Pechini 方法制备铌酸锂薄膜的研究

采用Pechini方法，以柠檬酸为配位剂与金属离子配位，在Pt/Ti/SiO₂/Si基片上制备了多晶铌酸锂(LiNbO₃)薄膜。以13C核磁共振、拉曼光谱和红外光谱分析研究了柠檬酸与金属离子的配位情况，提出了一种Nb-柠檬酸配合物可能的分子结构，即柠檬酸作为三齿配体，以端羧基、-OH和中间羧基与Nb离子配位。以TG-DTA对Li-Nb凝胶前驱体的热分解历程进行分析，以拉曼光谱和XRD分析了LiNbO₃薄膜在不同温度下热处理的相组成和结构。结果表明，600 ℃下退火2 h可得到单相多晶LiNbO₃薄膜，薄膜表面致密、平整，晶粒的平均尺寸为50 nm。     

(La0.57Ce0.1)Sr0.03MnO3纳米材料的低温合成及其磁热效应研究

采用聚合物前驱体方法,以H5DTPA为配位剂,低温下合成出(La0.57Ce0.1)Sr0.03MnO3纳米颗粒.用TGA-DTA对凝胶前驱体的热分解历程进行分析,采用XRD,高分辨透射显微镜(HRTEM)对凝胶前驱体不同温度下烧结所得粉体的相组成和微观结构进行研究.采用PPMS对(La0.57Ce0.1)Sr0.03MnO3纳米颗粒的磁性能进行了测量.结果表明:凝胶前驱体经600℃烧结2 h可以得到纯钙钛矿型(La0.57Ce0.1)Sr0.03MnO3纳米粉体,平均粒径为40～50 nm;(La0.57Ce0.1)Sr0.03MnO3纳米粉体的居里温度TC为368 K.     

在乙二醇溶液中合成复合金属醇盐和纳米NiFe2O4

在乙二醇溶液中用电化学法制备了镍、铁醇盐配合物NiFe2(OCH2CH2OH)8,将其溶液水解、真空干燥后在400℃煅烧2 h,得到纳米级NiFe2O4粉体.产物NiFe2(OCH2CH2OH)8通过红外光谱(FTIR)和拉曼光谱(Raman)进行表征,纳米NiFe2O4通过X射线粉末衍射(XRD)和电子显微镜(TEM、SEM)进行表征.实验表明,前驱体中含有OCH2CH2OH基团,可以有效克服水解与煅烧过程中的团聚现象,经400 ℃煅烧2 h得到的纳米NiFe2O4粉体,颗粒分散较好、纯度高,粒径在25～40 nm.     

铜源对溶胶-凝胶法制备La2CuO4晶体及光学性能的影响

以硝酸镧为镧源,柠檬酸为络合剂,水为溶剂,分别以硫酸铜,氯化铜和硝酸铜为铜源,采用溶胶-凝胶法制备了La2CuO4纳米晶。通过热重-示差扫描量热(TG-DSC),X射线衍射(XRD),红外光谱(IR),透射电子显微镜(TEM)和紫外-可见-近红外光谱(UV-Vis-NIR)等方法对La2CuO4粉体进行了测试和表征;研究了不同铜源对前驱体及La2CuO4粉体的热性能、相组成、官能团、显微结构及光学性能的影响。结果表明:以硫酸铜和氯化铜为铜源,600℃煅烧保温2 h,产物均含有杂质相,而以硝酸铜为铜源时,可获得单一的正交晶型的La2CuO4物相,晶粒尺寸80-100 nm。根据UV-Vis-NIR分析,La2CuO4的光学带隙依次为1.193 eV,1.258 eV,1.380 eV。     

Nd:GSAG纳米粉体的合成、晶体结构及光谱

采用共沉淀法,以NH4OH为沉淀剂制备了1％(原子分数)Nd3+:Gd3 Se2 Al3 O12前驱体,并在不同的温度下对前驱体进行煅烧.用X射线衍射(XRD)和红外光谱(FT-IR)技术对前驱体及煅烧后粉体的结构、微观形貌进行了研究.结果表明,前驱体在1000℃下煅烧n获得纯GSAG多晶相粉体.用X射线衍射宽化法估算粉体的平均晶粒尺寸为25 nm.通过X射线粉末衍射,用Rietveld全谱拟合方法对晶体结构进行了精修,得到1000℃下煅烧所得Nd:GSAG粉体的晶胞参数为a=b=c=1.24164(5)nm,α=β=y=90°.在室温下,测定了激发波长为808m的发射谱和检测波长为942 nm的激发谱.另外,测定了 942和1064 nm处的荧光衰减曲线,并用单指数函数进行了拟合,得到对应的荧光寿命分别为0.529和0.512 ms.     

