To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared...To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared by using a modified coprecipitation method. The phases, microstructures and conductivities of the YSZ, LSO and YSZ-LSO were investigated by X-ray diffraction, electron microscopy and complex impedance, respectively. The results show that the as-calcined powder of YSZ-LSO composite has the grain size less than 10 nm, and the as-sintered composite ceramics are composed of YSZ and LSO phases. The conductivity can be enhanced obviously by composite method. At 700 ℃, the conductivity of the composite ceramic is 0.125 S/cm, which is one order in magnitude higher than that of the YSZ ceramic and two orders in magnitude higher than that of LSO ceramic. By analyzing the impedance spectra and modulus spectra, the interfacial effect on the conductivity improvement was proposed.展开更多
The synthesis of high purity intermetallic FeAI nanoparticles using the flow-levitation （FL） method was reported. Iron and aluminium droplets were levitated stably at about 2 230℃. The morphology, clystal structure...The synthesis of high purity intermetallic FeAI nanoparticles using the flow-levitation （FL） method was reported. Iron and aluminium droplets were levitated stably at about 2 230℃. The morphology, clystal structure and chemical composition of FeAI nanoparticles were investigated by transmission electron microscopy （TEM）, high-resolution TEM, X-ray diffraction and energy dispersive spectrometry. The results show that the average particle size of these nanoparticles is about 34.5 nm. Measurements of the d-spacing from X-ray diffraction and electron diffraction studies confirm that the intermetallic nanoparticles have the same crystal structure （B2） as the bulk FeA1. A thin oxidation coating is formed around the particles when being exposed to air. Based on the XPS measurements, the surface coating of the FeAI nanoparticles is composed of Fe2O3 and FeAl2O4. Besides, hysteresis curve reveals that saturation magnetization （Ms） of FeA1 is 1.66 A/m2, and the coercivity is about 1.214×10^3 A/re.展开更多
The most remarkable effect in spinel ferrites is the strong dependence of properties on the state of structural disorder and,in particular,on the cation distribution.The structural characterization of a Co-Zn ferrite ...The most remarkable effect in spinel ferrites is the strong dependence of properties on the state of structural disorder and,in particular,on the cation distribution.The structural characterization of a Co-Zn ferrite nanoparticle sample was reported which prepared by wet chemical co-precipitation method.The samples were sintered at three different temperatures viz.650℃,850℃ and 1050℃ for 12 h.The structural details like:lattice constant and distribution of cations in the tetrahedral and octahedral interstitial voids have been deduced through X-ray diffraction (XRD) data analysis.Lattice constant was found to increase with the increase in Zn2+ ions and sintering temperature.Theoretical intensity ratios of (220),(400),(440) planes were considered,as these reflections are sensitive to cations on the A and B sites.Close agreement of the theoretical intensity ratio with the intensity ratio observed from XRD pattern supports the occupancy of Zn2+ ions and Co2+ ions on the octahedral and tetrahedral sites,respectively.展开更多
基金Project(50872155) supported by the National Natural Science Foundation of China
文摘To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared by using a modified coprecipitation method. The phases, microstructures and conductivities of the YSZ, LSO and YSZ-LSO were investigated by X-ray diffraction, electron microscopy and complex impedance, respectively. The results show that the as-calcined powder of YSZ-LSO composite has the grain size less than 10 nm, and the as-sintered composite ceramics are composed of YSZ and LSO phases. The conductivity can be enhanced obviously by composite method. At 700 ℃, the conductivity of the composite ceramic is 0.125 S/cm, which is one order in magnitude higher than that of the YSZ ceramic and two orders in magnitude higher than that of LSO ceramic. By analyzing the impedance spectra and modulus spectra, the interfacial effect on the conductivity improvement was proposed.
基金Project(10804101) supported by the National Natural Science Foundation of China
文摘The synthesis of high purity intermetallic FeAI nanoparticles using the flow-levitation （FL） method was reported. Iron and aluminium droplets were levitated stably at about 2 230℃. The morphology, clystal structure and chemical composition of FeAI nanoparticles were investigated by transmission electron microscopy （TEM）, high-resolution TEM, X-ray diffraction and energy dispersive spectrometry. The results show that the average particle size of these nanoparticles is about 34.5 nm. Measurements of the d-spacing from X-ray diffraction and electron diffraction studies confirm that the intermetallic nanoparticles have the same crystal structure （B2） as the bulk FeA1. A thin oxidation coating is formed around the particles when being exposed to air. Based on the XPS measurements, the surface coating of the FeAI nanoparticles is composed of Fe2O3 and FeAl2O4. Besides, hysteresis curve reveals that saturation magnetization （Ms） of FeA1 is 1.66 A/m2, and the coercivity is about 1.214×10^3 A/re.
文摘The most remarkable effect in spinel ferrites is the strong dependence of properties on the state of structural disorder and,in particular,on the cation distribution.The structural characterization of a Co-Zn ferrite nanoparticle sample was reported which prepared by wet chemical co-precipitation method.The samples were sintered at three different temperatures viz.650℃,850℃ and 1050℃ for 12 h.The structural details like:lattice constant and distribution of cations in the tetrahedral and octahedral interstitial voids have been deduced through X-ray diffraction (XRD) data analysis.Lattice constant was found to increase with the increase in Zn2+ ions and sintering temperature.Theoretical intensity ratios of (220),(400),(440) planes were considered,as these reflections are sensitive to cations on the A and B sites.Close agreement of the theoretical intensity ratio with the intensity ratio observed from XRD pattern supports the occupancy of Zn2+ ions and Co2+ ions on the octahedral and tetrahedral sites,respectively.
