共查询到20条相似文献,搜索用时 12 毫秒
1.
Qiaoji Zheng Dunmin Lin Xiaochun Wu Chenggang Xu Chun Yang K. W. Kwok 《Journal of Materials Science: Materials in Electronics》2010,21(6):625-629
New ternary (1−x)K0.5Na0.5NbO3–x(0.80LiSbO3–0.20CaTiO3) lead-free ceramics were fabricated by a conventional ceramic technique and their structure and piezoelectric properties
were studied. The results of X-ray diffraction reveal that LiSbO3 and CaTiO3 diffuse into the K0.5Na0.5NbO3 lattices to form a new solid solution with a perovskite structure. After the addition of LiSbO3 and CaTiO3, the cubic-tetragonal and tetragonal-orthorhombic phase transitions shift to lower temperatures. Coexistence of the orthorhombic
and tetragonal phases is hence formed in the ceramics with 0.03 < x < 0.07 at room temperature, leading to a significant enhancement of the piezoelectric properties. For the ceramics with x = 0.04–0.06, the piezoelectric properties become optimum: d
33 = 172–253 pC/N, k
P = 49.9–55.5%, k
t = 49.2–52.1% and T
C = 348–373 °C. The ceramic with x = 0.04 also exhibits a good thermal stability of piezoelectric properties. 相似文献
2.
H. Y. He 《Journal of Materials Science: Materials in Electronics》2012,23(5):995-1000
The nickel cobalt ferrite (Co0.5Zn0.5Fe2O4) nanopowders were synthesized by a sol–gel method and a hydrothermal method. Polyethylene glycol (PEG-4000) and carboxymethyl
cellulose (CMC) were used as the templating agents for controlling the anisotropy and the microstructure of the Co0.5Zn0.5Fe2O4 nanopowders. The microstructure and magnetic property of the synthesized powders were comparatively studied. The results
indicated that the synthesis technique and the template had remarkable dependence on the microstructure and the magnetic property
of the nanopowders. The powder synthesized by the sol–gel method without any template had a maximum saturation magnetization
of 73.6 emu g−1 closing to the value of the bulk material (80 emu g−1), while the PEG-4000 and CMC decreased the magnetization to 54.0 and 60.9 emu g−1. The three powders showed almost same coercivity (314–343 Oe). However, the PEG-4000 and CMC in the hydrothermal process
obviously decreased and increased the coercivity respectively from 1,464 Oe to 5 Oe and 4,304 Oe but had small effect of the
magnetization (55.5–59.0 emu g−1). 相似文献
3.
Gaofeng Liu Xiuli Chen Guisheng Huang Dandan Ma Huanfu Zhou 《Journal of Materials Science: Materials in Electronics》2017,28(5):3931-3935
In this paper, (1 ? x)(K0.5Na0.5)NbO3–xBi(Mg0.75W0.25)O3 (x = 0–0.015) lead-free dielectric ceramics were investigated. XRD analysis certified that the Bi(Mg0.75W0.25)O3 has diffused into (K0.5Na0.5)NbO3 to fabricate a new solid solution. The addition of Bi(Mg0.75W0.25)O3 depressed the orthorhombic–tetragonal phase transition temperature from 210 to 176 °C and tetragonal–pseudocubic phase transition temperature (Curie point) from 419 to 400 °C. As x = 0.005, the ceramics exhibited high relative permittivity (ε ~ 1325), low dielectric loss (tan δ < 2.9%) tan δ stability (Δε/ε168°C ≤ ±15%) in the temperature range of 168 ~ 369 °C. Especially, the ceramics also showed optimized piezoelectric constant (d 33 = 122 pC N?1) and remnant polarization (Pr = 32.57 μC cm–2). These results indicated that the BMW added ceramics have potential applications in ferroelectric and thermal stability devices. 相似文献
4.
Shaaban M. Salem E. M. Antar A. G. Mostafa S. M. Salem S. A. El-badry 《Journal of Materials Science》2011,46(5):1295-1304
(10Li2O–20GeO2–30ZnO–(40-x)Bi2O3–xFe2O3 where x = 0.0, 3, 6, and 9 mol%) glasses were prepared. A number of studies, viz. density, differential thermal analysis, FT-IR spectra,
DC and AC conductivities, and dielectric properties (constant ε′, loss tan δ, AC conductivity, σ
ac, over a wide range of frequency and temperature) of these glasses were carried out as a function of iron ion concentration.