钙钛矿型复合氧化物CaVO3的制备及对氧还原反应的电催化性能

以五氧化二钒、硝酸钙、柠檬酸和草酸为原料,采用溶胶-凝胶法制备出CaVO₃的前驱体,在氩气保护下1000 ℃煅烧2 h,成功制备出目标产物CaVO₃.对前驱体和目标产物分别进行了傅里叶变换红外(FTIR)光谱、热重(TG)分析、X射线衍射(XRD)和电导率等表征.在1 mol·L^-1的KOH电解质溶液中测试了样品的氧还原反应(ORR)催化性能.结果表明,修饰电极上(ORR)的电子转移数是1.5-1.7,发生的是2电子还原.     

二氧化硅-聚苯胺(SiO2-PANI)杂化透明导电薄膜的制备和表征

本文采用溶胶-凝胶法,以3-巯丙基三甲氧基硅烷(MPTMS)和聚苯胺为主要原料,制备得到有机-无机杂化透明导电薄膜.着重研究制备过程中醋酸、间甲酚和聚苯胺含量对薄膜结构、导电性和可见光透过率的影响.通过红外光谱可知,采用溶胶-凝胶法可制得结构稳定的杂化导电材料.醋酸作为水解缩聚反应的反应剂和催化剂,当其与3-巯丙基三甲氧基硅烷的物质的量比为0.4时.MPIMS的水解缩聚速率和聚苯胺掺杂入无机前驱体的掺杂速率达到平衡.此外,透明杂化导电薄膜的方块电阻随间甲酚和聚苯胺含量的增加而降低,当间甲酚和3-巯丙基三甲氧基硅烷的物质的量比为5,聚苯胺和二氧化硅的质量比为3/7时,薄膜的方块电阻为3.23 kΩ/□,可见光透过率为80%.     

新的燃烧工艺合成BaCe0.95Y0.05O3-δ纳米粉

应用基于pechini法改进的新的燃烧法合成了具有单一组成的BaCe0.95Y0.05O3-δ纳米粉体.用柠檬酸和乙二醇做金属离子螯合剂制得复合前驱物溶胶.在硝酸和氨水存在的条件下燃烧复合前驱物溶胶得到粒度小于100nm,形状均匀具有钙钛矿结构的BaCe0.95Y0.05O3-δ纳米粉体.通过调节硝酸和氨水的用量可以控制粉体的粒度,柠檬酸和乙二醇的用量影响产物中碳酸盐的含量.     

SrMoO_4∶Sm~(3+),Na~+红色荧光粉的形貌调控和发光性能

以Sm~(3+)为激活剂,Na~+为电荷补偿剂,柠檬酸为配位剂,乙二醇作为辅助配位剂,采用溶胶-凝胶法合成前驱体,然后在800℃下焙烧,成功制备了一系列SrMoO_4∶Sm~(3+),Na~+红色荧光粉。用X射线衍射仪、扫描电镜、荧光光谱和傅里叶变换红外光谱等手段对样品的物相、形貌、组成、发光性能和量子效率等进行测试和表征。分析结果表明:制备的SrMoO_4∶Sm~(3+),Na~+荧光粉均为四方晶系结构,掺杂离子的加入对基质晶体结构影响不大。在403 nm近紫外光激发下,产物有4个发射峰,分别位于563、600、647和707 nm处,归属于~5G_(5/2)→~6HJ(J=5/2,7/2,9/2,11/2)的电子跃迁,其中位于647 nm处的主发射峰的相对发光强度最大。当Sm~(3+)的掺杂物质的量分数为1%~3%时,发光强度最好,当浓度超过1%~3%时,会发生荧光猝灭。对实验数据进行分析,确定荧光猝灭机理是由于钐离子间交换作用引起的,并计算了能量传递的临界距离为1.77~2.56 nm。此外,还详细研究了乙二醇对SrMoO_4∶Sm~(3+),Na~+荧光粉形貌的影响,研究结果表明:乙二醇加入量为5 m L时,产物形貌均匀,呈球形或椭球形;且分散性较好;荧光强度最大。     

