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1.
Fe3BO6 can be an ideal compound for devising functional magnetic and dielectric properties in a single material for multiple applications such as electrodes, gas sensors, or medical tools. Useful to tailor such properties, here we report on a self-controlled Fe3BO6 growth in a specific shape of nanorods from a supercooled liquid precursor (an inorganic polymeric liquid or glass) of an initial composition (100 − x)B2O3 − xFe2O3, x = 40–50 mol%. B2O3 as a strong glass former co-bridges the Fe3+ ions in oxygen polygons primarily in a 2-D interconnected polymer network so that it dictates preferably a 1-D directional growth on the reaction Fe3+ species in form of a compound Fe3BO6, a favorable phase to nucleate and grow when annealing a precursor at 500–800 °C in ambient air. Distinct nanorods with a diameter ∼200 nm and 40–100 μm length have been formed on 10–15 min annealing a sample in microwave at moderate temperature 550 °C. A bonded surface B2O3 layer (15–25 nm thickness) has grown on the Fe3BO6 of the nanorods in situ in a specific structure. XPS bands in the Fe3+, B3+ and O2− species confer this model structure. A local BO3 → BO4 conversion has incurred in the boroxol (B3O4.5)n, n → ∞, rings in the surface layer, showing three distinct IR bands at 1035, 1215 and 1425 cm−1. 相似文献
2.
A novel Bi-doped P2O5-B2O3-Al2O3 glass was investigated, and strong broadband NIR (near infrared) luminescence was observed when the sample was excited by 445 nm, 532 nm, 808 nm and 980 nm lasers, respectively. The max FWHM with 312 nm, the lifetime with 580 μs and the σemτ product with 5.3 × 10− 24 cm2 s were obtained which indicates that this glass is a promising material for broadband optical amplifier and tunable laser. The effect of the introduction of B2O3 on the glass structure and Bi-ions illuminant mechanism were discussed and analyzed. It is suggested that the introduction of B2O3 makes the glass structure closer, and the broadband NIR emission derives from Bi0:2D3/2 → 4S3/2 and Bi+:3P1 → 3P0 transitions. 相似文献
3.
Trimanganese tetraoxide (Mn3O4) nanoparticles have been synthesized via hydrothermal process. Nevertheless, homogeneous nanoparticles of Mn3O4 with platelet lozange shape were obtained. The crystallite size ranged from 40 to 70 nm. The Mn3O4 product was investigated by X-ray diffraction, transmission electron microscopy (MET), and impedance spectroscopy. Electrical conductivity measurements showed that the as-synthesized Mn3O4 nanomaterial has a conductivity value which goes from 1.8 10−7 Ω−1 cm−1 at 298 K, to 23 10−5 Ω−1 cm−1 at 493 K. The temperature dependence of the conductivity between 298 and 493 K obeys to Arrhenius law with an activation energy of 0.48 eV. 相似文献
4.
Y. Du 《Materials Letters》2010,64(20):2251-2254
Orthorhombic Bi2Fe4 − xCrxO9 (x = 0.0, 0.25, and 0.75) nanoplatelets were synthesized by a simple hydrothermal method. The structure, morphology, and magnetic properties of the obtained powders have been characterized. Calculation of the lattice parameters of Bi2Fe4 − xCrxO9, as well as bond lengths and angles, was carried out by X-ray diffraction Rietveld refinement. The volumes of the metal-oxygen tetrahedra and octahedra were calculated to be sequentially increasing as the Cr doping level increases. The samples undergo an antiferromagnetic transition at 250 ± 5 K. The magnetic moments of the samples increase with higher Cr doping level. The 3d electron spin state for Fe3+ in the as-prepared samples is different, which is possibly due to the distortion of Fe-O tetrahedra and octahedra in the crystal structure after chromium substitution. 相似文献
5.
