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Kuroiwa Y. Aoyagi S. Sawada A. Ikawa H. Yamashita I. Inoue N. Atake T. 《Journal of Thermal Analysis and Calorimetry》2002,69(3):933-938
The crystal structures of BaTiO3 and PbTiO3 fine particles have been investigated by powder diffraction using synchrotron radiation high energy X-rays. It is revealed
that a BaTiO3 fine particle essentially consists of tetragonal and cubic structure components at 300 K, whereas a PbTiO3 fine particle consists of a tetragonal structure. Adopting a structure model for the BaTiO3 particle that a cubic shell covers a tetragonal core, the thickness of cubic BaTiO3 shell is estimated at almost constant irrespective of particle sizes. Successive phase transitions are detected in 100 nm
particles of BaTiO3 near the phase-transition temperatures of a bulk crystal. The changes in diffraction profiles are small, but they are apparent
for a most up-to-date powder diffractometry.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The crystal structure of Ba2Ti9O20 has been determined by comparison of experimental high-resolution electron micrographs with images simulated using structural models deduced from the micrographs in conjunction with crystallochemical principles. The structure consists of lamellae of hollandite-type structure alternating with BaTiO3-like units, which effectively immobilize the Ba ions. This material should be relatively more leach resistant to attack by aqueous sodium chloride solutions. The structure determination clarifies the observation that this material has unique properties as a microwave resonator, compared with other barium and alkali titanate structures. 相似文献
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In this study, the bulk ceramics with general formula (1 − y)BiFe1−xScxO3–yBaTiO3 (x = 0.1–0.3, y = 0.1–0.3 mol%) were prepared by the traditional solid-state method. Their structural, magnetic, dielectric properties were investigated. X-ray diffraction analysis indicated that all samples crystallized in pure perovskite structure. The structural phase transition from R3c to Pm-3m occurred when the amount of BaTiO3 exceeded 20 mol%. The room temperature M–H curves were obtained and scandium doping could decrease the magnetic coercive field. Thus the soft magnetic property of prepared solid solutions could be improved. Frequency dependence of dielectric constant and loss were studied. The results indicated that addition of an appropriate amount of scandium could reduce the dielectric loss. The dielectric losses of 0.7BiFe1−xScxO3–0.3BaTiO3 (x = 0, 0.1, 0.2, 0.3) at 1 kHz were 0.104, 0.094, 0.043 and 0.057 respectively. 相似文献
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Preparation and electrorheological characteristic of Y-doped BaTiO3 suspension under dc electric field 总被引:1,自引:0,他引:1
Jian-Bo Yin 《Journal of solid state chemistry》2004,177(10):3650-3659
The electrorheological (ER) effects of BaTiO3 or other perovskite materials with high dielectric constant are presumed to be large. However, their weak ER activity is very puzzling. In this study, we choose cubic BaTiO3 and first achieve its ER enhancement under dc electric field by modifying its intrinsic structure with doping rare earth Y ions, which are synthesized by means of sol-gel technique. DSC-TG, FT-IR, XRD, ICP and XPS techniques are used to characterize thermal, structure and component change of materials. It is demonstrated that Y3+ substitutes for Ba2+, which causes lattice-distorting defects. Rheological experiments show that Y-doped BaTiO3 suspension has notable ER effect and clear fibrillation structure under dc electric field, while the pure cubic BaTiO3 suspension suffers from electrophoretic effects and its ER effect is very weak. The ER effect of typical Y-doped BaTiO3 ER suspension is ten times that of pure BaTiO3 ER suspension. Based on the electrical measurements, the enhancement of ER activity of BaTiO3 may be attributed to the increase of conductivity due to Y-doping. The enhancement in ER activity of cubic BaTiO3 under dc electric field by doping rare earth Y ions is helpful to further understand the perovskite-based ER materials with high dielectric constant but low ER activity. 相似文献
