CaFe0.2Ti0.8O3-δ混合导体的电导和氧渗透性能研究

采用固相反应法制备了致密的高温混合导体ＣａＦｅ０．２Ｔｉ０．８Ｏ３－δ,测量它在９００－１１００℃的总电导率为０．０８－０．１１Ｓ／ｃｍ,氧渗透率为１０＾－８－１０＾－１０ｍｏｌ／ｃｍ＾－２．ｓ结合总电导与氧渗透的数据计算出样品的电子和离子导电率,在１１００℃时分为０．１１和８．５×１０＾－３Ｓ／ｃｍ;氧渗透活化能约为１７０ｋＪ／ｍｏｌ;氧离子和电子电导活化能分别为１７９±６和２２±２ｋＪ／ｍｏｌ     

褪色光度法测定土样中微量铬

在Ｈ２ＳＯ４介质中偶氧氯膦Ⅲ（ＣＰＡⅢ）与铬（Ⅵ）发生氧化褪色反应，该褪色反应的表观洋吸光系数ε５５００ｎｍ＝２．８１×１０＾３Ｌ．ｍｏｌ＾－２．ｃｍ＾－１，Ｃｒ（Ⅵ），０．８．０×１０６－４ｇ．Ｌ＾－１范围内符合比尔定律。本法用于土样中铬分析测定。结果满意。     

Cu(Ⅱ)对DApEM-V(Ⅴ)-H_3PO_4-Mn(Ⅱ)-OP阻抑作用的研究

在酸性介质中Ｃｕ（Ⅱ）能阻抑试剂ＤＡｐＥＭ与Ｖ（Ⅴ）的显色反应。研究了该反应的动力学参数,表观速度常数２．９１×１０－３ｓ－１,表观活化能为５２．８４ｋＪ·ｍｏｌ－１。从而建立了一种测微量Ｃｕ（Ⅱ）的动力学光度法。Ｃｕ（Ⅱ）含量在１．０～８．０μｇ·２５ｍＬ－１范围内,与ｌｇＡ０Ａ呈良好线性,表观摩尔吸光系数为１．１７×１０５Ｌ·ｍｏｌ－１·ｃｍ－１,检出限１．３４×１０－１０ｇ·Ｌ－１,该方法用于人发样品中Ｃｕ的测定,ＲＳＤ％为０．４３％～０．４５％,回收率为９６％～９９％。     

铜（Ⅱ）,N,N‘—双（3,5—二溴水杨醛缩）邻苯二胺配合物吸附波及其应用

在０．０１ｍｏｌ／ＬＮＨ３，Ｈ２Ｏ－ＮＨ４Ｃｌ溶液中，铜（Ⅱ）－Ｎ，Ｎ’－双（３，５－二溴水杨醛缩）邻苯二胺（Ｄｂｓａｌ－ｏ－ＰｈｄｎＨ２）配合物产生灵敏的吸附波，波的峰电位是－０．３８Ｖ（ｖｓ·ＳＣＥ），峰电流与铜（）的浓度在２．０×１０－８－８．０×１０－７ｍｏｌ／Ｌ范围内成正比，检测限是６×１０－９ｍｏｌ／Ｌ，本方法用于检测水中的铜，回收率为９７．５％～１０３％。     

稀土—偶氮胂Ⅲ配合吸附波法测定稀土元素

在ｐＨ值为３的ＮＨ３．Ｈ２Ｏ－ＮＨ４Ｃｌ介质中,镧,铈,镨与偶氮胂Ⅲ（ＡＳＡⅢ）形成配合物,并于－０．７１Ｖ（ｖｓ．ＳＣＥ）处产生灵敏的配合物吸附波峰电流与镧,铈,镨浓度分别为３．６×１０＾－８～１．４×１０＾－６ｍｏｌ／Ｌ,１．８×１０＾－８～８．６×１０＾－７ｍｏｌ／Ｌ,３．５×１０＾－８～７．０×１０＾－７ｍｏｌ／Ｌ范围内呈线性关系,测得镧与偶氮胂Ⅲ的配合比为１：１。稳定常数为４．５×１０＾     

