cross-sectional images. The results showed that after air exposure, the barium went carbonated. Annealing at sufficient temperature permitted to decompose the carbonate to benefit of a barium silicate. The silicate layer was formed by interdiffusion of barium with the initial SiO2 layer. 相似文献
14.
The Co-based granular thin films were deposited on the flexible substrate (Kapton) by magnetron sputtering. The films comprise of Co nanocrystallites and small amount of amorphous (Al,O)-rich inter-granular phase and have the electric resistivities in the range 50–120 μΩ cm, depending on the composition and thickness. The as-deposited films with thickness <80 nm have low coercivity (<20 Oe along hard direction), high permeability (up to 500) and resonance frequency up to 2.5 GHz. Compared to the rigid films, the flexible films have relatively higher coercivity and lower resonance frequency. A comparison between Co-based granular films and FeTaN continuous films has also been discussed. 相似文献
15.
M.M. El-OkrM.A. Salem M.S. SalimR.M. El-Okr M. AshoushH.M. Talaat 《Journal of magnetism and magnetic materials》2011,323(7):920-926
Cobalt ferrite nano-particles (CoFe2O4) were synthesized by the co-precipitation method with ammonium hydroxide as an alkaline solution. The reactions were carried out at different temperatures between 20 and 80 °C. The nano-particles have been investigated by magnetic measurements, X-ray powder diffraction and transmission electron microscopy. The average crystallite size of the synthesized samples was between 11 and 45 nm, which was found to be dependent on both pH value of the reaction and annealing temperatures. However, lattice parameters, interplane spacing and grain size were controlled by varying the annealing temperature. Magnetic characterization of the nano-samples were carried out using a vibrating sample magnetometer at room temperature. The saturation magnetization was computed and found to lie between 5 and 67 emu/g depending on the particle size of the studied sample. The coercivity was found to exhibit non-monotonic behavior with the particle size. Such behavior can be accounted for by the combination between surface anisotropy and thermal energies. The ratio of remanence magnetization to saturation magnetization was found to exhibit almost linear dependence on the particle size. 相似文献
16.
Ali Ghasemi 《Journal of magnetism and magnetic materials》2012,324(7):1375-1380
SrFe12−x(Zr0.5Mg0.5)xO19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films. 相似文献
17.
Preparation and optical properties of barium titanate thin films 总被引:1,自引:0,他引:1
Wei Cai Chunlin FuJiacheng Gao Qian GuoXiaoling Deng Chaoyang Zhang 《Physica B: Condensed Matter》2011,406(19):3583-3587
Barium titanate (BTO) films were prepared by sol-gel spin-coating technique. The crystal structure and optical properties of BTO films have been investigated. The results indicate that the BTO films are single perovskite phase having tetragonal symmetry. The band gap of the BTO films increases with the increasing of layer number and decreasing of solution concentration. The transmittance and band gap of the BTO films annealed at 900 °C is more than that of the BTO films annealed at 700 °C when wavelength is 200-1000 nm. When wavelength is 400-1000 nm, the absorption coefficient α obtained by experiment is higher than that obtained by calculation (close to zero). 相似文献
18.
A. Ghasemi A. Hossienpour A. Morisako A. Saatchi M. Salehi 《Journal of magnetism and magnetic materials》2006
M-type barium hexaferrite BaFe12−x(Mn0.5Cu0.5Ti)x/2O19 (x varying from 0 to 3 in steps of 1) have been synthesized by the usual ceramic sintering method. The ferrite powders possess hexagonal shape and are well separated from one another. The powder of these ferrites were mixed with polyvinylchloride plasticizer to be converted in to a microwave absorbing composite. X-ray diffraction (XRD), scanning electron microscope (SEM), ac susceptometer, vibrating sample magnetometer, and vector network analyzer were used to analyze its structure, electromagnetic and microwave absorption properties. The results showed that, the magnetoplumbite structures for all the samples have been formed. The sample having higher magnetic susceptibility and coercivity exhibits a larger microwave absorbing ability. Also, the present investigation demonstrates that microwave absorber using BaFe12−x (Mn0.5Cu0.5Ti)x/2O19 (x=2 and 3)/polyvinylchloride can be fabricated for the applications over 15 GHz, with reflection loss more than −25 dB for specific frequencies, by controlling the molar ratio of the substituted ions. 相似文献
19.
Preparation and characterization of patterned copper sulfide thin films on n-type TiO2 film surfaces
Micro-arrayed patterns of p-type copper sulfide (CuxS) thin films with positive and negative features were deposited onto the surfaces of n-type TiO2 semiconductor films via a selective nucleation and growth process from aqueous solution. The surface functional molecules of the UV photo-oxidised patterned SAMs were utilized to direct the nucleation and growth of CuxS crystallites. The resultant CuxS/TiO2 composite films with negative and positive CuxS patterns on the TiO2 film surface were investigated using SEM, XRD, XPS and a 3D Surface Profiler. It is demonstrated that regular and compact patterned films of Cu2S crystallites had been deposited onto the n-type TiO2 surface, with sharp edges demarcating the boundaries between the patterned Cu2S region and the TiO2 film region. The UV-vis spectra for three Cu2S/TiO2 films exhibit a wide absorption between 300 nm and 450 nm. The maximum wavelength differences in the spectra of Cu2S/TiO2 films and TiO2 film were attributed to the added absorption of Cu2S films at 302 nm and the unchanged adsorption of TiO2 films. The absorption intensities of the Cu2S/TiO2 films could be varied in the UV-vis range using the Cu2S patterned features (positive, negative). 相似文献
20.
《Current Applied Physics》2020,20(5):638-642
A series of bio-silica incorporated barium-ferrite-composites with the composition of (x)Bio-SiO2:(80-x)γ-Fe2O3:(20)BaO, where x = 0, 1, 2, and 3 wt% were prepared using the modified solid-state reaction method. The influence of different bio-silica (extricated from sintered rice husk) contents on the surface morphologies, structures, and magnetic characteristics of these composites were assessed. The relative complex permittivity and permeability were resolved using the Nicholson-Ross-Weir strategy in the frequency range of 8–13 GHz. Meanwhile, the reflection loss was estimated through the transmission/reflection line theory to assess the MW absorption properties of the composites. Incorporation of the bio-silica in the barium ferrite composites generated a new hexagonal phase (Ba3Fe32O51) and a tetragonal phase (BaFeSi4O10) which led to a decrease in the saturation magnetization and significant shift in the MW frequency absorption peak positions. 相似文献