摘要 LaMn 1 – x Fe x O 3(х = 0–1)钙钛矿是通过Pechini路线制备的,并通过X射线衍射分析,HR TEM,XPS和BET进行了表征。在甲烷和一氧化碳氧化反应中研究了它们的催化活性。根据X射线分析数据,х <0.4的样品为正交晶,而х > 0.4的样品为菱面体。在х = 0.4的样品中,由于在х处发生了同相相变,因此存在两种修饰≈0.4。与未取代的钙钛矿相比,由于具有La化合物的表面富集,与未取代的钙钛矿相比,在甲烷和CO氧化中具有更高的比表面积和更低的归一化催化活性。х = 0.6和0.8的样品在甲烷的催化氧化中表现出最低的活性和稳定性,这可能是由于甲烷氧化过程中碳酸盐和碳在表面的积累以及局部有序结构区域的额外形成所致。在表面上。
ferrite was attempted by doping individual alkalineearth elements (Ba, Ca and Sr) in its La site and Mg in Fe site to get the desired energy band characteristics. All doped compositions of LaFeO3 were synthesised by sol-gel method. Structural studies show the formation of secondary oxide phases when calcined at 800 °C and phase pure compounds when calcined at 1100 °C. Optical studies reveal the capability
摘要 通过在 La 位点掺杂各种碱土元素(Ba、Ca 和 Sr),在 Fe 位点掺杂 Mg,尝试提高镧铁氧体的光催化活性,以获得所需的能带特性。LaFeO3 的所有掺杂成分均通过溶胶-凝胶法合成。结构研究表明,在 800 °C 下煅烧时会形成二次氧化物相,在 1100 °C 下煅烧时会形成相纯化合物。光学研究揭示了这些钙钛矿具有可见光活性的能力,并表明在掺杂碱土元素后带隙变窄。通过刚果红 (CR) 染料降解研究和通过水分解析氢来测试光催化活性。结果表明,在自然氙灯照射下,在所有未掺杂和掺杂的 LaFeO3 合成组合物中,在 800°C 下煅烧后获得的掺杂 Mg 的 LaFeO3 复合材料具有更高的析氢速率和最高的刚果红(CR)染料降解率。本研究还提出了光催化活性的可能机制。
The intrinsic exchange bias effect in the LaMnO3 and LaFeO3 compounds
作者:Abd El-Moez A. Mohamed、Pablo Álvarez-Alonso、B. Hernando
DOI:10.1016/j.jallcom.2020.156713
日期:2021.1
antiferromagnetic (AFM) nature of these compounds. Nevertheless, an anomalous ferromagnetic (FM) behaviour is observed, which is more likely, arises from the spin canting effect in the Mn3+ and Fe3+ ions. The thermal variation of the magnetisation reciprocal (M−1) has confirmed the presence of this FM component below 110K in LaMnO3 and the Curie-Weiss behaviour above 160K. Also, the magnetic hysteresis loops below
Preparation of Nanosized Perovskite-type Oxides via Polyol Method
作者:M. Siemons、Th. Weirich、J. Mayer、Ulrich Simon
DOI:10.1002/zaac.200400300
日期:2004.10
Several perovskite-typenanosizedoxides were prepared via polyol-mediated synthesis. The crystallinity of the materials was analysed by X-ray diffraction (XRD). While the “as synthesized” materials are amorphous or show very poor crystallinity, highly ordered materials could be obtained by annealing at 700 °C. Morphology of the materials was analysed by scanning electron microscopy (SEM) and transmission
通过多元醇介导的合成制备了几种钙钛矿型纳米氧化物。通过X射线衍射(XRD)分析材料的结晶度。虽然“合成”材料是无定形的或显示出非常差的结晶度,但通过在 700 °C 下退火可以获得高度有序的材料。通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析材料的形态。材料的粒径介于 20 和 200 nm 之间。Darstellung nanopartikularer Oxide des Perowskittyps uber die Polyol-Methode Uber eine Polyol-vermittelte Synthese wurden mehrere nanoskalige Oxide mit Perowskitstruktur hergestellt。Die Kristallstruktur der Materialien wurden mittels Rontgendiffraktometrie
Catalytic Properties of Perovskite-Type Mixed Oxides (ABO<sub>3</sub>) Consisting of Rare Earth and 3d Transition Metals. The Roles of the A- and B-Site Ions
作者:Taihei Nitadori、Tatsumi Ichiki、Makoto Misono
DOI:10.1246/bcsj.61.621
日期:1988.3
(lanthanoid) elements, B=3d transition metals) for the oxidation of propane and methanol have been studied comparatively. It has been found that the catalytic activities of LnBO3 were principally determined by the B-site elements and were similar to those of the corresponding oxides of the B-site elements. The roles of the rare-earth ions of the A-site were secondary as long as they were trivalent. Upon the
比较研究了钙钛矿型混合氧化物(LnBO3 和 Ln0.8Sr0.2CoO3,Ln=稀土(镧系)元素,B=3d 过渡金属)对丙烷和甲醇氧化的催化活性。已经发现,LnBO3 的催化活性主要由 B 位元素决定,并且与 B 位元素的相应氧化物的催化活性相似。A 位的稀土离子的作用是次要的,只要它们是三价的。在用 Sr2+ 部分取代 Ln3+ 后,LnCoO3 的催化活性增加了数倍,所有稀土离子的增加幅度相似。这些结果表明,B 位金属的种类和价态对于控制氧化催化活性至关重要,
Catalytic combustion of soot over Ce and Co substituted three-dimensionally ordered macroporous La<sub>1−x</sub>Ce<sub>x</sub>Fe<sub>1−y</sub>Co<sub>y</sub>O<sub>3</sub> perovskite catalysts