共查询到20条相似文献,搜索用时 15 毫秒
1.
Mingquan Liu Xiangqian Shen Fuzhan Song Jun Xiang Ruijiang Liu 《Journal of Sol-Gel Science and Technology》2011,59(3):553-560
Sr0.8La0.2Zn0.2Fe11.8O19/poly(vinyl pyrrolidone) (PVP) composite fiber precursors were prepared by the sol–gel assisted electrospinning. Subsequently,
the M-type ferrite Sr0.8La0.2Zn0.2Fe11.8O19 nanofibers with diameters about 120 nm were obtained by calcination of these precursors at different heat treatment conditions.
The precursor and resultant Sr0.8La0.2Zn0.2Fe11.8O19 nanofibers were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive
X-ray spectrometer and vibrating sample magnetometer. With the calcination temperature increased up to 1,000 °C for 2 h or
the holding time prolonged to 12 h at 900 °C, the Sr0.8La0.2Zn0.2Fe11.8O19 particles gradually grow into a hexagonal elongated plate-like morphology due to the dimensional control along the nanofiber
length. These elongated plate-like particles will be linked one by one to form the nanofiber with a necklace-like morphology.
The magnetic properties of the Sr0.8La0.2Zn0.2Fe11.8O19 nanofibers are closely related to grain sizes, impurities and defects in the ferrite, which are influenced by the calcination
temperature, holding time and heating rate. After calcined at 900 °C for 12 h with a heating rate of 3 °C/min, the optimized
magnetic properties are achieved with the specific saturation magnetization 75.0 A m2 kg−1 and coercivity 426.3 kA m−1 for the Sr0.8La0.2Zn0.2Fe11.8O19 nanofibers. 相似文献
2.
Quentin Cacciuttolo Julien Vulliet Virginie Lair Michel Cassir Armelle Ringuedé 《Journal of Solid State Electrochemistry》2018,22(12):3663-3671
This paper is dedicated to the impact of pressure on the electrochemical behaviour of LSCF (La1-xSrxCoyFe1-yO3-δ) anode in high-temperature electrolysers. This study was carried out with symmetrical cells associating LSCF electrodes to a 3YSZ (yttrium-stabilised zirconia) electrolyte. Impedance spectroscopy measurements were performed using a three-electrode configuration, at temperature as high as 700 to 800 °C, in a pressure range from 1 to 30 bar. A clear improvement in terms of electrode resistance decrease is highlighted, mainly due to faster oxygen adsorption/desorption kinetics and a better supply of gas to electrochemical reaction sites. Other assumptions were considered and analysed, such as the impact of pressure on LSCF electrical conductivity and on the mechanical contacts. Thus, three contributions were determined as limiting steps at low pressure, up to 5 bar, whilst for higher pressure, the optimised conditions in operation are reached. This study completes a previous one related to a modelling approach. 相似文献
3.
Shiming Liu Xiaoliang Qian Jianzhong Xiao 《Journal of Sol-Gel Science and Technology》2007,44(3):187-193
Nano-crystalline La0.8Sr0.2Co0.5Fe0.5O3±δ powder has been successfully synthesized by microwave assisted sol–gel (MWSG) method. The decomposition and crystallization
behavior of the gel-precursor was studied by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis.
From the result of FT-IR and X-ray diffraction patterns, it is found that a perovskite La0.8Sr0.2Co0.5Fe0.5O3±δ was formed by irradiating the precursor at 700 W for 3 min, but the well-crystalline perovskite La0.8Sr0.2Co0.5Fe0.5O3±δ was obtained at 700 W for 35 min. Morphological and specific area analysis of the powder were done by transmission electron
microscopy (TEM), scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET). The surface areas measured was 38.9 m2/g and the grain size was ∼23 nm. Electrochemical properties of pure LSCF cathode on YSZ electrolyte at intermediate temperatures
were investigated by using AC impedance analyzer, which shows a low area specific resistance (0.077 Ω cm2 at 1073 K and 0.672 Ω cm2 at 953 K). Moreover, the synthesis period of 20 h usually observed for conventional heating mode is reduced to a few minutes.
Thus, the MWSG method is proved to be a novel, extremely facile, time-saving and energy-efficient route to synthesize LSCF
powders. 相似文献
4.
E. V. Shkol’nikov 《Russian Journal of Applied Chemistry》2011,84(10):1702-1709
The molar solubilities of solid oxides M2O3 and their hydrates at 25°C as functions of pH of aqueous media, as well as the acid-base equilibrium constants were calculated
for crystalline oxides and dissolved M(OH)3 hydroxides, where M = Cr, Fe, Co, by the thermodynamic method, taking into account the formation of mono- and polynuclear
hydroxo complexes. 相似文献
5.
