层状O2结构锂锰氧化物Li0.60[MgxCoyMn1-x-y]O2的制备及结构表征

本文采用离子交换法分别制备了双复合锂锰氧化物Li_0.60[Mg_xMn_1-x]O₂(0.05 ≤ x ≤ 0.15)和三复合锂锰氧化物Li_0.60[Mg_xCo_yMn_1-x-y]O₂(x=0.05，0.05 ≤      

空气中合成固溶体荧光粉Ba2(Zn, Mg)Si2O7:Ce3+,Eu2+,Eu3+及其发光特性

采用高温固相法在空气中合成了Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu,yCe³⁺系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu²⁺离子的4f⁶5d¹-4f⁷跃迁,590~725 nm红光区窄带谱源于Eu³⁺的⁵D₀-⁷F_J (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu³⁺在Ba_1.97-yZn_1-xMg_xSi₂O₇基质中被还原成了Eu²⁺;当x=0.1时,荧光粉Ba_1.97Zn_0.9Mg_0.1Si₂O₇:0.03Eu的绿色发光最强,表明Eu³⁺被还原成Eu²⁺离子的程度最大。当共掺入Ce³⁺离子后,形成Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺荧光粉体系,其发光随着Ce³⁺离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.01Ce³⁺,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba₂Zn_0.9Mg_0.1Si₂O₇基质中的能量传递与发光机理。     

中温固体氧化物燃料电池阴极材料Sm2-xCexCuO4的制备与性能研究

采用甘氨酸-硝酸盐法合成了新型中温固体氧化物燃料电池(ITSOFC)阴极材料Sm_2-xCe_xCuO₄(SCC，x=0.0～0.25)。利用XRD和SEM对材料的结构、化学稳定性和微观形貌进行分析表明，该阴极材料与电解质Ce_0.9Gd_0.1O_1.9(CGO)在1 000 ℃烧结时不发生反应;且烧结2 h后，二者之间形成良好的接触界面。利     

纳米Ce1—xMnxO2催化剂上乙醇催化氧化发光研究

研究了纳米Ce_1—xMn_xO₂上乙醇催化氧化发光特性, 重点考察了反应温度和催化剂组成(Ce/Mn比)对发光强度的影响规律. 为研究催化发光机理, 在相近的反应条件下考察了纳米Ce_1—xMn_xO₂上乙醇催化氧化反应的活性和选择性. 结果表明: 催化发光强度与催化反应中生成CH₃CHO的产率有很好的顺变关系, 表明CH₃CHO是导致C₂H₅OH分子在纳米Ce_1—xMn_xO₂催化剂上氧化发光的“活性分子”.     

CexTi1-xO2复合氧化物表面结构和体相结构的演变

利用X射线衍射、N₂吸附等温线、X射线光电子能谱、X射线吸收谱、H₂-程序升温还原、甲基橙选择化学吸附和等电点测定等方法研究了共沉淀方法制备的一系列Ce_xTi_1-xO₂复合氧化物的结构. 成功发展了甲基橙选择化学吸附和等电点方法研究Ce_xTi_1-xO₂复合氧化物的最外层表面结构, 并定义了“等价CeO₂表面覆盖度”来描述Ce_xTi_1-xO₂复合氧化物的最外层表面结构. Ce_xTi_1-xO₂复合氧化物 (x ≥ 0.7)形成立方萤石相固溶体, Ce_0.3Ti_0.7O₂表现出纯的单斜相, 而其它复合氧化物表现出混合相. Ce_xTi_1-xO₂复合氧化物最外层表面结构的演变行为不同于其体相结构.Ce_0.7Ti_0.3O₂立方萤石相固溶体最外层表面已经部分形成了单斜相Ce_0.3Ti_0.7O₂, 随Ce含量的降低, 单斜相Ce_0.3Ti_0.7O₂从最外层表面向体相生长. Ce_xTi_1-xO₂复合氧化物立方萤石相固溶体和单斜相Ce_0.3Ti_0.7O₂分别在相对较低和较高的温度表现出好的还原性能. 上述结果提供了全面和深层次的Ce_xTi_1-xO₂复合氧化物结构信息.     

