Y2O3对火法合成HA影响的扩散偶研究

采用嵌套式扩散偶法对比研究了添加稀土氧化物(1.0%Y2O3)和未添加稀土氧化物时羟基磷灰石的火法合成过程.试验选用CaO和CaHPO4·2H2O作为合成HA的原材料,制备成扩散偶放入管式炉中进行烧结,随炉冷却后进行XRD、SEM分析.结果表明:Y2O3能够促进γ-Ca2P2O7向β-Ca3(PO4)2转变;Y2O3参加了化学反应,生成了Ca3Y(PO4)3;掺杂试样的HA的峰值强度变强,可见Y2O3对Ca10(PO4)6(OH)2的生成有一定的加速作用.Ca元素的扩散系数由4.59×10-11 cm2/s提高为1.145×10-10 cm2/s.     

YBa2Cu3O7—x陶瓷氧扩散动力学

采用动态电导率的测量方法，研究了ＹＢａ２Ｃｕ３Ｏ７－ｘ陶瓷的氧扩散动力学过程，在５００－８５０℃温度范围内，氧分压为９６．８７ｋＰａ下而验证。     

Cu/Zn扩散偶的实验研究

用铆钉法将块体铜和块体锌制成Cu／Zn扩散偶，经真空炉扩散处理后，在扩散偶Cu／Zn界面处形成一个既不同于铜也不同于锌的扩散层。实验表明，除扩散温度和时间对扩散层有影响外，扩散偶的几何尺寸对扩散层的形成也有影响。扩散偶中锌销子的直径越小，形成扩散溶解层的速度越快，扩散厚度越大。     

Al／Cu／Mg扩散偶相界面的扩散机理

采用铆钉法制备了Al／Cu／Mg三元扩散偶,在真空炉进行扩散反应,利用SEM背散射电子像和微区电子探针分析,研究了扩散反应层的特征。在450℃下,Al／Cu／Mg三元扩散偶的三元交界处生成了五个三元化合物：Al6CuMg4,Al7Cu3Mg6,Al2CuMg,Al5Cu6Mg2和Cu5Al3。     

Zn/Fe及Zn/Fe-Mn固态扩散偶中金属间化合物的生长

采用Zn/Fe及Zn/Fe-Mn固固扩散偶方法,研究了锰对金属间化合物生长动力学的影响。对扩散偶在385℃扩散10～300min的研究结果表明,在Zn/Fe扩散偶中,扩散层以δ相为主,ζ相和δ相之间具有平直的界面,随扩散时间的延长,δ相的厚度增加,ζ相逐渐被消耗,厚度比dζ/dδ的值逐渐减小;在Zn/Fe-Mn扩散偶中,扩散层也以δ相为主,ζ相和δ相之间的界面更平直,铁基体中的锰在扩散初期促进δ相的生长,但在扩散后期促进ζ相生长。对Zn/Fe-Mn扩散偶中金属间化合物的生长动力学研究表明,0.4%(质量分数,下同)的锰使扩散层总厚度增加,当锰含量增加到1.2%以上时,扩散层总厚度反而开始下降。Zn/Fe、Zn/Fe-0.4%Mn、Zn/Fe-1.2%Mn及Zn/Fe-2.0%Mn四个扩散偶中总扩散层的生长均由扩散控制。     

Co-Zn扩散偶的界面迁移

采用铆钉法制备了界面为曲面的Co-Zn扩散偶,利用光学显微镜观察了扩散偶界面特征,并测量了扩散层厚度.研究结果表明,经过扩散热处理,Co-Zn扩散偶界面处形成了一个扩散溶解层,该扩散溶解层的厚度随温度的升高和保温时间的延长呈增大趋势.在扩散偶热处理过程中,Co/Zn界面处形成的扩散溶解层向锌侧迁移的速度较大,出现了明显的kirkendall效应.     

稳恒强磁场对Al-Cu扩散偶界面中间相形成和生长的影响

研究了稳恒强磁场作用下Al-Cu扩散偶界面中间相组成和扩散行为.结果表明:强磁场作用下扩散偶中间相厚度显著增加,并且随磁场强度增大,界面中间相组成发生变化.按照抛物线规律计算了强磁场作用下扩散偶中间相的扩散系数,发现在平行和垂直于磁场的两个方向上扩散系数有显著差异,垂直于磁场方向的扩散系数比平行于磁场方向更大.强磁场促进了Al-Cu扩散偶中Al和Cu原子的扩散,加速了界面中间相的形成和生长过程.磁场作用差异导致了扩散的各向异性.利用原子扩散理论初步分析了产生上述现象的原因.     