The analysis of the results indicate that, the density and molar volume decrease with an increasing of iron content indicates
structural changes of the glass matrix. The glass transition temperature T
g and onset of crystallization temperature T
x increase with the variation of concentration of Fe2O3 referred to the growth in the network connectivity in this concentration range, while glass-forming ability parameter ΔT decrease with increase Fe2O3 content, indicates an increasing concentration of iron ions that take part in the network-modifying positions. The FT-IR
spectra evidenced that the main structural units are BiO3, BiO6, ZnO4, GeO4, and GeO6. The structural changes observed by varying the Fe2O3 content in these glasses and evidenced by FTIR investigation suggest that the iron ions play a network modifier role in these
glasses while Bi2O3, GeO2, and ZnO play the role of network formers. The temperature dependence of DC and AC conductivities at different frequencies
was analyzed using Mott’s small polaron hopping model and, the high temperature activation energies have been estimated and
discussed. The dielectric constant and dielectric loss increased with increase in temperature and Fe2O3 content. 相似文献
5.
Chunhua Tian Yunchen Du Chunsheng Cui Zhiliang Deng Jianlei Xue Ping Xu Rong Qiang Ying Wang Xijiang Han 《Journal of Materials Science》2017,52(11):6349-6361
Rational design on the microstructure of microwave-absorbing materials is paving the way for upgrading their performances in electromagnetic pollution prevention. In this study, a Fe3O4/C composite with unique yolk–shell microstructure (YS-Fe3O4@C) is successfully fabricated by a silica-assisted route. It is found that carbon shells in this composite can make up the shortages of Fe3O4 microspheres in dielectric loss ability, while they may more or less attenuate the intrinsically magnetic loss of Fe3O4 microspheres. The microwave absorption properties of YS-Fe3O4@C are evaluated in the frequency range of 2.0–18.0 GHz in terms of the measured complex permittivity and complex permeability. The results demonstrate that YS-Fe3O4@C can exhibit much better performance than bare Fe3O4 microspheres and individual carbon materials, as well as core–shell Fe3O4/C composite (CS-Fe3O4@C), where strong reflection loss and wide response bandwidth can be achieved simultaneously. With an absorber thickness of 2.0 mm, the maximum reflection loss is ?73.1 dB at 14.6 GHz and a bandwidth over ?10.0 dB is in the range of 12.3–18.0 GHz. It can be proved that the unique yolk–shell microstructure is helpful to reinforce the dielectric loss ability and create an optimized matching of characteristic impedance in the composite. 相似文献
6.
Madan Lal Mamta Shandilya Ajith S. Kumar Radheshyam Rai Swapna S. Nair Ratnakar Palai 《Journal of Materials Science: Materials in Electronics》2018,29(1):80-85
Multiferroic ceramic composites of (1?x)Ba0.96Ca0.04TiO3–(x)ZnFe2O4 (BCT-ZF) were prepared from ferroelectric (FE) barium calcium titanate (BCT) and ferromagnetic (FM) zinc ferrite (ZF) by using the solid state reaction method with different mol% fractions of x (x?=?0.1 and 0.2). The preliminary structural studies carried out by X-ray diffraction at room temperature reveals that the samples have a tetragonal structure along with the cubic spinel ferrite phase. Raman spectra of the composites also confirm the existence of BCT phase and ZF phase. The room temperature ferroelectric polarization measurements as a function of magnetic field show the existence strong magnetoelectric coupling of 10.85 (mV/(cm.Oe). 相似文献
7.
M. I. Ivanovskaya D. A. Kotikov V. V. Pan’kov V. V. Zyryanov 《Inorganic Materials》2009,45(8):910-915
X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy have been used to investigate the structural phase transformations of SrCo0.5Fe0.5O3 ? δ-based mixed-oxide nanocomposites containing fine iron oxide particles. The nanocomposites have been prepared using sol-gel and mechanochemical processes. The addition of iron(III) oxide sol to SrCo0.5Fe0.5O3 ? δ xerogel is shown to enhance the thermal stability of the resultant cubic perovskite phase. The stabilization is due to partial shielding of the perovskite surface with a thin Fe2O3 layer, which hinders cobalt diffusion to the surface, preventing Co3O4 formation. 相似文献
8.
