共查询到20条相似文献,搜索用时 29 毫秒
1.
Liming Yu Jiujing Wang Shixun Cao Shujuan Yuan Jincang Zhang 《Journal of Materials Science》2007,42(14):5335-5339
The properties of light rare earth Nd substitution for heavy rare earth Dy in Dy3Fe5O12 (DyIG) garnet ferrite have been studied. The Nd
x
Dy3–x
Fe5O12 (x = 0, 0.25, 0.5, 0.75 and 1) (Nd:DyIG) garnet powders were prepared by sol–gel autocombustion followed by heat treatment.
The structure and the magnetic properties of the annealed powders were measured with X-ray diffraction (XRD), the Fourier
Transform Infrared (FT-IR) and the Physical Properties Measurement System (PPMS) techniques. The experimental results indicate
that a single Nd:DyIG garnet phase structure can be obtained after the samples annealed above 800 °C. With the Nd substitution
content increasing, the average lattice constants of the sample, the a−d super-exchange interaction strengthens and the magnetization of unit cell increase. The maximum saturation magnetization
is 13.86 emu/g for x = 1, and coercive force is about 136 Oe, for x = 0.75. The reason of increasing in magnetization with Nd substitution is also discussed. 相似文献
2.
Zhongjun Cheng Hua Yang Lianxiang Yu Wei Xu 《Journal of Materials Science: Materials in Electronics》2008,19(5):442-447
Re3+-substituted garnet nanoparticles Y3−x
Re
x
Fe5O12 (Re = Gd, Dy, Nd, Sm and La) were fabricated by a sol–gel method .The XRD patterns of all samples have only peaks of the
garnet structure and the sizes of nanoparticles rang from 34 to 69 nm. Results of VSM show that the saturation magnetization
of Y3−x
Gd
x
Fe5O12, Y3−x
Dy
x
Fe5O12 and Y3−x
Sm
x
Fe5O12 nanoparticles decrease evidently as the Re3+ concentration (x) is increased. The saturation magnetization of Y3−x
Nd
x
Fe5O12 and Y3−x
La
x
Fe5O12 increases firstly and then decreases as the Re3+ concentration (x) is increased. In the meanwhile, it is observed that may be due to the enhancement of the surface spin effects, the saturation
magnetization rises as the nanoparticle size is increased. 相似文献
3.
Venugopalan Anbarasu Appasamy Manigandan Thangavelu Karthik Kandasamy Sivakumar 《Journal of Materials Science: Materials in Electronics》2012,23(6):1201-1209
The synthesis and characterization of Y2−xFexO3 (where x = 0–0.3) compounds has been carried out for their importance in the field of multiferroic materials. The powder
X-ray diffraction reveal that the compounds Y1.95Fe0.05O3, Y1.9Fe0.1O3, Y1.85Fe0.15O3 and Y1.8Fe0.2O3 crystallize in tetragonal structure whereas Y1.75Fe0.25O3 and Y1.7Fe0.3O3 compounds crystallize in orthorhombic structure. The change in crystal system with respect to the concentration of Fe may
be attributed to the variation in occupancy position of Fe3+ into the Y3+ site of Y2O3 system. Variation in crystal structure, surface morphology and composition was studied by micro-Raman analysis, SEM and EDX
analysis. The shift in intense Raman signals from 426 to 385 cm−1 confirms the change in the crystal structure of the prepared compounds. Further it is also identified that the Eg mode of vibration is the dominant in the Fe substituted compounds. The substitution of Fe in the Y2O3 system leads to the increase in the intensity of resonance band, which indicates a large polarisability variation in the
Y2−xFexO3 compounds. Diffused reflectance studies show a red shift in energy gap values while increasing the concentration of Fe. The
room temperature magnetization and electron paramagnetic resonance studies reveal that the incorporation of Fe in the Y2O3 system leads to magnetic phase change from diamagnetic to ferromagnetic. The electric polarization studies imply that the
substitution of lower ionic radii element Fe3+ in the Y3+ site leads to distortion in the lattice and show the way to spontaneous dipole moment and it was found that the Y1.8Fe0.2O3 compound exhibits the possibility of multiferroic behaviour. Therefore this paper explores the possibility of inducing ferromagnetic
and ferroelectric behaviour in the Fe substituted yttrium oxide system. 相似文献
4.