乙二醇甲醚中电解锡电解液直接水解制备纳米SnO2

采用锡金属为阳极，在无隔膜电解槽中，电化学溶解锡于乙二醇甲醚中制备得到纳米SnO2前驱体Sn(OCH2CH2OCH3)4，将电解液直接水解经溶胶-凝胶法制备纳米SnO2，前驱体通过拉曼和红外光谱进行表征.纳米SnO2采用X射线粉末衍射(XRD)和透射电子显微镜(TEM)进行表征.实验表明,电解合成的Sn(OCH2CH2OCH3)4能够溶解于乙醇中, 适宜作为溶胶-凝胶(sol-gel)法制备纳米SnO2的原料，制得的纳米SnO2经600 ℃煅烧后呈球形单分散结构，晶型为四方锡石型, 比表面为62.58 m2·g－1，平均粒径在(10.0±0.4) nm左右.产率为89.3％，电流效率为86.9％.     

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.     

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.     

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.     

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。     

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.     

Preparation of ZrO2-TiO2-CeO2 and Its Application in the Selective Catalytic Reduction of NO with NH3

TiO₂,ZrO₂-TiO₂,andZrO₂-TiO₂-CeO₂ were prepared by co-precipitation method and characterized by X-ray diffraction (XRD), specific surface area measurements (BET), temperature programmed desorption (NH₃-TPD), oxygen storage capacity (OSC), and temperature programmed reduction (H₂-TPR). The results showed that ZrO₂-TiO₂-CeO₂ exhibited large number of surface strong acid, possessed some oxygen storage capacity, and strong redox property. The three materials were used as supports and the monolith catalysts were prepared with 1% (w) V₂O₅ and 9% (w)WO₃ for selective catalytic reduction (SCR) of NO with ammonia in the presence of excessive O₂, and the results of catalytic activity showed that the catalyst used ZrO₂-TiO₂-CeO₂ as support yielded nearly 100% NO conversion at 275 °C at a gas hourly space velocity (GHSV) of 10000 h⁻¹, and it had the best catalytic activity and showed great potential for practical application.     

The Phase Relations in the System In2O3–TiO2–MgO at 1100 and 1350°C

The phase relations in the system In₂O₃–TiO₂–MgO at 1100 and 1350°C are determined by a classical quenching method. In this system, there are four pseudobinary compounds, In₂TiO₅, MgTi₂O₅ (pseudobrookite type), MgTiO₃ (ilmenite type), and Mg₂TiO₄ (spinel type) at 1100°C. At 1350°C, in addition to these compounds there exist a spinel-type solid solution Mg_2−xIn_2xTi_1−xO₄ (0≤x≤1) and a compound In₆Ti₆MgO₂₂ with lattice constants a=5.9236(7) Å, b=3.3862(4) Å, c=6.3609(7) Å, β=108.15(1)°, and q=0.369, which is isostructural with the monoclinic In₃Ti₂FeO₁₀ in the system In₂O₃–TiO₂–MgO. The relation between the lattice constants of the spinel phase and the composition nearly satisfies Vegard's law. In₆Ti₆MgO₂₂ extends a solid solution range to In₂₀Ti₁₇Mg₃O₆₇ with lattice constants of a=5.9230(5) Å, b=3.3823(3) Å, c=6.3698(6) Å, β=108.10(5)°, and q=0.360. The distributions of constituent cations in the solid solutions are discussed in terms of their ionic radius and site preference effect.     

Microstructures of Some Bi-W-Nb-O Phases

Microstructures of three Bi-W-Nb-O phases have been examined by using high-resolution transmission electron microscopy. Bi₁₇W₂Nb₃O₃₉ and Bi₁₇WNb₃O₃₆ have incommensurate superstructures derived from the defect fluorite-type δ-Bi₂O₃ and can be regarded as intermediate phases between the type II solid solutions in the Bi-Nb-O and Bi-W-O systems. Bi₈W₂Nb₂O₂₃ has a Bi₂WO₆-like subunit cell with a stepped superstructure. Formation mechanisms of various superstructures are discussed.     

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.