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Silicon-containing polyimide/BaTiO3 nanocomposite films were prepared by the direct mixing of silicon-containing polyamic acid and BaTiO3 nanoparticles under ultrasonic wave irradiation, followed with thermal imidization. Structure and thermal properties were measured with FTIR, XPS, SEM, DSC and TGA. The results showed that the compatibility of BaTiO3 and a polyimide might be improved by the introduction of dimethylsilylene groups into the backbone of a polyimide; and BaTiO3 nanoparticles in the nanocomposites tended to form clusters. The clusters coalesced into a more uniform structure at a higher BaTiO3 filling than at a lower one.The interfacial interaction between BaTiO3 and the silicon-containing polyimide resulted in the increase of the glass transition and the thermal decomposition temperature. It was found that the nanocomposites exhibited lower infrared emissivity value than the pure polyimide and the magnitude of infrared emissivity value was related to the content of BaTiO3 in the nanocomposites. 相似文献
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BaTiO3 powders are prepared by sol-gel method by cotton template. Polypyrrole is pre-pared by chemical oxidation route in the emulsion polymerization system. Then BaTiO3-polypyrrole composites with different mixture ratios are prepared by as-prepared material.The structure, morphology, and properties of the composites are characterized with Infrared spectrum, X-ray diffraction, scanning electron microscope, and net-wok analyzer. The com-plex permittivity and reflection loss of the composites are measured at different microwave frequencies in S-band and C-band (0.03—6 GHz) employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3 to polypyrrole on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-polypyrrole composite is proposed. The BaTiO3-polypyrrole composite can find applications in suppression of electromagnetic interference and reduction of radar signature. 相似文献
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Delphine Gout 《Journal of solid state chemistry》2003,174(2):471-481
The Al-rich portion of the ternary Ce-Ni-Al has been investigated and a new ternary phase of composition Ce4Ni6Al23 has been found. This compound crystallizes in the monoclinic space group C2/m with the cell parameters a=16.042(8), b=4.140(4), c=18.380(8) Å and β=113.24(5)°. The structure has been determined by single crystal X-ray diffraction. The local environment of Ni and Ce is close to what is observed in the CeNi2Al5 and CeNiAl4 structures. Band structure calculations, using the tight-binding-linear muffin-tin orbital-atomic-spheres approximation (TB-LMTO-ASA) method, have been performed to understand the electronic structure of Ce4Ni6Al23 and the results are discussed in connection with those two other Ce-Ni-Al intermetallic compounds, which possess heavy-fermion behavior. Magnetic and heat capacity measurements have also been measured to analyze the low-temperature magnetic behavior of this new compound. 相似文献
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S.-L. Yang 《Journal of solid state chemistry》2009,182(4):855-3816
An alkali-metal indium phosphate crystal, K3In3P4O16, has been synthesized by a high-temperature solution reaction and exhibits a new structure in the family of the alkali-metal indium phosphates system. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group P21/n, and the following cell parameters: a=9.7003(18), b=9.8065(18), c=15.855(3) Å, β=90.346(3)°, V=1508.2(5) Å3, Z=4, R=0.0254. It possesses three-dimensional anionic frameworks with tunnels occupied by K+ cations running along the a-axis. The emission and absorption spectra of the compound have been investigated. Additionally, the calculations of energy band structure, density of states, dielectric constants and refractive indexes have been performed with the density functional theory method. Also, the two-photon absorption spectrum is simulated by two-band model. The obtained results tend to support the experimental data. 相似文献
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Wei-Long Zhang Hao Zhang Zhi Xie Song-Ling Yang Dan Zhao Chang-Zhen He Wen-Dan Cheng 《Solid State Sciences》2009,11(11):2008-2015
