共查询到20条相似文献,搜索用时 31 毫秒
1.
Chuye Quan Zhengfei Qin Yiyi Zhu Zhongchao Wang Jian Zhang Weiwei Mao Xingfu Wang Jianping Yang Xing’ao Li Wei Huang 《Journal of Materials Science: Materials in Electronics》2017,28(4):3278-3284
The multiferroic Bi0.9Ca0.1FeO3, Bi0.9Ca0.1Fe0.9Co0.1O3, Bi0.9Ca0.1Fe0.9Ni0.1O3, Bi0.9Ca0.1Fe0.9Cu0.1O3 samples were prepared by a simple sol–gel method. Rietveld refinement of X-ray diffraction data and Raman spectra reflect a structural phase transition from single phase (rhombohedral, pure BiFeO3) to two phase coexistence (rhombohedral R3c and cubic Fm-3 m). The structural distortion of Bi0.9Ca0.1Fe0.9Ni0.1O3 is very marked. SEM images show the co-doped nanoparticles having an average size of 50 nm. A contribution from the leakage current have been observed in the P–E loops. XPS results reveal that the concentration of Fe2+ and oxygen vacancy decreased after transition metal elements (Co, Ni, Cu) doped into Bi0.9Ca0.1FeO3. Moreover Co, Ni doping can enhance the saturation magnetization, while Cu doping can enhance the coercive field in Bi0.9Ca0.1FeO3. 相似文献
2.
Qingyu Xu Zheng Wen Jinlong Gao Xiao Liu Di Wu Shaolong Tang Bin Yang 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1497-1500
(Bi0.9Ba0.1)(Fe0.95Mn0.05)O3 films were prepared on LaNiO3-coated surface oxidized Si substrates. XRD and Raman measurements confirm that the (Bi0.9Ba0.1)(Fe0.95Mn0.05)O3 film has pure R3c structure. Clear ferromagnetism with saturated magnetization of about 25 emu/cm3 has been observed at room temperature. The ferroelectric properties of the (Bi0.9Ba0.1)(Fe0.95Mn0.05)O3 film was confirmed by the observation of the ferroelectric domains and the converse piezoelectric coefficient d
33 versus applied voltage hysteresis loops by piezoelectric force microscopy (PFM). The observation of ferromagnetism and ferroelectricity
in (Bi0.9Ba0.1)(Fe0.95Mn0.05)O3 films indicates the potential multiferroic applications. 相似文献
3.
A. A. Zatsiupa L. A. Bashkirov I. A. Vialikanava G. S. Petrov S. V. Shevchenko 《Inorganic Materials》2016,52(4):361-366
Bi2–хLaхFe4O9 and Bi2Fe4–2xTixCoxO9 ferrites have been prepared by solid-state reactions at a temperature of 1073 K. X-ray diffraction data indicate that, in the Bi2–хLaхFe4O9 system, the limiting degree of La3+ substitution for Bi3+ ions in Bi2Fe4O9 does not exceed 0.05 and that the limiting degree of substitution in the Bi2Fe4–2xTixCoxO9 system lies in the range 0.05 < x < 0.1. The specific magnetization and specific magnetic susceptibility of the samples have been measured at temperatures from 5 to 300 K in a magnetic field of 0.86 T. The field dependences of magnetization obtained for the Bi2–хLaхFe4O9 and Bi2Fe4–2xTixCoxO9 ferrites at temperatures of 300 and 5 K demonstrate that partial isovalent substitution of La3+ for Bi3+ ions in Bi2Fe4O9 and heterovalent substitution of Ti4+ and Co2+ ions for two Fe3+ ions leads to partial breakdown of the antiferromagnetic state and nucleation of a ferromagnetic state. 相似文献
4.
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
5.