Au-Ag系统的扩散系数及其扩散激活能的研究

在银基底上蒸镀80nm的金薄膜,然后用不同温度和时间间隔对这些样品进行热处理。再用PHI 550型俄歇电子能谱仪测出上述样品金膜中银的浓度剖面分布。根据银的浓度剖面分布及Hall公式算出Au-Ag系统的互扩散系数。由Leclaire公式计算出该系统的晶界扩散系数。从Arrhenius方程得出互扩散及晶界扩散激活能。并对实验和计算结果进行了讨论。     

TiO2/Fe2O3复合光催化超亲水性薄膜的研究

采用溶胶-凝胶法及浸渍提拉法在普通的载玻片上制得了TiO2/Fe2O3复合薄膜,通过对薄膜及相应干凝胶和粉体的DSC、XRD、UV透射光谱等的测量,分析了Fe2O3的含量对TiO2/Fe2O3复合薄膜的光催化及超亲水性能的影响.结果表明:复合薄膜均优于纯TiO2薄膜的光催化活性,Fe2O3的摩尔含量为0.5%时光催化活性最好;复合薄膜的亲水性能也随Fe2O3含量的不同而不同,Fe2O3的摩尔含量为0.05%～0.1%时得到了接触角为0°的超亲水性复合薄膜.     

镁含量和硅对铁-锌铝镁合金固-液扩散偶中Fe-Al反应层的影响

在热浸镀锌中,铁基表面Fe-Al化合物层的形成会影响镀层的生长和质量。将Fe/(Zn-11%Al-3%Mg)和Fe/(Zn-11%Al-x%Mg-0.2%Si)扩散偶在600℃下进行25min的固-液扩散实验,利用扫描电子显微镜(SEM)和能谱仪(EDS)研究了镁含量和硅对铁-锌铝镁合金固-液界面Fe-Al合金层形成的影响。结果表明,Fe/(Zn-11%Al-3%Mg)固-液扩散偶反应层由FeAl3和Fe2Al5相层组成;随着Mg含量的增加,Fe/(Zn-11%Al-x%Mg-0.2%Si)扩散偶中反应层的厚度呈现先增加后减少再增加的变化趋势,当镁含量为3%时反应层厚度最薄;Fe/(Zn-11%Al-3%Mg)扩散偶中Fe-Al反应层的平均厚度比Fe/(Zn-11%Al-3%Mg-0.2%Si)扩散偶中反应层的厚度大60μm,证明Si元素起到抑制Fe-Al反应层形成的作用。研究结果为解释Super Dyma合金镀层中不形成明显的Fe-Al抑制层提供了实验依据。     

Fe2O3/TiO2和ZnO/TiO2纳米颗粒薄膜的亲水性能和光催化性能的研究

采用溶胶-凝胶法在玻璃上制备了锐钛矿型TiO_2和过渡金属铁、锌离子掺杂的TiO_2薄膜,并通过XRD、XPS、AFM表征了合成的薄膜。结果表明铁和锌离子掺入后,TiO_2薄膜变的更加致密。铁离子和锌离子分别以Fe_2O_3和ZnO的形式存在,在紫外光照射下,TiO_2薄膜表现明显的亲水性,金属离子掺杂的TiO_2薄膜,亲水性能明显增强,铁离子掺入对光催化降解甲基橙有一定的抑制作用;少量的锌离子掺入对光催化降解甲基橙有促进作用,锌离子掺入量增大后,效果并不明显。     

TiO2/Fe2O3核-壳粒子的制备及光学性能

钛酸四丁酯(TBOT)水解产生的TiO2沉积在单分散准球形α-Fe2O3颗粒的表面,形成均匀、连续的核-壳结构.TiO2壳层的厚度约为30 nm.在500℃热处理后,TiO2壳层从非晶态转变为锐钛矿结构.在光激发下,TiO2/Fe2O3核-壳粒子的电子从TiO2价带跃迁到能量较低的α-Fe2O3导带,在可见光区产生新的强吸收峰.光谱计算结果表明TiO2价带与α-Fe2O3导带的能量差为1.6 eV.     

