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1.
Nd2O3添加量对BaTiO3陶瓷介电性能的影响   总被引:4,自引:0,他引:4  
BaTiO3 ceramics doped with Nd2O3(the additive content was respectively 0.001,0.002,0.003,0.005,0.01,0.03mol)were prepared by Sol-Gel method. Effects of Nd2O3 contents on the dielectric constant (ε), the dielectric loss (tanδ) ,the Curie-temperature (TC) and the resistivity (ρ) of BaTiO3 ceramic were studied. When Nd2O3 content was 0.001mol and 0.002mol, the dielectric constant was increased obviously, but the dielectric loss was also increased. When Nd2O3 content was 0.003mol, the dielectric constant was increased, and the dielectric loss was decreased, which was suitable for application in condenser. The resistivity was decreased obviously with the increasing of Nd2O3 contents, the resistivity was the smallest when Nd2O3 content was 0.001mol. The Curie-temperature was also decreased with the increasing of Nd2O3 contents.  相似文献   

2.
溶胶-凝胶法制备掺锰钛酸钡纳米粉体及其陶瓷   总被引:1,自引:0,他引:1  
The Mn-doped barium titanate nanosized powders and ceramics were prepared via the sol-gel process. The powders and ceramics were characterized by XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The influences of calcination temperature and Mn concentration on the microstructure, dielectric properties and phase composition of BaTiO3 nano-powders and ceramics were discussed. The results indicated that the BaTiO3-based powders doped with 1.0mol% Mn were mainly in cubic BaTiO3 phase, but the tetragonal phase became more evident when the calcination temperature increased. After sintering, Mn-doped ceramics were mainly composed of cubic BaTiO3. Specially, a new phase of hexagonal crystal BaTiO3 and BaMnO3 existed in the ceramics doped with 5.0mol% Mn and the ceramic grains were in ‘clintheriform’. The structure of ‘clintheriform’ led to the poor densification of ceramics, reducing the dielectric constant obviously. The dielectric constants of BaTiO3 ceramics first increased and then decreased as the Mn concentration increased. The room temperature dielectric constant was 2 290 and the lowest dielectric loss was 0.004 when the Mn concentration was 0.5mol%.  相似文献   

3.
The BaO-Al2O3-B2O3 glasses manufactured for solid oxide fuel cell(SOFC) sealing were studied. The effect of different nBaO/nB2O3 on crystal, thermal properties, density and infrared spectra of this system has been discussed. The results show that the trends of crystallization, glass transformation temperature, dilatometric softening temperature and density increase with nBaO/nB2O3 values. But a typical property deviation occurs when nBaO/nB2O3 is 0.875, and its coefficient of thermal expansion has the maximum at this point. The changes of properties can attribute to the conversion of boron from tetrahedral coordination to trigonal, breakage of the local glass network and interaction between the network modifiers. These can be proved by infrared spectra of glasses. Thermal properties of some studied samples are suitable for the sealing of SOFC using Sm doped ceria electrolyte and operating at 400~600 ℃.  相似文献   

4.
LaMgAl11O19∶Eun+(n=2,3) was synthesized by solid state reaction using H3BO3 as a flux at 1 400 ℃ for 4 hours. And their luminescent properties was investigated under UV and VUV excitation. Strong pure blue emission due to d-f transition of Eu2+ was observed in LaMgAl11O19∶Eu2+ both in 254 nm and 147 nm excitation. At the same time, red emission due to 5D07FJ (J=0, 1, 2, 3, 4) transition of Eu3+ also observed in LaMgAl11O19∶Eu3+. The dependence of emission intensity of blue/red emission on Eu2+ / Eu3+-content was evaluated. The result indicated that the blue emission intensity was arrived optimum when Eu2+-content was 0.10 mol·mol-1under both UV and VUV excitation while red emission intensity reached optimum when Eu3+-content was 0.125 mol·mol-1 under UV excitation. This suggests that LaMgAl11O19∶Eu2+ phosphors could be potential blue phosphor for the application in PDP.  相似文献   

