共查询到17条相似文献,搜索用时 15 毫秒
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Na Min ) Wei Li) Hongyan Li) Xuejun Jin) ) School of Materials Science Engineering Shanghai University Shanghai China ) School of Materials Science Engineering Shanghai Jiao Tong University Shanghai China 《材料科学技术学报》2010,26(9):776-782
Mssbauer spectrum and three dimensional atom probes(3DAP) were combined to investigate the mechanism of cementite dissolution in a cold-drawn eutectoid steel at a true strain of 2.89.The experimental results suggest that the dislocations play an important role in the dissolution of the cementite by sweeping across the nano-scaled cementite,and transferring carbon from cementite to ferrite inducing cementite decomposition.The mechanism of cementite dissolution in the steel is discussed in association with t... 相似文献
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DyFe_(10)Si_2合金的~(57)Fe变温Mssbauer谱学研究,发现温度在210K处,超精细场随温度有不连续变化。此温度对应于合金的自旋重取向温度。Si,Ti和V作为形成ThMn_(12)型结构的稳定化元素,造成各相应合金的自旋重取向温度有一些差别。分析了Si,Ti和V元素造成合金磁晶各向异性差别的原因,它使得DyFe_(10)V_2,DyFe_(11)Ti和DyFe_(10)Si_2合金的自旋重取向温度不同。DyFe_(10)Si_2合金的8i晶位四极劈裂在温度210K处改变符号。 相似文献
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The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst 相似文献
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B. P. Mikhailov L. P. Ichkitidze Yu. E. Grigorashvili A. B. Mikhailova V. F. Shamrai 《Inorganic Materials》2003,39(7):749-754
The microstructure, phase composition, texture, and superconducting properties (T
c, T
c, j
c(T), and R(T) at H= 0 and 5 mT) of (Bi,Pb)2Sr2Ca2Cu3O10 + ceramics (sintering at 840°C for 36 h) with ultrafine Si3N4 additions (0.05–0.2 wt %) are studied. The introduction of 0.05–0.1 wt % Si3N4 is shown to reduce the width of the superconducting transition by 2–3 K and to raise the critical current density at temperatures below 95 K. 相似文献
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N. Balchev K. Nenkov B. Kunev A. Souleva Ts. Tsacheva S. Hoste 《Journal of Superconductivity》2001,14(6):713-717
The effect of Sn doping in (Pb0.6Sn
y
Cu0.4 – y
)Sr2(Y1 – x
Ca
x
)Cu2O
z
with 0 y 0.3 and 0 x 0.7 was investigated. It was established that a nearly pure 1212 phase can be obtained at 0 y 0.1 and 0 x 0.3. The obtained XRD patterns as well as the results of the EDX and ICP-AES analyses showed that Sn substitution is possible in the (Pb,Cu)-1212 phase. Superconductivity was observed at 0.4 x 0.7. The onset of the diamagnetic transitions varied from 10 to 30 K. The influence of the strong Pb deficiency on the superconducting properties of the samples was discussed. 相似文献
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Veselova S. V. Tereshina I. S. Verbetsky V. N. Zakharov K. V. Vasil’ev A. N. 《Inorganic Materials》2021,57(5):475-480
Inorganic Materials - (Sm1–xErx)2Fe17 (x = 0.1, 0.4) solid solutions have been prepared by induction melting and then hydrided to give high hydrogen content materials: Sm1.8Er0.2Fe17H4.4 and... 相似文献
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Mukherjee S Acharya S Das D Chakrabarti PK 《Journal of nanoscience and nanotechnology》2010,10(9):5623-5633
Nanocrystalline NiFe2O4 with different particle sizes and nanocomposites of (NiFe2O4)(1-x)(Al2O3)x (x = 0.25, 0.40) were prepared by using co-precipitation method. In this method two techniques viz., 'ultrasonication' and 'magnetic stirring' during co-precipitation were used. The as prepared samples were annealed at different temperatures to obtain samples with different particle sizes. The formation of the nanocrystalline spinel phases of all the samples were confirmed by X-ray diffraction (XRD) patterns. The sizes of the nanoparticles of all the samples were calculated from the broadening of the (311) line in the XRD pattern. The distribution of sizes are remarkably less in samples obtained from 'ultrasonication' technique compared to those obtained in 'magnetic stirring' technique. The different soft magnetic quantities viz., coercive field, magnetization, remanance, hysteresis losses etc. were extracted from the ac hysteresis loops observed at different frequencies. The variations of coercive field and hysteresis loss as functions of frequency and particle sizes have been studied. M?ssbauer spectra of the samples along with the hysteresis loops recorded at room temperature indicate the presence of superparamagnetic (SPM) relaxations of the nanoparticles. Also, SPM relaxations have been introduced in the samples annealed at higher temperature by encapsulating the nanoparticles in non-magnetic matrix of Al2O3 with 40% coating. 相似文献
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Denisova L. T. Molokeev M. S. Aleksandrovskii A. S. Kargin Yu. F. Golubeva E. O. Denisov V. M. 《Inorganic Materials》2021,57(11):1158-1166
Inorganic Materials - Pb10 – xEux(GeO4)2 + x(VO4)4 – x (x = 0.1, 0.2, 0.3) Eu-substituted lead germanatovanadates with the apatite structure have been prepared by solid-state reactions,... 相似文献
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Hui Lu Jong Pyo Kim Sou Hwan Son Jung Hoon Park 《Materials Science and Engineering: B》2010,166(2):135-140
