AlN／蓝宝石模板上生长的 Al 0．6Ga0．4N薄膜结构与光学性能研究

采用MOCVD方法在 AlN/蓝宝石模板上生长高铝组分 Al0．6 Ga0．4 N 薄膜,并采用高分辨率XRD（HRXRD）及阴极荧光（CL）方法对其进行了表征．结果表明,AlGaN薄膜产生了相分离,其原因为厚膜中的应力弛豫及Al原子低的表面迁移率．     

Effects of surfactant addition to polyethylene oxide polymer electrolytes in low and high concentrations

The effect of surfactant addition to polyethylene oxide (PEO) polymer electrolytes is studied. The initial goal of the research was to determine if a self-assembled monolayer (SAM) of surfactant molecules could be formed at the polymer interfaces through what we describe as the “blooming” method. In this method, the surfactant is added to the polymer solution before casting and the surfactant migrates to the surface, due to differences between bulk and surface free energies, during removal of the solvent as the film is formed. The surfactant used had the chemical formula of H–(–CH₂–)₃₂–(–CH₂–CH₂–O–)₁₀–H where the hydrocarbon part of the molecule has the ability to self-assemble once they reach the surface of a PEO polymer electrolyte. These molecular surface layers stabilized the SEI layer formed between lithium metal and the polymer electrolyte. At a level of 8% by mass and above, there was significant interfacial stabilization. In addition to interface stabilization, it was found that the addition of the surfactant caused significant changes to the bulk of the polymer, yielding an order of magnitude higher conductivity in the bulk phase. The structure of the protective film at the surface was investigated by ATR-FTIR spectroscopy and AFM phase imaging.     

Valorization of fatty acid waste for bioplastics production using Bacillus tequilensis: Integration with dark-fermentative hydrogen production process

Synthesis of bioplastics (polyhydroxyalkanoates (PHA)) using Bacillus tequilensis, a newly isolated strain was investigated under aerobic condition using designed wastewater with synthetic acids (SA) and acidogenic fermented food waste (AFW) collected from biohydrogen (H₂) producing anaerobic bioreactors as substrates. The isolate showed the ability to grow and accumulate PHA in both the substrates, with simultaneous waste remediation. Higher PHA synthesis was observed with SA (59% dry cell weight) compared to AFW (36% dry cell weight) with good substrate removal (SA, 87%; AFW, 59%). The PHA composition showed presence of co-polymer [P(3HB-co-3HV)] with varying contents of hydroxy butyrate (HB, 80–90%) and hydroxy valerate (HV, 10–15%) in both the substrates. High dehydrogenase activity was observed which leads to the formation of considerable quantity of PHA. AFW from H₂ producing reactor as substrate contributes in reducing the production cost of both H₂ as well as PHA embedded with waste valorization.     

用移相比相法动态测量莫尔条纹细分误差

采用移相比相法测量高精度测角仪的莫尔条纹细分器的细分误差获得很好效果,文中叙述了测量原理、测量精度和实测比对结果。     

Synthesis of novel rare earth—Iron oxide chalcogenides with the La2Fe2O3Se2 structure

Our searches for new oxide chalcogenides of rare earths and Fe, Co, Ni, and Zn resulted in preparation of two new compounds Ce₂Fe₂O₃S₂ and Pr₂Fe₂O₃S₂ which are isostructural to La₂Fe₂O₃Se₂ and Sm₂Ti₂O₃Sb₂. Crystal structures of the new compounds Ce₂Fe₂O₃S₂ and Pr₂Fe₂O₃S₂ were determined from powder X-ray diffraction data. Magnetic measurements were performed for Ce₂Fe₂O₃S₂ and revealed behavior very similar to that of isostructural oxide chalcogenides of iron and pnictides of titanium. In particular, no superconductivity was observed down to 4 K. Crystal chemical factors determining the stability of the La₂Fe₂O₃Se₂ structure type are discussed.     

Optimization of the resonant frequency servo loop technique in the resonator micro optic gyro

Proportional integrator (PI) is always adopted in the resonant frequency servo loop in a resonator micro optic gyro (RMOG).The oscillation phenomenon is observed when adjusting the loop gain surpassing...     