CexPr1-xO2-δ复合氧化物的XRD和Raman表征

A series of Ce_xPr_1-xO_2-δ mixed oxides were synthesized by sol-gel method and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO₂ was observed. The samples were very well crystallized on decreasing x from 0.50 to 0.99. For Ce_xPr_1-xO_2-δ samples 465 cm^-1 and 1 150 cm^-1 Raman peaks are attributed to the Raman active F_2g mode of CeO₂. The broad peak at about 570 cm^-1 in the region of 0.3 ≤x≤ 0.99 can be linked to lattice defects resulting in oxygen vacancies. The new band at about 195 cm^-1 may be attributed to the asymmetric vibration caused by the formation of oxygen vacancies. Calcination temperatures had great effect on the peak intensity for CeO₂ but less effect on Ce_0.8Pr_0.2O_2-δ in Raman spectra. It might be due to the transformation of the colors for the mixed oxides, the insertion of Pr atom into the ceria lattice could enhance the sintering resistance and thermal stability of the mixed oxides.     

Mg掺杂In2O3-x催化剂光热催化CO2加氢

为提高光热催化CO₂加氢催化剂In₂O₃的催化活性,采用均相水热法制备Mg(OH)₂-In(OH)₃前驱体,通过高温煅烧和H₂-还原处理得到了富含氧空位的Mg掺杂In₂O_3-x(Mg-In₂O_3-x)催化剂。在300℃、常压、可见光照射条件下,CO₂加氢转化为CO的CO₂转化率可达31.20%,CO产生速率为14.22 mmol·gcat^-1·h^-1,CO选择性为100%。相比于单一In₂O_3-x催化剂,Mg-In₂O_3-x催化剂光热催化CO₂转化率及CO产生速率明显提高,这归因于Mg成功掺杂到In₂O₃形晶格中,促进In₂O₃表面氧空位的形成,进而对可见光响应效率大幅提高,并有效减缓光生电子-空穴的复合。     

Mg掺杂In2O3-x催化剂光热催化CO2加氢

为提高光热催化CO₂加氢In₂O₃催化剂的催化活性,采用均相水热法制备Mg (OH)₂-In (OH)₃前驱体,通过高温煅烧和H₂-还原处理得到了富含氧空位的Mg掺杂In₂O_3-x(Mg-In₂O_3-x)催化剂。在300℃、常压、可见光照射条件下,CO₂加氢转化为CO的CO₂转化率可达31.20%,CO产生速率为14.22 mmol·g_cat^-1·h^-1,CO选择性为100%。相比于单一In₂O_3-x催化剂,Mg-In₂O_3-x催化剂光热催化CO₂转化率及CO产生速率明显提高,这归因于Mg成功掺杂到In₂O₃晶格中,促进In₂O₃表面氧空位的形成,进而对可见光响应效率大幅提高,并有效减缓光生电子-空穴的复合。     

Y2O3对铝代α-Ni(OH)2电极材料高温性能的影响

固相法合成的样品,经X-射线粉末衍射(XRD)、扫描电镜(SEM)、红外光谱(FTIR)、电感螯合等离子体发射光谱(ICP-AES)、比表面积(BET)、热重分析(TGA)和滴定法(CT)等表征为α-Ni_0.81Al_0.19(OH)_2.19-2y(CO₃)_y·xH₂O(x=1.1~1.2,y=0.10~0.12)。为了改善其高温性能,样品经混掺不同量Y₂O₃后作为氢镍电池的正极材料,做了不同温度恒流充放电、微电极循环伏安(CV)和交流阻抗谱(EIS)测定。结果表明,60 ℃时掺Y₂O₃0.4wt%~1.2wt%,能提高样品不同倍率放电比容量达18.1％~42.0％,同时也改善了高温放电电位。     

纳米Ce1-xLaxO2-δ的微波引诱燃烧合成及其性能表征

Nanometer Ce_1-xLa_xO_2-δ solid solutions were synthesized by microwave-induced combustion process us-ing cerium nitrate hexahydrate， lanthanum nitrate hexahydrate and urea as raw materials. The process took only six minutes to obtain La₂O₃-doped CeO₂ nanopowders. The nanopowders were characterized by XRD， Laser Raman spectrum ， UV-Vis spectroscopy，field-emission scanning electron micrograph(FE-SEM)and TEM. The results revealed that the grain size of Ce_1-xLa_xO_2-δ varied from 20 to 40 nm calculated by Scherer formula through the plane of (111)， that oxygen vacancy was produced in the crystal lattices and the concentration of oxygen vacancy was increased with La doping， therefore the covalence of Ce-O bond was strenthened， which results in more intensive UV-C(200～280 nm)absorption. It can be seen from SEM that the porous appearance was obtained. Grain size is no more than 40nm observed from TEM.     

