Hydrothermal synthesis and Magnetocaloric effect of La0.5Ca0.3Sr0.2MnO3

The hydrothermal synthesis and magnetic entropy change for the perovskite manganite La_0.5Ca_0.3Sr_0.2MnO₃ have been studied. The La_0.5Ca_0.3Sr_0.2MnO₃ can be produced as phase-pure, crystalline powders in one step from solutions of metal salts in aqueous potassium hydroxide solution at a temperature of 513 K in 72 h. Scanning electron microscopy shows that the materials are made up of cuboid-shaped particles in typical dimension of 4.0×2.5×1.6 μm. Heat treatment can improve the magnetocaloric effect for the hydrothermal sample. The maximum magnetic entropy change ΔS_M for the as-prepared sample is 0.88 J kg⁻¹ K⁻¹ at 315 K for a magnetic field change of 2.0 T. It increases to 1.52 J kg⁻¹ K⁻¹, near its Curie temperature (317 K) by annealing the sample at 1473 K for 6 h. The hydrothermal synthesis method is a feasible route to prepare high-quality perovskite material for magnetic refrigeration application.     

Novel photoswitching dithienylethenes with ferrocene units

Two novel dithienylethenes with ferrocene units were synthesized by Wittig reaction. The structure of 2a has been established by X‐ray diffraction studies. They could reversibly interconvert between two thermally stable forms, an open and a closed one, using light of different wavelengths as triggers. Copyright © 2006 John Wiley & Sons, Ltd.     

粘土粒径及形态结构对粘土胶性能的影响

用超声波和离心方法将３种来源不同的粘土样品按粒分径分级，测定各级分粒径比表面积和结构，并制备相应级分的粘土胶进行物理力学性能测试，结果表明，在一定范围内，粘土粒径的变化仅对粘土胶的某些力学性能产生物明显的影响，而粘土粒子以其独特的形态结构对粘土胶产生显著的补强作用。     

Multiphonon vibrational relaxation in liquids: should it lead to an exponential-gap law?

The profound differences between solids and liquids notwithstanding, high-frequency vibrational energy relaxation in liquids seems to be well described by assuming that the excess energy is being transferred into discrete overtones of some fundamental intermolecular vibrations-precisely the way it is in crystalline solids. In a solid-state context, this kind of analysis can be used to justify the observation that relaxation rates fall off exponentially with the energy being transferred. Liquids, however, have a substantial degree of disorder, causing their relevant intermolecular spectra to have correspondingly diffuse band edges and large bandwidths. It is therefore not at all obvious what should become of this exponential-gap-law phenomenology. We show in this paper how near exponential-gap-law behavior can still be derived for vibrational energy relaxation in liquids. To do so, we take advantage of the simple dynamics that the high-frequency relaxation has when it is launched from an individual instantaneous configuration. Interestingly, the physically relevant region turns out not to be true asymptotic limit of our formalism, but for realistic liquid parameters the behavior in the physical regime differs only slightly from an exact exponential-gap law and is strikingly independent of the details of the intermolecular spectra.     

PPC/SBR并用弹性体的配方选择

利用正交法对丁苯橡胶（SBR）／聚丙撑碳酸酯（PPC）共混弹性体进行配方设计，得到了一个具有良好综合性能的配方。并通过方差分析得出PPC含量和马来酸酐（MA）用量是影响弹性体拉伸性能的最显著因素。     

四核钼簇合物的配体取代反应及产物Mo4S4(μ-OAc)2(dtp)4的晶体结构

标题化合物(Ⅰ)经由Mo₄S₄(μ-dtp)₄(Ⅱ)[dtp=S₂P(OEt)₂]和Ni(OAc)₂反应而得。(Ⅰ)晶体属单斜晶系,空间群P2/c,a=13.176(4),b=11.699(3),c=18.526(4)Å,β=116.11(3)°,V=2564(3)ų,Z