A process of preparing ZnO voltage sensitive ceramics doped with some oxides by coprecipitation was described in the paper. The thermal properties of ZnO nanometer powders and the current voltage characteristics of ...A process of preparing ZnO voltage sensitive ceramics doped with some oxides by coprecipitation was described in the paper. The thermal properties of ZnO nanometer powders and the current voltage characteristics of the ceramics have been investigated. The results showed that the six additive ZnO powders with hexagonal system were homogeneous grain size distribution in microstructure, the optimal reaction pH is 6.90±0.05, the temperature for calcining and sintering was at about 500 ℃ and 1100 ℃, respectively. The powders were also examined by SEM, IR and XRD etc, and the effect of doping La 2O 3 on the electrical properties of ZnO varistor was investigated too.展开更多
Silver-tin oxide powders were synthesized by the hydrothermal method with Ag(NH_3)_2^+ solution and Na_2SnO_3 solution as raw materials and Na_2SO_3 as reductant. The precipitation conditions of Na2SnO3 solution and t...Silver-tin oxide powders were synthesized by the hydrothermal method with Ag(NH_3)_2^+ solution and Na_2SnO_3 solution as raw materials and Na_2SO_3 as reductant. The precipitation conditions of Na2SnO3 solution and the reduction conditions of Ag(NH_3)_2^+ were also investigated. The powders prepared were characterized by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and energy spectrum analysis. The results show that pH value of the solution is a key parameter in the formation of Sn(OH)_4 precipitate and the reduction reaction of Ag(NH_3)_2^+ can release H+ ions, which results in synchronous precipitation of Sn(OH)_6~2- as Sn(OH)_4. The reduction of Ag(NH_3)_2^+ and precipitation of Na_2SnO_3 occur simultaneously and the coprecipitation of silver and tin oxide is reached by the hydrothermal method. The silver-tin oxide composite powders have mainly flake shape of about 0.3 μm in thickness and there exists homogeneous distribution of tin oxide and silver in the powder synthesized.展开更多
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
文摘A process of preparing ZnO voltage sensitive ceramics doped with some oxides by coprecipitation was described in the paper. The thermal properties of ZnO nanometer powders and the current voltage characteristics of the ceramics have been investigated. The results showed that the six additive ZnO powders with hexagonal system were homogeneous grain size distribution in microstructure, the optimal reaction pH is 6.90±0.05, the temperature for calcining and sintering was at about 500 ℃ and 1100 ℃, respectively. The powders were also examined by SEM, IR and XRD etc, and the effect of doping La 2O 3 on the electrical properties of ZnO varistor was investigated too.
基金Project(2001BA901A09)supported by the Key Program of Science and Technology Action of West China Development
文摘Silver-tin oxide powders were synthesized by the hydrothermal method with Ag(NH_3)_2^+ solution and Na_2SnO_3 solution as raw materials and Na_2SO_3 as reductant. The precipitation conditions of Na2SnO3 solution and the reduction conditions of Ag(NH_3)_2^+ were also investigated. The powders prepared were characterized by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and energy spectrum analysis. The results show that pH value of the solution is a key parameter in the formation of Sn(OH)_4 precipitate and the reduction reaction of Ag(NH_3)_2^+ can release H+ ions, which results in synchronous precipitation of Sn(OH)_6~2- as Sn(OH)_4. The reduction of Ag(NH_3)_2^+ and precipitation of Na_2SnO_3 occur simultaneously and the coprecipitation of silver and tin oxide is reached by the hydrothermal method. The silver-tin oxide composite powders have mainly flake shape of about 0.3 μm in thickness and there exists homogeneous distribution of tin oxide and silver in the powder synthesized.
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.