Zhanqiang Liu Fuqiang Huang Junkang Sun 《Materials Science and Engineering: B》2011,176(16):1313-1316
Li3 − xFe2 − xTix(PO4)3/C (x = 0-0.4) cathodes designed with Fe doped by Ti was studied. Both Li3Fe2(PO4)3/C (x = 0) and Li2.8Fe1.8Ti0.2(PO4)3/C (x = 0.2) possess two plateau potentials of Fe3+/Fe2+ couple (around 2.8 V and 2.7 V vs. Li+/Li) upon discharge observed from galvanostatic charge/discharge and cyclic voltammetry. Li2.8Fe1.8Ti0.2(PO4)3/C has higher reversibility and better capacity retention than that of the undoped Li3Fe2(PO4)3/C. A much higher specific capacity of 122.3 mAh/g was obtained at C/20 in the first cycle, approaching the theoretical capacity of 128 mAh/g, and a capacity of 100.1 mAh/g was held at C/2 after the 20th cycle. 相似文献
6.
Enhanced thermoelectric properties of NaCo2O4 by adding ZnO 总被引:1,自引:0,他引:1
The primary phase present in the as-sintered Na(Co1 − xZnx)2O4 (0 ≤ x ≤ 0.1) bodies was the solid solution of the constituent oxides with a bronze-type layered structure. The electrical conductivity of the Na(Co1 − xZnx)2O4 samples significantly increased with an increase in ZnO content. The sign of the Seebeck coefficient for all samples was positive over the whole temperature range (723-1073 K), i.e., p-type conduction. The power factor of Na(Co0.95Zn0.05)2O4 showed an outstanding power factor (1.7 × 10− 3Wm− 1 K− 2) at 1073 K. The power factor was above four times superior to that of ZnO-free NaCo2O4 (0.4 × 10− 3Wm− 1 K− 2). This originates from an unusually large Seebeck coefficient (415 μVK− 1) accompanied with high conductivity (127Ω− 1 cm− 1) at 1073 K. 相似文献
7.
Hiromichi Aono Kenji MoritaniTakashi Naohara Tsunehiro MaeharaHideyuki Hirazawa Yuji Watanabe 《Materials Letters》2011,65(10):1454-1456
We found the most promising powder material for the application of the thermal coagulation therapy for the treatment of cancerous tissues. The maximum heat generation ability (ΔT = 40-77 °C, 370 kHz, 1.77 kA·m− 1) was obtained for the powder materials by the calcination at 1100 °C for the Y3 − XGdXFe5O12 system. This ΔT value is higher than ca. ΔT = 30 °C in same magnetic field for fine FeFe2O4 particles as the candidate material for this type of therapy. The particle growth with the formation of the cubic single phase might influence to the high heat generation. As an unexpected result, the Gd3Fe5O12 (X = 3) has no heat generation ability in an AC magnetic field. 相似文献
8.
A homogeneous composite of MnO2/multi-wall carbon nanotubes (MnO2/MWCNTs) was rapidly and efficiently synthesized by a redox reaction of MnO4− and Mn2+ on the MWCNTs under ultrasonic irradiation. The structure and morphology of the obtained MnO2 and MnO2/MWCNTs composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. Electrochemical investigation indicated that the maximum specific capacitance of the MnO2/MWCNTs composite, measured by galvanostatic charge-discharge test, was 315 F g− 1, compared to the pristine MnO2 (192 F g− 1) and MWCNTs electrode (25 F g− 1), showing the synergistic effect of MWCNTs and MnO2. The homogeneous hybrid nanostructure and the good conductivity of MWCNTs were considered to be responsible for its preferable electrochemical performances. 相似文献
9.