Purnendu Parhi V. Manivannan Sandeep Kohli Patrick Mccurdy 《Bulletin of Materials Science》2008,31(6):885-890
A solid-state metathesis approach initiated by microwave energy has been successfully applied for the synthesis of orthovanadates,
M3V2O8 (M = Ca, Sr, and Ba). The structural, vibrational, thermal, optical and chemical properties of synthesized powders are determined
by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy,
differential scanning calorimetry, magnetic property measurements and diffused reflectance spectra in the UV-VIS range. The
direct bandgap of the synthesized materials was found to be 3·55 ± 0·2 eV, 3·75 ± 0·2 eV and 3·57 ± 0·2 eV for Ca3V2O8, Sr3V2O8 and Ba3V2O8, respectively. 相似文献
6.
Xiao Chun Zhou Lu Ping Zhong Qiu Ping Liu Ren Yun Kuang Hong Mei Chen 《Inorganic Materials》2009,45(11):1295-1298
New red emitting phosphors, Ca3(VO4)2:Eu3+,Bi3+, Ca3((P,V)O4)2:Eu3+ were synthesized by low temperature solid-state reaction and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and Fourier transform infrared spectroscopy. The results show that the red emission located at about 613 nm was ascribed to 5 D 0-7 F 2 transition of Eu3+. The effect of by Bi doping and by P doping was also investigated systematically. 相似文献
7.
In this paper, mixed Ca–Ba oxide Ca1 − x
Ba
x
Bi4Ti4O15 (CBBT) ceramics, fabricated by the improved traditional ceramics process were investigated by doping concentrations of Ba
ion up to x =\emph{x} {=} 0·9 (in steps of 0·1). At room temperature, an orthorhombic crystal system was confirmed using XRD, and their parameter was
obtained using the Rietveld method. Dielectric properties and phase transitions were studied and are explained in terms of
lattice response of these ceramics. A shift in ferroelectric–paraelectric phase transition (TC\emph{T}_{C}) to lower temperatures and a corresponding decrease in permittivity peak with increasing concentration of Ba2 + are also observed. The ferroelectric–paraelectric phase transition of CBBT compounds is of normal type in nature, differing
from the relaxor characteristic of BBT. The decrease of orthorhombicity in the lattice structure by the larger Ba2 + ion incorporation, indicating an approach of a and b, results in lower Curie temperature. Appearance of anomalous loss peaks of Ba-rich compounds at 530°C reveals a phase transition
development trend from ferroelectric orthorhombic structure to the paraelectric orthorhombic structure. Relationship of polarization
with lattice response is discussed. 相似文献
8.
Tianye Wang Wanyi Liu Yunhang Gao Shuxia Liu 《Journal of Materials Science: Materials in Electronics》2017,28(20):14949-14953
In this study, the effects of sodium oleate on synthesis of Bi2WO6/Bi2O3 loaded reduced graphene oxide photocatalyst was studied. The as-prepared composites were characterized by X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance and photoluminescence spectroscopy. The results suggested that addition of sodium oleate not only promoted synthesis of Bi2O3, but also enhanced the reduction of GO to graphene. When the amount of sodium oleate was 4 mol (Bi:SO?=?1:1), Bi2WO6/Bi2O3@RGO to the best visible-light photocatalytic activity can be synthesized by a facile one-step solvothermal process without further reduction reaction. Hence, it indicated that sodium oleate could affect the synthesis of the as-prepared composites and the photocatalytic activity for degradation of RhB. This study did provide not only a facile method to synthesize Bi2WO6/Bi2O3@RGO, but also a method to reduce graphene oxide to graphene. 相似文献
9.
Perovskite type (Ba0.85Ca0.15?2x Bi2x )(Zr0.1Ti0.9?x Cu x )O3 lead-free ceramics were prepared via a conventional solid-state reaction method. The phase structure, dielectric, ferroelectric properties and complex impedance were investigated in detail. XRD and dielectric measurements determined that single orthorhombic phase displayed in (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 at room temperature. With the introduction of Bi2O3/CuO, the phase structure exhibited the mixture of orthorhombic and tetragonal phases, and then turned to single tetragonal phase. In contrast to the sharp dielectric transition of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics, a broad dielectric peak coupled with a slight decrease in Curie temperature was observed in (Ba0.85Ca0.15?2x Bi2x )(Zr0.1Ti0.9?x Cu x )O3 ceramics with increasing x. The observed diffuse phase transition behavior was further confirmed by a couple of measurements with polarization loops and polarization current density curves. The structural and the composition fluctuations induced by ions doping should be responsible for the diffuse phase transition behavior. Furthermore, physical mechanisms of the conduction and relaxation processes were revealed by using impedance spectroscopy analyses. It was concluded that the conduction and relaxation processes were thermally activated, which was closely linked with the singly and doubly ionized oxygen vacancies. 相似文献
10.