5.
The spheric La2O3∶Eu nanocrystals were prepared using NH3·H2O-NH4HCO3 mixture as precipitant. The material was characterized by FTIR, XRD and TEM techniques. The luminescence properties of Eu3+ in spheric La2O3 were measured by three dimension spectra, emission and excitation spectra. The results indicate that the La2O3∶Eu nanocrystals are in hexagonal phase by annealing at 800 ℃, the crystal size is about 30 nm. The maximum emission and excitation wavelength were determined by three dimensional spectroscopy to be at 591 nm and 394 nm, respectively. In emission spectrum the band at 591 nm and 612 nm are corresponding to 5D0-7F1 and 5D0-7F2 transition of Eu3+ ions. With increasing in annealing temperature the differences of intensity of the two transitions are increased. This phenomenon shows that the luminescence intensity of La2O3∶Eu nanocrystals can be tuned by changing annealing temperature.  相似文献   

6.
类钙钛矿新铌酸盐Ba6LaTi3Nb3O21的合成、结构与介电特性   总被引:1,自引:0,他引:1  
A New Niobate Ba6LaTi3Nb3O21 was synthesized by high temperature solid state reaction in the BaO-La2O3-TiO2-Nb2O5 system. The chemical compositions, crystal structure, microstructure, density and melting point of the new compound were characterized by EPMA, XRD, DTA and so on. Ba6LaTi3Nb3O21 crystallizes the rhombohedral system with unit cell parameters a=0.57388(2) nm, c=4.928 3(3) nm, and space group R3m, Z=3. The structure may be described as six (Nb,Ti)O6 octahedra corner-sharing along c-axis to form perovskite layer connected by Ba atoms. The Ba6LaTi3Nb3O21 ceramics exhibits high dielectric of 74.1, low dielectric loss of 4.7×10-4 and small temperature coefficient of dielectric constant of -69 ppm·K-1 at 1 MHz due to its close structure and relative high dielectric polarizabilities of Ba2+, La3+, Ti4+ and Nb4+. Ba6LaTi3Nb3O21 might be a suitable candidate of high εr microwave dielectric ceramics.  相似文献   

7.
鲁晓明  宋富根  王波  李丽 《无机化学学报》2005,21(11):1687-1690
Cis-dioxo-catecholatotungsten(Ⅴ) complex (NH2CH2CH2NH3)4[WO2(OC6H4O)2]2(NH3CH2CH2NH3)·H2O (1) was synthesized at room temperature by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH3OH, CH3CN and NH2CH2CH2NH2. The crystal structure of complex was determined by X-ray diffraction structural analysis. The results show that complex belongs to monoclinic system with space group P21/c,a=0.712 8(3) nm, b=3.082 3(11) nm, c=0.982 8(4) nm, β=102.639(6)°, V=2.106 8(14) nm3, Z=2, R1=0.062 8, wR2=0.183 7. Compared the complex with its analogous complexes (NH2CH2CH2NH3)3[MoO2(OC6H4O)2], it is found that the coordination structure of W have no changes in the processing of electron transfer of tungsten-containing enzymes from the result of the similarity of the EPR spectra of the complexes and flavoenzyme from milk. CCDC: 272937.  相似文献   

8.
The novel seven-coordinate complex [(n-Bu)2Sn(C10H8N2O3)(C2H5OH)]2 (C10H8N2O32- is the dinegative ion of 2-oxo-propionic acid benzoyl hydrazone) was synthesized by the reaction of (n-Bu)2SnO with 2-oxo-propionic acid benzoyl hydrazone in 1∶1 molar ratio in benzene-ethanol (V/V, 3/1), and its structure was characterized by X-ray single crystal diffraction. The crystal belongs to a tetragonal system with space group I41/a, a=2.4890(2)nm, b=2.4890(2)nm, c=1.5170(3)nm, V=9.398(2)nm3, Z=8, F(000)=3968, Dc=1.366g·cm-3, and the structure was refined to final R1=0.0530, wR2=0.0971. The structure of the title complex is described as a dimer through weak interactions of Sn…O bonding and hydrogen bond. The tin atoms rendered sev-en-coordination in a distorted pentagonal bipyramid geometry structure, four oxygen atoms [O1, O2, O2#1 and O4] and one nitrogen atom N2 formed the equatorial plane and C11-Sn1-C15 is the axis. CCDC: 212696.  相似文献   