Solid state reactions in the Fe2O3-CaCO3-In2O3 system

The kinetics of solid-state reactions of powdered reactants were investigated by X-ray and by differential thermogravimetry in a magnetic field. Measurements revealed mutual diffusion of the Fe³⁺ and In³⁺ ions in the Fe₂O₃-In₂O₃ system heat treated for 3 h at 700 to 1400° C. Diffusion of indium into the Fe₂O₃ lattice caused a shift of the Curie temperature of the antiferromagnetic iron oxide towards lower temperatures. Only Caln₂O₄ was found between CaCO₃ and In₂O₃ up to 1400° C. Also, in the Fe₂O₃-CaCO₃-In₂O₃in system, the reaction started with the mutual diffusion of iron and indium and the forming of CaFe₂O₄. End-products were the magnetic -Ca₄Fe₁₄O₂₅ and CaFe₄O₇, and the non-magnetic CaFe₅O₇, depending on the In³⁺ concentration. Indium stabilized the magnetic calcium-iron oxide structures, shifting their Curie temperatures towards lower values.     

Surface Self-Transforming FeTi-LDH Overlayer in Fe2O3/Fe2TiO5 Photoanode for Improved Water Oxidation

Integrating hematite nanostructures with efficient layer double hydroxides (LDHs) is highly desirable to improve the photoelectrochemical (PEC) water oxidation performance. Here, an innovative and facile strategy is developed to fabricate the FeTi-LDH overlayer decorated Fe₂O₃/Fe₂TiO₅ photoanode via a surface self-transformation induced by the co-treatment of hydrazine and NaOH at room temperature. Electrochemical measurements find that this favorable structure can not only facilitate the charge transfer/separation at the electrode/electrolyte interface but also accelerate the surface water oxidation kinetics. Consequently, the as-obtained Fe₂O₃/Fe₂TiO₅/LDH photoanode exhibits a remarkably increased photocurrent density of 3.54 mA cm⁻² at 1.23 V versus reversible hydrogen electrode (RHE) accompanied by an obvious cathodic shift (≈140 mV) in the onset potential. This work opens up a new and effective pathway for the design of high-performance hematite photoanodes toward efficient PEC water oxidation.     

Preparation and characterization of novel magnetic ZrO2/TiO2/Fe3O4 solid superacid

Novel magnetic solid superacids were prepared by introducing TiO₂ and magnetic substrates by chemical co-precipitation method. The prepared materials were characterized by means of XRD, FT-IR, DSC and TEM techniques. The results indicated that the introduction of TiO₂ and magnetic substrates markedly hindered the phase transformation from tetragonal phase (t-ZrO₂) to monoclinic phase (m-ZrO₂) even calcined at 1200 °C. Furthermore, the solid superacids doped with magnetic substrates presented the superparamagnetic property. The morphology of the samples showed lamellar crystals with high purity and uniform size distribution, and the (101) lattice plane (d = 0.29 nm) could be clearly seen in the HRTEM image.     

Synthesis of polyaniline-modified Fe3O4/SiO2/TiO2 composite microspheres and their photocatalytic application

Polyaniline-modified Fe₃O₄/SiO₂/TiO₂ composite microspheres have been successfully synthesized by sol–gel reactions on Fe₃O₄ microspheres followed by the chemical oxidative polymerization of aniline. The synthesized multilayer-structured composites were characterized by TEM, XRD, TGA, UV–vis diffuse reflectance spectra and magnetometer. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light. The effect of polyaniline (PANI) amounts on the photocatalytic activity was investigated. The photocatalytic activity results show that the Fe₃O₄/SiO₂/TiO₂ composites with about 2.4 wt.%–4.1 wt.% PANI could show higher photocatalytic efficiency than that of Fe₃O₄/SiO₂/TiO₂. Furthermore, the PANI-Fe₃O₄/SiO₂/TiO₂ photocatalyst could be easily recovered using a magnet.     

原位生长法制备Fe3O4/TiO2纳米磁性复合体及其表征

采用原位生长法,以钛氧有机化合物为前驱物低温液相在磁性Fe3O4的表面直接形成纳米TiO2,制得Fe3O4/TiO2纳米磁性复合体,利用XRD、SEM、DLS、XPS和PPMS(磁性材料综合物性测量系统)对样品的结构和性能进行表征,并讨论Ti-O-Fe键的形成机理。结果表明:Fe3O4表面被锐钛型的TiO2包覆,且包覆效果良好。该磁性复合体颗粒分布均匀,平均粒径为59nm,饱和磁化强度为3.2emu/g,矫顽力为21Oe。