Biao Dong Hua Yang Lianxiang Yu Yuming Cui Weiqun Jin Shouhua Feng 《Journal of Materials Science》2007,42(13):5003-5006
Sm
x
BiY2–x
Fe5O12 (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) nanocrystals were fabricated by sol–gel method. Samples were characterized by powder X-ray
diffraction (XRD), thermal gravity analysis (TGA) and differential thermal analysis (DTA), transmission electron microscopy
(TEM), vibrating sample magnetometer(VSM). The samples were calcined at 850 °C and 1000 °C and the average size of the particles
were determined by Scherrer’s formula . In this paper, we discussed the effect of Sm3+ substitution for Y3+ on magnetic properties of BiY2Fe5O12. The magnetic properties of Sm
x
BiY2−x Fe5O12 are decreased with increasing content of Sm ion. 相似文献
5.
Yuanyuan Zhang Yue Chen Qiangwei Kou Zhe Wang Donglai Han Yantao Sun Jinghai Yang Yang Liu Lili Yang 《Journal of Materials Science: Materials in Electronics》2018,29(5):3665-3671
Zinc ferrite nanomaterials have been received significant attention in recent years on account of their potential applications in the fields of electronics, optoelectronics and magnetics. To enhance the magnetic properties of zinc ferrites, Nd-doped zinc ferrites (ZnFe2?xNdxO4, x?=?0, 0.01, 0.02, 0.03) nanoparticles (NPs) have been prepared by the sol–gel method. The effects of Nd doping concentration on the structural and magnetic properties of zinc ferrites were studied. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy indicated that the Nd ions were incorporated into the crystal lattice of ZnFe2O4 and substituted for the Fe3+ sites. Unlike pure zinc ferrites with paramagnetism, Nd doped ZnFe2O4 NPs were superparamagnetic at room temperature. Vibrating sample magnetometry results showed, with the increase of Nd content, the saturation magnetization of Nd doped ZnFe2O4 NPs increased. 相似文献
6.
A. Manigandan V. Anbarasu K. Sivakumar 《Journal of Superconductivity and Novel Magnetism》2011,24(6):1877-1884
The compounds Gd1−x
Nd
x
BaSrCu3O7−δ
(where x=0, 0.1 and 0.2) and Gd1−x
Dy
x
BaSrCu3O
y
(where x=0, 0.1 and 0.3) were synthesized using the solid state reaction technique. The tetragonal crystallization of the compounds
was identified by powder X-ray diffraction. The microrange crystallite formation and the substitution elements present in
the compounds were observed by SEM and EDX analyses. The suppression of superconducting transition temperature and the variation
of magnetization parameters for the substitution of rare-earth magnetic elements Nd and Dy ions were observed by low-temperature
electrical resistance and magnetization measurements. 相似文献
7.
Liang Fang Zhao Yang Hui Zhang Chunchun Li Xiyang Peng Changzheng Hu Dongjin Chu 《Journal of Materials Science: Materials in Electronics》2011,22(9):1208-1212
Polycrystalline samples of Ba4Ln2Fe2Ta8O30 (Ln = La and Nd) were prepared by a high temperature solid-state reaction technique. The formation, structure, dielectric
and ferroelectric properties of the compounds were studied. Both compounds are found to be paraelectrics with filled tetragonal
tungsten bronze (TB) structure at room temperature. Dielectric measurements revealed that the present ceramics have exceptional
temperature stability, a relatively small temperature coefficient of dielectric constant (τ
ε
) of −25 and −58 ppm/°C, with a high dielectric constant of 118 and 96 together with a low dielectric loss of 1.2 × 10−3 and 2.8 × 10−3 (at 1 MHz) for Ba4La2Fe2Ta8O30 and Ba4Nd2Fe2Ta8O30, respectively. The measured dielectric properties indicate that both materials are possible candidates for the fabrication
of discrete multilayer capacitors in microelectronic technology. 相似文献
8.