A simple co-precipitation technique has been successfully applied for the preparation of pure single phase CaBi4Ti4O15 (CBT) powders. Ammonium oxalate and ammonium hydroxide were used to precipitate Ca2+, Bi3+ and Ti4+ cations simultaneously. No pyrochlore phase was found while heating powder at 600 C and pure CBT phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 400. The ferroelectric hysteresis loop parameters of these samples were also studied. 相似文献
11.
V. T. Kavitha R. Jose S. Ramakrishna P. R. S. Wariar J. Koshy 《Bulletin of Materials Science》2011,34(4):661-665
Nanocrystalline Ba2NdSbO6, a complex cubic perovskite metal oxide, powders were synthesized by a self-sustained combustion method employing citric
acid. The product was characterized by X-ray diffraction, differential thermal analysis, thermogravimetric analysis, Fourier
transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The as-prepared powders
were single phase Ba2NdSbO6 and a mixture of polycrystalline spheroidal particles and single crystalline nanorods. The Ba2NdSbO6 sample sintered at 1500°C for 4 h has high density (∼ 95% of theoretical density). Sintered nanocrystalline Ba2NdSbO6 had a dielectric constant of ∼ 21; and dielectric loss = 8 × 10−3 at 5 MHz. 相似文献
12.
R. N. P. Choudhary Dillip K. Pradhan C. M. Tirado G. E. Bonilla R. S. Katiyar 《Journal of Materials Science》2007,42(17):7423-7432
The nanocrystalline fine powders (∼80 nm) of (Ba1−x
La
x
)(Fe2/3W1/3)1−x/4O3, (BLFW) (x = 0.0, 0.05, 0.10 and 0.15) were synthesized with a combined mechanical activation and conventional high-temperature solid-state
reaction methods. Preliminary X-ray structural analysis of pellet samples (prepared from fine powders) showed formation of
a single-phase tetragonal system. Detailed studies of dielectric properties (εr and tan δ) exhibit that these parameters are strongly dependent on frequency, temperature and La composition. The La-substitution
increases the dielectric constant and decreases the tan δ up to 10% substitutions of La at the Ba-site, and then reversed
the variation, and hence this composition is considered as a critical composition. This observation was found valid for structure,
microstructures, dielectric constant, electrical conductivity, J–E characteristics and impedance parameters also. Like in other perovskites (PZT, BZT), La substitution plays an important role
in tailoring the properties of Ba(Fe2/3W1/3)O3 ceramics. 相似文献
13.
Haibo Yang Jingjing Dai Ying Lin Ning Han Xiao Liu Jingjing Wang 《Journal of Materials Science: Materials in Electronics》2017,28(15):10853-10861
Polyaniline (PANI)/CoFe2O4/Ba3Co2Fe24O41 composite was prepared by an in-situ polymerization method. The phase structure, morphology and magnetic properties of the as-prepared PANI/CoFe2O4/Ba3Co2Fe24O41 composite were characterized by XRD, FT-IR, SEM, TEM, and VSM, respectively. The microwave absorption properties of the composite were investigated by using a vector network analyzer in the 2–18 GHz frequency range. The results show that the maximum reflection loss value of the PANI/CoFe2O4/Ba3Co2Fe24O41 composite reaches ?30.5 dB at 10.5 GHz with a thickness of 3 mm and the bandwidth of reflection loss below ?10 dB reaches up to 1.2 GHz. The excellent microwave absorption properties of the as-prepared PANI/CoFe2O4/Ba3Co2Fe24O41 composite due to the enhanced impedance match between dielectric loss and magnetic loss. 相似文献
14.