Li Sun Jianqin Guo Qing Ni Ensi Cao Yongjia Zhang Wentao Hao Lin Ju 《Journal of Materials Science: Materials in Electronics》2018,29(7):5356-5362
Mn1?xZnxFe2O4 (x?=?0.2–0.8) ferrite samples were successfully prepared by the sol–gel method. X-ray diffraction study reveals that single cubic spinel phase was formed in Mn1?xZnxFe2O4 samples. The SEM micrographs revealed that the microstructures change significantly with different Zn2+ doping concentration and sintering temperature while the grain size grow up to 9.48 μm for Mn0.6Zn0.4Fe2O4 sample sintered at 1100 °C. Further, the dielectric and magnetic measurements indicated that both Zn2+ doping and sintering temperature could affect both electrical and magnetic parameters such as dielectric constant and saturation magnetization in a great manner. The Mn0.6Zn0.4Fe2O4 sample sintered at 1100 °C for 8 h is found to show the largest M s value (77.30 emu/g) in this work. These results indicate that Zn2+ doping or sintering temperature can adjust the microstructures, dielectric and magnetic properties of Mn1?xZnxFe2O4 ferrites. 相似文献
9.
Wei Li Zhijun Xu Ruiqing Chu Jigong Hao Peng Fu Juan Du Zhenxing Yue 《Journal of Materials Science: Materials in Electronics》2016,27(9):8911-8915
The (100) oriented and random oriented 0.755Bi0.5Na0.5TiO3–0.065BaTiO3–0.18SrTiO3 (BNT–BT–ST) thin films were deposited on LaNiO3 (LNO) buffered Pt(111)/Ti/SiO2/Si substrates by the sol–gel processing technique. The orientation is controlled by the concentration of solution. The structure, dielectric and piezoelectric properties of the thin films are significantly affected by the crystallographic orientation. The (100) oriented BNT–BT–ST thin film has improved dielectric and piezoelectric properties. For the (100) oriented and random oriented BNT–BT–ST thin films, the dielectric constants are 660 and 550, the dielectric losses are 0.045 and 0.076 and the effective piezoelectric coefficients are 140 and 110 pm/V, respectively. The large piezoelectric response is attributed to the uniform microstructure and increased lattice distortion along (100) direction. 相似文献
10.
In this work, we have described the antibacterial activities of Fe3O4 nanoparticles with different organic parts, including Humic acid (HA), Nicotinic acid (Nico) and Histidine (His), and the antibacterial activity of MnFe2O4 nanoparticles coated with PANI and SiO2 against different bacteria and some standard antibacterial drugs. The present study revealed that the newly fabricated various Fe3O4 and MnFe2O4 nanocomposites, when combined with some different organic parts, are superiour antibacterial agents. Also, the synthesized nanocomposites can be easily separated from aqueous solution by magnetic filtration without any contamination of the medium. 相似文献
11.
Guo-Zhong Zang Xiu-Jie Yi Juan Du Zhi-Jun Xu Rui-Qing Chu Peng Fu Wei Li 《Journal of Materials Science: Materials in Electronics》2011,22(9):1282-1285
In order to obtain the morphotropic phase boundary (MPB) and good piezoelectric properties, lead-free (Na1.015−xKx)NbO3 (x = 0.32–0.35) piezoceramics were synthesized by conventional solid state sintering. The x-ray diffraction results show
that the lattice parameters of the monoclinic primitive cell peak at x = 0.34. The scanning electron microscopy and energy
dispersive spectroscopy reveal that the excess sodium may be an important reason for the abnormal growth of the grains larger
than 20 μm. All the samples exhibit double-like hysteresis loops and it may also be attributed to the excess Na+. Although the salient microstructure was found in the studied range, the piezoelectric and ferroelectric properties changed
slightly with increasing x from 0.32 to 0.35. The values of piezoelectric coefficient d
33 obtained in this study are as high as about 75 pC/N which is close to that of normally prepared (Na0.5K0.5)NbO3 ceramics with MPB structure. 相似文献
12.
Lead-free piezoelectric ceramics (1 − x)Bi0.5Na0.5TiO3–xBaNb2O6 (BNT–BN100x), a new member of the BNT-based group, was prepared by conventional solid state reaction. X-ray diffraction showed that BaNb2O6 (BN) diffused into the lattice of Bi0.5Na0.5TiO3 to form a solid solution with perovskite-type structure. The temperature dependence of dielectric constant εr revealed that the solid solution underwent two phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric
to paraelectric. Both the transition temperature T
d and T
m were shifted to lower with the increasing content of BaNb2O6. The temperature dependence of dielectric constant at different frequency revealed that the solid solution exhibited obviously
dielectric relaxation characteristics. The sample with x = 0.6 mol% exhibited excellent electrical properties, piezoelectric constant d
33 = 94 pC/N; electromechanical coupling factor k
p = 0.185. The results showed that BNT–BN100x ceramics were good candidates for use as lead-free piezoelectric ceramics. 相似文献
13.