Phase transition characteristics and dielectric properties of rare-earth (La,Pr, Nd,Gd) doped Ba(Zr0.09Ti0.91)O3 ceramics

A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba_1−yLn_2y/3)Zr_0.09Ti_0.91O₃ (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and dielectric properties is analyzed. A dramatic fall in the transition temperature occurs when BZT ceramic is doped with rare-earths. Moreover, diffusivity degree of the phase transition increases and a relaxor-type behaviour is induced due to both the increment of the lanthanide content and the increase of the ionic radius of the dopant element. High values of dielectric tunability are obtained for lanthanum doped BZT. A direct relation between transition temperature and tunability is discussed. Conclusively, low permittivity and high tunability materials can be obtained by the adequate substitution of rare-earths into BZT ceramics.     

硝酮类化合物环加成反应研究进展

硝酮类化合物是一类非常重要的有机合成中间体,它能够发生很多化学反应,其中最为重要的是加成反应,本文就硝酮类化合物其环加成反应做一简要评价。     

Preparation and properties of UV-cured acrylated silane intercalated polymer/LDH nanocomposite

A novel UV-cured polymer/layered double hydroxide (LDH) nanocomposite was prepared by modifying the LDH with sodium dodecyl sulfate (SDS) and [3-(methyl-acroloxy)propyl]trimethoxysilane (KH570) followed by UV irradiation after blended into a acrylate system. From the XRD analyses, the SDS-modified LDH-DS presented the basal spacing of 2.67 nm, whereas the further KH570-intercalated LDH-KH showed a slight decrease to 2.41 nm. After UV irradiated the exfoliated microstructure was formed, and observed by TEM and HR-TEM, showing the fine dispersion and random orientation of LDH in the polymer matrix. The storage modulus and glass transition temperature of the nanocomposite containing 5% LDH-KH increased to 47.5 MPa and 67.8 °C, respectively, from 39.7 MPa and 66 °C of the pure polymer from DMTA measurements. The tensile strength and Persoz hardness were enhanced to 10.6 MPa and 111 s, respectively, from 7.7 MPa and 85 s of the pure polymer.     

Phase diagrams of the systems Al2O3-ZrO2-Ln(Y)2O3 as a source of multiphase eutectics for creating composite structural and functional materials

Phase equilibria in the ternary systems Al₂O₃-ZrO₂-Ln₂O₃ (Ln = La, Nd, Sm, Gd, Er, Yb and Y) were investigated by identical methods in all range of concentrations and 1250-2700 °C temperature range using differential and derivative in solar furnace thermal analysis in controlled medias, X-ray diffraction phase analysis, local X-ray spectral analysis, chemical analysis, electron and optical microscopy, petrography. The phase diagrams of the systems studied are presented as isothermal at 1650 °C sections and melting diagrams. The interaction in the systems is characterized by the absence of ternary compounds and regions of appreciable solid solutions based on the binary compounds and components. Only narrow regions of ternary solid solutions were discovered at high temperatures by CALPHAD method and because of existing small solubility on the base of ZrO₂ in the binary bounding system Al₂O₃-ZrO₂. The phase equilibria in the systems are determined by zirconia as the most stable compound. Solidification in the systems is completed in eutectic reactions. The established interaction regularities allowed to forecast interaction and phase diagrams construction in systems with other lanthanides (Ce, Pr, Pm, Eu, Tb, Dy, Ho, Tm, Lu). New 13 quasibinary and 26 ternary eutectics were found for the first time. Their temperatures rise from 1660 °C for the La₂O₃ system to 1840 °C for the Lu₂O₃ system. Fluorite-type phases equilibrate with garnet-type phases for the systems from Tb₂O₃ to Lu₂O₃. In the systems from Pr₂O₃ to Gd₂O₃ they equilibrate with perovskite-type phases and β-Al₂O₃. On the base of microstructure investigations it was established that three-phase alumina-rich eutectics crystallizes according to the mechanism of cooperative growth. It opens up possibilities to obtain composite materials using directional solidification method.