Nanoparticles Y3−x−y
Ce
x
Gd
y
Fe5O12 (x = 0–0.1, y = 0–1.0) were fabricated by a sol–gel method. The crystalline structures and magnetic properties of samples were investigated
by X-ray diffraction (XRD), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and vibrating sample
magnetometer (VSM). The XRD patterns of Y3−x−y
Ce
x
Dy
y
Fe5O12 have only peaks of the garnet structure and the mean size range from 42 nm to 65 nm. The particle’s size observed for all
the samples analyzed by SPM are in good agreement with these data from XRD. The particle’s size ranged from 50 nm to 70 nm,
at the same time, there are small amount of reunited particles can be observed. XPS for Y2.9Ce0.1Fe5O12 gives two peaks at 885.15 and 905.15 eV attributing to Ce3+ 3d5/2 and 3d3/2, respectively. The results confirm the valence state of Ce atoms being +3. Results of VSM show that the saturation magnetization
is increased with increasing Ce content (x) and is decreased with increasing the Gd concentration (y) in a linear manner. The saturation magnetization is increased with increasing the particle’s size.
相似文献
Hua YangEmail: |
9.
Ce-substituted BaFe12O19 (BaCe
x
Fe12−x
O19, x = 0, 0.01, 0.03, 0.05) was prepared by citrate sol–gel method. The thermal decomposition process of precursor was investigated
by TG-DSC. The phase composition of the BaCe
x
Fe12−x
O19 was characterized by X-ray powder diffraction analysis (XRD) which reveals that the BaCe
x
Fe12−x
O19 crystallizes in a hexagonal structure. The lattice parameter of BaCe
x
Fe12−x
O19 increases slightly when Ce was substituted into BaFe12O19. The average crystallite size calculated from the XRD line broadening is about 30–33 nm and no intermediate phases are detected
in the XRD patterns. The transmission electron microscope (TEM) analysis indicates that the particles of samples obtained
are the rod-like morphology. 相似文献
10.
Suhua Fan Fengqing Zhang Guitao Liu Qingbo Tian Luyi Zhu 《Journal of Materials Science: Materials in Electronics》2011,22(12):1778-1782
Bismuth-layered compound Ca0.15Sr1.85Bi4−xNdxTi5O18 (CSBNT, x = 0–0.25) ferroelectric ceramics samples were prepared by solid-state reaction method. The effects of Nd3+ doping on their ferroelectric and dielectric properties were investigated. The remnant polarization Pr of CSBNT ceramics
increases at beginning then decreases with increasing of Nd3+ doping level, and a maximum Pr value of 9.6 μC/cm2 at x = 0.05 was detected with a coercive field Ec = 80.2 kV/cm. Nd3+ dopant not only decreases the Curie temperature linearly, but also the dielectric constant (εr) and dielectric loss tangent (tan δ). The magnitudes of εr and tan δ at the frequency of 100 kHz are estimated to be 164 and 0.0083 at room temperature, respectively. 相似文献
11.
Wen Chen Wenwei Wu Minmin Mao Chong Zhou Shifang Zhou Miaoyu Li Qing Wang 《Journal of Superconductivity and Novel Magnetism》2017,30(3):707-714
Barium hexagonal ferrites (BaNd x Fe12?x O 19) have been synthesized by initial high-energy milling of the precursors and calcining subsequently. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). XRD and SEM examinations reveal that a high-crystallized hexagonal BaNd x Fe12?x O 19 with lamellar morphology is obtained when the precursor is calcined at 1200°C in air for 3 h. The hexagonal crystalline structure of BaFe12 O 19 is not changed after doping Nd3+ ions in BaFe12 O 19. However, lattice parameters a and b values increase with an increase in Nd content at first, then decrease. Nd substitution may improve the magnetic properties of BaNd x Fe12?x O 19. BaNd0.1Fe11.9 O 19, obtained at 1050°C, has the highest specific saturation magnetization value (80.81 emu/g) and magnetic moment (16.21 μ B); BaNd0.2Fe11.8 O 19, obtained at 950°C, has the highest coercivity value, 4075.19 Oe. 相似文献
12.
Y2O3 + Nd2O3 co-stabilized ZrO2-based composites with 40 vol% WC were fully densified by pulsed electric current sintering (PECS) at 1350 °C and 1450 °C.
The influence of the PECS temperature and Nd2O3 co-stabilizer content on the densification, hardness, fracture toughness and bending strength of the composites was investigated.
