多重射流燃烧反应制备的TiO2/ SiO2纳米复合颗粒的形态和结构

TiO₂-SiO₂ nanocomposite particles were prepared in premixed H₂ / Air flame, and the morphology and structure of these nanocomposites were characterized by FTIR, XRD, TEM and HRTEM. The morphology of SiO₂ / TiO₂ nanocomposites was different from that of pure TiO₂ or SiO₂ nanoparticles, and the chemical bond of Ti-O-Si was found in the nanocomposites indicating that the TiO₂ / SiO₂ nanocomposites were not merely a physical mixture of TiO₂ and SiO₂. TiO₂ nanocrystalline grains with sizes of 1～2 nm were homogeneously dispersed in the amorphous SiO₂ matrix when TiCl₄ and SiCl₄ were mixed at molecular level in the flame. The particle size and rutile content decreased with increasing of SiO₂ molar ratio.     

磷改性β沸石催化剂上催化裂化轻汽油的醚化

在小型固定床反应装置上,考察了负载磷的β沸石催化剂的制备条件对其催化性能的影响以及醚化反应温度、压力、醇烯摩尔比、LHSV对醚化反应的影响。实验结果表明,浸渍磷的质量分数为2%的Hβ催化剂具有较好的醚化活性。在最佳反应条件(温度70 ℃,压力0.8 MPa,LHSV 1.0 h-1,醇烯摩尔比1.0)下,该催化剂的叔碳烯烃的总转化率可达到56.91%。负载磷后的催化剂具有活性好、选择性高、不易失活等优点。反应性能均优于Hβ催化剂。     

Growth,characterization, and Raman spectra of the 1T phases of TiTe2, TiSe2, and TiS2

High-quality large 1$T$ phase of Ti$X_2$ ($X ={\rm Te}$, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural analyses, and their properties are investigated by Raman spectroscopy. Several phonon modes have been observed, including the widely reported $A_{1g}$ and $E_g$ modes, the rarely reported $E_u$ mode ($\sim$183 cm$^{-1}$ for TiTe$_2$, and $\sim$185 cm$^{-1}$ for TiS$_2$), and even the unexpected $K$ mode ($\sim$85 cm$^{-1}$) of TiTe$_2$. Most phonons harden with the decrease of temperature, except that the $K$ mode of TiTe$_2$ and the $E_u$ and "$A_{2u}$/Sh" modes of TiS$_2$ soften with the decrease of temperature. In addition, we also found phonon changes in TiSe$_2$ that may be related to charge density wave phase transition. Our results on Ti$X_2$ phonons will help to understand their charge density wave and superconductivity.     

重费米子化合物 CemMnIn3m+2n(m = 1, 2, 3; n = 0, 1, 2; M = Co,Rh,Ir,Pt 及Pd) 的角分辨光电子能谱研究

重费米子材料以其新奇多变的宏观性质,复杂而难以理解的微观物理过程而受到广泛的关注,长期是凝聚态物理研究的重点。角分辨光电子能谱作为一种能够直接探测材料电子结构的实验手段,随着近年来实验技术的高度发展,能量和动量分辨率得到了极大的提高,能够有力地探测到强关联材料中更加精细的电子结构。使用角分辨光电子能谱探测重费米子材料的电子结构,为理解其各种物理过程提供强有力的实验证据,进而推进重费米子理论的发展。本文回顾 Ce 基重费米子材料 CemMnIn3m+2n (m = 1; 2; 3;n = 0; 1; 2;M =Co, Rh, Ir, Pt, Pd) 系列化合物的角分辨光电子能谱研究,包括电子结构的维度、近藤共振、f 电子与导带电子的杂化和电子结构随温度的变化等。