NixFe100−x films with a thickness of about 200 nm were deposited on SiO2/Si(1 0 0) substrates at room temperature by DC magnetron co-sputtering using both Fe and Ni80Fe20 targets. Compositional, structural, electrical and magnetic properties of the films were investigated. Ni76Fe24, Ni65Fe35, Ni60Fe40, Ni55Fe45, Ni49Fe51 films are obtained by increasing the sputtering power of the Fe target. All the films have a fcc structure. Ni76Fe24, Ni65Fe35, Ni60Fe40 and Ni55Fe45 films grow with crystalline orientations of [1 1 1] and [2 2 0] in the direction of the film growth while the Ni49Fe51 film has the [1 1 1] texture structure in the direction of the film growth. The lattice constant of the film increases linearly with increasing Fe content. All of the films grow with thin columnar grains and have void networks in the grain boundaries. The grain size does not change markedly with the composition of the film. The resistivity of the film increases with increasing Fe content and is one order of magnitude larger than that of the bulk. For all the films the magnetic hysteresis loop shows a hard magnetization. The Ni76Fe24 film has the lowest saturation magnetization of 6.75×10−2 T and the lowest saturation field of 8.36×104 A/m while the Ni49Fe51 film has a largest saturation magnetization of 9.25×10−2 T and the largest saturation field of 1.43×105 A/m. 相似文献
10.
Jin Won Kim 《Thin solid films》2010,518(22):6514-6517
V-doped K0.5Bi4.5Ti4O15 (K0.5Bi4.5 − x/3Ti4 − xVxO15, KBTiV-x, x = 0.00, 0.01, 0.03, and 0.05) thin films were prepared on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method. The thin films were annealed by using a rapid thermal annealing process at 750 °C for 3 min in an oxygen atmosphere. Among them, KBTiV-0.03 thin film exhibited the most outstanding electrical properties. The value of remnant polarization (2Pr) was 75 μC/cm2 at an applied electric field of 366 kV/cm. The leakage current density of the thin film capacitor was 5.01 × 10−8 at 100 kV/cm, which is approximately one order of magnitude lower than that of pure K0.5Bi4.5Ti4O15 thin film capacitor. We found that V doping is an effective method for improving the ferroelectric properties of K0.5Bi4.5Ti4O15 thin film. 相似文献
11.
M-substituted Ca(Cu3−xMx)Ti4O12 (CCMTO) ceramics, where M = Fe and Ni, were synthesized and the influence of M substitutions for Cu on the crystal structure and ferroelectric properties of CCMTO ceramics were investigated in this study. From the variations in the lattice parameters of CCMTO ceramics, the solubility limit of Ni substitution for Cu in CaCu3−xNixTi4O12 (CCNTO) ceramics was x = 0.2, whereas that of CaCu3−xFexTi4O12 (CCFTO) ceramics was x = 0.05. The crystal structural analysis of CCMTO ceramics revealed that the single phase of CCMTO ceramics belongs to the I23 non-centrosymmetric space group of I23; as a result, the Pr and Ec values of CCFTO ceramics at x = 0.05 were 1.8 μC/cm2 and 40 kV/cm, respectively. The ferroelectric behavior of CCMTO ceramics by the M substitutions for Cu may be related to the displacement of a Ti4+ cation in the TiO6 octahedra and tilting of the Ti–O–Ti angle because of the non-centrosymmetric space group. 相似文献
12.
Mg0.4Al2.4O4 single crystal was grown by the Czochralski method. The measured specific heat values are 0.804-1.06 J g− 1 K− 1 in the temperature range from 298.15 to 573.15 K. The calculated thermal conductivity components are 11.37, 11.47 and 10.77 W m− 1 K− 1 along the [111], [004] and [22?0] direction at 298.15 K. The Vickers microhardness values are 1328-1414 kg mm− 2. These experimental results show that Mg0.4Al2.4O4 crystal is a promising substrate for GaN-based LEDs. 相似文献
13.