N. N. Gedam P. R. Padole S. K. Rithe G. N. Chaudhari 《Journal of Sol-Gel Science and Technology》2009,50(3):296-300
Thick film of nanocrystalline Co0.8Ni0.2Fe2O4 was obtained by sol–gel citrate method for gas sensing application. The synthesized powder was characterized by X-ray diffraction
(XRD) and transmission electron microscopy. The XRD pattern shows spinel type structure of Co0.8Ni0.2Fe2O4. XRD of Co0.8Ni0.2Fe2O4 revels formation of solid solution with average grain size of about 30 nm. From gas sensing properties it observed that nickel
doping improves the sensor response and selectivity towards ammonia gas and very low response to LPG, CO, and H2S at 280 °C. Furthermore, incorporation of Pd improves the sensor response and stability of ammonia gas and reduced the operating
temperature upto 210 °C. The sensor is a promising candidate for practical detector of ammonia. 相似文献
6.
T. I. Chupakhina G. V. Bazuev E. V. Zabolotskaya 《Russian Journal of Inorganic Chemistry》2010,55(2):247-253
A new oxide phase La1.5Sr1.5 Mn1.25Ni0.75O6.67 ± 0.05, a member of the An + 1 BnO3n+1(n=2) Rad-dlesden—Popper homologue series, was synthesized, and its structure and magnetic properties characterized. Magnetic
anomalies associated with the competition between antiferromagnetic and ferromagnetic orders are observed in the range of
the temperatures studied (2-400 K). The ESR spectra of the compound feature the constriction of a magnetic signal and a shift
toward g(Mn4+). 相似文献
7.
B. K. Kasenov E. S. Mustafin S. N. Merkur’eva M. A. Akubaeva Sh. B. Kasenova S. T. Edil’baeva R. Sh. Erkasov 《Russian Journal of Inorganic Chemistry》2007,52(10):1514-1515
La2M 3 II Mn4O12 (M = Mg, Ca, Sr, or Ba) manganites have been synthesized by ceramic technology from lanthanum oxide, manganese(III) oxide, and magnesium, calcium, strontium, or barium carbonate. X-ray powder diffraction shows that these compounds crystallize in cubic perovskite space group Pm3m. 相似文献
8.
In this work we used electrochemical polarization for oxidizing and reducing, in a controlled way, the Ruddlesden-Popper phase La4Ni3O10. With a careful choice of electrochemical parameters, we were able to obtain samples of La4Ni3O10± never obtained before. The oxygen stoichiometry can range between 9.78 (=–0.22) and 10.12 (=0.12). The oxidized phase, La4Ni3O10.12, was obtained using a galvanostatic mode (I=20 A) and the reduced phase, La4Ni3O9.78, using potentiostatic conditions (E=0.46 V). The evolution of the electrical conductivity has been studied as a function of . 相似文献
9.
V. M. Zainullina 《Russian Journal of Inorganic Chemistry》2009,54(1):100-114
The electronic structure of the Sn0.875M0.125O2 compounds (M = Cr, Mn, Co) with a rutile structure and magnetic moments of the transition metal atoms in them were calculated by the ab initio spin-polarized linear muffin-tin orbital method. The electron density and electron localization function maps for these compounds were constructed. Based on these data, the effect of the composition of these phases on the electronic spectrum, chemical bond, and magnetic and transport properties were analyzed. 相似文献
10.
L. S. Pechen E. V. Makhonina A. M. Rumyantsev Yu. M. Koshtyal V. S. Pervov I. L. Eremenko 《Russian Journal of Inorganic Chemistry》2018,63(12):1534-1540
Layered Li-rich transition metal oxides are considered among the most promising cathode materials for high energy density lithium-ion batteries. It was studied how the method and conditions of synthesis of Li-rich oxides Li1.2Mn0.54Ni0.13Co0.13O2 affect their electrochemical properties. Coprecipitation methods and modified Pechini process were used. It was shown that it is necessary to carefully choose the synthesis conditions when using the modified Pechini method because of their significant effect on the morphology of Li-rich oxides. Samples were obtained with high electrochemical characteristics: capacity discharge of 260–270 mAh/g (16 mA/g) and 60–70 mAh/g (988 mA/g) within the voltage range of 2.5–4.8 V. 相似文献
11.
T. B. Tatarintseva O. V. Mikhailov N. I. Naumkina T. Z. Lygina 《Russian Journal of Coordination Chemistry》2005,31(2):101-107
Electrophilic substitution reactions Zn2+ M2+ (M = Mn, Co, Ni, Cu, Cd) in thin gelatin layers with immobilized zinc(II) hexacyanoferrate brought in contact with the aqueous solutions of d-element chlorides are studied. In all cases (except for Mn(II)), Zn atoms are partially replaced by all metals in question with the formation of the corresponding binuclear ZnM hexacyanoferrates(II). No complete replacement of Zn(II) to mononuclear hexacyanoferrate(II) of substituting metal occurs in neither of the cases.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 110–116. Original Russian Text Copyright © 2005 by Tatarintseva, Mikhailov, Naumkina, Lygina. 相似文献
12.
