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1.
研究了Na_3Zr_(2-x)Mg_xSi_(2-2x)P_(1+2x)O_(12)系统的组成、结构和电性能。结果表明:Mg~(2+)能在一定的组成范围内取代Na_3Zr_2Si_2PO_(12)中的Zr~(4+)形成固溶体,单相固溶体区域延伸至x=0.5;当x=0.4时固溶体的结构由单斜转变为三方。固溶体的电导率随x的增加而降低。本文还从结晶化学的角度讨论了Na_3Zr_(2-x)Mg_xSi_(2-2x)P_(1+2x)O_(12)系统的组成、结构和电性能的关系。  相似文献   

2.
The Raman spectra of glasses in the ternary (Ge2S3) x (As2S3)1−x and (GeS2) x (As2S3)1−x systems are reported. It is shown that the degree of disorder in the (Ge2S3) x (As2S3)1−x glasses increases with an increase in the Ge content. The differences in the spectra of glasses with the same molar content of As2S3 are discussed in terms of the changes occurring in the local structure due to deviations from the stoichiometry. The observed changes in the intensity of the boson peak indicate changes in the medium-range order structure of the glasses under study.  相似文献   

3.
Low temperature 57Fe Mössbauer spectroscopic studies on CaO(Fe2O3)1−x(Al2O3)x, written as CF1−xAx, have been carried out. In view of the earlier findings based on room temperature data, the spectra have been analysed by assuming three Fe sites: two belonging to CF phase and the third site for the Fe atoms distributed in the CA phase. The Fe sites pertaining to the CF phase experience hyperfine field of about 49T and 47T, respectively, at 20K; whereas the third site is paramagnetic at this temperature.  相似文献   

4.
Intermediate-stage sintering has been investigated in lead orthophosphovanadates Pb3(VO4)2(1−x)(PO4)2x. It was found that rich-vanadium compounds such as Pb3(VO4)2 and Pb3(VO4)1.6(PO4)0.4 densify rapidly with important grain growth. For these compounds grain growth is controlled by grain boundaries and densification occurs by a mixed mechanism with lattice and grain boundary diffusion. For Pb3(PO4)2, sintering mechanism supports a model of grain-boundary-controlled densification and grain growth is a surface diffusion-controlled pore drag mechanism. Moreover, the presence of phosphorus in compounds' formulae, tends to decrease the grain-boundary mobility, preventing pore-boundary separation. The kinetics analysis highlights the importance of vanadium substitution in modifying the diffusion coefficient of rate-limiting species.  相似文献   

5.
《应用陶瓷进展》2013,112(4):185-189
The microstructure and properties of Ca doped lanthanum chromate [La0.9Ca0.1CrO3 (LCCO)] and zirconia (ZrO2) composites [abbreviated as (1???x)LCCO/xZrO2, x?=?0–30?wt-%] prepared by solid state reaction method are investigated in this paper whose potential application in heat resistant ceramics are also discussed. The growth and fusion of the LCCO grains are hindered by the ZrO2 grains, which make the matrix grains refined. In the stable system, it is discovered that the density of the composites decreases, the porosity increases and the decrease amplitude of the bend strength after thermal shock at 600°C reduces with the increasing ZrO2 content, which results in diminishing the bend strength gradually and enhancing the thermal shock resistance. When x?=?10–15?wt-%, the samples show the best thermal shock resistance realising a maximum thermal cycle times of 8. The material with x?=?20?wt-% exhibits excellent slag resistance.  相似文献   

6.
研究了Li_(1 x)Ti_(2-x)Ga_xP_3O_(12)和Li_(1 2x)Ti_(2-x)Mg_xP_3O_(12)系统的组成、结构和电性的关系。在这两个系统中,Ga~(3 )和Mg~(2 )都能在一定的组成范围内取代LiTi_2P_3O_(12)中的Ti~(4 )形成固溶体,并使电导率提高。电导率极大值分别出现在x=0.6和x=0.3处,其在300℃左右的值为8.4×10~(-3)和5.3×10~(-3)s/cm。 比较了Ga~(3 )、Mg~(2 )和In~(3 )三种离子取代Ti~(4 )对电性的影响,并从结晶化学角度讨论了它们的差异。  相似文献   

7.
Ho2O3 and Tm2O3 doped Bi2O3 composite electrolyte type materials for solid oxide fuel cells (SOFCs) operating at intermediate-temperature were investigated. The bismuth-based ceramic powders were produced by using conventional solid-state synthesis techniques. The products were characterized by means of scanning electron microscopy (SEM), X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), and the four-point probe technique (4PPT). XRD and DTA/TG measurements indicate that all of the samples have the stable fluorite type face centered cubic (fcc) δ-phase. 4PPT measurements were performed in the temperature range 150–1000 °C in air and these measurements showed that the electrical conductivity of the samples decrease with increasing amount of Tm2O3. This increase in the electrical conductivity of the samples could be attributed to the increase in the numbers of highly polarizable cations and oxide ion vacancies. The highest conductivity value was found as 5.31×10?1 Ω cm?1 for the (Bi2O3)1?x?y(Ho2O3)x(Tm2O3)y ternary system (for x=20 and y=5 mol%) at 1000 °C. The activation energies of the samples were calculated from log σ graphics versus 1000/T. These calculated results showed that the translation motion of the charge carriers, oxygen vacancies, and space charge polarizations are responsible for the change in activation energy as a function of temperature.  相似文献   

8.
以CrF3为掺杂原料,采用高温固相法合成阴阳离子共掺杂LiMn2–xCrxO4–3xF3x锂离子电池正极材料。用X射线衍射、扫描电镜、充放电实验、循环伏安及交流阻抗等表征材料的结构、形貌和电化学性能,分析阴阳离子复合掺杂对材料结构和性能的影响。结果表明:掺杂材料LiMn2–xCrxO4–3xF3x具有完整的尖晶石结构。阴阳离子复合掺杂能改善尖晶石LiMn2O4的循环性能,当摩尔掺量x=0.10,电压为3.0~4.35V、充放电倍率为0.1C时,首次放电容量为120.1mA·h/g,室温、高温循环20次容量保持率分别为97.5%和94.1%。循环伏安实验发现:复合掺杂改性材料具有两对更完整、对称性更好的氧化还原峰。  相似文献   

9.
用电沉积法制得Cu_(2x)In_(2-2x)Se_2(铜铟硒)(0<x<1)薄膜 ̄[1]并用EDAX对其组成进行分析.对薄膜电极的光电化学性能、光谱响应、能隙与x的依赖关系进行了研究.借助于现场微区扫描光电流谱观察了热处理、薄膜厚度、光极化对薄膜电极的光电性能影响.研究了Pb(NO_3)_2有效的浸渍对薄膜光电性能的影响.  相似文献   

10.
11.
El-Kameesy  S. U.  El-Zaiat  S. Y.  Youssef  G. M.  Saudi  H. A.  El-Fiki  S. A.  Abu-raia  W. A. 《SILICON》2019,11(3):1505-1515
Silicon - Optical spectral analysis of a glass system with composition xPbO – 20 SiO2–10 Na2O – (70 - x) B2O3, where x = 20, 30, 40, 50 and 60 mol %, was studied. The investigated...  相似文献   

12.
Lithium ion conductors, Li3−2x(In1−xZrx)2(PO4)3 (0≦x≦0·20), were synthesized by a solid state reaction. A superionic conductive phase of Li3In2(PO4)3 was stabilized down to room temperature, assisted by the substitution of Zr4+ for In3+ sites of Li3In2(PO4)3. TG-DTA analysis indicated no phase transition in the samples with x superior to 0·05. The substituted samples showed much higher ionic conductivity by a couple of magnitude than that of Li3In2(PO4)3. In particular, the highest conductivity at room temperature was 1·42×10−5 Scm−1 for Li2·8(In0·9Zr0·1)2(PO4)3. Thin films with the composition of Li2·8(In0·9Zr0·1)2(PO4)3 was prepared by a sol–gel method. A coating solution was made from lithium isopropoxide, indium isopropoxide, zirconium isopropoxide and diphosphorus pentaoxide. Well crystallized films were obtained on silicon dioxide and quartz glass substrates by dropping the coating solution, followed by firing over 873 K. In the temperatures above 473 K the lithium ionic conductivity of the film was slightly higher than that of sintered samples prepared by the solid state reaction at 1373 K.  相似文献   

13.
The (AgBr)x(LiPO3)(1−x) (x=0.4 and 0.5) and [(AgI)x(AgBr)0.4−x](LiPO3)0.6 (x=0.1, 0.2, and 0.3) superionic electrolytes have been prepared by conventional melt quenching using a twin roller. These electrolytes are characterized by X-ray diffraction, SEM, and energy dispersive X-ray analysis (EDAX) for structural investigation. Electrical characterizations have been carried out by the AC impedance analysis. The conductivity of LiPO3 glassy system at room temperature is improved by doping with the silver bromide (AgBr)x(LiPO3)(1−x) and the mixture of silver iodide, silver bromide (AgI-AgBr-LiPO3 system) up to 10−5 and 10−3 Ω−1 cm−1, respectively (improvements by four or five orders of magnitude). The frequency response of ionic conductivity has been analyzed by universal dynamic response model (Jonscher's law) and AC conductivity data are fitted using the Jonscher's power law. The conductivity values obtained by the power law and impedance plots are comparable. The frequency exponent (n) has a value between 0 and 1. The AgI-AgBr-LiPO3 system shows the mixed alkali effect. Summerfield scaling master curve is temperature dependent, which may be due to the contribution of the both lithium and silver ions to ionic conduction.  相似文献   