9.
[Zn(DMF)6]H2SiW12O40·(CH3)2NH的合成,晶体结构及性质   总被引:1,自引:0,他引:1  
The title compound [Zn(DMF)6]H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X-ray diffraction. The crystal belongs to monoclinic, space group C2/m, a=2.0654(4)nm, b=1.3306(3)nm, c=1.3194(3)nm, β=119.59(3)°, V=3.1531(11)nm3, Dc=3.606Mg·m-3, Z=2, R=0.0462, Rw=0.0836. The title compound comprises of a [Zn(DMF)6]2+ unit, a polyanion and a free (CH3)2NH molecule. The ESR spectrum of the title compound shows that charge-transfer between organic groups and polyanion takes place under irradiation of the sunlight in solid state. The TG study of the title compound shows that it had four stages of the weight loss, and the increase of the de-composition temperature for the polyanion shows that the stability of the polyanion was enhanced due to the influence of Zn2+ ion. CCDC:175866.  相似文献   

10.
LiNi0.5Mn1.5O4 was prepared by rheological method using CH3COOLi, Ni(CH3COO)2 and Mn(CH3COO)2 as raw materials. XRD and SEM results show that LiNi0.5Mn1.5O4 synthesized at 850 ℃ has cubic spinel structure with clearly defined shape and particle size of 0.2~0.4 μm. Electrochemical tests show that the LiNi0.5Mn1.5O4 presents a plateau near 4.7 V and delivers the maximum discharge capacity of 140.5 mAh·g-1. After 100 cycles, the capacity loss per cycle was only 0.015% discharged at 0.2C and the capacity retention was more than 76.3% discharged at 2.0C at room temperature and the capacity loss per cycle was only 0.32% discharged at 0.2C at 55 ℃.  相似文献   

11.
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   

12.
研究了温度、时间、浓度等对A3钢片上Ni-P-Zn3(PO4)2、Ni-P-ZnSnO3和Ni-P-ZiSiO3纳米复合合化学镀层外貌的影响,用扫描电子显微镜(SEM)观察外貌、称重法测定厚度;通过10%NaCl溶液、1%H2S气体加速腐蚀试验,10%CuSO4溶液点滴试验等多种手段测定其耐腐蚀性能,用X-射线光电子谱(XPS)及俄歇电子能谱(SES)测定其价态组成,结果表明:在最佳施镀条件下,可得光亮、致密、耐腐蚀性强于A3钢、磷化膜及Ni-P镀层的纳米复合化学镀层,镀层的原子百分组成约为(%):Ni-P-Zn3(PO4)2:Ni70.00,P12.47,Zn3(PO4)213.93,C3.6;Ni-P-ZnSnO3;Ni77.56,P10.00,ZnSnO39.84,C2.6;Ni-P-NiSiO3,Ni83.00,P10.96,ZnSi5.15,C0.89.  相似文献   

13.
用液相反应-前驱物烧结法制备了Cr2(WO4)3和Cr2(MoO4)3粉体。298~1 073 K的原位粉末X射线衍射数据表明Cr2(WO4)3和Cr2(MoO4)3的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10-6 K-1和(1.612±0.003)×10-6 K-1。用热膨胀仪研究了Cr2(WO4)3和Cr2(MoO4)3在静态空气中298~1 073 K范围内热膨胀行为,即开始表现为正热膨胀,随后在相转变点达到最大值,最后表现为负热膨胀,其负热膨胀系数分别为(-7.033±0.014)×10-6 K-1和(-9.282±0.019)×10-6 K-1。  相似文献   

14.
The microwave irradiation technique was used to prepare three Zintl phase compounds Na3SbTe3, NaSbTe2 and K3SbTe3. The as-prepared products were analyzed and characterized by XRD, EDX and SEM techniques. Higher microwave oven power and shorter irradiation time are required for the synthesis of Na3SbTe3, whereas lower oven power and longer irradiation time are needed for NaSbTe2. Moderate microwave irradiation conditions facilitate the formation of pure K3SbTe3. Pure phase of Na3SbTe3 are directly obtained by this technique for the first time. Compared with the traditional high-temperature solid-state synthesis, the microwave reaction required a considerable shortened reaction time for the preparation of the three Zintl compounds. The initial driving force for these reactions originates from the interaction of microwave electric field with alkali metals (Na and K) and Sb powders.  相似文献   

15.
La2(CO3)3 nanowires were prepared in the nonionic surfactant microemulsion(Triton X-100/cyclohexane/water)system. Transmission electron microscopy (TEM) and selected area electronic diffraction (SAED) were used to characterize the shape and size of the products. The results showed that the pH value and concentration of mother solution, temperature and aging time all could affect the morphology and size of the La2(CO3)3 nanowires. The lengths of the nanowires were more than 10 μm and the diameters were in the range of 30~200 nm.  相似文献   