The present investigation correlates the propagation of ultrasonic waves with various micro structural features of nano La0.69Sr0.31MnO3 (LSMO) perovskites with different grain sizes. A solid state reaction followed by the ball milling technique was used to synthesize the nano LSMO perovskite samples with various grain sizes. The occurrence of ferro-paramagnetic transition temperature (Tc) was explored through the observed anomalous behaviour in ultrasonic velocities, attenuations and elastic moduli. As the particle size gets reduced, lower Tc and broader transitions are observed due to the distribution of grain boundaries. The diffusion of the FM–PM phase transition along with decrease in Tc is correlated due to the effect of particle size. Furthermore structural, vibrational and electrical properties of nanosized LSMO perovskite samples with different grain sizes were studied by XRD, FTIR, BET surface area measurement, HRSEM, TEM and four probe conductivity studies. The phase of the synthesized nano LSMO perovskite samples are perfectly indexed to pure rhombohedral perovskite type crystal structure. The conductivity study proves the semiconductor nature of the nano LSMO perovskite samples. In addition to this, the peak broadening in ultrasonic studies at phase transition is in line with the observation made from the XRD pattern for the prepared nano LSMO perovskite samples. 相似文献
13.
I. G. Fomina Zh. V. Dobrokhotova G. G. Aleksandrov O. Yu. Proshenkina M. L. Kovba A. S. Bogomyakov V. N. Ikorskii V. M. Novotortsev I. L. Eremenko 《Russian Chemical Bulletin》2009,58(1):11-20
Methods were developed for the controlled thermal synthesis of high-spin cubane-like pivalates {MII
4(μ3−OR)4} (M = Co or Ni; R = H or Me) starting from mono-and polynuclear complexes. The solid-state thermal decomposition of the known
pivalate clusters [MII
4(μ3−OMe)4−(μ2−OOCBut)2(η2−OOCBut)2(MeOH)4] and the new clusters [M4II(μ3)−OH4(η1−OOCBut)3−(μ−(NH2)2C6H2Me2)3(η1−(NH2)2C6H2Me2)3]+(OOCBut)− (M = Co or Ni) was studied by differential scanning calorimetry and thermogravimetry. The thermolysis of cubane-like CoII
and NiII pivalates is a destructive process. The phase composition of the decomposition products is determined by the nature
of coordinated ligands and the structural features of the metal core. 相似文献
14.
L. R. Gonsalves S. C. Mojumdar V. M. S. Verenkar 《Journal of Thermal Analysis and Calorimetry》2011,104(3):869-873
Cobalt zinc ferrite, Co0.8Zn0.2Fe2O4, nanoparticles have been synthesized via autocatalytic decomposition of the precursor, cobalt zinc ferrous fumarato hydrazinate.
The X-ray powder diffraction of the ‘as prepared’ oxide confirms the formation of single phase nanocrystalline cobalt zinc
ferrite nanoparticles. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric and differential
thermal analysis. The precursor has also been characterized by FTIR, and chemical analysis and its chemical composition has
been determined as Co0.8Zn0.2Fe2(C4H2O4)3·6N2H4. The Curie temperature of the ‘as-prepared oxide’ was determined by AC susceptibility measurements. 相似文献
15.
The impedance of a porous gold electrode in contact with solid electrolyte La0.88Sr0.12Ga0.82Mg0.18O2.85 and the effect of the manufacture conditions on its polarization resistance are studied at 600–800°C in air. The overall oxygen reaction rate on a gold electrode is described as the sum of two partial constituents, namely, the oxygen exchange at the gas/electrolyte interface at the gold/gas/electrolyte triple-phased boundary.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 190–197.Original Russian Text Copyright © 2005 by Shkerin, Sokolova, Khlupin, Beresnev.This revised version was published online in April 2005 with corrections to the article note and article title and cover date. 相似文献
16.
The air,Au/La0.88Sr0.12Ga0.82Mg0.18O2.85/Au,air cells are studied by an impedancemetry method before and after a week-long exposure at 700°C to atmospheres of hydrogen, humid air, and carbon dioxide. Blank specimens of the same electrolyte are examined by methods of x-ray diffraction, Raman scattering (RS), and x-ray photoelectron spectroscopy. The fact that the shape of the RS spectra and the shape of the electrode impedance dispersion alter unequivocally suggests that, at the very least, the electrode surface interacts with all the gases. The interaction in question is reversible in the case of hydrogen and carbon dioxide. In the case of water vapor, the interaction is irreversible.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 198–205.Original Russian Text Copyright © 2005 by Shkerin, Kovyazina, Beresnev, Kalashnikova, Martemyanova.This revised version was published online in April 2005 with corrections to the article note and article title and cover date. 相似文献
17.