The formation of magnetite nanoparticles on the sidewalls of multi-walled carbon nanotubes 总被引:1,自引:0,他引:1
Linear polyethyleneimine (PEI) was used as a non-covalent functionalizing agent to modify multi-walled carbon nanotubes (MWCNTs). Fe3O4 nanoparticles were then formed along the sidewalls of the as-modified MWCNTs through a simple solvothermal method. X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, and vibrating sample magnetometry were used to characterize the MWCNT/Fe3O4 nanocomposites. Results indicated that Fe3O4 nanoparticles with diameters ranging from 50 to 200 nm were attached to the surface of the MWCNTs by electrostatic interaction. PEI was found to improve the electrical conductivity of the MWCNT/Fe3O4 nanocomposites. The magnetic saturation value of these magnetic nanocomposites was 61.8 emu g−1. These magnetic MWCNT/Fe3O4 nanocomposites are expected to have wide applications in bionanoscience and technology. 相似文献
14.
David H. O’Neil Vladimir L. Kuznetsov Robert. M.J. Jacobs Martin O. Jones Peter P. Edwards 《Materials Chemistry and Physics》2010
Highly conducting (σ ∼ 2.6 × 103 Ω−1 cm−1) In4Sn3O12 films have been deposited using pulsed laser deposition (PLD) on glass and quartz substrates held at temperatures between 350 and 550 °C under chamber pressures of between 2.5 and 15 mTorr O2. The crystallinity and the surface roughness of the films were found to increase with increasing substrate temperature. Electron concentrations of the order of 5 × 1020 cm−3 and mobilities as high as 30 cm2 V−1 s−1 were determined from Hall effect measurements performed on the films. Fitting of the transmission spectral profiles in the ultra-violet–visible spectrum has allowed the determination of the refractive index and extinction coefficient for the films. A red-shift in the frequency of plasmon resonance is observed with both increasing substrate temperature and oxygen pressure. Effective masses have been derived from the plasma frequencies and have been found to increase with carrier concentration indicating a non-parabolic conduction band in the material In4Sn3O12. The optical band-gap has been determined as 3.8 eV from the analysis of the absorption edge in the UV. These results highlight the potential of these films as lower In-content functional transparent conducting materials. 相似文献
15.
Ferroelectric Na0.5La0.5Bi4Ti4O15 (NaLaBTi) thin films were prepared by a chemical solution deposition method. The NaLaBTi thin films annealed at 750 °C under oxygen atmosphere were randomly oriented polycrystalline. Electrical properties of the NaLaBTi thin films were compared to Na0.5Bi4.5Ti4O15 thin films and better properties were observed in the NaLaBTi thin films. Remnant polarization (2Pr) and coercive electric field (2Ec) were 43 µC/cm2 and 204 kV/cm at an applied electric field of 478 kV/cm, respectively. Leakage current density was 1.95 × 10− 6 A/cm2 at 100 kV/cm. Dielectric constant and dielectric loss were 805 and 0.05 at 1 kHz, respectively. Switchable polarization was suppressed by 15% after 1.44 × 1010 switching cycles. 相似文献
16.
Submicron layered LiNi0.5Mn0.5O2 was synthesized via a co-precipitation and solid-state reaction method together with a quenching process. The crystal structure and morphology of the materials were investigated by X-ray diffraction (XRD), Brunauer–Emmett and Teller (BET) surface area and scanning electron microscopy (SEM) techniques. It is found that LiNi0.5Mn0.5O2 material prepared with quenching methods has smooth and regular structure in submicron scale with surface area of 0.43 m2 g−1. The initial discharge capacities are 175.8 mAh g−1 at 0.1 C (28 mA g−1) and 120.3 mAh g−1 at 5.0 C (1400 mA g−1), respectively, for the quenched samples between 2.5 and 4.5 V. It is demonstrated that quenching method is a useful approach for the preparation of submicron layered LiNi0.5Mn0.5O2 cathode materials with excellent rate performance. In addition, the cycling performance of quenched-LiNi0.5Mn0.5O2 material was also greatly improved by AlF3 coating technique. 相似文献
17.
