Magnetic properties of quasi-two-dimensional La2NiO4

Magnetic susceptibility studies on single crystals of nearly stoichiometric La₂NiO₄ with the applied field both parallel and perpendicular to the c axis show a transition at 204 K below which two-dimensional canted antiferromagnetic order seems to exist. This oxide also undergoes a transition from isotropic to anisotropic susceptibility near 100 and 250 K.     

Improved catalytic properties of Co3O4-impregnated La2O3/MgO over Co3O4/MgO catalyst in the oxidative dehydrogenation of ethylbenzene

Research on Chemical Intermediates - A series of lanthanum oxide (La2O3—2–14 wt%)-encapsulated Co3O4/MgO catalysts and bare Co/MgO solid oxides were prepared by wetness...     

粉末固相反应合成LaCoO3-δ动力学的等温热重实验研究

用等温热重分析方法在830℃、860℃和890℃研究了La2O3和Co3o4粉末反应合成LaCoO3-δ的动力学.用常见的固相反应动力学模型对实验所得的反应分数和反应时间关系进行拟合分析的基础上,综合考虑粉末固相反应的特征得出反应前期、中期和后期可能分别为随机形核一快速生长、界面化学反应及固态离子三维扩散控速.三个阶段的表观活化能分别为133.4±3.4、183.5±21.5和135.1±303kJ/mol.     

La对选择性加氢催化剂Co/γ-Al2O3的改性研究

应用XPS、DTG、DTA和XRD技术，分析了La提高催化剂Co-La／γ-Al2O3活性的原因．加入La后，XPS分析得出，Co2p在催化剂表层含量是未加前的1．65倍；DTG和DTA表征显示，La对催化剂的热效应影响很小；XRD分析表明，La的加入提高了Co3O4的分散度．     

Thermochemische Untersuchungen zum System Bi/Se/O. I. Das Phasendreieck Bi2Se3/Bi2O2Se/Se

Thermochemical Investigation on the System Bi/Se/O. I The Phase Triangle Bi₂Se₃/Bi₂O₂Se/Se By total pressure measurements of compositions in the subsystem Bi₂Se₃/Bi₂O₂Se/Se was shown, that in thermodynamic equilibrium the three phases Bi₂Se₃/Bi₂O₂Se/Se coexist. The barogram of the triangle reduces to the barogram of the line Bi₂Se₃? Se, the compound Bi₂O₂Se is not from influence of the total pressure in the investigated temperature range.     

The crystal structures of Co3Se4 and Co7Se8

The crystal structures of Co₃Se₄ and Co_6.8Se₈ have been refined from twinned single crystal and powder X-ray diffraction data. The refined structures are isostructural to the Cr_3±xSe₄ and Cr₇Se₈ types, respectively. The structures are described as superstructures of the Cd(OH)₂-type structure, where the empty layers of unoccupied octahedra are replaced with alternating Co filled and empty [100] rods and Co filled Kagomè nets for Co₃Se₄ and Co_6.8Se₈, respectively. The structure of Co₃Se₄ is not a substructure of Co₇Se₈ and the path from Co₇Se₈ to Co₃Se₄ by removing 1/4 of the Co atoms in the Kagomè nets involves both gain and loss of symmetry. Yet the refinements of Co_6.8Se₈ suggest an extended homogeneity field.     

Zur Kenntnis von Ba6La2Co4O15

About Ba₆La₂Co₄O₁₅ Ba₆La₂Co₄O₁₅ were prepared and investigated by X-ray single crystal work. It crystallizes with hexagonal symmetry, space group C–P6₃mc; a = 11.8082; c = 7.0019 Å; Z = 2. Ba²⁺ show face connected BaO₆-octahedra and larger polyhedra of C.N. = 10 and 12. Co³⁺ is surrounded by four and six (tetrahedra, octahedra) oxygen. The Ba²⁺ and La³⁺ ions occupy one point position statistically.     

Disordered La3Cu4.88Se7

The crystal structure of copper(I) lanthanum selenide, La₃Cu_4.88Se₇, obtained from the La₂Se₃–Cu₂Se quasi‐binary system, has been investigated using X‐ray single‐crystal diffraction. The positions of the La and Se atoms are ordered and lie on mirror planes, whereas all positions for the Cu atoms are partially occupied. The crystal is built from edge‐sharing [LaSe₆] and [LaSe₇] polyhedra. The five positions for the Cu atoms determine an ionic diffusion pathway in the structure.     

Characterization and structural approach to crystalline La2O3-MgO-B2O3

In this paper, a vitreous domain of the ternary system: xLa2O3-yMgO-zB2O3 characterised by X-ray diffraction is shown. Structural approach using vibrational spectroscopy and optical probe is realized for some of these glasses and compared to crystalline LaMgB5O10.     

负载型La0.8Sr0.2CoO3燃烧催化剂中Co(Ⅱ)与载体γ-Al2O3的相互作用

一般认为稀土钙钛矿型La0.8Sr0.2CoO3是CO氧化、碳氢(HC)化合物完全氧化和NOx还原的良好氧化物催化剂.用复合硝酸盐溶液浸渍γ-Al2O3制取负载型催化剂La0.8Sr0.2CoO3/γ-Al2O3(LSC/γ-Al2O3),负载量15%(质量分数).采用XRD, TPR, BET和二甲苯完全氧化催化剂活性测试等手段,研究了CoAl2O4的形成过程,催化剂经750 ℃焙烧, Co(Ⅱ)已进入γ-Al2O3体相,并有大量的CoAl2O4尖晶石形成. 若在γ-Al2O3表面涂敷一层以MgAl2O4为主相的覆盖层,在一定程度上能够阻挡Co2+离子进入γ-Al2O3的晶格,并有效地生成出LSC活性相,提高了其完全氧化的催化活性.     

