在碱性条件(pH=8~9)下,采用聚合物辅助燃烧法合成了YBa 1- x Sr x Co 2O 5+δ( x =0、0.5)四方相双钙钛矿结构纳米粉体,考察了焙烧温度和保温时间对粉体合成的影响;通过XRD和FSEM对纳米粉体的物相结构和微观形貌进行了表征,并测试了YBa ...在碱性条件(pH=8~9)下,采用聚合物辅助燃烧法合成了YBa 1- x Sr x Co 2O 5+δ( x =0、0.5)四方相双钙钛矿结构纳米粉体,考察了焙烧温度和保温时间对粉体合成的影响;通过XRD和FSEM对纳米粉体的物相结构和微观形貌进行了表征,并测试了YBa 1- x Sr x Co 2O 5+δ阴极半电池在600~800 ℃空气条件下的电化学阻抗谱。结果表明,焙烧温度以 1 000 ℃为宜,保温时间对YBa 1- x Sr x Co 2O 5+δ纳米粉体的物相影响较大;YBa 1- x Sr x Co 2O 5+δ纳米粉体颗粒均匀,平均粒径约为100 nm;YBa 1- x Sr x Co 2O 5+δ阴极半电池具有良好的电催化活性,表明Sr替代部分Ba可以提高阴极材料的电化学性能。展开更多
Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2-4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN...Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2-4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders. At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na+ ions. The as-prepared colloidal Nb2O5-nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃for 1 h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.展开更多
Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)...Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN) nanopowders. At first, Nb_2O_5reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassysubstance after cooling was dispersed and washed several times in distilled water to remove the Na^+ions. The as-prepared colloidal Nb_2O_5·nH_2O was subsequently mixed with acetic solution ofbarium acetate and magnesium acetate according to the required molar proportions and followed bygelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwaveQ-factor, of 10397 at 1,45GHz.展开更多
One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface r...One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition展开更多
文摘在碱性条件(pH=8~9)下,采用聚合物辅助燃烧法合成了YBa 1- x Sr x Co 2O 5+δ( x =0、0.5)四方相双钙钛矿结构纳米粉体,考察了焙烧温度和保温时间对粉体合成的影响;通过XRD和FSEM对纳米粉体的物相结构和微观形貌进行了表征,并测试了YBa 1- x Sr x Co 2O 5+δ阴极半电池在600~800 ℃空气条件下的电化学阻抗谱。结果表明,焙烧温度以 1 000 ℃为宜,保温时间对YBa 1- x Sr x Co 2O 5+δ纳米粉体的物相影响较大;YBa 1- x Sr x Co 2O 5+δ纳米粉体颗粒均匀,平均粒径约为100 nm;YBa 1- x Sr x Co 2O 5+δ阴极半电池具有良好的电催化活性,表明Sr替代部分Ba可以提高阴极材料的电化学性能。
文摘Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2-4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders. At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na+ ions. The as-prepared colloidal Nb2O5-nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃for 1 h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.
文摘Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN) nanopowders. At first, Nb_2O_5reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassysubstance after cooling was dispersed and washed several times in distilled water to remove the Na^+ions. The as-prepared colloidal Nb_2O_5·nH_2O was subsequently mixed with acetic solution ofbarium acetate and magnesium acetate according to the required molar proportions and followed bygelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwaveQ-factor, of 10397 at 1,45GHz.
文摘One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition
