Bi掺杂对La0.1Sr0.9TiO3陶瓷热电性能的影响

在5% H₂+95% N₂（V/V）还原气氛中1 500℃烧结4 h制备La_0.1Bi_xSr_0.9-xTiO₃（x=0、0.05、0.075、0.1）陶瓷,并对其组成、显微结构和热电性能进行研究。结果表明：掺Bi试样的主晶相均为SrTiO₃,当Bi掺杂量大于0.075时,样品中出现少量Bi₂O₃杂相;掺Bi试样的晶粒发育完全,形状规则,结合紧密,显示出Bi₂O₃良好的助烧效果。另外,Bi元素掺入使La_0.1Sr_0.9TiO₃陶瓷的电导率和Seebeck系数绝对值显著增加,说明Bi元素的掺入可有效提高材料的载流子浓度和载流子迁移率。其中,x=0.075时试样的功率因子最大,在400℃时为692 μW·m^-1·K^-2。虽然其热导率比未掺杂Bi试样有所提高,x=0.075时试样的ZT值在500℃时仍可达0.172,比未掺杂Bi试样提高了130%。     

多级孔La_(0.9)Ce_(0.1)Fe_(1-x)Co_xO_3的制备、表征及对CO+NO的催化活性

以三嵌段共聚物PEG-PPG-PEG (P123,M=5800)为软模板合成了6个多级孔钙钛矿型氧化物La_(0.9)Ce_(0.1)Fe_(1-x)Co_xO_3(x=0, 0.2, 0.4, 0.6, 0.8, 1.0),用XRD, SEM, BET, XPS对其进行表征,并测试了样品对CO+NO的催化活性。结果表明:在B位进行Co掺杂,催化剂的形貌及物化特性发生了显著变化。Co掺杂量在x=0.2时,样品La_(0.9)Ce_(0.1)Fe_(0.8)Co_(0.2)O_3的比表面积、孔容和表面B位金属含量最大,催化活性最佳,在反应温度为276, 242℃时分别对CO, NO的转化率达到90%。     

中温固体氧化物燃料电池La_(0.8-x)Bi_xSr_(0.2)FeO_(3-δ)阴极材料研究

通过高温固相法制备出La_(0.8-x)Bi_xSr_(0.2)FeO_(3-δ)(LBSF)阴极粉体和铒稳定氧化铋(ESB)电解质粉体,通过XRD分别确定其成相温度以及相互之间的化学相容性;以LBSF作为阴极, ESB作为电解质,构成LBSF|ESB|LBSF对称电池,利用交流阻抗法测试阴极的极化行为;用扫描电子显微镜观察电池的断面微结构。结果表明:通过固相合成的LBSF阴极材料呈立方钙钛矿结构。在同一温度下,电导率随Bi_2O_3的掺杂量增加而降低;但极化阻抗随着Bi_2O_3的掺杂量增加而降低,当x=0.4时, LBSF(0.4)的极化阻抗达到最小, 650℃时为1.05Ω·cm~2, 900℃时低达0.17Ω·cm~2。研究结果表明:LBSF是良好的固体氧化物燃料电池阴极材料。     

固体电解质Ce_(0.9)Er_(0.1-x)Pr_xO_(1.95+δ)的微观结构及电性能

采用柠檬酸溶胶-凝胶法制备了固体电解质Ce0.9Er0.1-xPrxO1.95+δ(x=0.02~0.08),利用X射线粉末衍射(XRD)、原子力显微镜(AFM)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和交流阻抗谱研究了样品的微观结构和电性能.XRD结果表明,800℃煅烧的所有样品均形成了单相立方萤石结构;Raman光谱结果表明,Ce0.9Er0.05Pr0.05O1.95+δ具有氧缺位的立方萤石结构;XPS分析表明,Ce0.9Er0.05Pr0.05O1.95+δ存在氧缺位,Pr3+离子和Pr4+离子共存;AFM观测结果表明,1300℃下烧结的样品比1400℃下烧结的样品致密;交流阻抗谱结果表明,Pr掺杂量x=0.05时,Ce0.9Er0.05Pr0.05O1.95+δ的电导率最高(σ600℃=1.34×10-2S/cm,Ea=0.90 e V),比未掺杂Pr的Ce0.9Er0.1O1.95(σ600℃=8.81×10-3S/cm,Ea=0.92 e V)提高了52%,说明在Ce0.9Er0.1O1.95中适量掺杂Pr可提高材料的电导率,降低活化能.     

低温热氧化法制备Bi_2Mo_3O_(12)介质薄膜

通过直流磁控溅射法在Si/Si O_2/Pt基片表面沉积摩尔比为2∶3的Bi/Mo多层薄膜。系统研究了热氧化温度对上述薄膜的物相组成、微观形貌、介电性能的影响。X-射线衍射(XRD)数据表明,420~480℃可热氧化形成介质薄膜。420℃氧化,薄膜的物相为Bi_2O_3、Mo O_3、Bi_2Mo O_6和Bi_2Mo_3O_(12);450℃和480℃氧化,薄膜的主相均为Bi_2Mo_3O_(12),另有少量Bi_2Mo O_6存在。扫描电镜(SEM)观察结果显示,薄膜在450℃即已致密、均匀。介电性能测试结果显示,480℃氧化的介质薄膜,具有较优的介电性能:1 k Hz测量,介电常数约15.6,介电损耗约0.65%;5.55 k V/mm电场强度下,漏电流密度约3.4×10~(-7) A/mm~2。考虑到Bi/Mo薄膜极低的成膜温度(480℃)及直流磁控溅射Bi/Mo金属薄膜较大的沉积速率(92 nm/min),直流磁控溅射Bi/Mo金属薄膜,然后热氧化成Bi_2Mo_3O_(12)介质薄膜,在工业上具有应用价值,有望应用于嵌入式薄膜电容器的制备。     

SOLID STATE CHEMISTRY OF La_(1-x)Li_(x)MnO_3 AND RELATED COMPOUND

A series of perovskite type oxides La_(1-x)A_(x)MnO_3(x=0.1 for A=Li,Na,K;x=0.1～0.5 for A=Li)have been prepared by impregnation.Experimental results showed that the substitution of La~(3 ) by Li~ inLaMnO_(3 ?) greatly increased the selectivity to ethane and ethylene for theoxidative coupling of methane.Temperature-programmed desorption of oxygenproved the presence of oxygen vacancies in the oxide lattice.The higher Mn~(4 )/Mn_t ratio in oxide made the formation of oxygen vacancies easier on the oxidesurface.The general formula of the oxides is La_(1-x)Li_(x)Mn＇V＇_(y)O_(3-y),V=vacancy.     

Ca、Bi掺杂Ba_(0.67)Sr_(0.33)TiO_3陶瓷弛豫特性研究

通过低成本固相法制备了Ca、Bi掺杂Ba_(0.67)Sr_(0.33)TiO_3陶瓷.利用透射电子显微镜(TEM)和阻抗分析仪分析技术,详细研究了Ca、Bi掺杂Ba_(0.67)Sr_(0.33)TiO_3陶瓷的弛豫特性.研究发现Ca、Bi掺杂使BST陶瓷呈现显著的铁电弛豫行为,且随着掺杂量的增加,介电峰弥散程度和弛豫强度逐渐增强.     

La1-xSrxCoO3(x=0,0.2,0.4,0.6,0.8)钙钛矿型氧化物的催化性能及改性

通过溶胶-凝胶法制备出A位Sr掺杂的钙钛矿型氧化物La_(1-x)Sr_xCoO_3(x=0,0.2,0.4,0.6,0.8),并将其作为催化剂应用于双功能氧电极中。测试结果表明,A位Sr的掺杂的La_(1-x)Sr_xCoO_3比LaCoO_3具有更高的电催化活性,并且La_(0.6)Sr_(0.4)CoO_3在氧还原和氧析出反应中均表现出最优的催化性能,最大电流密度分别达到0.244 A·cm~(-2)(-0.6 V vs Hg/HgO)和0.303 A·cm~(-2)(1 V vs Hg/HgO)。为进一步提高催化剂的催化活性,将水热法制备的α-MnO_2纳米管与La_(0.6)Sr_(0.4)CoO_3复合作为双功能催化剂。当α-MnO_2的质量分数为40%时,比起单一的α-MnO_2或钙钛矿氧化物,α-MnO_2/La_(0.6)Sr_(0.4)CoO_3复合材料表现出协同效应,有更好的双功能电催化活性,使双效氧电极具有更好的电化学性能及稳定性。     

Ba0.98Bi0.02(Ti0.9Zr0.1)1-xCuxO3陶瓷的介电性能、弛豫行为与结晶化学特性

采用固相合成法,Bi3+作施主掺杂A位,Cu2+作受主掺杂B位,制备了Ba0.98Bi0.02(Ti0.9Zr0.1)1-xCuxO3(x=0,0.01,0.02,0.03)陶瓷样品。借助XRD、LCR等研究了该陶瓷的结构与介电性能。结果表明:当x=0.03时,陶瓷样品出现第二相。通过GULP模拟,缺陷偶极子的稳定性从低到高依次为:[2BiBa.+VBa″]、[2BiBa.+CuTi/Zr″]、[CuTi/Zr″+VO..],结合实验可知:介电弛豫程度与晶体中缺陷偶极子的存在形式相关,其中x=0.01时,晶体中以[2BiBa.+CuTi/Zr″]为主。随Cu2+掺杂量的增加,介电常数增加,介电常数与B位键价和呈反比变化、与八面体BO6的体积呈正比变化。     

Bi/BiVO4&Bi4V2O11复合催化剂的制备及其光催化性能

经由溶剂热反应、光辅助还原过程制备Bi/Bi VO_4Bi_4V_2O_(11)纳米复合光催化材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、N_2吸附-脱附等温线和光致发光(PL)等手段对该复合物进行表征。实验结果表明当金属Bi与BiVO_4Bi_4V_2O_(11)的质量比值为0.8,可见光照射30 min时,Bi/BiVO_4Bi_4V_2O_(11)复合催化剂对罗丹明B(RhB)的降解率可达95.6%。此外,Bi/BiVO_4Bi_4V_2O_(11)对四环素(TC)的降解也表现出增强的光催化性能。Bi/BiVO_4Bi_4V_2O_(11)复合材料提升的光催化性能可能归因于金属Bi的表面等离子体共振(SPR)效应、拓宽的可见光吸收范围和增大的比表面积。此外,提出了复合光催化剂可能的光催化机理。     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Non-centrosymmetric Ba3Ti3O6(BO3)2

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.     

Ion-beam irradiation of lanthanum compounds in the systems La2O3-Al2O3 and La2O3-TiO2

Thin crystals of La₂O₃, LaAlO₃, La_2/3TiO₃, La₂TiO₅, and La₂Ti₂O₇ have been irradiated in situ using 1 MeV Kr²⁺ ions at the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), Argonne National Laboratory (ANL). We observed that La₂O₃ remained crystalline to a fluence greater than 3.1×10¹⁶ ions cm⁻² at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (T_c) of 647 K for LaAlO₃, 840 K for La₂Ti₂O₇, 865 K for La_2/3TiO₃, and 1027 K for La₂TiO₅. The T_c values observed in this study, together with previous data for Al₂O₃ and TiO₂, are discussed with reference to the melting points for the La₂O₃-Al₂O₃ and La₂O₃-TiO₂ systems and the different local environments within the four crystal structures. Results suggest that there is an observable inverse correlation between T_c and melting temperature (T_m) in the two systems. More complex relationships exist between T_c and crystal structure, with the stoichiometric perovskite LaAlO₃ being the most resistant to amorphisation.     

A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

LiNi0.8Co0.15Al0.05O2正极材料的FePO4包覆改性

使用液相包覆工艺对LiNi_(0.8)Co_(0.15)Al_(0.05)O_2(NCA)材料进行FePO_4包覆改性,利用FePO_4优异的结构稳定性与热稳定性,对NCA的长期可靠性与安全性能进行改良。重点研究FePO_4包覆对NCA材料的改性效果,以及不同包覆量造成的NCA材料电化学性能差异。表面包覆的FePO_4保护层,能够防止NCA材料与电解液直接接触发生副反应,抑制长期循环过程中过渡金属离子的溶出,保持结构的长期稳定性。当包覆量为1.0%(w/w)时,NCA材料表现出最优的综合性能,充放电循环800次后,容量保持率依然高达95%,25℃下存储100 d后,容量保持率也高于95%,达到了兼顾能量密度、使用寿命及安全性能的理想效果。     

Crystal growth, structural characterization and magnetic properties of Ca3CuRhO6, Ca3Co1.34Rh0.66O6 and Ca3FeRhO6

Single crystals of Ca₃CuRhO₆, Ca₃Co_1.34Rh_0.66O₆ and Ca₃FeRhO₆ were synthesized by high temperature flux growth in molten K₂CO₃ and structurally characterized by single crystal X-ray diffraction. While Ca₃Co_1.34Rh_0.66O₆ and Ca₃FeRhO₆ crystallize with trigonal (rhombohedral) symmetry in the space group , Z=6: Ca₃Co_1.34Rh_0.66O₆a=9.161(1) Å, c=10.601(2) Å; Ca₃FeRhO₆a=9.1884(3) Å, c=10.7750(4) Å; Ca₃CuRhO₆ adopts a monoclinic distortion of the K₄CdCl₆ structure in the space group C2/c, Z=4: a=9.004(2) Å, b=9.218(2) Å, c=6.453(1) Å, β=91.672(5). All crystals of Ca₃CuRhO₆ examined were twinned by pseudo-merohedry. Ca₃CuRhO₆, Ca₃Co_1.34Rh_0.66O₆, and Ca₃FeRhO₆ are structurally related and contain infinite one-dimensional chains of alternating face-sharing RhO₆ octahedra and MO₆ trigonal prisms. In the monoclinic modification, the copper atoms are displaced from the center of the trigonal prism toward one of the rectangular faces adopting a pseudo-square planar configuration. The magnetic properties of Ca₃CuRhO₆, Ca₃Co_1.34Rh_0.66O₆, and Ca₃FeRhO₆ are discussed.     