Yannan QianRui Wang Lili XingYanling Xu Chunhui YangXinrong Liu 《Optical Materials》2012,34(5):884-888
The effect of In3+ ion on the optical characteristics of Er3+ ion in Er/Yb:LiNbO3 crystal under 980 nm excitation has been investigated. The Er and Yb contents in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES). A significant enhancement of 1.54 μm emission was observed for Er/Yb:LiNbO3 crystal doped with 1 mol% In2O3. The studies on the UV-vis absorption and the OH− absorption spectra indicate that the threshold concentration of In3+ ion decreases with the Er/Yb doping in Er/Yb/In:LiNbO3 crystal. The 1 mol% In2O3 doping results in the reduction of absorption cross section in the UV-vis region, meaning the formation of Er3+ cluster sites. The enhancement of 1.54 μm emission is attributed to the larger probabilities of the cross relaxation processes 4S3/2 + 4I15/2 → 4I9/2 + 4I13/2 (Er), 4S3/2 + 4I15/2 → 4I13/2 + 4I9/2 (Er) and 4I9/2 + 4I15/2 → 4I13/2 + 4I13/2 (Er) induced by Er3+ cluster sites. 相似文献
18.
In this work, environmentally friendly magnetite nanoparticles (Fe3O4 MNPs) were used to adsorb chlorotetracycline (CTC) from aqueous media. Fe3O4 MNPs exhibit ultrahigh adsorption ability to this widely used antibiotic. The adsorption behavior of CTC on Fe3O4 MNPs fitted the pseudo-second-order kinetics model, and the adsorption equilibrium was achieved within 10 h. The maximum Langmuir adsorption capacity of CTC on Fe3O4 (476 mg g−1) was obtained at pH 6.5. Thermodynamic parameters calculated from the adsorption data at different temperature showed that the adsorption reaction was endothermic and spontaneous. Low concentration of NaCl and foreign divalent cations hardly affected the adsorption. Negative effect of coexisting humic acid (HA) on CTC adsorption was also observed when the concentration of HA was lower than 20 mg L−1. But high concentration of HA (>20 mg L−1) increased the CTC adsorption on Fe3O4 MNPs. The matrix effect of several environmental water samples on CTC adsorption was not evident. Fe3O4 MNPs were regenerated by treatment with H2O2 or calcination at 400 °C in N2 atmosphere after separation from water solution by an external magnet. This research provided a high efficient and reusable adsorbent to remove CTC selectively from aqueous media. 相似文献
19.
A novel approach, combining in-situ composite method with electrospinning, was used to prepare high magnetic Fe3O4/poly(vinyl alcohol) (PVA) composite nanofibers. Fe3O4 magnetic fluids were synthesized by chemical co-precipitation method in the presence of 6 wt.% PVA aqueous solution. PVA was used as stabilizer and polymeric matrix. The resulting Fe3O4/PVA composite nanofibers were characterized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffractometer (XRD), respectively. These composite fibers showed a uniform and continuous morphology, with the Fe3O4 nanoparticles embedded in the fibers. Magnetization test confirmed that the composite fiber showed a high saturated magnetization (Ms = 2.42 emµ·g-1) although only 4 wt.% content. 相似文献
20.
0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3(PNN-PZT) ceramics with different concentration of xFe2O3 doping (where x = 0.0, 0.8, 1.2, 1.6 mol%) were synthesized by the conventional solid state sintering technique. X-ray diffraction analysis reveals that all specimens are a pure perovskite phase without pyrochlore phase. The density and grain size of Fe-doped ceramics tend to increase slightly with increasing concentration of Fe2O3. Comparing with the undoped ceramics, the piezoelectric, ferroelectric and dielectric properties of the Fe-doped PNN-PZT specimens are significantly improved. Properties of the piezoelectric constant as high as d33 ~ 956 pC/N, the electromechanical coupling factor kp ~ 0.74, and the dielectric constant εr ~ 6095 are achieved for the specimen with 1.2 mol% Fe2O3 doping sintered at 1200 °C for 2 h. 相似文献