N. V. Golubko G. M. Kaleva A. V. Mosunov N. V. Sadovskaya E. D. Politova 《Inorganic Materials》2016,52(9):925-931
We have studied the effect of Bi(Mg0.5Ti0.5)O3 additions on the phase formation, structural parameters, microstructure, and dielectric properties of solid solutions in the region of a morphotropic phase boundary in the BiFeO3–BaTiO3 system. Single-phase samples with the perovskite structure have been obtained and the addition of Bi(Mg0.5Ti0.5)O3 has been shown to raise the Curie temperature of the ceramics and improve their dielectric properties. 相似文献
14.
Song Chen Shuren Zhang Xiaohua Zhou Bo Li 《Journal of Materials Science: Materials in Electronics》2011,22(3):238-243
The low-temperature co-fired ceramic (LTCC) composites containing quartz based on the eutectic system BaO–Al2O3–SiO2–B2O3 are fabricated at the sintering temperature below 980 °C. Preparation process and sintering mechanism were described and
discussed, respectively. The results indicated that the addition of quartz to the eutectic system can availably improve dielectric
properties of the LTCC composites. In addition, The LTCC composites with optimum compositions, which were obtained by the
regulation of an Al2O3 content in the composite, can express excellent dielectric properties (permittivity: 5.94, 5.48; loss: 7 × 10−4, 5 × 10−4), considerable CTE values (11.7 ppm. °C−1, 10.6 ppm. °C−1) and good mechanical properties (128 MPa,133 MPa). 相似文献
15.
New lead-free ceramics (1–x)NaNbO3–xBi0.5K0.5TiO3 have been fabricated by the conventional ceramic sintering technique, and their ferroelectric and piezoelectric properties
have been studied. The results of X-ray diffraction reveal that Bi0.5K0.5TiO3 diffuses into the NaNbO3 lattices to form a new perovskite-type solid solution with orthorhombic symmetry. The addition of a small amount of Bi0.5K0.5TiO3 (x ≥ 0.025) transforms the ceramics from antiferroelectric to ferroelectric. The ceramic with x = 0.10 possesses the largest
remanent polarization P
r and thus exhibits the optimum piezoelectric properties, giving d
33 = 71 pC/N, k
p = 16.6% and k
t = 39.7%. The ceramics with low doping level of Bi0.5K0.5TiO3 are normal ferroelectrics and the ferroelectric-paraelectric phase transition becomes diffusive gradually with the doping
level x of Bi0.5K0.5TiO3 increasing. Our results show the (1–x)NaNbO3–xBi0.5K0.5TiO3 ceramics is one of the good candidates for lead-free piezoelectric and ferroelectric materials. 相似文献
16.
In this study, NaNO3, Bi(NO3)3·5H2O, Ba(NO3)2, Ti(OC4H9)4 and citric acid were successfully introduced to fabricate lead-free piezoelectric (Na0.5Bi0.5)0.94Ba0.06TiO3 [NBBT] nanopartical powders by a novel modified sol–gel auto-combustion method. The resultant products were characterized
by the X-ray diffraction analysis and transmission electron microscope method. (Na0.5Bi0.5)0.94Ba0.06TiO3 + Mn(NO3)2 [NBBTM] can be sintered by the traditional solid-state reaction, and the effects of NBBT doped different amounts of Mn(NO3)2 at various sintering temperatures upon phase formation, microstructure as well as piezoelectric properties were further studied.
The experimental results show that it was helpful to control their chemical ingredients and microstructure to prepare nanocrystalline
single phase NBBT powders. Where is the X-ray diffraction result of the corresponding ceramics to prove the existence of the
mixing between rhombohedral and tetragonal phases at the MPB compositions. Doping 0.015 mol% Mn(NO3)2 into NBBT at 1,090 °C, piezoelectric constant (d
33) and relative dielectric constant (εr) reach the superior value of 159pC/N and 1,304, respectively, and dielectric loss (tan δ) and electromechanical coupling
factor (K
t) are 2.5% and 65%, respectively. 相似文献
17.
Lanfang Gao Yanqiu Huang Liang Liu Tiantian Liu Chunfeng Liu Fei Zhou Xinwu Wan 《Journal of Materials Science》2008,43(18):6267-6271
(1 − x)BaTiO3–x(Bi0.5Na0.5)TiO3 (x ranged from 0.01 to 0.96) ceramics were fabricated by the conventional ceramic technique. The crystal structure, as well
as dielectric and piezoelectric properties of the ceramics were studied. All the ceramics formed single-phase solid solutions
with perovskite structure after sintering in air at 1150–1250 °C for 2–4 h. The crystal structure and microstructure varied
gradually with the increase of (Bi0.5Na0.5)TiO3 (BNT) content. The Curie temperature, T
c, shifted monotonously to high temperature as BNT increased. The ceramics with 20–90 mol% BNT had relatively low and stable
dielectric loss characteristics. The piezoelectric constant, d
33, enhanced with the increase of BNT content through a maximum value in a composition of 93 mol% BNT and then tended to decrease.