The best combination of properties was obtained for a 1 mol% Y2O3 and 0.75 mol% Nd2O3 co-stabilized composite densified for 2 min at 1450 °C under a pressure of 62 MPa, resulting in a hardness of 15.5 ± 0.2
GPa, an excellent toughness of 9.6 ± 0.4 MPa.m0.5 and an impressive 3-point bending strength of 2.04 ± 0.08 GPa. The hydrothermal stability of the 1 mol% Y2O3 + 1 mol% Nd2O3 co-stabilized ZrO2-WC (60/40) composites was compared with that of the equivalent 2 mol% Y2O3 stabilized ceramic. The double stabilized composite did not degrade in 1.5 MPa steam at 200 °C after 4000 min, whereas the
yttria stabilized composite degraded after less than 2000 min. Moreover, the (1Y,1Nd) ZrO2-WC composites have a substantially higher toughness (~9 MPa.m0.5) than their 2Y stabilized equivalents (~7 MPa.m0.5). 相似文献
13.
Jing Wang Huifang Xu Jianwei Song Haijiao Zhang Beiling Gao Yudong Huang 《Journal of Materials Science》2011,46(9):2955-2962
Lightweight composite hollow spheres with conductive and magnetic properties were prepared by using Hollow Glass Spheres (HGS)
as substrate. The morphology, composition, conductive, and magnetic properties of the resultant products were characterized
by SEM, EDX, XRD, FTIR spectra, conductivity measurement, and vibrating-sample magnetometry. Polyaniline (PANI) were in situ
polymerized on HGS with increasing ratios of PANI to HGS, resulting in the enhanced conductivity of HGS/PANI composites from
1.3 × 10−2 S/cm to 4.4 × 10−2 S/cm. Lightweight glass/Fe3O4-PANI composite hollow spheres (HGS/Fe3O4-PANI) with conductivity of 5.4 × 10−3 S/cm and magnetization of 9.25 emu/g were prepared by deposition of Fe3O4 nanoparticles onto HGS via electrostatic adsorption first, and then polymerization of aniline onto HGS/Fe3O4. The glass/PANI-Fe3O4 composite hollow spheres (HGS/PANI-Fe3O4) composed of Fe3O4 as the outmost layer and PANI as the inner layer were prepared for comparison. The conductivity and magnetization of HGS/PANI-Fe3O4 were 1.1 × 10−4 S/cm and 2.61 emu/g, respectively. 相似文献
14.
Ying Wang Lei Ni Xiang Ming Chen 《Journal of Materials Science: Materials in Electronics》2011,22(4):345-350
Ca1−3x/2Nd
x
Cu3Ti4O12 (x = 0, 0.1, 0.2) ceramics were prepared by a solid state reaction process, and single-phased structures were obtained for all
the compositions. The dielectric characteristics of pure and Nd-substituted CaCu3Ti4O12 ceramics were investigated together with the microstructures. The mixed-valent structures of Cu+/Cu2+ and Ti3+/Ti4+ in the present ceramics were confirmed by X-ray photoelectron analysis. The dielectric relaxation in the low temperature
range was examined in detail and the variation of dielectric constant and dielectric loss was attributed to the modification
mixed-valent structures. 相似文献
15.
O. Ya. Manashirov A. N. Georgobiani V. B. Gutan E. M. Zvereva A. N. Lobanov 《Inorganic Materials》2011,47(9):1006-1011
We have identified general relationships between the spectral and kinetic properties of the IR Stokes luminescence bands of
Y1 − x − y
Nd
x
Pr
y
PO4 solid solutions in the spectral range 0.86–1.40 μm under 0.810-μm laser excitation. The results have been used to formulate
technical requirements for the purity of rare-earth oxides for the fabrication of efficient YPO4:Nd3+ IR phosphors and to develop a fast YPO4:Nd3+, Pr3+ IR phosphor that allows the decay time of the Nd3+ IR Stokes luminescence bands in the range 0.86–1.40 μm to be tuned from 50 to 170 μs by varying the ratio of the Nd3+ and Pr3+ concentrations. 相似文献
16.
G. D. Nipan V. A. Ketsko A. I. Stognij A. V. Trukhanov T. N. Kol’tsova M. A. Kop’eva L. V. Elesina N. T. Kuznetsov 《Inorganic Materials》2010,46(4):429-433
Using pyrohydrolytic synthesis, we have obtained a continuous series of Mg(Fe1 − x
Ga
x
)2O4 + δ solid solutions, as checked by X-ray diffraction. The magnetization and coercivity of the samples have been determined from
field dependences in applied magnetic fields of ±5 T, and their conductivity has been assessed using current-voltage measurements
at 300 K in electric fields from −200 to +200 V. The effective band gap of the solid solutions has been evaluated from their
absorption spectra obtained by diffuse reflectance measurements. The optimal composition for spintronic applications is Mg(Fe0.8Ga0.2)2O4 + δ. 相似文献
17.