微米级硫钨酸铵在氢气中的热分解动力学

用ＤＴＡ法和ＸＲＤ法研究了粒度为６３～７４μｍ的硫钨酸铵在氢气中的热分解机理，用Ｋｉｓｓｉｎｇｅｒ法、Ｆｒｅｅｍａｎ－Ｃａｒｏｌ法和Ｃｏａｓｔ－Ｒｅｄｆｅｒｎ法测得硫钨酸铵热分解反应三个阶段的活化能分别为（５３±０．５），（１２７±０．５），（３００±０．８）ｋＪ／ｍｏｌ，反应级数分别为０．８，０．６，１．５．硫钨酸铵在氢气中的热分解分四步进行，即（ＮＨ４）２ＷＳ４·Ｈ２Ｏｓ→（ＮＨ４）２ＷＯ４（ｓ）＋Ｈ２Ｏ（ｇ）→ＷＳ２（ｓ）＋２ＮＨ３（ｇ）＋Ｈ２（ｇ）＋２Ｓ（１）＋Ｈ２Ｏ（ｇ）→ＷＳ２（ｓ）＋２ＮＨ３（ｇ）＋２Ｈ２Ｓ（ｇ）＋Ｈ２Ｏ（ｇ）→ＷＳ２（ｓ）＋Ｗ（ｓ）＋２ＮＨ３（ｇ）＋２Ｈ２Ｓ（ｇ）＋Ｈ２     

2.5次微分溶出伏安法同时测定水中痕量钴和镍

在０．０１ｍｏｌ／ＬＮＨａ·Ｈ２Ｏ＋ＮＨ４Ｃｌ（ｐＨ＝８．９）和２．０×１０－６ｍｏｌ／Ｌ酸性铬兰Ｋ（ＡＣＢＫ）溶液中，钴和镍均产生非常灵敏的还原波，峰电位分别是－０．５２Ｖ和－０．６４Ｖ（８８·ＳＣＥ），峰电流与钻和镍的浓度分别在３．０×１０－８～５．０×１０－７ｍｏｌ／Ｌ和２．０×１０－～４２×１０－７ｍｏｌ／Ｌ范围内成直线关系，该法用于测定水中痕量钴和镍，结果令人满意。     

褪色光度法测定土样中微量铬

在Ｈ２ＳＯ４介质中偶氮氯膦Ⅲ（ＣＰＡⅢ）与铬（Ⅵ）发生氧化褪色反应，该褪色反应的表观摩尔吸光系数ε５５０ｎｍ＝２．８１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，Ｃｒ（Ⅵ）在０～８．０×１０－４ｇ·Ｌ－１范围内符合比尔定律。本法用于土样中铬分析测定，结果满意。     

新发光试剂N-(β-羧基丙酰基)异鲁米诺的合成及性能的研究

合成了新发光试剂Ｎ－（β－羧基丙酰基）异鲁米诺（ＣＰＩＬ），并对其化学发光性能进行了研究。ＣＰＩＬ在ＮａＨＣＯ３－ＮａＯＨ介质中与Ｈ２Ｏ２反应，线性范围为２×１０－１０～１×１０－８ｍｏｌ／ＬＣＰＩＬ，检测限为１×１０－１０ｍｏｌ／Ｌ，测定１×１０－９ｍｏｌ／Ｌ　ＣＰＩＬ溶液，相对标准偏差为６．４％。Ｃｏ２＋对ＣＰＩＬ的化学发光反应具有催化增强作用（增强１０倍），当体系中加入一定量的Ｃｏ２＋溶液时，ＣＰＩＬ的浓度在４×１０－１１～１×１０－９ｍｏｌ／Ｌ从范围内具有良好的线性关系，检测限为８×１０－１２ｍｏｌ／Ｌ，灵敏度高于文献报道的ＡＢＥＩ－Ｃｏ２－ＮａＣＩＯ发光体系。     

硫代硫酸盐法添加氯化钠和十二烷基磺酸钠浸取金矿

对湖北氧化铁型金矿进行了Ｎａ２Ｓ２Ｏ３法添加ＮａＣｌ而不加Ｃｕ２＋的浸取条件优化研究,当［Ｓ２Ｏ２－３］＝０．８ｍｏｌ／Ｌ、［ＮＨ３］＝１～２ｍｏｌ／Ｌ、［ＮａＣｌ］＝１．０ｍｏｌ／Ｌ、浸取温度５０℃、浸取时间为３ｈ时,浸出率达到９８％．对广东河台、山东招远硫化金矿进行了浸取研究,当［Ｓ２Ｏ３２－］＝０．８ｍｏｌ／Ｌ、［ＮＨ３］＝２ｍｏｌ／Ｌ、［ＮａＣｌ］＝１．０ｍｏｌ／Ｌ、十二烷基磺酸钠１１．０ｍｏｌ／Ｌ、浸取温度５０℃、浸取时间３ｈ时,浸取率分别达到９６％和９３％．     

Preparation of dual-phase composite BaCe0.8Y0.2O3/Ce0.8Y0.2O2 and its application for hydrogen permeation