A. L. Gushchin K. A. Kovalenko M. N. Sokolov D. Yu. Naumov E. V. Peresypkina A. V. Virovets V. P. Fedin 《Russian Chemical Bulletin》2007,56(9):1707-1711
The reactions of the oxalate complexes [M3Q7(C2O4)3]2− (M = Mo or W; Q = S or Se) with MnII, CoII, NiII, and CuII aqua and ethylenediamine complexes in aqueous and aqueous ethanolic solutions were studied. The previously unknown heterometallic
complexes [Mo3Se7(C2O4)3Ni(H2O)5]·3.5H2O (1) and K3{[Cu(en)2H2O]([Mo3S7(ox)3]2Br)}·5.5H2O (2) were synthesized. In these complexes, the oxalate clusters serve as monodentate ligands. The K(H2en)2[W3S7(C2O4)3]2Br·4H2O salt (3) was isolated from solutions containing CoII, NiII, or CuII aqua complexes and ethylenediamine. The reaction of [Mo3Se7(C2O4)3]2− with HBr produced the bromide complex [Mo3Se7Br6]2−, which was isolated as (Bu4N)2[Mo3Se7Br6] (4). Complexes 1–3 were characterized by X-ray diffraction, IR spectra, and elemental analysis. The formation of 4 was detected by electrospray mass spectrometry.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1645–1649, September, 2007. 相似文献
18.
V. N. Krasil’nikov A. P. Tyutyunnik V. G. Zubkov I. F. Berger L. Ya. Perelyaeva I. V. Baklanova 《Russian Journal of Inorganic Chemistry》2011,56(4):491-500
Synthesis was performed and physicochemical properties were studied for the M4V2O3(SO4)4 complexes, where M = K, Rb, or Cs. Their crystal structures were determined using the set of data from X-ray diffraction and neutron diffraction studies. All compounds crystallize in a triclinic lattice (space group \(P\bar 1\), Z = 2) with the parameters: a = 7.7688(2), 7.8487(1), 8.1234(1) Å; b = 10.4918(3), 10.8750(2), 11.1065(1) Å; c = 11.9783(4), 12.1336(2), and 11.8039(1) Å; α = 76.600(2)°, 77.910(1)°, 79.589(1)°; β = 75.133(2)°, 75.718(1)°, 87.939(1)°; γ = 71.285(2)°, 72.189(1)°, 75.567(1)°; V = 881.78(5), 945.42(3), 1014.34(2) Å3 for K, Rb, Cs, respectively. The structure of M4V2O3(SO4)4 was found to be formed by discrete complex anions V2O3(SO4) 4 4? incorporating two oxygen-bridged vanadium atoms in a distorted octahedral oxygen environment. The sulfate groups are coordinated by the vanadium atoms in the chelating mode with a large scatter of S-O interatomic distances and OSO angles. Every VO6 octahedron has a short terminal vanadium-oxygen bond with a length of about 1.6Å. The V2O3(SO4) 4 4? complex anions in potassium and rubidium compounds differ from that in Cs4V2O3(SO4)4 in the type of symmetry and mutual spatial orientation. The vibrational spectra were presented and interpreted in line with the structural analysis data. 相似文献
19.
S. N. Shkerin S. A. Uporov V. N. Yudin S. F. Solodovnikov E. S. Zolotova A. S. Tolkacheva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(11):2292-2296
The static magnetization of CsNa5M3(MoO4)6 single phase molybdates, where M = Co, Ni, and Mn, is measured at 4–300 K in magnetic fields of up to 20 kOe. It is shown that the materials are paramagnetic. Magnetization as a function of temperature is described using the Curie–Weiss law. The intrinsic magnetic moments of the phases are found to be 9.759 (Co), 6.958 (Ni), and 12.203 Bohr magnetons for manganese molybdates. It is concluded that the charge state of Co, Ni, and Mn cations in the compounds is +2. 相似文献
20.
A. M. Chernysheva P. A. Shelyganov I. V. Kazakov A. Y. Timoshkin 《Russian Journal of General Chemistry》2017,87(4):665-669
Structural, spectral, and thermodynamic characteristics of complex amidoboranes M2[M1(NH2BH3)4] (M1 = Al, Ga; M2 = Li, Na, K, Rb, Cs) were calculated by the B3LYP/def2-SVPD quantum-chemical method. The procedure for the synthesis of these compounds by reactions of alkali metal amidoboranes with aluminum and gallium chlorides was suggested and experimentally tested. Reaction products were characterized by the NMR and IR spectroscopy and X-ray phase analysis. 相似文献