Na2Cd2I6L2(H2O)6 [L = Urotropine]: An interesting precursor for synthesizing CdO particles

A coordination polymer, Na₂Cd₂I₆L₂(H₂O)₆ [L = Urotropine] has been employed as sole precursor to synthesize CdO particles. Two different preparation methods viz (i) pyrolysis of the title compound at 700 °C for 2 h and (ii) forming cadmium hydroxide from the title compound followed by pyrolysis at 700 °C for 2 h have been used for the synthesis of nano sized CdO-I and CdO-II, respectively. From powder XRD data the lattice parameters (0.4701 and 0.4696 nm respectively for the two samples) and particle size (~ 77 and 30 nm for CdO-I and CdO-II) have been evaluated. Morphology of the two varieties of CdO is widely different as is evident from their SEM images. The estimated values of the band gap of 2.53 eV and 2.59 eV for CdO-I and CdO-II respectively are obtained from the optical spectral analysis.     

以酚醛树脂热解炭包覆天然鳞片石墨的复合材料作为锂离子二次电池负极材料的研究

以酚醛树脂包覆天然鳞片石墨后进行了热处理,将所制备的不同热解炭包覆层厚度和不同最高热处理温度（HTTmax）的复合材料作为锂离子二次电池的负极,以金属锂片作为对电极,在1MLiPF6／EC＋DEC（1：1）电解液中考察了其恒电流充、放电特性和粉末微电极循环伏安特性。     

Interface modification of carbon fibers with TiC/Ti2AlC coating and its effect on the tensile strength

A uniform TiC/Ti₂AlC gradient coating was obtained on carbon fibers via an in-situ reaction in molten salts. The results indicated that in-situ growth of TiC/Ti₂AlC coating caused strong interfacial bonding and surface defects. In this case, evident stress concentration was induced and cracks penetrated the fiber easily during tensile loading. Thus the tensile strength of carbon fibers was dramatically decreased to 78?±?13?MPa. In order to improve the performance of the as-prepared TiC/Ti₂AlC-coated carbon fibers, a pyrolytic carbon layer was pre-fabricated on carbon fibers. By introducing pyrolytic carbon layer, the interfacial bonding strength and surface defects were reduced accordingly. These improvements lead to a decrease of stress concentration and cracks propagation, and facilitate the interfacial debonding during tensile loading. As a result, the tensile strength of the fiber was significantly increased to 550?±?72?MPa. This fact indicates that pre-fabricating a pyrolytic carbon layer on carbon fibers is an effective method to improve the reliability of the TiC/Ti₂AlC-coated carbon fibers. The present work also provides a feasible way to fabricate TiC/Ti₂AlC interphase for high-performance Cf/SiC composites.