Phase equilibria in the system La2O3-Na2O-P2O5: Binary phase diagram La(PO3)3-NaPO3

In the ternary system La₂O₃-Na₂O-P₂O₅, the binary system La(PO₃)₃-NaPO₃ was examined by means of thermal (heating and cooling), dilatometric, X-ray powder diffraction and microscopic analyses. The occurrence of the phosphate NaLaP₄O₁₂ was confirmed and its temperature of congruent melting was determined to be 1174 C. The powder data indicate a monoclinic system with the lattice constantsa=12.36(6);b=13.45(0);c=6.57(4) å; =109.48;V=1030.97 å³. The investigations were carried out on monocrystals.

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Zusammenfassung Das binäre Teilsystem La(PO₃)₃-NaPO₃ des ternären Systemes La₂O₃-Na₂O-P₂O₅ wurde mittels thermischer, dilatometrischer, Röntgendiffraktions- und mikroskopischen Methoden untersucht. Es wurde die Existenz des Phosphates NaLaP₄O₁₂ und dessen kongruenter Schmelzpunkt von 1174 C festgestellt. Die Röntgendiffraktionsaufnahmen lassen auf ein monoklines System mit den Gitterkonstantena=12,36(6),b=13,45(0),c=6,57(4) å,=109,48 undV=1030,87 å³ schliessen. Die Untersuchungen wurden an Einkristallen durchgeführt.

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( ), , La(PO₃)₃-NaPO₃, La₂O₃-Na₂O-P₂O₅. NaLaP₄O₁₂, 1174. -, - - , , 350, 750 840. NaLaP₄O₁₂ a=12,36 å,b=13,45 å,=6,57 å,=109,48 V=1030,97 å³. 500 820. La(PO₃)₃ 1050, 820 — -, - . 2–2,5 % .

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The author thank Dr. T. Znamierowska and Dr. J. Matuszewski for helpful discussions and G. Orczykowska for translation of the text. This work was supported by grant CPBP-01.18.     

Phase equilibria in the system La2O3-Na2O-P2O5

In the ternary system La₂O₃-P₂O₅-Na₂O the partial system La₂O₃-Na₄La₂P₄O₁₅-LaPO₄ has been examined by the thermal, dilatometric X-ray and microscopic analyses and its phase diagram provided. The lanthanum oxyphosphate La₃PO₇ melts incongruently at the 1590°C temperature and crystallizes in a monoclinic systema=11.20 Å,b=11.94 Å,c=7.01 Å,=93.79 andV=936.97 ų.

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Zusammenfassung Mittels Thermo- und dilatometrischer Analyse, Röntgendiffraktionsuntersuchungen und Mikroskopie wurde das Teilsystem La₂O₃ - Na₄La₂P₄O₁₅ - LaPO₄ des ternären Systemes La₂O₃ - P₂O₅ - Na₂O untersucht und ein Phasendiagramm entwickelt. Lanthanoxyphosphat La₃O₇ schmilzt inkongruent bei 1590°C und kristalliert in einem monoklinen System mita=11.20 Ä,b=11.94 Ä,c=7.01 Å,=93.79 undV=936.97 ų.

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The author thanks Mrs. B. Lagódka for the technical assistance (thermogravimetric analyses). The thermal study was supported by grant CPBP.     

Pressure-induced buckling of spin ladder in SrCu2O3

Pressure-induced structural phase transition of spin ladder compound SrCu2O3 was investigated by synchrotron X-ray powder diffraction with a diamond anvil cell (DAC). The change was characterized by a buckling of the Cu2O3 plane in the rung direction of the ladder. The structure of the high-pressure phase was found to be essentially the same as that of CaCu2O3. Application of an external pressure of 3.4 GPa therefore affected the structure in the same manner that the chemical (internal) pressure does.     

Synthesis of La3+/Co3O4 Nanoflowers for Sensitive Detection of Chlorpromazine

Russian Journal of Electrochemistry - In this study, a sensitive electrochemical sensor for chlorpromazine was established based on La3+/Co3O4 nanoflower. The La3+/Co3O4 nanoflower exhibited...     

Y2O3, La2O3, Sm2O3对氧化铝瓷烧结及力学性能的影响

研究了3种稀土氧化物对氧化铝陶瓷烧结性能和力学性能的影响.结果表明 含Y2O3,La2O3,Sm2O3的添加剂促进了氧化铝瓷的烧结,提高了氧化铝瓷的力学性能.Y2O3和Sm2O3掺量为0.50%,La2O3掺量为0.75%时氧化铝瓷在1600或1620 ℃保温2 h烧结,相对密度达98.9%以上,强度超过439 MPa,断裂韧性达5.15 MPa·m1/2以上.微观结构分析表明,Y2O3,La2O3,Sm2O3抑止氧化铝晶粒生长,细化晶粒,使晶粒尺寸较均匀形成致密化结构.     

微波场中Co／La2O3催化甲烷部分氧化制合成气

近年来，对甲烷部分氧化制合成气（ＰＯＭ）的研究，一直十分活跃［１～８］．该反应常用的催化剂是负载型贵金属（Ｒｈ）和过渡金属（Ｎｉ和Ｃｏ）．由于贵金属的价格昂贵，因而Ｎｉ和Ｃｏ受到人们的极大重视，但Ｎｉ和Ｃｏ在反应温度较高时，易发生催化剂的挥发流失和烧...