Li_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3,Na_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3的离子交换研究

研究了在不同温度下的NaNO3和AgNO3水溶液中Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3离子交换行为.实验表明Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3均显示出了高选择性与Na+和Ag+进行离子交换的特征,且对Ag+的选择性高于Na+.升高温度可显著提高Ag/Li和Ag/Na的交换反应速度.     

Crystal growth, structure determination, and optical properties of new potassium-rare-earth silicates K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)

Single crystals of K₃RESi₂O₇ (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K₃RESi₂O₇ that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment, while in K₃LuSi₂O₇, containing the smallest of the rare earths, lutetium is found solely in an octahedral coordination environment. The structure of K₃LuSi₂O₇ crystallizes in space group P6₃/mmc with a=5.71160(10) Å and c=13.8883(6) Å. The structures containing the remaining rare earths crystallize in the space group P6₃/mcm with the lattice parameters of a=9.9359(2) Å, c=14.4295(4) Å, (K₃GdSi₂O₇); a=9.88730(10) Å, c=14.3856(3) Å, (K₃TbSi₂O₇); a=9.8673(2) Å, c=14.3572(4) Å, (K₃DySi₂O₇); a=9.8408(3) Å, c=14.3206(6) Å, (K₃HoSi₂O₇); a=9.82120(10) Å, c=14.2986(2) Å, (K₃ErSi₂O₇); a=9.80200(10) Å, c=14.2863(4) Å, (K₃TmSi₂O₇); a=9.78190(10) Å, c=14.2401(3) Å, (K₃YbSi₂O₇). The optical properties of the silicates were investigated and K₃TbSi₂O₇ was found to fluoresce in the visible.     

Metal-organic deposition of YBa2Cu3Ox and Bi2Sr2Ca1Cu2Ox films on various substrates starting from different fluorine-free metallorganic compounds

YBa₂Cu₃O_x (Y-123) and Bi₂Sr₂Ca₁Cu₂O_x (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature (T _c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).     

Decomposition of P2S2N4(Si(CH3)3)4A12C14 as Studied by FT-Raman and Quantum Chemistry Means

The dimeric title compound decomposes upon heating to give the monomer and desulphurized monomer as shown by FT-Raman and quantum chemical means.     

Near infrared study of aqueous rare-earth ethylsulfates

The near infrared spectra of aqueous solutions of the ethylsulfates of La, Nd, Gd, Tb, Er, Yb, Lu, Y, and Na have been determined from about 0.2 mol-dm^–3 to nearly saturation. The extinction coefficients of water have been calculated taking into account the absorption of ethylslfate anions determined in separate experiments. Their values appeared to be nearly the same as that of pure water. The relative contents of free OH groups in 0.5 and 0.7M solutions have been estimated from the absorbances at 1160 nm. They were lower in solutions of the heavy rare-earth ethylsulfates (Tb, Er, Yb, Lu) than in equimolar solutions of the lighter ones (La, Nd), confirming our previous view that secondary hydration of the heavy trivalent rare-earth cations is distinctly stronger than that of the lighter ones. A comparison of the spectra of these aqueous ethylsulfates with those of perchlorates shows that the structure-breaking ability of the C₂H₅SO ₄ ^– ion is much smaller than that of perchlorate anion.     

B2O3-Bi2O3-ZnO-Al2O3玻璃助烧剂对BaTiO3陶瓷烧结条件、晶体结构和介电性能的影响

通过调节B₂O₃-Bi₂O₃-ZnO-Al₂O₃(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO₃)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明：添加适量的BBZA玻璃能够有效地将BaTiO₃陶瓷烧结温度由1 350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO₃的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO₃陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO₃晶粒表面。优化的BaTiO₃陶瓷制备条件如下：BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO₃陶瓷介电常数达到1 364,介电损耗低至1.2%。     

The crystal chemistry of Bi6TP2O15+x, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi6TiP2O16

The crystal structures of compounds with nominal compositions Bi₆FeP₂O_15+x (I), Bi₆NiP₂O_15+x (II) and Bi₆ZnP₂O_15+x (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5) Å, β=96.154(4)°; for (II) a=11.259(7), b=5.461(4), c=11.109(7) Å, β=96.65(1)°; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6) Å, β=131.932(1)°. Least squares refinements on F² converged for (I) to R1=0.0554, wR₂=0.1408; for (II) R₁=0.0647, wR₂=0.1697; for (III) R₁=0.0385, wR₂=0.1023. The crystals are complexly twinned by 2-fold rotation about , by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi₄ tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO₄ moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350 K. Between 4.2 and 250 K it is paramagnetic, μ_eff=6.1 μ_B; a magnetic transition occurs above 250 K.     