The maximum value, 148 pC/N, of piezoelectric constant d
33 together with the electromechanical coupling factors, k
t, 19.8% and k
p, 15.8%, were obtained when BNT was 93 mol%. 相似文献
18.
Rajendra Kumar Singh A. Srinivasan G. P. Kothiyal 《Journal of materials science. Materials in medicine》2009,20(1):147
Magnetic bioglass ceramics (MBC) are being considered for use as thermoseeds in hyperthermia treatment of cancer. While the bioactivity in MBCs is attributed to the formation of the bone minerals such as crystalline apatite, wollastonite, etc. in a physiological environment, the magnetic property arises from the magnetite [Fe3O4] present in these implant materials. A new set of bioglasses with compositions 41CaO · (52 ? x)SiO2 · 4P2O5 · xFe2O3 · 3Na2O (2 ≤ x ≤ 10 mol% Fe2O3) have been prepared by melt quenching method. The as-quenched glasses were then heat treated at 1050°C for 3 h to obtain the glass-ceramics. The structure and microstructure of the samples were characterized using X-ray diffraction and microscopy techniques. X-ray diffraction data revealed the presence of magnetite in the heat treated samples with x ≥ 2 mol% Fe2O3. Room temperature magnetic property of the heat treated samples was investigated using a Vibrating Sample Magnetometer. Field scans up to 20 kOe revealed that the glass ceramic samples had a high saturation magnetization and low coercivity. Room temperature hysteresis cycles were also recorded at 500 Oe to ascertain the magnetic properties at clinically amenable field strengths. The area under the magnetic hysteresis loop is a measure of the heat generated by the MBC. The coercivity of the samples is another important factor for hyperthermia applications. The area under the loop increases with an increase in Fe2O3 molar concentration and the. coercivity decreases with an increase in Fe2O3 molar concentration The evolution of magnetic properties in these MBCs as a function of Fe2O3 molar concentration is discussed and correlated with the amount of magnetite present in them. 相似文献
19.
I. A. Leonidov M. V. Patrakeev E. B. Mitberg O. N. Leonidova V. L. Kozhevnikov 《Inorganic Materials》2006,42(2):196-201
The oxygen content of the double cobaltite PrBaCo2O5 + δ was determined by coulometric titration in broad temperature and oxygen pressure ranges, and the partial thermodynamic functions of oxygen were evaluated. The results on the nonstoichiometry and structural properties of PrBaCo2O5 + δ demonstrate that, at 5 + δ < 5.3, this cobaltite has a high-temperature phase with lattice parameters a = 11.774 Å, b = 11.932 Å, and c = 7.609 Å. The composition dependences of \(\Delta \bar H(O)\) and \(\Delta \bar S(O)\) indicate that the 3ap × 3ap × 2ap orthorhombic structure persists in the range 5.15 ≤ 5 + δ ≤ 5.30. Some of the Co3+ ions are shown to disproportionate according to the scheme 2Co3+=Co2++Co4+. 相似文献
20.
Yang Liu Qiangwei Kou Dandan Wang Lei Chen Yantao Sun Ziyang Lu Yuanyuan Zhang Yaxin Wang Jinghai Yang Scott Guozhong Xing 《Journal of Materials Science》2017,52(17):10163-10174
To minimize saturation magnetization (Ms) degradation and simultaneously maintain the optical and magnetic responsiveness characteristics of Fe3O4/Au nanocomposites, we successfully prepared Fe3O4–Au seeds composite nanoparticles (NPs) by a novel seed deposition process. The effects of gold seeds coating amounts and the concentration of Fe3O4 NPs on the morphologies of final products are extensively characterized. The results of energy-dispersive spectrometry mapping show that the gold seeds are uniformly adhered onto the Fe3O4 NPs surfaces in precisely controlled amount. Importantly, with the electronic redistribution between Fe3O4 and Au NPs interfaces, the obvious position shifting of Fe 2p and Au 4f electronic binding energy peaks is observed. Upon increasing surface coatings of gold seeds, the electron deficiency on the gold NPs leads to the redshift of the absorption peak. Though Ms declines slightly due to the diamagnetic contribution from decorated gold seeds, the developed Fe3O4–Au seeds composite NPs possess the robust magnetic responsiveness and they are amenable to be separated and recycled by the external magnet, which facilitates great potential applications in biological, medical and photocatalytic fields. 相似文献