柠檬酸盐法合成钙钛矿型复合氧化物纳米固体材料LaFeO_3

纳米固体材料(或称毫微晶材料)是近几年发展起来的新兴材料,这是由尺寸为纳米数量级(通常粒径<10～15 nm)的微晶颗粒聚集而成的块状或者薄膜人工固体,其原子排列状态既不同于传统的晶态、非晶态,又不同于尺寸为纳米数量级的超微粒,其结构特点使该材料具有与传统材料极不相同的特殊性能,已引起世界各国科学家的高度重视,但是由于     

制备高比表面多孔Ti-Si复合氧化物材料的新方法

Ti- Si复合氧化物多孔材料在异相催化、催化剂载体等方面引起了人们的普遍关注 .将具有痕量Ti的 Si O2 玻璃用于纤维、膜及光学玻璃的制造中 ,在较宽的温度范围内显现出较低的热膨胀系数 [1] .特定组成的 Ti- Si复合氧化物在一些酸催化反应中具有相当的活性 [2～ 6 ] ,如苯酚胺化、乙烯水合、丁烯异构化、 2 -异丙醇脱水、 1 ,2 -二氯乙烷分解等反应 .另一些组成的 Ti- Si复合氧化物多孔材料已被用于选择性氧化反应中 [7] .Ti- Si复合氧化物的物理化学性能与材料自身的组成及均匀性有关 ,常规的制备方法有共沉淀法 [2 ,3,5] 和溶胶 -凝…     

锂铁氧体纳米晶磁性的研究

研究了颗粒平均直径由9.1—860nm范围的锂铁氧体纳米晶的磁性.它们的比饱和磁化强度σ_s随其颗粒尺寸减小而线性减小.测量了样品A(颗粒直径为D=860nm),样品B(D=11.8nm)和样品C(D=9.1nm)的比饱和磁化强度随温度的变化曲线σ(T)和穆斯堡尔谱.发现样品B和C的居里温度比样品A的低50℃.从样品C的σ(T)曲线看,样品C好像由二种磁相所构成.利用超顺磁和表面磁性讨论了样品C的特异磁性. 关键词：     

THEOREM OF CORRESPONDING RELATION AND ITS APPLICATION TO ISOBARIC PHASE DIAGRAMS

The theorem of corresponding relation between the total number, Φ, of different phases inneighboring phase regions (abbreviated to NPRs) and the dimension, R_1, of their phase bound-ary and the corollaries of this theorem are derived from phase rule. Applying this theorem andits corollaries, both the boundary rule and Palatnik-Landau's contact rule of phase regionsmay be deduced. The ten empirical rules for constructing complicated ternary phase diagramsfrom phase diagram units may be explained theoretically. The relation between NPRs and theirboundaries in unary, binary, ternary and quaternary isobaric phase diagrams of different typesmay be explained without any supplementary concept.     

THE RELATION BETWEEN THE DIMENSIONS OF BOUNDARY AND PHASE BOUNDARY IN ISOBARIC PHASE DIAGRAMS

The relation between the dimensions of boundary and phase boundary in isobaric phase diagrams has been proved theoretically in this paper.