14.
In the perovskite solar cells (PSCs), traps of the perovskite film or interface are the research focus, which can severely hinder charge transfer and benefit charge recombination, thus weakening the photoelectric performance of the devices. Herein, a Thioacetamide (TAA) interfacial layer is used to passivate the traps of PSCs. Comparing to the control device (17.65%), the TAA-based solar cells can achieve an enhanced efficiency of 19.14%. It is found that the passivation caused by TAA occurs through the interactions of sulfur in TAA with undersaturated Pb in perovskite and Ti4+ in TiO2, resulting in a faster and more efficient charge transfer and a greatly reduced trap density from 3.36 × 1016 cm−3 to 1.93 × 1016 cm−3. It is shown that the modification method using TAA may be helpful for passivating traps and obtaining excellent photoelectric properties of PSCs.  相似文献   

15.
采用自助熔剂法,制备出了F-掺杂的不刺眼(Ca_(0.45)Sr_(0.5)Eu_(0.05))_7(SiO_3)_6Cl_(2-2x)F_(2x)(0.5≤x≤0.9)LED用单基质白光荧光粉;利用XRD、SEM、荧光光谱等测试手段对该类荧光粉的结构、形貌及发光性能进行表征。研究表明:通过自助熔剂法合成得到了高结晶性的单基质白光荧光粉;在紫外光激发下有两个发射峰,峰位分别位于466nm和578nm左右,发光范围涵盖整个可见光区;分析认为两个发射带归结为处于两个不同发光中心上的Eu~(2+)的5d-4f发射;当掺杂量x为0.5、0.7、0.9时,在338nm激发下荧光粉均发白光。  相似文献   

16.
以Sm_2O_3和Ce(NO_3)·6H_2O为原料,采用溶胶凝胶法和固相烧结法合成了Sm_xCe_(1-x)O_(2-x/2)陶瓷材料。研究了材料的相结构和显微组织,热导率和热膨胀。结果表明:合成的Sm_xCe_(1-x)O_(2-x/2)陶瓷纯净并具有单一的萤石结构。其显微组织致密,晶界清晰。Sm_2O_3掺杂能降低CeO_2的热导率,其1000℃时的热导率在2.2~2.6 W/m·K之间,与氧化钇部分稳定氧化锆的热导率相当;Sm_xCe_(1-x)O_(2-x/2)陶瓷的热膨胀随Sm_2O_3含量的增加而降低,其1200℃时的热膨胀系数大于13×10~(-6)/K。  相似文献   

17.
The influence of the structure on the catalytic methane activation coupling activity has been shown for La2x Y2–2x O3 (0 x 1) compounds. A perovskite structure leads to total oxidation (CO, CO2) whereas a bixbyite structure results in C2 hydrocarbon formation. This change in selectivity is interpreted in terms of the difference in oxygen environment of lanthanum in the two stuctures.  相似文献   

18.
采用传统电子陶瓷的制备方法制备了(1-2x)PbNb2O6-xSrTiO3-xTiO2(x=0.005~0.025)高Curie温度(θc)压电陶瓷.X射线衍射分析表明:所有样品在1 250℃保温2h烧结均形成铁电性的斜方钨青铜型结构(tungsteu bronze structure,TB).相对介电常数-温度(εr-θ)曲线表明:该体系具有高的θc(500~560℃).测试了不同掺杂量对陶瓷介电和压电性能的影响,发现材料的θc、压电常数(d33)和机电耦合系数(κp)随着x值的增加先增加后降低.当x=0.02时,陶瓷的d33达到最大值,为83pC/N,θc为550℃,κp达33.4%,材料的介电常数Εθ33/ε0为217,为组成的最优配方.  相似文献   

19.
The mechanism of cation replacement in the Li1–x H x AlO2; 0.00 x 0.90 system was investigated with XRD. Examination of the peak position and intensity associated with the 018 and 110 Bragg reflections in a series of partially replaced samples showed that the cation replacement process proceeded by a two phase mechanism. Catalytic characterization of LiAlO2 with the 2-propanol probe reaction revealed the formation of the condensation products methyl-cyclopentene, 4-methyl-2-pentanone, and 4-methyl-2-pentanol. These products were seen in addition to propylene and acetone. Catalytic characterization of Li1–x H x AlO2;x = 0.90 with 2-propanol showed a significant decrease in condensation activity and no change in the propylene/acetone ratio relative to LiAlO2. This suggests that the decrease in the amount of lithium eliminated the basic sites necessary for the condensation reactions.  相似文献   

20.
New multi-component glasses of Se78 ? x Te20Sn2Pb x (0 ≤ x ≤ 6) system have been synthesized using melt-quench technique. Differential Scanning Calorimetric measurements are performed at different heating rates under non-isothermal conditions to study the glass transition kinetics of prepared chalcogenide glass. Different kinetic parameters such as the activation energy of glass transition, thermal stability, glass forming ability etc have been determined. The composition dependence of kinetic parameters of glass transition is also discussed.  相似文献   

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