16.
采用简单的化学偏聚法合成出Ag3PO4纳米颗粒、磷酸钴(Co3(PO42,CoP)纳米片以及它们两者的纳米复合结构(CoP/Ag3PO4),同时还比较了它们的可见光催化活性. 采用场发射扫描电镜(FESEM)、X 射线衍射(XRD)、紫外-可见(UV-Vis)吸收光谱以及光致发光谱等手段对其形貌、结构、光学以及可见光催化性能等进行表征. 结果表明,CoP/Ag3PO4复合纳米结构的可见光降解甲基橙(MO)的速率和循环稳定性均明显优于其它两种物质. 这表明CoP应该起着共催化剂的作用,它能够抑制光生电子与空穴之间的复合,并且提供大量高活性的光生空穴. 此外,我们还发现CoP/Ag3PO4降解另一种阳离子型染料——罗丹明B(RhB)的能力则远不如纯Ag3PO4,这可能是与光催化剂的表面性质发生改变有关,造成更低的RhB吸附能力. 本文提供了一种廉价制备高效可见光催化剂的新方法.  相似文献   

17.
The ternary BaO-TiO2-B2O3 glasses containing a large amount of TiO2 (20-40 mol%) are prepared, and their optical basicities (Λ), the formation, structural features and second-order optical nonlinearities of BaTi(BO3)2 and Ba3Ti3O6(BO3)2 crystals are examined to develop new nonlinear optical materials. It is found that the glasses with high TiO2 contents of 30-40 mol% show large optical basicities of Λ=0.81-0.87, suggesting the high polarizabity of TiOn polyhedra (n=4-6) in the glasses. BaTi(BO3)2 and Ba3Ti3O6(BO3)2 crystals are found to be formed as main crystalline phases in the glasses. It is found that BaTi(BO3)2 crystals tend to orient at the surface of crystallized glasses. The new XRD pattern for the Ba3Ti3O6(BO3)2 phase is proposed through Rietvelt analysis. The second harmonic intensities of crystallized glasses were found to be 0.8 times as large as α-quartz powders, i.e., I2ω(sample)/I2ω(α-quartz)=0.8, for the sample with BaTi(BO3)2 crystals and to be I2ω(sample)/I2ω(α-quartz)=68 for the sample with Ba3Ti3O6(BO3)2 crystals. The Raman scattering spectra for these two crystalline phases are measured for the first time and their structural features are discussed.  相似文献   

18.
采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。  相似文献   

19.
The two new compounds, Sr4Cu3(AsO4)2(AsO3OH)4·3H2O (1) and Ba2Cu4(AsO4)2(AsO3OH)3(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As2O5-H2O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å3, Z=4 for 1; space group P42/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å3, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu2+-(XO4)3− layers (X=P5+, As5+) linked by M cations (M=alkali, alkaline earth, Pb2+, or Ag+) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu2O8 centrosymmetric dimers crosslinked by As1φ4 tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu2O8 centrosymmetric dimers of CuO5 edge-sharing polyhedra, crosslinked by As1O4 tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.  相似文献   

20.
We present an efficient way to search a host for ultraviolet (UV) phosphor from UV nonlinear optical (NLO) materials. With the guidance, Na3La2(BO3)3 (NLBO), as a promising NLO material with a broad transparency range and high damage threshold, was adopted as a host material for the first time. The lanthanide ions (Tb3+ and Eu3+)-doped NLBO phosphors have been synthesized by solid-state reaction. Luminescent properties of the Ln-doped (Ln=Tb3+, Eu3+) sodium lanthanum borate were investigated under UV ray excitation. The emission spectrum was employed to probe the local environments of Eu3+ ions in NLBO crystal. For red phosphor, NLBO:Eu, the measured dominating emission peak was at 613 nm, which is attributed to 5D0-7F2 transition of Eu3+. The luminescence indicates that the local symmetry of Eu3+ in NLBO crystal lattice has no inversion center. Optimum Eu3+ concentration of NLBO:Eu3+ under UV excitation with 395 nm wavelength is about 30 mol%. The green phosphor, NLBO:Tb, showed bright green emission at 543 with 252 nm excited light. The measured concentration quenching curve demonstrated that the maximum concentration of Tb3+ in NLBO was about 20%. The luminescence mechanism of Ln-doped NLBO (Tb3+ and Eu3+) was analyzed. The relative high quenching concentration was also discussed.  相似文献   

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