Two compounds Pb2In4P6O23 and Pb2InP3O11 in the new family of lead indium phosphates were synthesized by high temperature solution growth (HTSG) method and structurally characterized by X-ray single crystal diffraction, powder diffraction and electron microscopy. Two title compounds display different types of 3D architectures with interesting tunnel structure are built up of the InO6 octahedra and PO4 tetrahedra, sharing the corners or edges, and the Pb2+ cations are sitting in the tunnel. The structure of Pb2In4P6O23 features a novel 3D open framework which can be considered as built from the layer of {In4(P2O7)(PO4)2}2− parallel to the ac plane interconnected by bridging the single PO4. The structure of Pb2InP3O11 can be described by the assemblage of [InP2O11] units with monophosphate groups. The stereochemical activity of the PbII lone pair has also been discussed. The electronic band structure calculations for the two compounds have also been performed with the density functional theory method. The study of calculations and optical diffuse reflectance absorption spectrum measurement show both compounds are indirect band-gap insulators. 相似文献
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Potential energy surface (PES) for the reactions of XO (X = F, Cl and Br) with CH3SO and CH3SO2 have been calculated at MP2/6-311++G(d, p)//B3LYP/6-311++G(d, p) level. It is revealed that all the reactions take place on both singlet and triplet surfaces. The reaction mechanisms of XO (X = F, Cl and Br) with CH3SO and CH3SO2 are similar: the hydrogen abstraction channel of singlet-state PES, which has the overall negative activation energy, should be the dominant channel and CH2SO (CH2SO2) + HOX should be the main products. The reactions of CH3SO (CH3SO2) with XO become thermodynamically favored in the sequence of FO, ClO and BrO. The topological analysis of electronic density shows that a four-member-ring structure appears in the dominant reaction pathway, it turns to three-member-ring structure via a T-shaped structure and the ring structure disappears as the reaction proceeds. Furthermore, the scope of the structure transition region, the appeared position of the four-member-ring structure and the position of T-shaped structure correlated well to the atom which linked to the four-member-ring structure. 相似文献
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Yurij B. Kuz’ma Volodymyr Babizhetskyj Igor Veremchuk Nadija Chaban 《Journal of solid state chemistry》2004,177(2):425-430
New borides have been synthesized and their crystal structures have been determined using X-ray single-crystal methods, namely: Er0.917Ni4.09B, own structure type, space group P6/mmm, a=14.8399(3), c=6.9194(3) Å, RF=0.0545, and ErNi7B3, own structure type, space group I41/amd, a=7.6577(2), c=15.5798(5) Å, RF=0.0451. The relationship between these structures and the structure types of CeCo4B, Y0.915Ni4.12B and Sc4Ni29B10 has been discussed. 相似文献
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以沉淀法制备的Cu_2O为牺牲模板剂,采用水热法制备La施主掺杂的BaTiO_3钙钛矿半导体纳米晶,借助X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)、X射线光电子能谱((XPS)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)表征La掺杂的BaTiO_3晶的物相、微观形貌及光催化性能。结果表明,La掺杂BaTiO_3构建了晶体缺陷,有效提高了BaTiO_3的光催化性能。当掺杂量为4%(w/w)时,样品的光催化性能最好,在可见光照射360 min后,对4-硝基苯酚溶液的降解率可达到93.2%。该催化剂5次循环后的活性仍然大于86.7%,表明La施主掺杂的BaTiO_3是一种有效的可见光催化剂。 相似文献
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Mehrnoosh Atashfaraz Mojtaba Shariaty-Niassar Satoshi Ohara Kimitaka Minami Mitsuo Umetsu Takashi Naka Tadafumi Adschiri 《Fluid Phase Equilibria》2007
Fine BaTiO3 nanoparticles were prepared by hydrothermal synthesis under supercritical condition (400 °C and 30 MPa) from mixture of barium hydroxide and titanium dioxide as starting precursors. First, conditions for synthesizing BaTiO3 were examined by using batch reactors. High pH condition, pH > 13, is necessary to obtain phase pure BaTiO3. The reason was discussed based on the solubility of titanium dioxide, which that dissolution–recrystallization process is essential for the synthesis of BaTiO3 nanoparticles. Rapid heating of the starting precursors by mixing with high temperature water in a flow reactor is effective to synthesize smaller size and narrower particle size distribution for the BaTiO3 nanoparticles, compared with the case of slow heating with a batch reactor. 相似文献
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Hyunsoo Park 《Journal of solid state chemistry》2004,177(1):159-164
The compound previously reported as Ba2Ti2B2O9 has been reformulated as Ba3Ti3B2O12, or Ba3Ti3O6(BO3)2, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO3:BaTiB2O6 (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F2)=0.039 for 504 unique reflections. Ba3Ti3O6(BO3)2 is isostructural with K3Ta3O6(BO3)2. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba3Ti3O6(BO3)2 is equal to 95% of that of LiNbO3. 相似文献