N. Sai Krishna S. Kaleemulla G. Amarendra N. Madhusudhana Rao C. Krishnamoorthi I. Omkaram D. Sreekantha Reddy 《Journal of Materials Science: Materials in Electronics》2015,26(11):8635-8643
The (In1?xCrx)2O3 powders as well as thin films of x = 0.03, 0.05 and 0.07 were synthesized using a solid state reaction and an electron beam evaporation technique (on glass substrate), respectively. The influence of Cr doping concentration on structural, optical and magnetic properties of the In2O3 samples was systematically studied. The X-ray diffraction results confirmed that all the Cr doped In2O3 samples exist cubic structure of In2O3 without any secondary phases presence. The chemical composition analyses showed that all the Cr doped In2O3 compounds were nearly stoichiometric. The X-ray photoelectron spectroscopy analysis of the Cr doped In2O3 thin films showed an increase of oxygen vacancies with Cr concentration and the existence of Cr as Cr3+ state in the host In2O3 lattice. A small blue shift in the optical band gap was observed in the powder compounds, when the dopant concentration increased from x = 0.03 to x = 0.07. In thin films, the band gap found to increase from 3.63 to 3.74 eV, with an increase of Cr concentration. The magnetic measurements show that the undoped In2O3 bulk powder sample has the diamagnetic property at room temperature. And a trace of paramagnetism was observed in Cr doped In2O3 powders. However (In1?xCrx)2O3 thin films (x = 0.00, 0.03, 0.05 and 0.07) samples shows soft ferromagnetism. The observed ferromagnetism in thin films are attributed to oxygen vacancies created during film prepared in vacuum conditions. The ferromagnetic exchange interactions are established between metal cations via free electrons trapped in oxygen vacancies (F-centers). 相似文献
15.
S. Varaprasad K. Thyagarajan Y. Markandeya K. Suresh G. Bhikshamaiah 《Journal of Materials Science: Materials in Electronics》2018,29(16):13606-13613
Synthesis of Sr2FexMo2?xO6 (x?=?0.8 to 1.5 with a step increment of 0.1) (SFMO) double perovskite oxides were done by sonochemical method at relatively low preparation temperature (950 °C). Purity and existence of all elements (Sr, Fe, Mo, and O) in SFMO compound have been analyzed by energy dispersive X-ray spectroscopy (EDS). Lattice parameters and unit cell volume were studied by X-ray powder diffraction (XRD). The structural transition from tetragonal to cubic occurs around composition x?=?1.1 has been noticed from XRD data. Scanning electron microscopy (SEM) confirmed grain sizes of SFMO series, which are found to be in the range of 75–185 nm. Perovskite formation has been confirmed by Fourier transform infrared spectroscopy (FTIR) spectrum analysis. Investigations of Magnetic properties have been carried out using Vibrating Sample Magnetometer (VSM) at applied magnetic field from ??20 to +?20 kOe. Saturation magnetization is found to increase from x?=?0.8 to 1 and then decreases from x?=?1 to 1.5, the behavior is correlated with degree of Fe/Mo ordering. 相似文献
16.
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
17.
Rajesh Narayana Perumal G. Subalakshmi E. Varadarajan S. Sadhasivam G. Vinitha 《Journal of Materials Science: Materials in Electronics》2018,29(4):2638-2644
The SrLa2?xO4:xEu3+ phosphors are synthesized through high-temperature solid-state reaction method at 1473 K with various doping concentration. Their phase structures, absorption spectra, and luminescence properties are investigated by X-ray diffraction (XRD), UV–Vis spectrophotometer and photoluminescence spectrometry. The intense absorption of SrLa2?xO4:xEu3+ phosphors have occurred around 400 nm. The prominent luminescence spectra of the prepared phosphors exhibited bright red emission at 626 nm. The doping concentration 0.12 mol% of Eu3+ is shown to be optimal for prominent red emission and chromaticity coordinates are x?=?0.692, y?=?0.3072. Considering the high colour purity and appropriate emission intensity of Eu3+ doped SrLa2O4 can be used as red phosphors for white light emitting diodes (WLEDs). 相似文献
18.