The mercury chromates Hg6Cr2O9 and Hg6Cr2O10—Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

The basic mercury(I) chromate(VI), Hg₆Cr₂O₉ (=2Hg₂CrO₄·Hg₂O), has been obtained under hydrothermal conditions (200 °C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K₂Cr₂O₇. Hydrothermal treatment of microcrystalline Hg₆Cr₂O₉ in demineralised water at 200 °C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg₆Cr₂O₁₀ (=2Hg₂CrO₄·2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg₆Cr₂O₉: space group P2₁2₁2₁, Z=4, a=7.3573(12), b=8.0336(13), , 3492 structure factors, 109 parameters, R[F²>2σ(F²)]=0.0371, wR(F² all)=0.0517; Hg₆Cr₂O₁₀: space group Pca2₁, Z=4, a=11.4745(15), b=9.4359(12), , 3249 structure factors, 114 parameters, R[F²>2σ(F²)]=0.0398, wR(F² all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg₆Cr₂O₉ contains three different Hg₂²⁺ dumbbells, whereas Hg₆Cr₂O₁₀ contains two different Hg₂²⁺ dumbbells and two Hg²⁺ cations. The Hg^I-Hg^I distances are characteristic and range between 2.5031(15) and 2.5286(9) Å. All Hg₂²⁺ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg²⁺ cations is nearly linear with two tightly bonded O atoms at distances around 2.07 Å. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66 Å. Upon heating at temperatures above 385 °C, Hg₆Cr₂O₉ decomposes in a four-step mechanism with Cr₂O₃ as the end-product at temperatures above 620 °C.     

Structural study of the NaCdVO4-Cd3V2O8 and CdO-V2O5 sections of the ternary system Na2O-CdO-V2O5

The NaCdVO₄-Cd₃V₂O₈ and CdO-V₂O₅ sections of the ternary system Na₂O-CdO-V₂O₅ have been studied and the crystal structures of Cd₃V₂O₈ and Cd₁₈V₈O₃₈ compounds were determined from single-crystal X-ray diffraction data. Cd₃V₂O₈ crystallizes with the maricite-type structure in space group Pnma, a=9.8133(10) Å, b=6.9882(10) Å, c=5.3251(10) Å and Z=4, whereas Cd₁₈V₈O₃₈ crystallizes in space group P1 with a new-type structure, a=8.5761(14), b=8.607(3), c=12.896(2) Å, α=95.64(1), β=102.45(1), γ=108.42(1)° and Z=1. The Cd₃V₂O₈ structure is made up of Cd1O₄ infinite chains of edge-sharing Cd1O₆ octahedra which are parallel to the b direction. The Cd1O₄ chains are linked together by VO₄ tetrahedra and strongly distorted Cd2O₄ tetrahedra. The structure of Cd₁₈V₈O₃₈ is based on an ordered three-dimensional framework of cadmium and vanadium polyhedra that share corners. The distorted CdO₆ octahedra, CdO₅ trigonal bipyramids and CdO₅ square pyramids share corners, edges or faces.     

Structure and magnetism of NaRu2O4 and Na2.7Ru4O9

The structures of NaRu₂O₄ and Na_2.7Ru₄O₉ are refined using neutron diffraction. NaRu₂O₄ is a stoichiometric compound consisting of double chains of edge sharing RuO₆ octahedra. Na_2.7Ru₄O₉ is a non-stoichiometric compound with partial occupancy of the Na sublattice. The structure is a mixture of single, double and triple chains of edge-shared RuO₆ octahedra. NaRu₂O₄ displays temperature independent paramagnetism with . Na_2.7Ru₄O₉ is paramagnetic, χ₀= with and a Curie constant of 0.0119 emu/mol Oe K. Specific heat measurements reveal a small upturn at low temperatures, similar to the upturn observed in La₄Ru₆O₁₉. The electronic contribution to the specific heat (γ) for Na_2.7Ru₄O₉ was determined to be15 mJ/mole_Ru K².