电感耦合等离子体光谱法(ICP-AES)测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量

针对银精矿样品复杂,难消解的特点,研究了不同酸溶法和碱熔法对样品的消解情况,建立了硝酸,盐酸,氢氟酸,高氯酸消解银精矿的方法。根据元素灵敏度和抗干扰性,选定各元素的测定波长。通过酸溶样和碱熔样测定结果比对,验证了方法准确性。建立了四酸消解-电感耦合等离子体光谱法测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的方法,元素的线性相关系数均在0.9999以上。通过共存元素干扰实验,确定了银精矿中高含量元素(铜、铅、锌、铁、锑、铋等)对测定元素结果没有影响。方法检出限：Cu 0.0063 mg/L, Pb 0.0159 mg/L ,Zn 0.0090 mg/L,As 0.0192 mg/L, Cd 0.0093 mg/L ,Ca 0.0084 mg/L, Mg 0.0075 mg/L, Mn 0.0081 mg/L。测定下限：Cu 0.0105mg/L,Pb 0.0265 mg/L, Zn 0.0150 mg/L, As 0.0320 mg/L, Cd 0.0155 mg/L, Ca 0.0140 mg/L, Mg 0.0125 mg/L,Mn 0.0135 mg/L。3个样品的相对标准偏差在0.87%~3.56%之间,加标回收率在95.00%~103.56%之间。方法流程短,操作简单,快速,灵敏度和再现性高,结果准确可靠,可以满足银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的测定。     

Structural studies of five layer Aurivillius oxides: A2Bi4Ti5O18 (A=Ca, Sr, Ba and Pb)

The room temperature structures of the five layer Aurivillius phases A₂Bi₄Ti₅O₁₈ (A=Ca, Sr, Ba and Pb) have been refined from powder neutron diffraction data using the Rietveld method. The structures consist of [Bi₂O₂]²⁺ layers interleaved with perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks. The structures were refined in the orthorhombic space group B2eb (SG. No. 41), Z=4, and the unit cell parameters of the oxides are a=5.4251(2), b=5.4034(1), c=48.486(1); a=5.4650(2), b=5.4625(3), c=48.852(1); a=5.4988(3), b=5.4980(4), c=50.352(1); a=5.4701(2), b=5.4577(2), c=49.643(1) for A=Ca, Sr, Ba and Pb, respectively. The structural features of the compounds were found similar to n=2-4 layers bismuth oxides. The strain caused by mismatch of cell parameter requirements for the [Bi₂O₂]²⁺ layers and perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks were relieved by tilting of the TiO₆ octahedra. Variable temperature synchrotron X-ray studies for Ca and Pb compounds showed that the orthorhombic structure persisted up to 675 and 475 K, respectively. Raman spectra of the compounds are also presented.     

Structure Study of Bi2.5Na0.5Ta2O9 and Bi2.5Nam−1.5NbmO3m+3 (m=2-4) by Neutron Powder Diffraction and Electron Microscopy

The crystal structures of Bi_2.5Na_0.5Ta₂O₉ and Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=3,4) have been investigated by the Rietveld analysis of their neutron powder diffraction patterns (λ=1.470 Å). These compounds belong to the Aurivillius phase family and are built up by (Bi₂O₂)²⁺ fluorite layers and (A_m-1B_mO_3m+1)^2- (m=2-4) pseudo-perovskite slabs. Bi_2.5Na_0.5Ta₂O₉ (m=2) and Bi_2.5Na_2.5Nb₄O₁₅ (m=4) crystallize in the orthorhombic space group A2₁am, Z=4, with lattice constants of a=5.4763(4), b=5.4478(4), c=24.9710 (15) and a=5.5095(5), b=5.4783(5), c=40.553(3) Å, respectively. Bi_2.5Na_1.5Nb₃O₁₂ (m=3) has been refined in the orthorhombic space group B2cb, Z=4, with the unit-cell parameters a=5.5024(7), b=5.4622(7), and c=32.735(4) Å. In comparison with its isostructural Nb analogue, the structure of Bi_2.5Na_0.5Ta₂O₉ is less distorted and bond valence sum calculations indicate that the Ta-O bonds are somewhat stronger than the Nb-O bonds. The cell parameters a and b increase with increasing m for the compounds Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=2-4), causing a greater strain in the structure. Electron microscopy studies verify that the intergrowth of mixed perovskite layers, caused by stacking faults, also increases with increasing m.