Guo-hua Chen Jun-tao Liu Hua-rui Xu Chang-rong Zhou Min-hong Jiang Xin-yu Liu 《Journal of Materials Science: Materials in Electronics》2011,22(8):915-919
Ultrafine strontium barium niobate (Sr0.3Ba0.7Nb2O6, SBN30) powders were prepared by urea method starting from a precursor solution constituting of Sr (NO3)2, Ba (NO3)2, NbF5, urea and polyvinyl alcohol (PVA) as surfactant. Their structural behavior and morphology were examined by means of X-ray
diffractometry (XRD) and Scanning electron microscopy (SEM). The results showed that the SBN30 powders crystallized to a pure
tetragonal phase at annealing temperatures as low as 750 °C. The average particle size of SBN powders subjected to 750 °C
was of the order of 150–300 nm. With increasing calcination temperature,however, the average particle size of the calcined
powders increased. The SBN30 ceramic prepared from urea method can be sintered at temperature as low as 1,225 °C. The transition
temperature from the ferroelectric phase to the paraelectric phase and the relative dielectric permittivity of the SBN30 powder
were less than the corresponding values of the bulk ceramic. The permittivity and loss tangent (tan δ) at room temperature
(1 kHz) was found to be 930 and below 0.025. 相似文献
19.
A series of intergrowth bismuth-layered ferroelectric Bi7Ti4NbO21 materials are reactive-sintered at 1050 to 1150 °C from Bi3TiNbO9 and Bi4Ti3O12 parent phases to infer their structural characters and microstructure relations. Various types of stacking faults are revealed
in the intergrowth structure with extra Bi3TiNbO9 or Bi4Ti3O12 layer(s) by high-resolution transmission electron microscopy; some faults with even spacing form locally new intergrowths
of Bi10Ti5Nb2O30 and Bi11Ti7NbO33. Co-growth of Bi7Ti4NbO21 epitaxially grown onto the remaining Bi4Ti3O12 grains is found in the low temperature sintered samples, while the Bi4Ti3O12 co-growth onto the intergrowth grains is also found in the high temperature samples. Both co-growths are created from intergranular
melts during a solution-precipitation process, which is consistent with the anisotropic growth of the intergrowth structure
and the presence of a Bi-rich intergranular phase. The populations of different stacking faults are found to decrease with
the increase of their thickness and also with the increase of sintering temperature, indicating that they are remnants survived
from dissolution to imbed via precipitation into the intergrowth structure, which should be created from the smaller but much
abundant one-layered remnants of the parent phases. This leads to a new model of structural reorganization by such one-layered
units to form the intergrowth structure in this solution-precipitation process. Such incomplete dissolution is initiated by
the preferential melting of interleaved [Bi2O2]2+ sheets to enable the exfoliation of perovskite layers to re-order into the intergrowth structure. This reorganization model
re-defines the reactive sintering as an evolution process of Bismuth-layered structures. 相似文献
20.
Ruqu Han Songtao Dong Yuanxiang Wang Xiaoxi Li Yamei Zhang 《Journal of Materials Science: Materials in Electronics》2017,28(19):14234-14239
Nd1?xBaxCoO3 (0?≤?x?≤?0.2) ceramics was synthesized by solid state reaction. All the samples have an orthorhombic perovskite structure (Space group P n m a). The electrical transport property indicates that Ba doped NdCoO3 ceramics goes through semiconductor–metal phase transition. The electrical resistivity of Nd1?xBaxCoO3 (0?≤?x?≤?0.15) ceramics decreases, while the electrical resistivity of Nd0.8Ba0.2CoO3 ceramics increases with the increase of temperature. The chemical-sensing property shows that Nd1?xBaxCoO3 ceramics is very sensitive to oxygen. Also, increasing Ba2+ doping concentration can reduce the oxygen desorption rate and increase the sensitivity of resistivity. These results indicate that Ba2+ doped NdCoO3 ceramics is not only the good candidate of the cathode materials of solid fuel cells but also the good materials of gas sensor devices. 相似文献