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Single crystals of CsHo3Te5 and Cs3Tm11Te18 have been grown as byproducts in the synthesis of CsLnZnTe3 (Ln=Ho or Tm) through the reaction of Ln, Zn, and Te with a CsCl flux at 850 °C. The crystal structures have been determined from single-crystal X-ray diffraction data. CsHo3Te5 crystallizes in space group Pnma of the orthorhombic system whereas Cs3Tm11Te18 crystallizes in the space group C2/m of the monoclinic system. Each of the compounds adopts a three-dimensional structure; each possesses tunnels built from LnTe6 octahedra that are filled with Cs atoms. The pseudo-rectangular tunnel in CsHo3Te5 is large enough in cross-section to accommodate two symmetrically equivalent Cs atoms. In the Cs3Tm11Te18 structure there are two different sized tunnels: the smaller one is only large enough to host one Cs atom per unit cell whereas the larger one can accommodate two Cs atoms. The electronic structure of CsHo3Te5 was calculated. The band gap is estimated to be about 1.2 eV, consistent with the black color of the crystals. 相似文献
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The study of the BaTiO3-BaLiF3 system in platinium-sealed tubes has allowed one to determine the influence of the addition of BaLiF3 on the crystallographic and dielectric properties of BaTiO3. The ferroelectric Curie temperature decreases as the rate of substitution increases.A ceramic with a composition Ba(Ti0.965Li0.035)O2.895F0.105 has a Curie temperature TC close to 280 K. The corresponding maximum of the permittivity ?′r max. at TC increases from 1000 to 5600 when the sintering temperature rises from 850 to 1300°C. This enhancement has been compared with that observed for a ceramic sintered from BaTiO3 and LiF at 930°C (?′r max. > 6000). It appears that the sintering process in that case cannot be due mainly to formation of a solid solution between BaTiO3 and BaLiF3. 相似文献
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BaTiO3/bismaleimide/epoxy/glass fiber reinforced composites were prepared using E-glass fiber (E-GF) and silane coated E-glass fiber (SC-EGF) separately as reinforcement. BaTiO3 nanoparticles were prepared by hydrothermal method. Results show that the addition of BaTiO3 nanoparticles has significant effects on the mechanical and dielectric properties of the composite. Both E-GF and SC-EGF reinforced BaTiO3/bismaleimide/epoxy composites with 2 wt percentages of BaTiO3 nanoparticles showed improved tensile strength, flexural strength and dielectric constant and those with 3% showed high dielectric strength indicating this composition is more adaptable for high voltage insulating applications. Dielectric constants and dielectric loss of the fabricated nanocomposites have been obtained at higher frequencies (in GHz) by using Vector Network Analyser at room temperature and was found to be highest for the BMI-Epoxy nanocomposite with 1% weight nanofiller. 相似文献
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Xiao-Wu Lei Guo-Hua Zhong Min-Jie Li Jiang-Gao Mao 《Journal of solid state chemistry》2008,181(9):2448-2455
Two new ternary ytterbium transition metal stannides, namely, Yb3CoSn6 and Yb4Mn2Sn5, have been obtained by solid-state reactions of the corresponding pure elements in welded tantalum tubes at high temperature. Their crystal structures have been established by single-crystal X-ray diffraction studies. Yb3CoSn6 crystallizes in the orthorhombic space group Cmcm (no. 63) with cell parameters of a=4.662(2), b=15.964(6), c=13.140(5) Å, V=978.0(6) Å3, and Z=4. Its structure features a three-dimensional (3D) open-framework composed of unusual [CoSn3] layers interconnected by zigzag Sn chains, forming large tunnels along the c-axis which are occupied by the ytterbium cations. Yb4Mn2Sn5 is monoclinic space group C2/m (no. 12) with cell parameters of a=16.937(2), b=4.5949(3), c=7.6489(7) Å, β=106.176(4)°, V=571.70(8) Å3, and Z=2. It belongs to the Mg5Si6 structure type and its anionic substructure is composed of parallel [Mn2Sn2] ladders interconnected by unusual zigzag [Sn3] chains, forming large tunnels along the c-axis, which are filled by the ytterbium cations. Band structure calculations based on density function theory methods were also made for both compounds. 相似文献