The perovskite La0.6Sr0.4M0.3Fe0.7O3?δ (M = Co, Ti) powders have been synthesized by the citrate gel method. The structural and chemical stability of the La0.6Sr0.4M0.3Fe0.7O3?δ (M = Co, Ti) oxides were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The electrical conductivities of the sintered La0.6Sr0.4M0.3Fe0.7O3?δ (M = Co, Ti) ceramics were measured. The results demonstrate the chemical stability in H2/helium (He) atmosphere of the La0.6Sr0.4Ti0.3Fe0.7O3?δ oxide is improved significantly compared to that of the La0.6Sr0.4Co0.3Fe0.7O3?δ oxide. The incorporation of Ti3+/4+ ions in the perovskite structure can significantly stabilize the neighboring oxygen octahedral due to the stronger bonding strength, leading to the enhanced structural and chemical stability of the La0.6Sr0.4Ti0.3Fe0.7O3?δ. In addition, the perovskite La0.6Sr0.4M0.3Fe0.7O3?δ (M = Co, Ti) oxides possess much higher chemical stability in CO2/He atmosphere than that of Ba0.5Sr0.5Co0.8Fe0.2O3?δ oxide, in which the perovskite structure is destroyed completely in a flowing CO2-containing atmosphere. 相似文献
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Ensieh Ganji Babakhani Jafar Towfighi Laleh Shirazi Ali Nakhaeipour Akbar Zamaniyan Zahra Shafiei 《材料科学技术学报》2012,28(2):177-183
Perovskite-type Ba 0.5 Sr 0.5 Co 0.8 Fe 0.1 R 0.1 O 3 δ (R=Al,Mn,Fe,Ce,Cr,Ni,Co) oxide membranes were exploited and synthesized.Oxygen behavior,order-disorder transition and phase stability of these composite oxides were investigated by combined analysis of X-ray diffraction (XRD),temperature programmed desorption (TPD),thermogravimetric-differential thermal analysis (TG-DTA).Oxygen permeation through these membranes was studied by the gas chromatography (GC) method using a high-temperature permeation cell in a wide temperature range from 700 to 950 C.High permeation fluxes were observed for these materials.The high permeation flux was about 3.19 ml·min 1 ·cm 2 under air/He gradients at 950 C,which was achieved for Ba 0.5 Sr 0.5 Co 0.8 Fe 0.1 Ni 0.1 O 3 δ (BSCFNiO) membrane.The results of analysis showed no phase transition for BSCFNiO oxide with increasing temperature and XRD pattern of this material after O 2-TPD indicated to sustain a pure perovskite structure after oxygen permeation process. 相似文献
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Double U(VI) phthalates with NH 4 + , K+, and Cs+ ions in the outer sphere were synthesized. The X-ray phase analysis shows that their structures are similar. Single crystals were prepared and the structure of K4[(UO2)4(μ3-O)2(C6H4C2O4)4] ? 3H2O was solved. In the [(UO2)4O2(C6H4C2O4)4]4? anions forming the main structural motif, each bridging oxygen atom μ3-O combines one pentagonal and two hexagonal bipyramids, which, in turn, are combined in centrosymmetrical tetramers. The phthalate ions have coordination capacity equal to 3; each ligand coordinates U(1) in the bidentate fashion via one carboxy group and U(2) in the bidentate fashion to form a planar seven-membered chelate ring. 相似文献
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A. G. Belous O. N. Gavrilenko E. V. Pashkova K. P. Danil'chenko O. I. V'yunov 《Inorganic Materials》2004,40(8):867-873
The effects of the nominal composition and synthesis conditions on the lithium nonstoichiometry of La2/3 – x
Li3x
4/3 – 2x
Nb2O6 (I) and La2/3 – x
Li3x
4/3 – 2x
Ta2O6 (II) solid solutions are studied. The results demonstrate that lithium losses can be reduced from 26–30 to 14–15 mol % in system I and from 15 to 4 mol % in system II. It is shown that the disturbance of electroneutrality caused by Li nonstoichiometry in the solid solutions is eliminated via the formation of oxygen vacancies in positions O(1) (1f: 1/2 1/2 0) and O(2) (1h: 1/2 1/2 1/2) of the cation-deficient perovskite structure. The optimal lithium ion conductivity is offered by solid solutions with /3x 2.6 and x 0.136–0.143. 相似文献
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Two procedures for preparing the compounds M(NpO4)2·nH2O (M = Mg, Ca, Sr, Ba) using boric acid were suggested. In the first procedure, samples of freshly prepared salts M3(NpO5)2·nH2O (M = Ca, Sr, Ba) are treated with excess 0.5 M H3BO3 with vigorous stirring. In the process, the initially light green salts rapidly transform into black products of the general composition M(NpO4)2·nH2O. In the second procedure, a measured volume of a Np(VII) solution with a known LiOH concentration was added to excess 0.5 M H3BO3 solution containing a calculated amount of Mg, Ca, Sr, or Ba nitrate. The reaction yields black precipitates of the same compounds as in the previous case. After washing with water and drying in an oxygen stream, the final products contain a small impurity of Np(VI). The IR spectra suggest that the compounds obtained are structurally related to the previously studied salts MNpO4 (M = K–Cs), i.e., in their lattices there are neptunium–oxygen layers built of NpO23+ cations and bridging O atoms. New data on the properties of the compounds M3(NpO5)2·nH2O with M = Ca, Sr, and Ba were also obtained. 相似文献