Dual-phase ceramic membranes composed of BaCe_0.8Y_0.2O₃ (BCY) and Ce_0.8Y_0.2O₂ (CYO) were successfully synthesized by solid state reaction method for hydrogen permeation. The influences of the BCY/CYO volume ratios on phase composition, microstructure, chemical stability and electrical property were investigated. The hydrogen permeation of the dual-phase composite was characterized as a function of temperature and feed side hydrogen partial pressure. The results showed that there was no reaction between the two constituent oxides observed under the preparation conditions. The dual-phase composite with different BCY/CYO volume ratios after sintering at 1550 °C exhibited dense structure, as well as good stability in 4% H₂/Ar, wet Ar and pure CO₂ atmosphere. The conductivity of the dual-phase composite increased with the content of CYO increasing and 30BCY–70CYO exhibited the highest total conductivity of 2.6×10⁻² S cm⁻¹ at 800 °C in 4% H₂/Ar. The hydrogen permeability of 30BCY–70CYO sample was improved as the temperature and the hydrogen partial pressure in feed gas increased. The hydrogen permeation flux of 1.7 μmol cm⁻² s⁻¹ was achieved at 850 °C.     

溶胶-自蔓延法制备La0.8Sr0.2Mn0.8Ni0.2O3催化剂的优化条件

采用溶胶-凝胶-自蔓延法合成较大比表面积的钙钛矿型复合氧化物La_0.8Sr_0.2Mn_0.8Ni_0.2O₃催化剂,研究了pH、苹果酸用量和焙烧温度对催化剂的影响,通过XRD、BET和SEM等分析手段对催化剂进行了表征。结果表明,pH=3、苹果酸用量为金属离子总物质的量2倍和焙烧温度600 ℃为最佳制备工艺条件。催化剂在低温对CO催化燃烧显示出良好的催化活性。     

Modeling of U-shaped Ba0.5Sr0.5Co0.8Fe0.2O3-δ hollow-fiber membrane for oxygen permeation

A mathematic model is developed for the perovskite-type mixed ionic-electronic conducting (MIEC) membrane,which makes it possible to simulate the process of oxygen separation in the U-shaped Ba0.5Sr0.5Co0.8Fe0.2O3-δ hollow-fiber membrane.The model correlates the oxygen permeation flux to the measurable variables.The trends of calculated results for purge operation coincide well with the experimental data,therefore the model is considerable for flux prediction under vacuum operation.Higher oxygen separation efficiency can be achieved with vacuum operation than purge operation.Parameter study with vacuum operation reveals that oxygen permeation flux increases with higher vacuum levels,and vacuum pressure of around 1.013 × 103 Pa is the optimal.Also,vacuum operation on the lumen side is much more efficient to achieve higher oxygen permeation flux compared with compression mode on the shell side.     

A permeation model study of oxygen transport kinetics of BaxSr1-xCo0.8Fe0.2O3-δ

Ba_xSr_1-xCo_0.8Fe_0.2O_3-δ (BSCF) materials with different Ba doping amounts are widely applied as membranes for oxygen separation and electrodes in solid oxide cells. Different opinions were put forward about the effect of Ba contents on the oxygen transport kinetics. In this work, an oxygen permeation model was first used to investigate the effect of Ba content in BSCF (x = 0, 0.1, 0.3, 0.5, 0.7) on the oxygen transport kinetics. The permeation resistance constants were obtained separately through fitting the condition experimental data to the model. With the increase of Ba content, the interfacial oxygen exchange resistance constants of both sides decrease quickly and then increase slightly, while bulk diffusion resistance remains monotone decreasing. The improvement of oxygen permeation flux is mainly contributed by the enhancement of interfacial oxygen exchange kinetics. It is inferred that Ba element may play an important role in the interfacial oxygen reactions.     

Ce_(0.8)Sm_(0.2)O_(1.9)-BaCe_(0.8)Sm_(0.2)O_(2.9)复合电解质的晶界电导

分别采用机械混合法和一步溶胶-凝胶法制备摩尔比为1:1的Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)-BaCe_(0.8)Sm_(0.2)O_(2.9)(BCS)复合电解质,研究了不同制备方法对复合电解质SDC-BCS的显微结构以及电化学性能的影响。结果表明:相比于机械混合法,一步溶胶-凝胶法制得的复合电解质中的SDC和BCS两相的分布更加均匀;且与单相电解质SDC相比,复合电解质中SDC和BCS的相界能够为质子和氧离子提供传输通道,有利于晶界电导率的提高。另外,一步溶胶-凝胶法制备的复合电解质制作的单电池,具有较高的开路电压和最大功率密度,在700℃时分别达到0.914 V和0.281 W/cm~2。     

