采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理...采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理温度提高,当热处理温度为1000℃时,所得纯相镧掺杂六角铁氧体粉体Ba位La掺杂量x（摩尔分数）可达0.20;镧元素掺杂抑制了后续热处理过程中晶粒长大,对于所合成产物的颗粒呈现出一定细化作用,这在较高热处理温度下更为明显;镧掺杂改性六角钡铁氧体的吸波效率与吸波频带随着镧掺杂量的提高而改变;当镧掺入量x为0.15时,所得镧掺杂六角钡铁氧体/石蜡混合物具有良好的吸波性能：在厚度为2 mm时其最高吸收损耗达-15 d B,吸收损耗高于-10 d B的吸收频带为13-16 GHz,频带宽度为3 GHz。展开更多
Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. ...Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. The formation of such hollow structure with the regular polyhedral particle shape was based on a solvent-controlled Ostwald ripening coupled self-templating process. The mixed solvent promoted the formation of the regular solid particles at the beginning of solvothermal reaction and drove the Ostwald ripening as the reaction went on. Owing to the Ostwald ripening and self-assembly of nano crystallites, ceria nano particles converted into the hollow structures with regular polyhedral shape during the solvothermal process just by increasing solvothermal reaction time. The as-synthesized hollow ceria nano powders exhibited strong absorptions in the UV-vis spectrum and the evaluated energy band gaps increased according to the shape evolution and size decrease of the nano particles, which demonstrated obvious blue shift effects.展开更多
The manufacture process of 8mol% Y-2O-3 stabilized ZrO-2(YSZ) from nano powders, including the forming and sintering stages, was studied. During the forming process of YSZ powders, the relative density of YSZ increase...The manufacture process of 8mol% Y-2O-3 stabilized ZrO-2(YSZ) from nano powders, including the forming and sintering stages, was studied. During the forming process of YSZ powders, the relative density of YSZ increases lineally with the forming press,and the sintering linear shrinkage of YSZ to the forming press compiles to the parabola trend. When the forming press exceeding 500MPa, the samples with lower shrinkage and high density were obtained. The sintering temperature of YSZ decreases greatly because of the small size and high active surface of YSZ powders. As a result, the beginning sintering temperature of YSZ made in the experiment is as low as 825℃, and the end sintering temperature is 1300-1350℃. The relative density of YSZ ceramic by solid sintering at 1300-1350℃ is more than 97%, with little and small pores in the uniform microstructure.展开更多
采用溶胶-凝胶法合成了Ni-Mn共掺杂Ba Ti O3纳米粉体,同时研究了工艺参数对其形貌的影响。通过X-射线衍射(XRD)和扫描电子显微镜(SEM)表征手段,分析了Ba Ti O3纳米粉体的结构和组成。实验结果表明,该方法可以制备出单纯的立方相,粒径均...采用溶胶-凝胶法合成了Ni-Mn共掺杂Ba Ti O3纳米粉体,同时研究了工艺参数对其形貌的影响。通过X-射线衍射(XRD)和扫描电子显微镜(SEM)表征手段,分析了Ba Ti O3纳米粉体的结构和组成。实验结果表明,该方法可以制备出单纯的立方相,粒径均匀,颗粒大小在250 nm左右的Ba Ti O3纳米粉体,适量Ni-Mn共掺杂不仅能保持Ba Ti O3立方晶格的稳定性,还能抑制杂质Ba CO3的形成。展开更多
文摘采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理温度提高,当热处理温度为1000℃时,所得纯相镧掺杂六角铁氧体粉体Ba位La掺杂量x（摩尔分数）可达0.20;镧元素掺杂抑制了后续热处理过程中晶粒长大,对于所合成产物的颗粒呈现出一定细化作用,这在较高热处理温度下更为明显;镧掺杂改性六角钡铁氧体的吸波效率与吸波频带随着镧掺杂量的提高而改变;当镧掺入量x为0.15时,所得镧掺杂六角钡铁氧体/石蜡混合物具有良好的吸波性能：在厚度为2 mm时其最高吸收损耗达-15 d B,吸收损耗高于-10 d B的吸收频带为13-16 GHz,频带宽度为3 GHz。
基金supported by the National Natural Science Foundation of China(51103125,51102073)China Postdoctoral Science Foundation(2015M570483)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Chemistry)
文摘Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. The formation of such hollow structure with the regular polyhedral particle shape was based on a solvent-controlled Ostwald ripening coupled self-templating process. The mixed solvent promoted the formation of the regular solid particles at the beginning of solvothermal reaction and drove the Ostwald ripening as the reaction went on. Owing to the Ostwald ripening and self-assembly of nano crystallites, ceria nano particles converted into the hollow structures with regular polyhedral shape during the solvothermal process just by increasing solvothermal reaction time. The as-synthesized hollow ceria nano powders exhibited strong absorptions in the UV-vis spectrum and the evaluated energy band gaps increased according to the shape evolution and size decrease of the nano particles, which demonstrated obvious blue shift effects.
文摘The manufacture process of 8mol% Y-2O-3 stabilized ZrO-2(YSZ) from nano powders, including the forming and sintering stages, was studied. During the forming process of YSZ powders, the relative density of YSZ increases lineally with the forming press,and the sintering linear shrinkage of YSZ to the forming press compiles to the parabola trend. When the forming press exceeding 500MPa, the samples with lower shrinkage and high density were obtained. The sintering temperature of YSZ decreases greatly because of the small size and high active surface of YSZ powders. As a result, the beginning sintering temperature of YSZ made in the experiment is as low as 825℃, and the end sintering temperature is 1300-1350℃. The relative density of YSZ ceramic by solid sintering at 1300-1350℃ is more than 97%, with little and small pores in the uniform microstructure.
文摘采用溶胶-凝胶法合成了Ni-Mn共掺杂Ba Ti O3纳米粉体,同时研究了工艺参数对其形貌的影响。通过X-射线衍射(XRD)和扫描电子显微镜(SEM)表征手段,分析了Ba Ti O3纳米粉体的结构和组成。实验结果表明,该方法可以制备出单纯的立方相,粒径均匀,颗粒大小在250 nm左右的Ba Ti O3纳米粉体,适量Ni-Mn共掺杂不仅能保持Ba Ti O3立方晶格的稳定性,还能抑制杂质Ba CO3的形成。