A. I. Stognij N. N. Novitskii O. L. Golikova A. V. Bespalov R. Gieniusz A. Maziewski A. Stupakiewicz M. N. Smirnova V. A. Ketsko 《Inorganic Materials》2017,53(10):1069-1074
Amorphous yttrium iron garnet films ranging in thickness from 100 to 600 nm have been produced on single-crystal silicon substrates by sputtering a polycrystalline target with the composition Y3Fe5O12 (yttrium iron garnet) by a mixture of argon and oxygen ions. Before film growth, AlO x or SiO2 buffer layers up to 0.8 μm in thickness were grown on the Si surface. The heterostructures were crystallized by annealing in air at a temperature of 950°C for 30 min. The properties of the films were studied by magneto-optical techniques, using Kerr effect and ferromagnetic resonance measurements. The Gilbert damping parameter reached 2.8 × 10–3 and the effective planar magnetic anisotropy field was independent of the nature of the buffer layer. This suggests that the thin-film heterostructures obtained in this study are potentially attractive for use in spin-wave semiconductor devices. 相似文献
18.
xBaTiO3 + (1 − x)Ni0.93Co0.02Cu0.05Fe2O4 (x = 0.5, 0.6, 0.7, 0.8) composites with ferroelectric–ferromagnetic characteristics were synthesized by the ceramic sintering
technique. The presence of constituent phases in the composites was confirmed by X-ray diffraction studies. The average grain
size was calculated by using a scanning electron micrograph. The dielectric characteristics were studied in the 100 kHz to
15 MHz. The dielectric constant changed higher with ferroelectric content increasing; and it was constant in this frequency
range. The relation of dielectric constant with temperature was researched at 1, 10, 100 kHz. The Curie temperature would
be higher with frequency increasing. The hysteresis behavior was studied to understand the magnetic properties such as saturation
magnetization (M
s). The composites were a typical soft magnetic character with low coercive force. Both the ferroelectric and ferromagnetic
phases preserve their basic properties in the bulk composite, thus these composites are good candidates as magnetoelectric
materials. 相似文献
19.
Yu Cheng Lai Yen Hwei Chang Yen Chia Chen Hui-Jan Lin Guo Jo Chen 《Journal of Materials Science》2007,42(16):6887-6894
This study investigates how the addition of Co to a Fe59Pt41 alloy with compositions in the range of Fe59Pt41–Co59Pt41 affects the crystallographic ordering temperatures and magnetic properties of sputter-deposited films. Introducing Co into
the (Fe1−x
Co
x
)59Pt41 film affects the activation energy of atomic migration and grain growth, thus leading to a higher annealing temperature of
the L10 phase formation. At a Co concentration of x = 0.2, the saturation magnetization was maximum, at 1,480 emu/cm3, and the (Fe0.8Co0.2)59Pt41 film exhibited a coercivity of about 4 kOe. 相似文献
20.
The thermoelectric power and d.c electrical conductivity of x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses were measured. The Seebeck coefficient (Q) varied from +88 μ V K−1 to −93 μV K−1 as a function of V2O5 mol%. Glasses with 10 and 15 mol% V2O5 exhibited p-type conduction and glasses with 25 and 30 mol% V2O5 exhibited n-type conduction. The majority charge carrier reversal occurred at x = 20 mol% V2O5. The variation of Q was interpreted in terms of the variation in vanadium ion ratio (V5 +/V4 +). d.c electrical conduction in x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses was studied in the temperature range of 150 to 480 K. All the glass compositions exhibited a cross over from
small polaron hopping (SPH) to variable range hopping (VRH) conduction mechanism. Mott parameter analysis of the low temperature
data gave values for the density of states at Fermi level N (EF) between 1.7 × 1026 and 3.9 × 1026 m−3 eV−1 at 230 K and hopping distance for VRH (RVRH) between 3.8 × 10−9m to 3.4 × 10−9 m. The disorder energy was found to vary between 0.02 and 0.03 eV. N (EF) and RVRH exhibit an interesting composition dependence. 相似文献