Effect of optimal GDC loading on long-term stability of La0.8Sr0.2Co0.2Fe0.8O3-δ/Gd0.2Ce0.8O1.9 composite cathodes

Three types of La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ/Gd_0.2Ce_0.8O_1.9 (LSCF/GDC) composite cathodes with different optimal GDC loading are fabricated through electrospinning, screen printing and solution infiltration method. Constant current polarization with current density of 100 mA cm^?2 at 750°C is applied to test the stability of LSCF/GDC composite cathodes. After constant current polarization for 144 h, the polarization resistance (R_p) of 280 nm-nanofiber skeletal LSCF/GDC composite cathode after pore-forming exhibits the minimum increase, from 0.062 Ω cm² to 0.098 Ω cm². Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) results show that the microstructure and surface chemical composition of the cathode maintain stable during the constant current polarization. Combined with the X-ray diffraction (XRD) result, a relationship among GDC loading, stress, Sr surface segregation and long-term stability is established.     

Effect of Y doping on transport properties of La0.8Sr0.2MnO3 polycrystalline ceramics

In this study, La_0.8-xY_xSr_0.2MnO₃ (LYSMO) polycrystalline ceramics were prepared by means of sol-gel technique using methanol as solvent. X-ray diffraction (XRD) showed all samples to possess standard perovskite structure. Scanning electron microscopy (SEM) revealed samples with high compactness and grain size from 27.80 to 29.73 μm. Resistivity–temperature tests indicated sharp metal-insulator transition behavior of all samples accompanied by rapid transformation from ferromagnetism to paramagnetism (FM-PM). As Y³⁺ doping amounts rose, radius of A-site ions decreased, metal-insulator transition temperature (T_p) of polycrystalline samples shifted to lower temperatures, and resistivity increased. Temperature coefficient of resistance (TCR) and magnetoresistance (MR) were affected by introduction of Y³⁺. At x = 0.06, peak TCR and peak MR reached 4.85% K⁻¹ and 52.34%, respectively. Using double exchange (DE) interaction mechanism, electric transport performances of as-prepared ceramics were explained. These findings look promising for future applications of LYSMO materials in magnetic devices and infrared detectors.     

Effect of Gd doping on electrical transport properties of La0.8Sr0.2MnO3 polycrystalline ceramics

Gd doped La_0.8Sr_0.2MnO₃ (La_0.8-xGd_xSr_0.2MnO₃, LGSMO) ceramics were prepared by a sol-gel method. X-ray diffraction (XRD) patterns showed that all samples exhibited distorted perovskite structures, R_3c. When the Gd³⁺ content x > 0.03, the crystal structure changed to orthorhombic, Pnma. Scanning electron microscopy (SEM) images showed that the ceramics characterize high density and grain boundary connectivity, and higher Gd³⁺ doping decreased the grain size from 26.72 μm to 7.42 μm. The temperature dependence of resistivity showed a transition from a low-temperature metal to a high-temperature insulator. The resistivity increased with Gd doping content, and the metal-insulator transition temperature, T_P, increased first and then decreased, while the temperature coefficient of resistance (TCR) of the samples first decreased and then increased with Gd³⁺, and the magnetoresistance (MR) increased first and then decreased. The peak TCR at x = 0.06 was 5.18%·K^?1, and MR at 0.04 was 34.57%. The electrical transport properties of the ceramics were explained based on the double exchange (DE) interaction mechanism. The obtained material may have application prospects in magnetic devices and infrared detectors.     

Preparation and Oxygen Permeation Properties of BaCrOx Coated Ba0.5Sr0.5Co0.8Fe0.2O3- Tubular Membrane

Barium-chromium oxide (BaCrO_x) coated Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) tubular membranes were successfully prepared and evaluated for oxygen separation applications under high pressure–temperature conditions. The oxygen permeation flux was measured in accordance with the temperature, air pressure, and retentate flow rate, ranging from 750–950°C, 3–9 atm, and 200–1000 mL/min, respectively. The permeation testing on the BaCrO_x coated BSCF tubular membranes showed that the oxygen flux increased as the temperature, pressure, and retentate flow rate increased. The oxygen permeation flux was 5.7 mL/(min cm²) with temperature, pressure, and retentate flow rate of 900°C, 9 atm, and 1000 mL/min, respectively. The temperature dependence of the oxygen permeation process is further investigated, and the Arrhenius pre-exponential factor, as well as the apparent activation energy, is determined.